Lec 3 Cells to Tissues

Question 1

Most cells form tissues - what are the types of tissues, which one is different and why?

Answer 1

muscle tissue
nervous tissue
epithelial tissue
connective tissue
connective is odd one out as its many different tissue

Question 2

what holds cells together?

Answer 2

cell- cell adhesion molecules
extracellular matrix proteins (fibres)
internal external scaffolding
close proximity pressure affects

Question 3

what are the differences between epithelial and connective tissue

Answer 3

connective tissue is - 
plentiful extracellular matrix
few cells spread within
matrix rich in fibres like collagen - matrix bears mechanical stress
cells not directly attached

epithelial
cells in tightly bound epithilia sheets
very little extra cellular matrix - just the basal lamia underneath the epithilium
cell-cell adhesion attach cells - bear the mechanical stress

Question 4

what is the primary cell of connective tissue?

Answer 4

the mesenchymal stem cell (differentiates into all connective tissues)
it produces most extracellular fibers that anchor cells into place
at first it can inter convert between cell types before settling
produces bone, cartilage ect

Question 5

where do we find epithelial tissue, why ?

Answer 5

line all cavities and free surfaces of the body

specialised junctions between cells help form tissue barriers, to inhibit transfer of water, acids ect

epithelia mostly rest on connective tissue, through a basement membrane.

connective tissue binds epithelia to other tissues to produce an organ

Question 6

name lateral epithelial cell adherence systems in order

Answer 6

tight junctions
adhesion junctions
desmosomes
gap junctions 
cell adhesion molecules - intergins

all cell adhesion systems require calcium to function

Question 7

name basal surface adhesion systems

binds to basal lamina/basement membrane

Answer 7

hemi - desmosomes
focal adhesion
intergrins
proteoglycan

Question 8

what is a tight junction?

Answer 8

forms a seal and selective barrier

prevents leakage of molecules

prevent pathogens from gaining entry to systems (why we have an epithelial layer)

Question 9

what is an adherence junction?

Answer 9

joins two actin bundle sin cells together

Question 10

what is a desmosome?

Answer 10

joins intermediate filaments in two cells

strongest junction
bears mechanical stress

Question 11

gap junction

Answer 11

allows passge of small molecules / ions ect

for cell communication, ion transport

Question 12

hemidesmosome

Answer 12

anchors intermediate filaments in the cell (made of keratin) to the basal lamina (which attaches to connective tissue via elastin, fibirillin, collagens)

Question 13

focal adhesions

Answer 13

anchors actin filaments in the cell to the basal lamina

actin allows for immune patrolling and wound contraction

Question 14

what is the basal lamina (basement membrane)

Answer 14

A thin, acellular layer to which epithelial cells are anchored

Question 15

what are integrins used for

Answer 15

Integrins play an important role in basement mebrane– Transmembrane proteins which connect the cell cytoskeleton to the ECM
Physical attachment
Signal transduction
Immune patrolling and cell migration

Question 16

what is the mucosal membrane ?

Answer 16

it lines the hollow organs - GI tract, urinary tract, respiratory tract.
it secretes mucus, a thick protective fluid with enzymes, immunoglobulins ect

to stop pathogens and dirt from entering the body
prevent loss of water (dehydration) from tissues
lubrication

Question 17

what makes up the mucous membrane

Answer 17

epithelium
basal lamina
lamina Propecia (smooth muscle for contraction)

Question 18

outline what the respiratory tract is

Answer 18

for gaseous transport and exchange

made up of a conducting portion (trachea) and a respiratory portion (bronchioles to aveoli)

Question 19

what is the role of cartilage in the trachea?

Answer 19

hyaline cartialge - C shaped ring to prevent the trachea from collapsing under vaccum.

Question 20

what is the function of the mucosal membrane in respiratory tract

Answer 20

• secretions (produced by goblet cells full on enzymes) from submucosa provide a block to stop pathogens entering system and cillia on the epithilia. the cillia wave forms the mucocilliary escalotor to move them to the stomach for digestion

Question 21

What is the function and structure of the urinary tract?

Answer 21

large basal lamina producing mucus to act as a barrier to keep in acidic urine in

tight junctions to prevent urine escape

ureter and bladder have thick muscle layer to maintain pressure, prevent bursting.

essential nutrients are absorbed by kidney
prevention of pathogen entry
removal of waste products

Question 22

What is the function of the mucosa in the GI tract?

Answer 22

absorb substances from the lumen (large SA to achieve this- folding of mucosa epithilal cells, microvilli and peristaltic actions)

prevent pathogens - lamina propria contains lymphatic tissue to aid this

move contents and expel waste - peristalsis

Question 23

what are the layers of the gi tract ?

Answer 23

mucosa lines the lumen

muscularis mucosa - thin smooth muscle layer

submucosa - connective tissue layer

muscularis externa - peristalsis - two directions of smooth muscle layers - inwards and along

the serosa - secretes fluid - connective tissue - also stops expansion that would burst the GI

the stomach has rugae - folds that increase SA
jejunum has villii for SA

Question 24

give examples of specialised structures on the apical domain

Answer 24

microvilli - border in the GI tract - increase SA for adsorption

sterovilli - sensory - inner ear

cilia - form a moving stroke - mucocilliary escalator

Question 25

what is the structure and function of cells in the stomach (GI tract)

Answer 25

Mucosa - epithilium - the gastric mucosa secrets acid, digestive enzymes
lamina propria,
muscularis mucosae
the submucosa
muscalaris externa - multidirectional, contract for peristalsis
folded into rugae to increase SA