Tissues

Tissues

Tissues Definition: a group of closely associated cells that perform related functions and are similar in structure  Between cells: nonliving extracellular extracellular material  Four basic types of tissue…function tissue…function 

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Epithelium…covering  Connective tissue…support  uscle tissue…movement  !ervous tissue…control

Epithelia "plural# 

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Epithelium: sheet of cells that covers a body surface or lines a body cavity$ also form most of the body%s glands &oles: as interfaces and as boundaries Functions: 'rotection (bsorption )ensory reception *on transport )ecretion Filtration Formation of slippery surfaces for movement

)pecial characteristics of epithelia   

Cellularity )peciali+ed contacts 'olarity Free upper "apical# surface  ,ower "basal# surface contributing basal lamina to basement membrane 

)upport by connective tissue   (vascular but innervated 

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Without  vessels  With nerve endings 

&egeneration

Classification of epithelia  (ccording to thic-ness

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.simple/ 0 one cell layer   .stratified/ 1 more than one layer of cells "which are named according to the shape of the cells in the apical layer# 

 (ccording to shape

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.s2uamous/ 1 wider than tall  .cuboidal/ 1 as tall as wide  .columnar/ 0 taller than wide

to protect

where diffusion is important

where tissues are involved in secretion and absorption: larger cells because of the machinery of production3 pac-aging3 and energy re2uirements

“ciliated” literally = eyelashes (see next page)

)tratified: regenerate from below

&are…

&are…

Endothelium ( simple s2uamous epithelium that lines the interior of the circulatory vessels and heart

esothelium )imple s2uamous epithelium that lines the peritoneal3 pleural and pericardial cavities and covers the viscera

4lands Epithelial cells form them  'roduction 5 secretion of needed substances  (re a2ueous "water0based# "water0based# products  The protein product is made in rough E&3 pac-ed into secretory granules by 4olgi apparatus3 released from the cell by exocytosis 

Classification of glands 

By where they release their product 

Exocrine: external secretion onto body surfaces "s-in# or into body cavities  Endocrine: secrete messenger molecules "hormones# which are carried by blood to target organs$ .ductless/ glands 

By whether they are unicellular or multicellular 

Exocrine glands unicellular or multicellular 

6nicellular: goblet cell scattered within epithelial lining of intestines and respiratory tubes

'roduct: mucin mucus is mucin 5 water 

ulticellular exocrine glands

Epithelium0walled duct  and a secretory unit 

Examples of exocrine gland products any types of mucus secreting glands  )weat glands of s-in  7il glands of s-in  )alivary glands of mouth  ,iver "bile#  'ancreas "digestive en+ymes#  ammary glands "mil-# 

Endocrine glands  Ductless glands

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&elease hormones into extracellular space 

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8ormones are messenger molecules

8ormones enter blood and travel to specific target organs

Epithelial surface features 

,ateral surface  (dhesion proteins  Tongue and groove wavy contours  Cell 9unctions: see next slide 

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Basal surface 

Basal lamina: noncellular sheet of protein together with reticular fibers form basement membrane

 (pical surface

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Cell unctions 

Tight 9unctions 

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 (dherens 9unctions 

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)o close that are sometimes impermeable Transmembrane lin-er proteins

Desmosomes 

 (nchoring 9unctions  Filaments anchor to the opposite side 

4ap 9unctions 

 (llow small molecules to move between cells

 (pical surface features 

icrovilli 1 maximi+e surface area Fingerli-e extensions of the plasma membrane of apical epithelial cells  7n moist and mucus secreting epithelium  ,ongest on epithelia that absorb nutrients "small intestine# or transport ions "-idneys# 

"continued#

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Cilia 

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;hipli-e motile extentions of the apical surface membranes

Flagellum 

,ong isolated cilium  7nly found as sperm in human

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Four basic types of tissue 

Epithelium Connective tissue Connective tissue proper "examples: fat tissue3 fibrous tissue of ligaments#  Cartilage  Bone  Blood 

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uscle tissue !ervous tissue

Classes of Connective Tissue: note the cell types and great variety of subclasses

Connective Tissue 

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7riginate from embryonic tissue called mesenchyme ost diverse and abundant type of tissue any subclasses "see previous slide# Function: to protect3 support and bind together other tissues 

Bones3 ligaments3 tendons  (reolar cushions$ adipose insulates and is food source  Blood cells replenished$ body tissues repaired 

Cells separated from one another by large amount of nonliving extracellular matrix

Extracellular atrix explained    

!onliving material between cells 'roduced by the cells and then extruded &esponsible for the strength Two components =

7f fluid3 adhesion proteins3 proteoglycans ,i2uid3 semisolid3 gel0li-e or very hard

Fibers: collagen3 elastic or reticular

Basic functions of connective tissue reviewed )upport and binding of other tissues  8olding body fluids  Defending the body against infection 

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macrophages3 plasma cells3 mast cells3 ;BCs

)toring nutrients as fat

Classes of Connective Tissue

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Classes of Connective Tissue

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Classes of Connective Tissue

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Classes of Connective Tissue

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Membranes that combine epithelial sheets plus underlying connective tissue proper "see next slide# 

Cutaneous membranes 

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ucous membranes3 or mucosa 

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)-in: epidermis and dermis ,ines every hollow internal organ that opens to the outside of the body

)erous membranes3 or serosa 

)lippery membranes lining the pleural3 pericardial and peritoneal cavities  The fluid formed on the surfaces is called a transudate 

)ynovial membranes 

,ine 9oints

"a# Cutaneous membrane "b# ucous membrane "c# )erous membrane

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Four basic types of tissue 

Epithelium Connective tissue uscle tissue )-eletal  Cardiac  )mooth 

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!ervous tissue

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Four basic types of tissue Epithelium Connective tissue uscle tissue !ervous tissue 

!eurons  )upporting cells 

Tissue response to in9ury  

*mmune: ta-es longer and is highly specific *nflammation 

!onspecific3 local3 rapid  *nflammatory chemicals  )igns: heat3 swelling3 redness3 pain 

&epair 1 two ways 

&egeneration  Fibrosis and scarring  

)evere in9uries Cardiac and nervous tissue

Tumors "neoplasms#: abnormal growth of cells  (denoma 1 neoplasm of glandular epithelium3 benign or malignant  Carcinoma 1 cancer arising in an epithelium "@A of all human cancers#  )arcoma 1 cancer arising in mesenchyme0derived tissue "connective tissues and muscle# 