PT3 Science Chapter 19 Blood Circulation and Transport

PT3 Science Chapter 19: Blood Circulation and Transport 19.1 Transport System in Humans 1. The human transport system is called The Circulatory System 循环系统. a. It consists of Heart, Heart, thousands of Blood Vessels and Vessels and Blood which Blood which flows inside these vessels. 2. Structure and function of the human heart

a. Heart  –  cone-shaped,  cone-shaped, muscular organ, it is about the size of a fist, situated in the Thoracic Cavity 胸腔 between the lungs.  b. The wall of heart is made up of Cardiac Muscles 心脏肌. c. The heart is made up by four Chambers. Chambers. i. Two chambers at top  –  Right Atrium and Atrium and Left Atrium ( Atrium ( Atria  Atria in ).心房  plural ). ii. Two chambers at bottom  –  Right Ventricle and Ventricle and Left Ventricle. Ventricle.心室 d. There are three types of Valves inside Valves inside the heart. i. Tricuspid Valve 三尖瓣膜 –  it  it is found between the right atrium and right ventricle. ii. Bicuspid Valve 二尖瓣膜 –  it  it is found between left atrium and left ventricle. iii. Semilunar Valves 半月膜 –  they  they are situated at the beginning of the pulmonary artery and the aorta. These valves allow blood to flow in only one direction, direction, from atria to the ventricles. e. Vocabulary i. Aorta 大动脉  –  largest  largest artery in human body, it carries oxygenated  blood to all parts of the body except except the lungs. lungs. PT3 Science

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PT3 Science Chapter 19: Blood Circulation and Transport ii. Pulmonary Artery 肺动脉 –  it carries deoxygenated blood from the right ventricle to the lungs. iii. Pulmonary Vein 肺静脉 –  it returns oxygenated blood from the lungs to the left atrium. iv. Coronary Artery 冠状动脉 –  it supplies blood to the cardiac muscles. v. Coronary Vein 冠状静脉 –  it carries blood away from the cardiac muscles. f. The function of the heart is to pump blood to all parts of the body. g. The rhythmic contractions and relaxations of the walls ensure a continuous  blood circulation in the human body. h. The sequence of the pumping action of the heart i. Blood from body flows into the right atrium while blood from the lungs flows into the left atrium. ii. Both atria contract and push blood through the valves into the ventricles. iii. Both ventricles contract and force the blood artery and the aorta. The valves are closed to prevent blood from flowing back into the atria. 3. Blood vessels and their functions a. The human circulatory system is called a Closed System because blood flows in blood vessels that are connected .  b. There are three types of blood vessels in our body  –  Arteries, Veins and Capillaries. i. Arteries branch into smaller vessels called Arterioles. In turn, arterioles branch into very small vessels called Capillaries. ii. Capillaries join together to form bigger vessels called Venules. Venules join to form Veins. Artery  Arteriole  Capillary  Venule Vein →

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PT3 Science Chapter 19: Blood Circulation and Transport

iii. Blood flow in veins is helped by the Valves, which prevent blood from  flowing backwards . iv. The contraction of skeletal muscles also helps blood flow in one direction inside veins. 4. Path of blood flow in the circulatory system a. The human circulatory system is called a Double Circulatory System  because the blood in the body is pumped twice through the heart .  b. The human circulatory system can be divided into two parts. i. The Pulmonary Circulation 肺循环 –  it goes from the heart to lungs and back to the heart. ii. The Systematic Circulation 体循环 –  it goes from the heart to all parts of the body except the lungs and back to the heart.

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PT3 Science Chapter 19: Blood Circulation and Transport

1. Vena Cava 腔静脉（上或下） Vena Cava Valves are present Carries deoxygenated blood Blood flows through the blood vessel slowly

Pulmonary Vein Valves are present Carries oxygenated blood Blood flows through the blood vessel slowly

19.2 Human Blood 1. Blood is renewable living tissue. 2. A healthy adult has about 5 litres of blood in body and makes up 9% of body weight. 3. The composition of blood is as follows: a. Plasma  (55%) i. A pale yellowish liquid made up of 90% of water and 10% of soluble substances (glucose, amino acids, mineral salts, blood proteins, hormones and waste materials).  b. Cellular Components (45%)  –  red blood cells, white blood cells and platelets. i. Red Blood Cells 1. Produced in the Bone Marrow 骨髓. 2. Biconcave Disc with large surface area  to volume ratio. 3. No nuclei. 4. 5 000 000 000 (5 billion) red blood cells per 1 cm3 of blood.

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PT3 Science Chapter 19: Blood Circulation and Transport 5. Each red blood cell contains a pigment called Haemoglobin, which transport oxygen in the form of Oxyhaemoglobin to all living cells. 6. Lifespan: 120 days. ii. White Blood Cells 1. Produced in Bone Marrow and Lymph Nodes 淋巴结. 2. 3. 4. 5. 6.

Irregular  in shape and their shape can change. Have nuclei. 8 000 000 (8 million) white blood cells per 1 cm3 of blood. Protect the body against diseases and fight infections. Two types of white blood cells. a. Lymphocytes 淋巴细胞 i. Produce antibodies to kill germs.  b. Phagocytes 噬菌细胞 i. Carry out Phagocytosis 吞噬作用 by

surrounding the bacterium, swallowing it, digesting them thus killing it. 7. Lifespan: 2 to 4 days. iii. Platelets 1. Small fragments of cells from larger cells in the bone marrow. 2. 250 000 000 (250 million) platelets per 1cm3 of blood. 3. Help in the Clotting of Blood to stop bleeding. 4. Lifespan: 4 days. 4. Functions of blood a. Act as a Transport Medium. i. Carries dissolved gases (oxygen, carbon dioxide), digested food substances (glucose, amino acids, and minerals), hormones and waste products from one part of the body to another. ii. Oxygen is carried in red blood cells. Other substances are carried in blood plasma.  b. Protects the body against diseases. i. Carried out by the white blood cells. c. Blood maintains the body temperature at 37 C. i. Heat is distributed from Liver  to all parts of body by the blood plasma. 5. Blood groups and compatibility a. Four main groups  –  A, B, AB and O. i. Blood group O  –  Universal Donors, can donate blood to other blood groups. ii. Blood group AB  –  Universal Recipients, can receive blood from all  blood groups.  b. The transfer of blood from a donor to a recipient is called Blood Transfusion. c. The donor ’s blood must be compatible with the recipient’s blood. Otherwise, °

Agglutination 凝集 or Coagulation 凝结 of blood occurs inside the blood vessels which may result in the death of the recipient. PT3 Science

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PT3 Science Chapter 19: Blood Circulation and Transport 6. Importance of blood donation a. Condition of blood donation for donor: i. Generally healthy ii. Age between 18 and 65 years iii. Weighs at least 50 kg iv. Has a haemoglobin level of at least 1.25 mg per litre of blood for males, 1.20 mg per litre of blood for females.  b. Donated blood is collected in plastic bags which contain Sodium Citrate, to prevent blood coagulation. c. Donated blood is stored in Blood Banks at hospital at 4 C, which can last for 40 days. d. Blood transfusion is given to patient who i. Loses a lot of blood ii. During surgery or childbirth °

iii. To treat certain diseases (leukaemia 血癌 and haemophilia 血友病) 19.3 Transport System in Plants 1. Water and food are carried from one part of plant to other parts. 2. Transport of Food a. Food produced in the leaves through Photosynthesis moves out through the Phloem Tissues 韧皮部.  b. Food (glucose) moves upwards to the shoots for growth. c. Food moves downwards along the phloem tissues to the roots. d. Glucose is used by root cells or stored as starch in roots. 3. Transport of Water a. Water and dissolved minerals are absorbed by root hairs.  b. Water is transported upwards through the Xylem Tissues 木质部. c. Water keeps the cells in leaves turgid, also used for Photosynthesis. d. Water is lost as vapour  through the Stomata 呼吸孔 during Transpiration 蒸

散作用. 4. Transport tissues in plants a. The transport system in plants is made up of Xylem and Phloem tissues, they are found in roots, stems and leaves.  b. Xylem Tissues i. Made up of Xylem Vessels which are dead cells with no nucleus nor cytoplasm. ii. Form long tubes with thick walls. iii. Form the woody tissues of plants. iv. Provide mechanical support to plants. v. Transport water and dissolved minerals from the roots up the stems to the leaves. c. Phloem Tissues i. Made up of living cells. ii. Phloem cells are arranged to form long tubes with separating walls in  between. PT3 Science

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PT3 Science Chapter 19: Blood Circulation and Transport iii. Transport food (glucose) from the leaves to all parts of the plant.

Vocabulary o

Upper epidermis 上表皮

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Lower epidermis 下表皮

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Vascular bundle 维管束

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Pith 木髓

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Cambium 形成层

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Cortex 真皮层

5. Wilting 植物的萎缩 a. In the morning, the stem of non-woody plant is upright and the leaves are well spread out because the cells are turgid 充水. In the afternoon, the stem is no longer upright and the leaves droop or wilt  because there is not enough water inside the plant.  b. On the upper and lower surfaces of the leaf are tiny pores called Stomata  (Stoma in singular form), usually more stomata on the lower surface of a leaf. 6. Transpiration and function of stomata a. What is Transpiration?  It is defined as the loss of water in a form of water vapour.  b. The water vapour evaporates through the stomata  on the leaves and lenticels

皮孔 on the stem of a plant. i. Stomata  is a tiny pore between two bean-shaped cells called Guard Cells, which contains chloroplasts and carry out photosynthesis during day time.

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PT3 Science Chapter 19: Blood Circulation and Transport ii. Guard cells control the opening and closing of the Stomata. iii. Stomata are usually open during the day to allow exchange of oxygen and carbon dioxide during photosynthesis and respiration. 7. Factors that affect of transpiration a. Light Intensity  –  intensity increases, the rate of transpiration also increases.  b. Temperature  –  the higher the temperature it is, the greater is the evaporation of water vapour. c. Humidity  –  the lower humidity is, the higher is the rate of transpiration. d. Air Movement  –  on windy day, the wind blows water vapour away from stomata. Thus more water is lost. 8. The rate of transpiration can be measured using a Bubble Potometer  or a Weight Potometer . 9. Role of transpiration in transport. a. It helps transport water and dissolved minerals from the roots to the leaves.  b. It helps the roots to absorb water . c. The evaporation of water vapour from the leaves keeps the plant cool in hot weather. d. It removes excess water  from the plant.

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