High-School-Biology-Reviewer.doc

Biology Reviewer Cell Theory 1. All living things are structurally made up of cells. (Matthias Scheliden, Theodor Schwann) 2. The cell is the fundamental unit of life. (Henry Dutrochet) 3. Cells come from the division of pre-existing cells. (Rudolf Virchow) Robert Hooke- coined the term cell; English Father of Microscopy Anton Van Leeuwenhoek- discovered bacteria and other microscopic organisms in rainwater; studied structure of plant and animal cells; Father of Microscopy Francesco Redi and Lazzaro Spallanzani- disproved Theory of Spontaneous Generation

Light Microscope- image is formed by absorption of light in the specimen and its transmission through a set of lenses a. Bright-field- bright, lighted microscopic field b. Dark-field- bright image of the specimen against a dark field of view at an oblique angle c. Phase-contrast- enhances the density differences in the organelles causing certain structures to appear brighter or darker than the others; for observing living cells in their natural condition d. Differential-interference-contrast- contrasting brighter or darker appearance of various organelles through technical optical methods

Robert Brown- discovered nuclei within cells

e. Immuno-fluorescent- certain type of protein can be determined

Felix Dujardin- noted that all living things contain a thick jelly fluid (sarcode)

f.

Matthias Schleiden (botanist) and Theodor Schwann (zoologist)- all plants and animals are made up of cells Johannes Purkinje- coined the term protoplasm, the living matter of the cell Rudolf Virchow- “omnia cellula e cellula” or cells come from pre-existing cells Louis Pasteur- proof of Virchow’s Theory of Biogenesis Zaccharias Janssen- first compound microscope Microscopy

Confocal- use laser beams and special optics for ‘optical sectioning’; 3D

Electron Microscope- uses a beam of electrons and magnetic or electrostatic fields as lenses a. Transmission electron microscope- a beam of electrons is aimed through a very thin specimen; magnetic fields bend the beam of electrons b. Scanning electron microscope- specimen is thinly coated by a metal and then bombarded with electrons

Fractionation- takes cells to separate major organelles for the study of their individual functions Homogenization- disruptions of cells

a. Nucleoplasm- semifluid medium separated from the cytoplasm by nuclear membrane; consists of nucleoproteins, granules and fibrils b. Nuclear membrane- a double membrane, each a phospholipid bilayer, with nuclear pores

Cellular Structure Three Major Parts: Cytoplasm- main metabolic life activities; largely water; reservoir for the entry and exit of materials in the cell; consists of: a. A thick, semifluid aggregate of chemical compounds (cytosol) b. Internal membrane (cytomembrane) Protein- most abundant among the organic components of the cytoplasm; provides materials for the growth and development of the cell Cell membrane- outer boundary of the cell; consists of a double layer of fats or lipid (phospolipid or glycolipid) with scattered proteins; differentially permeable; has three major functions: a. Separates the contents of the cell from the external environment b. Regulates the passage of materials into and out of the cell c. Allows communication with other cells Nucleus- ‘control center’ of the cell; regulates and coordinates all the activities of the cell; consists of:

c. Nuclear pores- pathways for the exchange of materials between the nucleus and the cytoplasm d. Nucleolus- suspended in the nucleoplasm; composed of RNA and protein molecules; site where the subunits of ribosomes are formed e. Chromatin- composed of DNA; coils and becomes condensed into chromosomes Organelles in the Cytoplasm: Mitochondria- largest organelle in cell; ‘powerhouse’ of eukaryotic cells; sites of cellular respiration; made up of: a. Cristae- folds; provide more surface area for greater cellular respiratory productivity b. Matrix- inner cavity into which the cristae project c. Intermembrane space- narrow region between the inner and outer membranes Ribosomes- sites of protein synthesis; of two types: a. Bound- attached to the endoplasmic reticulum; make secretory proteins

b.

Free- suspended in the cytosol; produce proteins that are localized in the cytosol

Different kinds of protein: a. Channel Protein- allows a particular molecule/ion to cross the cell membrane freely as it enters/exits the cell

Cytomembrane System- network of pathways through which materials flow to the different parts of the cytoplasm; passage for the entry and exit of certain substances in the cell Endoplasmic Reticulum- transport of lipids and membrane proteins; has two kinds: a. Rough ER- protein synthesis

Ex. Cystic fibrosis b. Carrier Protein- selectively interacts with a specific molecule/ion so that it can cross the cell membrane to enter/exit the cell; transports sodium ions and potassium ions across the cell membrane; requires ATP energy c. Cell Recognition Protein- a glycoprotein that identifies the cell Ex. MHC (major histocompability complex) d. Receptor Protein- a protein that is shaped in such a way that a specific molecule can bind to it Ex. Pygmies are short not because they do not produce growth hormones but because their cell membrane growth hormone receptions are faulty and cannot interact with growth hormone. e. Enzymatic Protein- a protein that catalyzes a specific reaction Ex. Adenylate cyclase that is involved in metabolism mRNA copies code of DNA  nucleus  cytoplasm— tRNA translates message ribosomes—amino acids protein

b. Smooth ER- fat metabolism; forms vesicles for transporting large molecules to other cell parts Golgi Apparatus- named after Camillo Golgi; modifying, sorting and packaging macromolecules for secretion or for delivery to other organelles Lysosomes- produced by the Golgi apparatus; ‘digestive sacs’; destruction or repair of defective parts of the cell Peroxisomes- contain oxidative enzymes; convert fatty acids into sugar in seed germination Vacuoles- large membranos storage sacs in cells (smaller ones are called vesicles); storage of water or food; excretion of waste materials; intracellular digestion; space filling, cell turgor Cell Cycle Stages Mitosis- division of nucleus; 2 diploid cells in one division (46 chromosomes) Prophase- no pairing of chromosomes; nuclei and nuclear membrane disappear; spindle fibers are formed; homologous chromosomes (synapsis) Metaphase- diploid number of dyads; alignment; tetrads at equator

Anaphase- sister chromatids separate; migration

Cell Reproduction

Telophase- 2 diploid daughter cells; reverse prophase

Reproduction- ability of an organism to increase in number and produce their own kind; process in which living things can perpetuate their species

Interphase- stage between two successive divisions Gap 1 or G1 phase- cells increase in size; RNA synthesis Synthesis or S phase- DNA synthesis; chromosomes are replicated (sister chromatids)

Sexual Reproduction- involves union of gametes Asexual Reproduction- offspring is genetically identical with its single parent; results in the formation of clones Budding- ‘buds’ or outgrowths from the parent cell/body grow into new individuals

Gap 2 or G2 phase- continuation of RNA synthesis and protein synthesis; increase in size

Ex. Yeast, Hydra

Meiosis- 2 haploid daughter cells (23 chromosomes); for male gonads to produce sperm cell

Spore Formation- spores (haploid) germinate into new individuals without fertilization

Meiosis I

Ex. Bread molds, mosses and ferns

Prophase- pairing of homologous chromosomes; formation of tetrads

Fission- single-celled organisms

Metaphase- tetrads at equator

Ex. Bacteria, some protozoans

Anaphase- homologous chromosomes separate

Fragmentation- parent body breaks up into several pieces that develop into new organisms

Telophase- haploid daughter cells Meiosis II

Ex. Sponges, flatworms

Prophase- dyads are present (one dyad per homologous chromosome)

Regeneration- growth of lost body part of an animal

Metaphase- dyads at equator (haploid number)

Ex. Sea star

Anaphase- sister chromatids separate (chromosomes)

Skeletal System

Telophase- four daughter cells

Skeleton

Functions of Bones:

9 fused vertebrae—sacrum (5 vertebrae fused into one), coccyx (4 vertebrae fused into one)

a) Support

Rib cage- protects the heart and lungs

b) Protection

Appendicular Skeleton

c) Calcium storage

Bones of the forelimb

d) Blood cell production

Shoulder girdle

e) Serves as body framework

Bones of the hind limbs

Shapes of Bones:

Pelvic girdle

a) Flat- red marrow; scapula, skull, ribs b) Irregular- vertebra c) Long- yellow marrow (fatty substances)

Joints 1. Immovable- no movement, ex. suture 2. Slightly/Partially movable- ex. Cervical vertebrae

d) Short The human body has 260 bones:

3. Movable a) Ball and socket- one bone is cup-like and the other is rounded; rotation

Axial Skeleton Skull- protects the brain Backbone- or vertebral column; protects the spinal cord; gently curved like a double S; consists of: 24 movable vertebrae—7 cervical vertebrae (neck region), 12 thoracic vertebrae (chest region), 5 lumbar vertebrae

Ex. Shoulder, hips b) Hinge- forward and backward movement Ex. Elbow, knee c) Pivot- rotate 180° Ex. Atlas, axis d) Gliding- bones slide with one another

Ex. Wrist and ankle Bone Tissue

11. Haversian canal- interconnecting channels containing nerves and blood vessels that supply the body cells

1. Periosteum- tough membrane covering of a bone

12. Synovial fluid- lubricant secreted by a connective tissue membrane surrounding a joint

2. Epiphysis- spongy end part of long bones

13. Bursae- sacs of fluid that cushion a joint against shock

3. Compact bones- hard outer part of long bones; gives bone resiliency

14. Osteocytes- mature bone cells that secrete the hard bony matrix

Calcium phosphate- gives hardness and strength of bones

15. Osteoblasts- bone-forming cells (secrete protein matrix of bone)

4. Diaphysis- the shaft

16. Osteoclasts- bone-absorbing cells (removing bony substances)

5. Spongy bone- or cancellous; softer part of the bone containing small spaces; makes up most of the volume of bone; contains bone marrow 2 Types of Bone Marrow: a) Red bone marrow- fat and blood-producing cells; produce RBC All the bone marrow during infancy is red. b) Yellow bone marrow- fatty tissue; produce WBC

Bone Growth and Development Bone development consists of change in number of bones, growth in bone size and change of composition. Osteogenesis or Ossification- process of bone formation 1. Intramembranous Ossification- mainly occurs during formation of the flat bones of the skull; bone is formed from mesenchyma tissue Steps:

6. Joint- point where two bones meet

a) Development of ossification center

7. Haversian system- circular-patterned units in the cross-section of the bone

b) Calcification

8. Lamellae- rings within the Haverian system

c) Formation of trabeculae

9. Lacunae- small cavities between adjacent lamellae

d) Development of periosteum

10. Canaliculi- small branching canals interconnected to lacunae

2. Endochondral Ossification- occurs in long bones, e.g., limbs; bone formed from cartilage

Steps: a) Development of cartilage model b) Growth of cartilage model c) Development of primary ossification center d) Development of secondary ossification center

Striated

Few striations or none

Striated

Cell shape

Cylindrical

Spindle

Branching

Movement

Voluntary

Involuntary

Involuntary

Structures of Muscles

e) Formation of articular cartilage and epiphyseal plate

1. Sarcolemma- muscle cell membrane; acts as cover

Ossification- hardening of bones is mainly postnatal, beginning in the first year and ending during puberty; begins at the ossification center; dependent upon secretion of a hormone from the thyroid glands Importance of Ossification:

2. Sarcoplasm- muscle cytoplasm; holds organelles 3. Sarcoplasmic reticulum- muscle endoplasmic reticulum; transport unit 4. Myofibrils- muscle filaments; muscle cell contractile subunit

a) Because the bones of babies are soft, they can easily be deformed b) Bones in childhood are less subject to fracture or breaks than they will be after ossification Change in the Number of Bones: At birth the human body has about 350 bones, but by the time adulthood rolls around, some of our bones have fused together to give us a total of 206 bones

a) Actin- thin filaments with troponin and tropomyosin for muscle contraction b) Myosin- thick filament; crosses bridges/heads that holds actin filament during muscle contraction 5. Sarcomere- functional unit of myofibril “sarco”- jelly-like

Muscular System

“myo”- muscle

Types of Muscles: Skeletal Number of nuclei/cell

Presence of striations

Multinucleated

Smooth One

Cardiac One or two

Digestive System- for energy production Ingestion Two Phases of Ingestion

1. Mechanical- physical change in food

Sphincter- cardiac/esophoseal bulb at the end of the esophagus; regulates entry and exit

2. Chemical- enzymes (organic catalysts that speed up chemical reaction) act on food

Stomach- contains strongest acid- HCl acid; contains gastric acids

Absorption Elimination or defecation Mouth

Pepsin enzyme + HCl = peptide bond Three Layers: 1. Longitudinal 2. Circular

Teeth (32)

3. Angled/Oblique

Tongue- smooth muscle; contains taste buds (detects chemical) Salivary glands Mucus membrane Nasal cavity

Circulatory System- process in which blood is delivered to the capillaries where exchange of molecules take place

Palade

Importance: transport of

Uvula

1. Food nutrients

Esophagus

2. Respiratory gases

Epidymis

3. Cellular wastes

Dymis

Organs of Circulatory System: Peristalsis- rhythmic movement Bolus Mastecation- constant grinding of food

A. Heart- double pumping organ/machine; right side pumps deoxygenated blood and left side pumps oxygenated blood Pericardium- outer covering Septum- structure that separates right side to left side

Layers of Heart Wall .40 seconds

1. Epicardium- protects the barriers of the heart

D

D

2. Myocardium- muscle contraction and propulsion of blood 3. Endocardium- lines the chambers of the heart where blood passes through

S- Systole

Trabeculae- fiber in muscles found in endocardium

D- Diastole

Visceral pericardium- a cavity filled with fluid that avoids friction due to contraction

Heart contracts by 70x/min. or heartbeat lasts about .85seconds.

Pericarditis- disease where there is water in the heart B. Valves

Heart Sounds: 1. Lub- vibration of heart when atrioventricular valves closes 2. Dupp- vibrations of the heart when the semilunar valves closes

1. Antrioventricular valves- between atria and ventricles a. Tricuspid- has three cups/flaps at the right side of the heart b. Bicuspid (or mitral)- has two flaps at the left side of the heart 2. Semilunar valves a. Pulmonary semilunar valve- between right ventricle to pulmonary arteries b. Aortic semilunar valve- between left ventricle to aorta Cardiac Cycle (lasts .85 seconds)

Cardiac Conduction System Nodal Tissue- has muscular and nervous characteristics which causes heart to beat independently of any nervous stimulation 1. Sinoatrial node (SA)- initiates heartbeat and automatically send out an excitation impulse every .85 seconds to cause atria to contract. It is called as the pacemaker because it keeps heartbeat regular. 2. Antrioventricular node (AV)- signals ventricles to contract by way of a special fiber, Purkinje fiber Purkinje fiber causes ventricles to contract.

Time

Atria

Ventricle

.15 seconds

S

D

.30 seconds

D

S

Electrocardiogram- electrical recording device to study heartbeat by recording voltage changes occurring during heart contraction ECG- record results; has waves:

1. P wave- excitation and contraction of atria 2. QRS wave- ventricular excitation and contraction 3. T wave- recovery of ventricles from contraction a. Sinus tachycardia- fast heartbeat due to fast pacemaker b. Ventricular fibrillation- irregular heartbeat due to irregular stimulation of ventricles c. Mitral stenosis- mitral/bicuspid obstructed

The very muscular wall with many elastic fibers allows the artery to withstand and maintain a high blood pressure.

Pocket valves close to prevent back flow of blood. This is essential to get blood back to heart. As capillary is one cell thick, it is very leaky as substances like oxygen and glucose can pass out and carbon dioxide move in.

1. Nose- has two nasal cavities separated by a septum; ciliated cells at the upper portion as odor receptors lacrimal (tear gland) duct and communicates with cranial sinuses during cold or allergic reactions causing inflammation, mucus accumulation and sinus headache. As air entered, it is filtered by cilia, warmed by heat given off by blood vessels lying close to surface lining of air passages, and moistened by wet surface of the passages. Its air moves out, if loses moisture. Nasopharynx- passage of air from nose through throat 2. Pharynx- connection point of air and food passages found at the back of the throat Glottis- a slitlike opening between the vocal cords (elastic ligaments) at the top of the larynx and is covered by a flap of tissue (epiglottis) to prevent the passing of food 3. Larynx (voice box)- sound is produced. Pitch of voice depends upon the length, thickness, degree of elasticity of vocal cords and the tension at which they are held. Voice growth of larynx is much rapid and accentuated in males producing “Adam’s apple”. Their voice breaks due to inability to control vocal cords. 4. Trachea (wind pipe)- has C-shaped cartilaginous rings and ciliated mucus membrane. If an object blocked this passage, a tube is inserted in an incision on the throat as an artificial air intake and exhaust duct through the operation called tracheoctomy 5. Bronchi- two divided tubes from the trachea that are branched into bronchioles 6. Bronchioles- smaller brances with thinner walls and terminates in alveoli

Respiratory System- complete process of getting oxygen to body cells for cellular respiration and the reverse process of ridding the body of carbon dioxide by the cells Air passages:

7. Alveoli- air packets/sacs (300M, with total cross-sectional area of 50-70m 2) where gasses are exchanged in its one layered squamous epithelium surrounded by blood capillaries and lipoprotein lining that lowers lung surface tension that

prevents them from closing. Premature babies die when lipoprotein is not present in their lungs (Infant respiratory distress syndrome). Lungs- coneshaped organ lying on both sides of the heart within thoracic cavity (ribs, sternum and muscles) above the dome-shaped horizontal muscle, diaphragm and are enclosed by the pleural membranes (outer and inner). Normally, intrapleural pressure is less than atmospheric pressure that causes air to enter. Lung capacities: 1. Tidal volume- amount of air moved in and out of the lungs (500 ml) that can be increased by deep breathing 2. Vital capacity- total volume of air that can be moved in and out during a single breath. It is the total sum of tidal, inspiratory reserve and expiratory reserve volumes 3. Inspiratory reserve volume- increased inspiration (3,100 ml) by contrasting the thoracic muscles. 4. Expiratory reserve volume- increased expiration by 1, 400 ml of air 5. Residual volume- remain air in the lungs that is no longer useful for gas exchange purposes Factors Affecting Lung Capacity: 1. Activity 2. Health condition 3. Higher altitude 4. Gender

Dead space- air passages that are filled with air that never reaches the lungs. Breathing through a tube increases the amount of dead space beyond maximal inhaling capacity that can cause death to the individual because the air inhaled never reaches the alveoli. Components of Respiration: A. Breathing- entrance and exit of air in and out of lungs Importance: To supply the body with oxygen and the metabolic end product carbon dioxide must also be eliminated by breathing process C6H12O6 + 6O2  6H2O + 6CO2 Normal breathing is 14-20x/min. Person at rest utilizes 250ml of O 2/min. and 500ml/min. with mild exercise. Mechanism of Breathing: When breathing, there is a continuous column of air from the pharynx to the alveoli of the lungs because air passages are open. 1. Inspiration- active phase of breathing; induced by: a. Concentrated CO2 and H+ ions in the blood causing the respiratory center in the medulla oblongata to be stimulated, and b. Chemoreceptors in the carotid bodies (in carotid arteries) and aortic bodies (in aorta) to respond to H+ ion concentration, CO2 and O2 in blood c. Nerve impulses causes diaphragm to contract and lowers, rib cage muscles contract and move upward and outward increasing the size of the thoracic cavity and lungs to expand. As the lungs expand, air pressure within enlarged alveoli lowers.

2. Expiration- happens when: a. The expanded lungs with stretched alveoli stimulate special receptors in the alveolar walls to initiate nerve impulses to travel to the breathing center. b. Medulla oblongata inhibits and stops sending signals to the diaphragm and the rib cage causing it to relax and resume its shape. The abdominal organs press up against the diaphragm, rib cage moves down and inward and the lungs recoil as air is pushed out. B. External Respiration- exchange of gases between air in the alveoli and blood in the pulmonary capillaries through diffusion determined by the pressure or tension gradient carried as bicarbonate ion (HCO3). H+ + HCO-3  H2CO3  H2O + CO2 ↑ (CO2 leaves the body) The enzyme carbonic anhydrase present in the RBC speeds up the reaction. The respiratory pigment hemoglobin gives up the H ions it has been carrying causing HHb to be Hb (hemoglobin). Hemoglobin more readily takes up O 2 and becomes oxyhemoglobin (HbO2). Hb + O2  HbO2 ↓ (O2 is entering the body) Hemoglobin takes up O2 more readily at the warmer and more acidic pH f the tissues. C. Internal Respiration- exchange of gases between blood in systematic capillaries and tissue fluid by reducing hemoglobin from oxyhemoglobin as oxygen diffuses out of blood into the tissues. HbO2  Hb + O2

Diffusion of O2 out of blood into the tissues occur because the O2 concentration of tissue fluid is low (the cells continuously use up O2 in the cellular respiration). Diffusion of CO2 into blood from the tissues occur because CO2 concentration of tissue fluid is high. CO2 enters the blood taken by haemoglobin forming carbominohemoglobin (HbCO2) which disassociates to H+ ions and bicarbonate ions (HCO3-). Carbonic Anhydrase speeds up the reaction. CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3The globin portion Hb combines with excess H+ ions produced by the reaction, and Hb becomes HHb making blood pH fairly constant. The bicarbonate ion diffuses out of the RBC cells and is carried in the plasma. D. Cellular respiration- production of ATP in cells External Respiration Process: alveoli to blood 1. H+ HCO3-  H2CO3  H2O + CO2 ↑ 2. HbCO2  Hb + CO2 ↑ 3. Hb + O2  HbO2 ↓ Internal Respiration Process: blood to cells/tissues 1. HbO2  Hb + O2 ↓ 2. Hb + CO2  HbCO2 3. HbCO2  H2CO3 H+ + HCO-3 Mechanism of Breathing

Inspiration

Expiration

4. Renal- kidney

1. Medulla sends stimulatory messages to the diaphragm and rib muscles.

1. Stretch receptors in lungs send inhibitory messages in medulla.

2. Diaphragm contracts and flattens.

2. Diaphragm relaxes and resumes a dome position.

1. Common cold- viral infection; scratchy throat, watery mucus discharge from nasal cavities

3. Rib cage moves up and out.

3. Rib cage moves down and in.

2. Influenza (flu)- viral infection; fever, aches and pains in the joints

4. Lungs expand.

4. Lungs recoil.

5. Negative pressure builds in lungs (air does not force the lungs open because lungs are pulled open as air comes in).

5. Positive pressure builds up in lungs.

3. Bronchitis- viral infection from nasal cavities to sinuses (sinusitis), to middle ears (otitis media), to the larynx (laryngitis), and bronchi. Acute bronchitis is caused by secondary bacterial infection with heavy mucus discharge and coughing and responds to antibiotic therapy. Chronic bronchitis is caused by constant irritation of bronchi lining resulting to loss of cilia and normal cleansing action; caused by smoking

6. Air is pulled in.

Components of Air

5. Systemic- intarbody Respiratory Infections and Diseases

4. Strep throat- bacterium streptococcus pyogenes infection; difficulty swallowing and fever; can lead to rheumatic fever if not treated with antibiotics Inspired Air (% volume)

Expired Air (% volume)

Nitrogen

79.00

79.60

Oxygen

20.96

16.02

Carbon Dioxide

0.04

4.38

Five Types of Circulation: 1. Pulmonary- lungs 2. Coronary- heart 3. Ephatic portal- ‘pancreas’, ‘stomach’, digestive system

5. Pneumonia- bacterial/viral infection; lobes of lungs are filled with mucus and pus 6. Tuberculosis- tubercle bacillus infection 7. Emphysema- caused by smoking that leads to the destruction of lung tissue with ballooning/inflation of the lungs due to the trapped air. The bronchioles collapse causing cutting off of renewed oxygen supply in alveoli. The trapped air makes alveolar walls to rupture, thus exchange of gases are reduced and insufficient amount of oxygen reaches the heart and the brain.

8. Pulmonary fibrosis- caused by inhalation of silica (sand), coal dust and asbestos leading to building of fibrous connective tissues in the lungs that enables breathing capacity to be seriously impaired. Excretory System- involves the ridding off of unwanted substances such as the end product of metabolism 1. Ammonia (NH3) – amino acid metabolism excreted by kidneys 2. Urea – ammonia metabolism excreted by kidneys and skin 3. Uric acid – nucleotide metabolism created by the kidneys. Excess uric acid precipitates out of the plasma. Gout is a painful ailment caused by crystals of uric acid collected in joints.

hydrogen ions are excreted and few sodium ions and bicarbonate ions are reabsorbed); thus making ions balance 2. Maintains blood volume under the control of hormones ADH (increases the permeability of collecting duct to absorb water) Diuresis – increased amount of urine, less ADH secretion Antidiuresis – decreased amount of urine, more ADH secretion And aldosterone (maintains Na+ and K+; increases Na+ in blood causes water to reabsorb that leads to increase blood volume and blood pressure)

4. Creatinine – creatine phosphate metabolism excreted by the kidneys

2. Skin – has sweat glands to excrete sweat (water, salt and urea) to keep body temperature within normal range

5. Bile pigment – haemoglobin metabolism excreted by the liver. Jaundice is a skin discolour condition caused by bile pills from a blocked bile duct

3. Liver – excretes bile pigments

6. Carbon dioxide – bicarbonate ions (HCO3-) excreted by the kidneys as end product of cellular respiration 7. Ions – important to the pH, the osmotic pressure, and the electrolyte balance of blood. The balance of potassium and sodium ions is important to nerve conduction, calcium ions to muscle contraction, iron ions in haemoglobin metabolism excreted by the large intestine, magnesium ions help many enzymes to function properly. 8. Water – excreted by the kidneys Organs of excretion: 1. Kidneys – primary excretory organ and consistently rid the body of urea. It has regulatory functions: 1. For the adjustment of blood pH and ion balance (excretion of hydrogen ions (H+) and ammonia (NH3) and reabsorption of sodium ions and bicarbonate ions (HCO3-) if blood is acidic. If blood is basic only, few

4. Lungs – excrete carbon dioxide and water (moisture by blowing onto cool mirror) 5. Large Intestine – excrete salts, iron and calcium directly into its cavity by the epithelial cells lining it Urinary System (Path): 1. Kidneys – 2 bean-shaped reddish brown organ at fist size that forms urine compound of metabolic waste products. It’s external structure features a depression where renal blood vessels and ureters enter. Internal structure involves: o Cortex – outer granulated layer which dips down in between o

Medulla – radially striated or lined layer that contains conical masses of tissue called renal pyramids. At the tip of each pyramid there is a tube that joins with others to form the renal pelvis.

o

Renal pelvis – inner space/cavity that is continuous with the ureter

Nephron – known as the renal/kidney tubules. It is made up of: 



Bowman’s capsule – double-walled cup of specialized cells that allow easy passage of molecules located at the cortex that contains a capillary tuft called glomerulus. Proximal convoluted tubule – highly coiled region of nephron’s cortex with cells that are cuboidal with many mitochondria and inner brush border



Loop of Henle – cells are flat and tubes become narrow making a U-turn located at the medulla



Distal convoluted tubule – cells are cuboidal, with mitochondria but no brush border at the cortex



Collecting duct – a tube that receives urine from several distal convoluted tubule are located at the medulla

2. Ureters – muscular tubes that convey urine from the kidneys toward the bladder by peristaltic action 3. Urinary bladder – hollow, muscular organ that holds 600 mL of urine. In males, it lies ventral to the rectum, the seminal vesicles, and the vas deferens. In females, it is ventral to the uterus and the upper vagina 4. Urethra – extends from urinary bladder to the external opening. In males, its length averages 15 cm when penis is relaxed. In females, it is only about 2.5 cm long making bacterial invasion possible Steps in Urine formation 1. Pressure filtration – blood pressure forces small molecules (water, glucose, amino acids, salts, urea, uric acid, creatine) form the glomerulus into Bowman’s capsule 2. Selective absorption – diffusion and active transport return molecules (water, glucose, amino acids, salts) to blood at proximal convoluted tubule

3. Tubular excretion – active transport moves molecules (uric acid, creatine, hydrogen ions, ammonia, penicillin) from blood into the distal convoluted tubule 4. Reabsorption of water – along the length of the nephron and notably at loop of Henle and collecting duct, water returns by osmosis following active reabsoprtion of salt 5. Excretion – urine formation rids body of metabolic wastes (water, salts, urea, uric acid, ammonia, creatinine) Problems with kidney functions: 1. Urethritis – infection of the urethra 2. Cystisis – infection of the urinary bladder 3. Pyelonephritis – infection of the kidney 4. Glomerulus damage – glomerulus blockage – no fluid moves into the tubules, or glomerulus are more permeable even blood cells and albumin is present in urine 5. Uremia – extensive glomerulus damage and waste substances are accumulated in blood 6. Edema – fluid concentration in body tissues due to retention of water and salts 7. Loss of consciousness and heart failure imbalance of ionic composition in body fluids Kidney failure replacement/remedies 1. Kidney transplant – survival rate from a relative is 97% and 95% from a nonrelative 2. Dialysis – utilizing a kidney machine / CAPD (continuous ambulatory peritoneal/abdominal dialysis) which diffuses dissolved molecules through a semipermeable membrane. A fresh amount of dialysate is introduces directly into the abdominal cavity from a bag attached to a permanently implanted plastic tube. Wastes and water molecules pass into the dialysate from the

surrounding organs before the fluid is collected 4 or 8 hours later. Individuals can go about his/her normal activities during CAPD

a2. Thalamus- sorts out all information from the sense organs as well as the other parts of the brain before relaying them to the cerebrum (sends information towards cerebrum)

3. Hemodialysis – patient’s blood is passed through a semipermeable membranous tube that is in contact with a balanced salt (dialysis) solution (dialysate). In a 6hr hemodialysis, 50-250g of urea are removed from a patient, which greatly exceeds the urea clearance of normal kidneys. Patient needs to undergo treatment only about twice a week and cannot do any activities during the treatment.

a3. Hypothalamus- controls the secretion of many hormones; regulates blood pressure, body temperature, and responses to satisfy physiological needs; controls emotions

Nervous System- accountable for quick reaction to external and internal stimuli

b. Midbrain- connected to sensory nerves of eyes

Functions:

c. Hindbrain 1. Sensory Input- sends signals through sensory receptors to the central nervous system (CNS)

c1. Pons and medulla oblongata c2. Cerebellum- balance, coordination of movement

2. Integration- CNS integrates and formulates appropriate reaction from the sensory input

c3. Brain stem

3. Motor Output- facilitates the action in the efferent nerves (muscles and glands) II.

Parts of the Nervous System I.

B. Spinal Cord- pathway towards the brain

Central Nervous System- the body’s main control center A. Brain- control center of the nervous system; responsible for behaviour Parts of the Brain: a. Forebrain- where major processing centers are found a1. Cerebrum- most anterior or most dorsal region of the nervous system (memory and intelligence)

Peripheral Nervous System or PNS- nerves that project from CNS 1. Somatic Nervous System- sensory and motor neurons 2. Automatic Nervous System- motor neurons only; involves the: b1. Sympathetic Nervous System- controls the internal organs during stressful situations and increased activity b2. Parasympathetic Nervous System- controls the internal organs during routine conditions

The Twelve Cranial Nerves:

3. Oculomotor (eye movements)

b. Amphetamines- lose weight; increase alertness; elevate mood, reduce feelings of fatigue and hunger, facilitate powers of concentration , and increase the desire and capacity to carry out work; induce exhilarating feelings of power, strength, energy, self-assertion, focus and enhanced motivation; need to sleep or eat is diminished

4. Trochlear (eye movements)

c. Cocaine- in nucleus accumbens; local anesthetics

1. Olfactory (smell) 2. Optic (vision)

5. Trigeminal (facial sensation and jaw movements) 6. Abducent (eye movements) 7. Facial (facial expression and taste) 8. Acoustic or Vestibulocochlear (hearing and balance) 9. Glossopharyngeal (taste and throat sensation) 10. Vagus (breathing, circulation and digestion) 11. Spinal Accessory (movement of neck and back muscles) 12. Hypoglossal (tongue movement) Drugs and the Nervous System: 1. Stimulants- drugs that exert their action through excitation of the CNS; used to enhance mental alertness and reduce drowsiness and fatigue a. Coffee- If the dosage of caffeine is increased above 200g (about two cups of coffee), it does not increase mental performance but may increase nervousness, irritability, tremors and headaches

2. Sedative- induce sleep a. Barbiturates- depress the reticular formation (thus promoting sleep) and in high doses =, the medulla oblongata (thus stopping breathing) 3. Opiates- effective painkillers; control coughing, breathing and intestinal motility; exceedingly addictive, quickly producing tolerance and dependence a. Morphine- used as painkiller b. Codeine- used as painkiller and in cough medicine c. Heroin- more effective as a painkiller than morphine and codeine; so highly addictive that its use is illegal 4. Marijuana- drowsiness, dulling of pain, perception distorting effects of the psychedelics Endocrine System- utilizes chemical messengers that bring about the coordination of body parts. Hormones- chemical messengers that influence the metabolism of the receiving cell Categories of Chemical messengers:

1. Pheromones - act a distance between individuals 2. Traditional Endocrine Hormones & Secretions of Neurosecretory cells - act a distance within the individual. 3. Prostaglandin & Neurotransmitter substances - local messengers Types of Hormones 1. Peptide/Polypeptide/Protein/Amino acid hormones- coded by genes & synthesized at the ribosomes; activates exciting enzyme in the cell (combines with receptors, produces cAMP, activates a certain cell and so on); acts on the target cell with a lesser period of effect 2. Steroid Hormones- produced by adrenal cortex, testes, ovaries (combines with receptors, enters the nucleus, binds with chromatin, activates a particular gene and synthesis of certain enzymes), ex. Anabolic/Synthetic Steroids (1930); prevents muscle atrophy to burn victims and surgery patients; prolonged use leads to stunted growth, high blood cholesterol, liver cancer and mood swings. Endocrine Glands and Hormones

b) Anterior - "master gland"; controls secretion of other endocrine glands; produces hypothalamic-releasing & inhibiting hormones • Growth Hormone/Somatotropin (GH)- cell division, protein synthesis, bone growth • Lactogenic Hormone/Prolactin (LTH)- mammary gland development; milk production • Melanocyte-Stimulating Hormone (MSH) • Thyroid-Stimulating Hormone (TSH)- stimulates thyroid gland • Adrenocottinocotropic Hormone (ACTH)- stimulates adrenal (cortisol) • Gonodotropic Hormones- stimulates the gonads  Lutinizing Hormone  Follicle-Stimulating Hormone 3. Thyroid Gland - iodine is actively transported

1. Hypothalamus - regulates internal environment (water level, temperature, blood pressure, etc.)

• Thyroxin- increases metabolic rate

2. Pituitary Gland- connected to hypothalamus

• Calcitonin- regulates the calcium level in the blood and opposes the action of the parathyroid hormone.

a) Posterior • Antidiuretic Hormone/Vasopressin (ADH)- promotes H2O reabsorption in the kidney • Oxytocin- uterine contraction; artificially induce labor; produce milk in mammary glands

4. Parathyroid Gland • Parathyroid Hormone/Parathormone (PTH)-increases calcium level and decreases phosphate level in blood 5. Adrenal gland a) Cortex

level

• Glucocorticoids/Cortisol- Amino acid to glucose; raises blood glucose

• Mineralocorticoids/Aldosterone- regulates level of sodium & potassium • Sex hormones b) Medulla • Norepinephrine- responses associated with fight or flight response; blood glucose level and metabolic rate increases. • Epinephrine- responses associated with fight or flight response; blood glucose level and metabolic rate increases. 6. Pancreas - Islets of Langerhans produces & secretes hormones • Insulin- secreted when there is a high level of glucose in the blood • Glucagon- stimulates breakdown of stored nutrients; causes blood level to rise 7. Gonads - determines sexual characteristic

8. Thymus - active and largest during childhood. cells

• Thymosin- aids in the differentiation of T cells and stimulates immune

9. Pineal Gland - receives nerve impulses via eyes (optic tract) • Melatonin- Circadian rhythms in sleep cycle 10. Other glands a) Heart • Atrial Natriuretic Hormone b) Stomach • Gastric juice (HCL & Pepsin ) c) Small Intestine • Intestinal Juices Diseases Related to the Endocrine System

a) Testes - male

Diabetes Insipidus - inability to produce ADH

• Androgen (Testosterone)- develops and maintains male sex characteristics

Giantism - associated with GH (too much)

b) Ovaries - female • Estrogen- development and maintains female sex characteristics • Progesterone- stimulate growth of uterine lining

Dwarfism - associated with GH (too little) Acromegaly - associated with GH (abnormal growths in the body) Hypothyroidism - low level of thyroxin in the blood

Hyperthyroidism - high level of thyroxin in blood

Renin - enzyme from the kidney that converts:

Simple Goiter - lack of thyroxin

a) Angiostensinogen to Angiostenin I

Cretinism - extreme hypothyroidism during infancy/childhood

b) Angiostenin I to Angiostenin II

Myxedema - lethargy, weight gain

- releases Aldosterone to raise Blood Pressure by constricting arteries and absorbing sodium and H2O

Exopathalmic goiter - too much thyroxin Tetany - drop in calcium level Addison's disease - inability to maintain glucose level in the blood Cushing's Syndrome - high-level hormone secretion Diabetes Melitus - high level of cortisol, deficiency of insulin Acidosis - buildup of acids in blood Feedback Mechanism- regulates the activities of most endocrine glands in the secretion of hormones a) Negative Feedback – Homeostasis; last step is against the first step b) Positive Feedback - last step stimulates the first step Types of Diabetes

Reproductive System Importance 1. Production and development of egg cell for possible fertilization 2. Preparation of the uterus for implantation of embryo 3. Production of progesterone and estrogen Parts 1. Ovary- main organ; there are two ovaries; contains hundreds of thousands of follicles, as a girl; puberty is when the first meiotic division occurs; coitussecond meiotic division 2. Oviduct- of fallopian tube (2); has finger-like projections at the end (fimbrae) that sweeps the egg cell towards the fallopian tube; sight for fertilization; where egg cell and sperm cell meets

1. Type I (Juvenile-Onset Diabetes)- not producing insulin

*Ectopic Pregnancy-fertilization occurs outside the fallopian tube; development of fetus on abdomen; cuts off nourishment of fetus

2. Type II (Maturity-Onset Diabetes)- produces insulin but cells don't respond due to faulty receptor or lack of glucose

*2 egg cell + 2 sperm cell= fraternal twins

3. Uterus- where the embryo develops; most glandular and most vascular organ due to number of blood vessels; mostly made up of tissue and muscles

can no longer hold no fertilization occurs; mature egg cell

3-6 months in mother

Menstruation- uterine lining (endometrium) thickens with estrogen and progesterone; without fertilization, it sheds 4. Cervix- vaginal canal; elastic; opens so that the baby may go out 5. Vagina- birth canal; receives the sperm cell; site of ovulation; exit of menstrual flow Meiosis I

6. Vulva- external structure of female 7. Labia Majora 8. Labia Minora

Folds with pubic hair; protection from dirt

Meiosis II

10. Mons Pubis- fatty prominence underlying the pubic hair

9. Vestibule- cleft between labia minora which contains the urethra and the vaginal opening *Hymen- ring of tissue that partially closes the vagina; “indication of virginity”; can be destroyed during childhood

11. Clitoris- has erectile tissue homologous to penis and is capped by a pea-shaped glans; has sensitive receptors (sexually sensitive organ) Regulations of Hormone Levels 1. Ovarian Cycle a. Follicular Phase (1-13 days)- FSH promotes the development of the follicle and it secretes estrogen

Primary Follicles

Secondary Follicles

Graafian Follicles

Corpus Luteum

Primary Oocytes

Secondary Oocytes

-contains mature

-produces progesterone

2,000,000

before puberty,

mature egg cell;

that thickens lining of

300,000- 400,000

will burst when it

uterus; disintegrates if

b. Ovulation (day 14)- mature egg cell is released followed by menstruation c. Lutheal Phase (15-28 days)- LH promotes the development of the corpus luteum as it secretes progesterone until it regenerates and menstruation occurs again 2. Uterine Cycle- FSH starts to increase production for maturation of follicle

a. Menstruation (1-5 days)- uterine lining disintegrates and blood vessel rupture

1st pair- auditory cavity 3rd pair- thymus 2nd pair- tonsils 4th pair- parathyroids

b. Proliferative phase (6-13 days)- increased production of estrogen to thicken the endometrium and become vascular and glandular

Developmental Stages

c. Ovulation (day 14) d. Secretory phase (15-28 days)- increased production of progesterone by corpus luteum for endometrium thickness and uterine glands to mature producing a thick mucoid secretion. If pregnancy does not occur, corpus luteum disintegrates *Within five days, fertilized egg must be in fallopian tube. * Females have four hormones: estrogen, progesterone, LH and FSH *Androphose- diminish of progesterone Fetal Stages Development- concerns with the events and processes that occurs as a single cell becomes a complex organism. Processes of Development 1. Growth- cell divides gets larger and divides again 2. Differentiation- when cells become specialized in structure & function 3. Morphogenesis- when body parts are shaped and patterned into a certain form "Ontogeny Recapitulate Phylogeny"- Latin saying which means the development of the embryo retraces the evolution of its species. Example: Gill Clefts are developed pharyngeal pouches in advanced vertebration.

A. Embryonic Development 1st Week- early developmental stages 1. Cleavage- cell division w/o growth (from fallopian tubes to uterus) 2. Morula- solid ball of cells (embryo reacts at 3rd day) 3. Blastula- (5th day) cavity is formed called blastocysts having 2 main parts: tropoblasts (outer and becomes the chorion) and inner mass (becomes the fetus) 4. Gastrula- (2nd week) implantation of the embryo at the uterine wall due to the enzyme secreted by the tropoblast that digest away some of the tissue and blood vessels of the uterine wall & secretion of HCG (Human Chorion Gonadotropin) as basis for pregnancy test that appears in the urine & maintains the corpus luteum in secreting estrogen and progesterone that lasts for 3 mos. At 5 mos. the placenta begins to secrete estrogen and progesterone in greater amount as corpus luteum degenerates, formation of the 3 embryonic layers- ectoderm, mesoderm and endoderm 5. Neurula - (3rd Week) appearance of the nerve cord and heart; development of the Nervous System - (4th-5th weeks) formation of the 4th extraembryonic embrane (allantois) that later becomes the umbilical cord connecting the developing embryo to the placenta; human features appear (head, arms, legs) - (6th-8th weeks) brain development; neck formation; NS development for reflex actions; all organ systems are established; placenta is mature and fully functioning; 1 1/2 inches long and weighs like an aspirin tablet B. Fetal Development

2-4 mos. - large head, flat nose, eyes apart and ears distinctively present, sex are determined; heart beat is felt; skeleton ossified; 6 1/2 inches long and 1/2 lb 5-7 mos. - movement, eye lids open, pink-colored skin, have lanugs covered with greasy cheese like substance (vernix caseosa) for protection from amniotic fluid, 12 inches long and 3 lbs. 8-9 mos. - fetus rotates so head is towards the cervix- 21 inches long and 7lbs Gestation- period of pregnancy, normally lasts for 38 weeks (266 days) Parturition- labor and expulsion of the fetus; contraction of the uterine wall every 15-20 minutes for every 20-30 seconds or 15 minutes for 40 seconds or more. Stages of Labor: 1.) Dilation of the cervix- expulsion of the mucus plug from the cervical canal which prevents bacteria and sperm from entering the uterus during pregnancy 2.) Expulsion of the baby- epinotony is done or incision to enlarge the vaginal opening; stitched later then healed 3.) Expulsion of afterbirth- placenta is expelled after 15 minutes of delivery; (uterus) uterine muscles contract and uterus shrinks Human Development After Birth Infancy → Childhood → Adulthood → Aging Gerontology- study of aging

Causes of Aging: 1. Genetic in Origin: life span in species is specific (humans, 110 years). Children of long-lived parents tend to live longer than those of short-lived parents. The number of times a cell divides is specific (50x). Mutation can lead to the production of non-functional protein thus contributes to the aging process. 2. Whole Body Process: decline in hormonal system as the cell lack receptors that enable them to respond. Example: Reproductive System and Immune System. Reason: Protein collagen become increasingly cross-linked as people age causing stiffening and loss of elasticity of organs. Researchers now have found that glucose has the tendency to attach to any type of protein that is the first step in cross-linking process and ends with the formation of Advanced Glycosylation End products (AGEs). This explains why cataracts develop, artherosclerosis, diabetes, etc. Solution: Researchers presently are experimenting a drug aminoguanidine which can prevent development of AGEs. 3. Extrinsic Factors: due to poor health habits; diet and exercise, cigarette smoking, alcohol, inadequate calcium intake Menopause- sex hormones declined/fall in amount; uterus and cervix reduced in size; walls of oviducts and vagina become thin; external genitals become less pronounced Andropause- in males, androgen falls gradually at 50-90 years but sperm production continues *Females have longer lives than males because estrogen offers protection against circulatory disorders like heart disease and stroke in males at 40s but females only after menopause.

Birth Defect Detections 1. Amniocentesis- fetus is tested by getting amniotic fluid in a syringe → centrifuge → cell culture for biochem studies and chromosome analysis 2. Chorionic Villi Sampling- embryo is tested by getting cells from chorionic villi (placenta) using a suction tube and ultrasound scanner 3. Laparoscopy- obtaining eggs for screening for IVF usinf laparoscope (telescope) and aspirator for biochem studies and chromosome analysis

Molecular Genetics Mendelian Genetics Mutations Types of Mutations: b. Point Mutation- change in very small segment of DNA (single nucleotide/pair) c. Gene Mutation- change in chemical nature of DNA d. Chromosomal Mutation- change in the structure/number of chromosome Cell Type Mutation:

1. Cri-du-chat (deletion 5)-“cry of the cat”; intellectual disability and delayed development, destructive facial features, small head size (microcephaly), low birth weight, weak muscle tone (hypotonia), in infancy, most common in female (1:20,000-50,000) 2. Patau Syndrome (trisomy 13)- disrupts normal development and can result to heart and kidney defects, motor and mental retardation, extra digits, microcephaly, low-set ears, failure of forebrain to divide properly, eye defects, cleft palate, spinal defects, abnormal genitalia 3. Edward’s Syndrome (trisomy 18)- growth deficiency, abnormal skull shape and facial features, clenched hands, Rocker bottom feet and cardio and renal abnormalities 4. Philadelphian Sydrome (translocation 9 & 22)- chromosomal abnormality associated with chronic mycelogenous leukemia (CML leukemia and unregulated growth of predominantly myeloid cells in the bone marrow and accumulation of these cells in the blood 5. Down Syndrome (trisomy 21)- has mental retardation and other conditions, low muscle tone which makes difficulty in gross motor and fine motor skills along with articulating speech B. Sex Aberration 1. Turner Syndrome (XO)- monosomy 45X, short stature, underdevelop sexual features, mental retardation

13. Somatic Cell Mutation- produces a mutant phenotype in only a part of the organism; not a heritable trait

2. Klinefelter’s Syndrome (XXY)- 47XY, tall male with normal stature but small testes, sterile, trisomy 23

14. Germ Cell Mutation- producing a heritable change

3. Metafemale (XXX)- trisomy 23, 47X, super female with short stature, mental retardation and underdevelop reproductive structures; sterile

A. Chromosomal Aberrations

Forms of Chromosomal Aberration:

Incomplete Dominance- alleles that lack dominance relationships and result in heterozygous that have an intermediate phenotype that is distinct from either homozygous parent

1. Duplication 2. Deletion

Codominance- alleles that lack dominant and recessive relationships and are both observed phenotypically; the phenotypic effect of each allele is observable in the heterozygous condition

3. Inversion 4. Translocation- non-homologous chromosomes

Sex-Related Inheritance

Gene Disorder Detection:

Sex-linked traits- genes located on the x chromosome only (x-linked genes); recessive trait, ex. colorblindness, hemophilia

1. Amniocentesis- involves the insertion of a needle through the abdominal wall and uterus of mother and into the amniotic fluid surrounding the fetus

Sex-influenced traits- trait that is dominant in one sex and recessive in the other, ex. baldness

2. Ultrasomography- involves the use of high-frequency sound waves to produce the image of a fetus on a monitor

Sex-limited traits- trait that develops only in the presence of sex chromosomes, ex. Plumages, skin color of animals

3. Fetoscopy- an instrument, endoscope, is used to view fetus inside the uterus

DNA Technology Non-Mendelian Patterns of Heredity Multiple Alleles- involves more than two alleles are identified at a gene locus. Dominant hierarchy should be defined: Dominant: capital letter Recessive: lowercase letter Alleles between two extremes: lowercase letter with suitable superscript Polygenes- several genes are involved in a given trait, ex. eye color, strand of hair trait

Evidences of Evolution Evolution- the process of change by which new species develop from pre-existing species Types: 1. Convergent evolution- there is an increase in similarities among species derived from different ancestors and resulting from similar adaptations to similar environments 2. Divergent evolution- there is an increase in the differences among descendants of a single ancestral species as time passes

Evidences of Evolution:

15. Jean-Baptiste Lamarck’s

e. Fossils- remains and traces of organisms that once lived; imprints of animal and plant parts mostly found in sedimentary rocks (strata). Age is determined by using radioactive dating. The time in which half the radioactive atoms of a certain kind in rocks or fossils will break down into atoms of another element is called the half-life.

a) Theory of Need- production of new body part results from a need.

f.

c) Theory of Inheritance and Acquired Characteristics- all that has been acquired or changed in structure of individuals during their life is transmitted by heredity to the next generation.

Comparative anatomy- similarities and differences in structures of living things. Homologous structures- parts of different organisms that are similar in structure but serve different functions. It shows evolutionary descent from a common ancestor. Vestigial organs- parts of many animals that serve little or no function at all. Believed as remnants of organs that were once functional in an ancestral form. Analogous structures- parts that are similar in function but differ in internal structure. This does not suggest evolution from a common ancestor.

g. Comparative embryology- vertebral embryo have notochord and gill puches at some time. Embryological development suggests that organisms have descended from a common ancestor. h. Comparative biochemistry- similarities in the sequences of bases in DNA result in similarities in the proteins made. The greater the biochemical similarities among different groups of organisms, the closer is the evolutionary relationships. Types of Evolution:

b) Theory of Use and Disuse- organs remain active and strong as long as they are used but disappear gradually with disuse.

16. Charles Darwin’s Natural Selection Theory- involves 

Overproduction- favourable conditions allow a population to increase in size and pressures can limit the number that can survive.



Variation- organisms differ in size, behaviour and other features.



Competition- due to pressures, organisms compete to survive.



Survival of the fittest- best adapted organism to the environment survive.



Reproduction- survivors reproduce and pass their traits to their offspring.



Speciation- population changes when some traits are not passed on and differs enough from the original population and new species arise. This is brought about by:

a) Geographic isolation- a situation in which interbreeding between two populations of a species is prevented by a physical barrier. b) Reproductive isolation- a situation in which two populations can no longer interbreed and produce fertile offspring. Adaptive radiation- a branching out of a population through variation and adaptation to occupy many environments. Artificial Selection- changes of organisms with man’s intervention (artificial breeding). Example: use of tissue culture and genetic engineering processes. Evolution of Man: Australophitecus africanus- discovered in 1934 and named by Dr. Dart in Africa  Homo habilis- 1964 by Dr. Leaky Pithecanthropus erectus- 1937 in Java  Homo neanderthalensis Homo sapiens (Cro-Magnon man)  Homo sapiens (modern man) Mechanism of Evolution