Connective tissue

Question 1

What is connective tissue? and where does it come from ?

Answer 1

Tissues that provide structure, strength and support

derived from embryonic mesoderm

Characterised by abundance of matrix with few cells

ECM consists of fibres and ground substance

Question 2

What are the 3 properties of connective tissue?

Answer 2

1. Tensile strength (collagen)
2. Elasticity (elastin)
3. Volume (ground substance)

Question 3

What is the ECM made up of?

Answer 3

Fibres and ground substance and tissue fluid

Question 4

What is the ECM produced by?

Answer 4

Fibroblasts

Question 5

What do fibres contribute to ECM?

Answer 5

Tensile strength, elastic recoil and defined structure

Question 6

What is ground substance made of?

Answer 6

Glycosaminoglycans and glycoproteins

Question 7

What does ground substance contribute to ECM?

Answer 7

Hydration → Resistance to compression
10% GAGs in ECM, the rest is water so lots of spaces for diffusion
Fibre cross-linking

Question 8

What is type I collagen?

Answer 8

Main structural collagen. forms skin, tendons, ligaments and bone

Question 9

What is another name for type II collagen?

Answer 9

Hyaline cartilage

Question 10

What does hyaline cartilage make up?

Answer 10

Nose and larynx

Question 11

What does type III collagen make up?

Answer 11

Liver, bone marrow, lymphoid organs

Question 12

What is another name for type III collagen?

Answer 12

Reticular collagen

Question 13

What is the function of elastin fibres?

Answer 13

Allow tissues to respond to stretch and distension

Question 14

What causes skin ageing?

Answer 14

Reduced density of collagen and elastin

Question 15

What is the function of fibroblasts?

Answer 15

Secrete, maintain and recycle ECM

(synthesise and secrete GAGs, collagen, elastin and other ECM parts)

Question 16

What is the main fibre in connective tissue and how is it made?

Answer 16

Collagen fibres- secreted by ECM to form tropo-collagen monomer

Question 17

What is ground substance?

Answer 17

semi-solid gel that provides volume and compression resistance

Question 18

4 tissue types

Answer 18

nerve

muscle

connective

epithelium

Question 19

what is the epithelium and its functions

Answer 19

derived from either one of the 3 germ layers (ectoderm, mesoderm, endoderm)

tissue which covers or lines a surface of an organ.

has a free surface - exposed to external environment

functions:

protects underlying tissue

separates areas of body

thermoregulation

hormone release

absorption

Question 20

what is muscle tissue and where is it derived from ?

Answer 20

derived from mesoderm

composed of cells (or multinucleated syncytia) whose cytoplasm contains filaments made of contractile proteins (actin, myosin etc)

Question 21

what is nervous tissue and where is it derived from?

Answer 21

develop from neuro-ectoderm

consist of cells of which possess axons and dendrites which conduct impulses when stimulated

Question 22

Where can epithelia be found?

Answer 22

epithelia - on surfaces

endothelium - lining blood vessels

mesothelium - lining body cavities

Question 23

types of epithelium

Answer 23

simple - 1 layer

stratified = many layers

cuboidal = cube shaped

columnal = tall

transitional = can change shape

Question 24

what type of epithelium shape and where would it be found :

A) provides protection ?

B) facilitates diffusion?

C) is absorbative/secretory ?

D) is stretchy?

Answer 24

stratified squamous ; areas of wear and tear e.g skin, oesophagus

simple squamous ; alveoli and capillaries

columnar (space needed for lots of organelles) ; small intestine/glands

with cilia as well if absorbative

transitional ; bladder

Question 25

Where in the body would we expect to find * Simple squamous? * Simple columnar? * Simple columnar with microvilli? * Columnar (pseudostratified) with cilia? * Simple cuboidal * Stratified squamous? * Transitional?

Answer 25

alveoli , endothelium glands small intestine lining airways in gland ducts /convoluted tubules in kidneys areas of wear and tear bladder

Question 26

basement membrane structure(what is it made of) and functions

Answer 26

sheets of matrix (not cells) that site between the epithelium and connective tissue ## Footnote •Composed mainly of type 4 collagen, glycoproteins (laminin secreted by epithelial cells. Fibronectin from fibroblasts) and glycosaminoglycans (GAGs) i.e the basement membrane is made by the cells above and below it functions: * adhesion of epitelium to organ below, * barrier (selectively permeability), * organisation of cells (controlling growth and differentiation) - tells cells which way is up

Question 27

shape and structure of glands

Answer 27

secretory portion has a columnar epithelium duct part has cuboidal epithelium glands are derivatives of epithelia

Question 28

difference between exocrine and endocrine glands

Answer 28

•Exocrine glands Secrete their products onto the epithelial surface directly or via a duct for **local** action e.g. Sweat glands, liver •Endocrine glands Release their secretions directly into the blood to act on different tissues e.g. Pituitary and thyroid glands far acting

Question 29

what is merocrine

Answer 29

merocrine - release via golgi vesicles

Question 30

elastin fibres structure

Answer 30

stropoelastin polymerises to elastin requires fibrillin(glycoprotein) for assembly

Question 31

what is type III collagen called what is its main features

Answer 31

reticulin mesh of thin branched fibres

Question 32

process of collagen formation

Answer 32

procollagen made by fibroblasts inside the cell assembled into collagen fibres outside cell

Question 33

name the 3 main examples of glycoproteins found in ECM

Answer 33

fibrillin - a microfibre needed to make elastin fribronectin - involved in maintaining collagen structure / binds to cells via integrins (membrane-spanning receptor proteins) laminin (forms major part of BM)

Question 34

glycosaminoglycans examples and functions

Answer 34

they are polysaccharide chains made of repeating disaccharide units hydrophilic so attract water stabilize the CT by binding to collagen and elastic fibers, cells and water. also absorb forces * Chondroitin sulfate * Heparan sulfate * Hyaluronan * Keratan sulfate

Question 35

types of connective tissue

Answer 35

●Loose: packing material - filling gaps between glands ●Dense: tough physical support: dermis, organ capsule, ligaments, tendons ●Areolar: fatty ●Specialised support: cartilage and bone ●Metabolic: adipose tissue ●Immune: contain immune cells (mast cells, tissue macrophages, WBCs, plasma cells) and effect repair

Question 36

what is apocrine

Answer 36

apocrine - release via budding of membrane

Question 37

what is holocrine ?

Answer 37

holocrine - release via cell death

Question 38

roles of connective tissue

Answer 38

Mechanical and structural role carry blood and lymph vessels Mediate exchange of nutrients, metabolites and waste products from blood and tissues