Epithelia & supporting tissue (W2)

Question 1

What are the 4 basic tissue

Answer 1

• epithelial
• supporting
• muscular
• nervous

Question 2

What is the function of epithelial

Answer 2

• containment
• selective diffusion
• absorption
• secretion
• physical protection

Question 3

What is surface epithelia , where is is found and what is it involved in

Answer 3

• cover and line all body surface , cavities and tube
• Involved in containment, selective diffusion, absorption, secretion and physical protection

Question 4

What does all surface epithelia contain

Answer 4

cytokeratin intermediates filaments
- makes it recognisable by immunohistochemistry

Question 5

What are all epithelia supported by

Answer 5

Basement membrane

Question 6

Describe the basement membrane

Answer 6

• separates epithelial from underlying supporting tissue
• doesn’t contain BV and are dependant on diffusion for nutrients jh

Question 7

What is the function of the basement membrane

Answer 7

provide metabolic support & binds to underlying support tissue

Question 8

What is the basement membrane celled in nerve and muscle tissue

Answer 8

external lamina

Question 9

Describe the shape of the basement membrane

Answer 9

sheet-like arrangements of extra-cellular matrix proteins which act as interface between support tissue and parenchymal cells

Question 10

What are the main constituents of the basement membrane

Answer 10

• collagen type 4
• glycoproteins laminin
• entactin
• fibroxnectin

Question 11

What layers are the basement membrane composed of

Answer 11

• Lamina lucida
• Lamina densa
• Lamina fibroreticularis

Question 12

Describe the 3 layers of basement membrane

Answer 12

1. Lamina lucida
   - relatively transparent
2. Lamina densa
   - intermediate elcetron-dense layer
3. Lamina fibroreticularis
   - electrolucent layer which emerge with supporting tissue underneath
   - mainly tyope 3 collagen & fibronectin

Question 13

Describe simple squamous and where it is found

Answer 13

• flattened irregular epithelium forming continuous surface (pavement epithelium)
• found lining surfaces f gases e.g., lungs

Question 14

Describe simple cuboidal and where it is found

Answer 14

• round nucleus located in cell centre (gives clue to shape)
• lines small suits and excretory, secretory or absorptive functions

Question 15

Describe simple columnar and where it is found

Answer 15

• taller cuboidal cells
• elongated nuclei an located towards the base, apex of centre of cytoplasm
• located in small intestine, gall bladder or play a secretory role

Question 16

Describe simple stratified epithelia

Answer 16

• consisting of 2+ layers
• flattened cells at the top
• cuboidal at base

Question 17

Why is stratified epithelium poor for absorption

Answer 17

thickness of cell layers

Question 18

Describe stratified squamos and where it is found

Answer 18

adapted to withstand constant abrasion and desiccation due to tough non-living surface layer composed of protein keratin wrapped in plasma membrane

Question 19

Why is the nuclei eventually lost in stratified epithelium

Answer 19

the cell matures

Question 20

Describe stratified cuboidal and where it is found

Answer 20

• thin ( only 2 or 3 cells)
• more robust
• found lining larger excretory ducts
• not involved in significant secretory or absorptive activity

Question 21

Describe stratified transitional and where it is found

Answer 21

• highly nucleated
• found in urinary tract and is highly specialised to accommodate stretch and toxicity of urine

Question 22

What does stratified transitional look like when
- relaxed
- stretched

Answer 22

• when relaxed, surface cells are large and rounded
• when stretched, intermediate and surface layers are extremely flattered

Question 23

What is glandular epithelium

Answer 23

• primarily involved in secretion

Question 24

Describe simple tubular glands and where they are located

Answer 24

• single straight tubular lumen which secretary products are discharged
• large intestine

Question 25

Describe simple coiled tubular glands and where they are located

Answer 25

- tightly coiled in 3D - sweat glands

Question 26

Describe simple branched glands and where they are located

Answer 26

- several tubular secretory portions which converge onto a single unbranched duct - stomach mucus

Question 27

When do endocrine glands lose their connection to the epithelial surface

Answer 27

during development

Question 28

How can secretion be controlled

Answer 28

by metabolic factors e.g., glucose

Question 29

What do most endocrine glands contain

Answer 29

clusters of secretary cells each with own basement membrane surrounded by rich network of blood vessels

Question 30

What is supporting tissue

Answer 30

provides structural and metabolic support for other tissues and organs

Question 31

What are supporting tissue derived from

Answer 31

precursor cells in primitive (metal) supporting tissue - mesenchyme

Question 32

What is the function of supporting tissue

Answer 32

mediates exchange of nutrients, gases and metabolites between tissues and circulatory system

Question 33

What is supporting tissue composed of

Answer 33

- specialised cells - extracellular matrix (ground substance and fibres)

Question 34

What determines the physical properties of the supporting tissue

Answer 34

extracellular matrix component

Question 35

What are the 2 main fibrous components of supporting tissue

Answer 35

- collagen - elastin

Question 36

Describe collagen

Answer 36

- provides tensile strength - secreted as tropocollagen which polymerises in the extracellular matrix to from collagen

Question 37

What are the main types of collagen and where are they found

Answer 37

- Type 1 - found in dermis, tendons, ligaments, bone and fibrous supporting tissue - Type 2 - found in hyaline cartilage - Type 3 (reticulin) - delicate branching supporting meshwork in highly cellular tissues e.g, liver bone and lymphoid organs - Type 4 - mesh-like structure in basement membrane - Type 7 - anchors fibrils that link to the basement membrane

Question 38

Name some examples of mesenchyme

Answer 38

- fibroblast (most come cells) - responsible for secreting extracellular matrix - my-fibroblasts - contractile function + secretion of extracellular matrix

Question 39

What is primitive mesenchyme

Answer 39

embryonic tissue which all connective tissue is derived from

Question 40

Describe the shape of mesenchymal cells

Answer 40

- stellate shape with delicate branching cytoplasmic extensions - oval nuclei

Question 41

What are mature fibroblastas

Answer 41

maintain the integrity of tissue by slow turnover of the extracellular matrix constituents

Question 42

Describe the shape of mature fibroblasts

Answer 42

- condensed elongated in the direction of the collagen bundles

Question 43

What is adipose tissue and where is is found

Answer 43

- fat storage - found in isolation or clumps in tissue

Question 44

Why does adipose tissue have a rich blood supply

Answer 44

to release energy

Question 45

What is the function of adipose tissue

Answer 45

releasing several proteins

Question 46

What is brown adipose

Answer 46

- highly specalised tissue found in newborns - importnat role in temperature regulation - arrnaged in lobules seperated by fibrous septae which convey blood vessels and nerves

Question 47

What is white adipose

Answer 47

- thermal insulator and a cushion against mechinal shock in sites