1
Q
what are epithelia
A
sheets of cells that line body cavities and surfaces
- most common cell type in the body
- avascular
2
Q
basic structural features of human cells
A
- plasma membrane bound
- contains cytoplasm
- contains organelles
3
Q
plasma membrane features
A
- creates distinct environments
- selective barrier
- dynamic to meet cell needs
- lipid bilayer
4
Q
plasma membrane function
A
- protection
- communication
- transportation
5
Q
lipid bilayer
A
- thin polar membrane
- 2 layers of lipid molecules
6
Q
plasma membrane lipid composition
A
phospholipids
- 75%
glycolipids
- 5%
cholesterol
- 20%
small amounts of other lipids
- eg. PIP2
7
Q
phospholipid composition
A
hydrophilic region
- alcohol
- phosphate
hydrophobic region
- fatty acid tail
8
Q
glycolipid composition
A
hydrophilic region
- sugar
hydrophobic region
- fatty acid tail
9
Q
cholesterol composition
A
hydrophilic region
- OH group
hydrophobic region
- steroid region
- fatty acid tail
10
Q
plasma membrane permeable to
A
- non-polar
- uncharged
- lipid soluble
- eg. gases and steroid hormones
11
Q
plasma membrane impermeable to
A
- ions
- large, charged molecules
- water soluble
12
Q
plasma protein functions
A
transport
- channels and transporters
signalling
- receptors
connection to ECM and other cells
13
Q
two main groups of proteins
A
- integral
- peripheral
14
Q
integral proteins
A
- anchored to membrane
15
Q
peripheral proteins
A
- on outside or inside of membrane
- may attach to integral proteins or phospholipids
16
Q
fluid mosaic model
A
- membrane is dynamic
- lipids can move within their monolayer
- proteins can move and be added and removed
- membrane components reflect the functions of the cell
17
Q
what determines the mode of cell transport
A
- what is being moved
- how much is on either side of the membrane
- how much is being moved
18
Q
types of transport
A
- passive
- facilitated
- active
- bulk
19
Q
passive transport
A
- requires concentration gradient
- lipid soluble/nonpolar/uncharged
20
Q
facilitated transport
A
- requires concentration gradient
- water soluble/polar/charged
- uses channel/pore or transporter/carrier (can be gated or open)
21
Q
active transport
A
- moves against concentration gradient
- requires ATP
22
Q
bulk transport
A
- mediated by vesicles
- large molecules or large volumes of small molecules
23
Q
the cytoskeleton is essential for
A
- cell division
- cell movement
- vesicle movement within cells
24
Q
the cytoskeleton helps
A
- maintain internal organisation and cell structure+shape
25
is the cytoskeleton static or dynamic
dynamic, changing to meet needs of cells
26
cytoskeleton components
- microfilaments
- microtubules
- intermediate filament
27
intermediate filament structure
- ~10nm
- 50+ types made of different proteins
- cytokeratins most abundant in renal/gi epi
28
microfilament structure
- 2 globular actin protofilaments twisted in a helix -> f-actin
- ~7nm
- can be assembled into large filaments, networks, and 3D structures
29
microfilament functions
- movements (muscles)
- cell junctions (adherens)
- cell structure (cortical network)
- microvilli (increase SA)
30
microtubule structure
- tubulin alpha and beta form heterodimers then wind into a large hollow tube like helix
- ~25nm diameter
- interacts with motor proteins
31
microtubule function
- organelle movement and vesicle trafficking
- motility (cilia and flagella)
32
intermediate filament functions
support networks within the cell
cell junctions
- desmosomes and hemidesmosomes
- resist shearing forces
33
organelle
- a subcellular structure with specific functions
- form defined areas and environments within the cell
- often membrane bound
34
nucleus
- control centre, normally one per cell
- contains most of the cells DNA
- contains nucleolus
- surrounded by the nuclear envelope, which contains pores
35
nucleolus
makes rRNA and ribosomal subunits
36
nuclear envelope
- double membrane
- continuous with ER
- channels made of nucleoporins
allow things in and out of the nucleus
37
things exiting the nucleus
- mRNA
- tRNA
- ribosomal subunits
38
things entering the nucleus
- building materials
- energy
- control signals
39
endomembrane system
interconnected system that functions to modify, package, and move proteins and lipids
40
endomembrane composition
- endoplasmic reticulum
- golgi apparatus
- vesicles
41
smooth ER
- no ribosomes on surface
- synthesises lipids
- metabolises carbs
- detoxification processes
- stores calcium ions
42
rough ER
- covered with ribosomes on the surface
- role in protein synthesis
43
rER in protein synthesis
- proteins enter the rER lumen
- proteins are modified, folded, and packaged into vesicles
- transported to golgi
44
golgi apparatus
a series of membrane sacs and vesicles
45
golgi function
- vesicles arrive from ER at the cis face
- proteins modified, glycosylated, sorted into vesicles
- vesicles leave from trans face
46
vesicle types
transport vesicles
- move contents within cell
secretory vesicles
- move contents out of the cell
47
vesicles
- membrane bound
- move along microtubules via motor proteins - “walking”
48
how do mitochondria generate energy?
- consume glucose and oxygen
- produce CO2, water, and ATP
49
mitochondria
- site of cellular respiration
- double membrane structure
- number per cell depend on energy demands
50
cholesterol importance in cell membranes
- maintains membrane fluidity and reduces thermal impacts
51
epithelial functions
- protection
- secretion
- absorption
52
epithelial types
- surface
- glandular
53
glandular epithelium
- primarily involved in secretion
- invaginations of the surface
- connected to surface via ducts
54
classifications of surface epithelium
- shape of cell
- number of layers
- surface specialisations
55
cell specialisations
- microvilli
- cillia
- basolateral folding
- basement membrane
56
microvilli
- finger-like cellular extensions
- 0.5-1um
- cytoplasmic core with parallel bundles of actin inserting into terminal web
57
microvilli actin function
- stability of microvilli
- elongation of microvilli
- contraction of microvilli
58
cilia
- specialised organelles on apical surface
- 10 um
- 9 microtubule doublets
59
microtubule doublets
primary
- non-motile
- mechanical and chemical sensors
secondary
- central doublet
- dyneins
60
basolateral foldings
- deep invaginations or plasma membrane
- increase SA
- prominent cells with high transport rates
- often lots of mitochondria
61
basement membrane
- sheets of ECM
- connect epithelium to underlying tissue
- made of basal lamina and reticular lamina
62
basal lamina
- lamina lucida
- lamina dense
63
reticular lamina
lamina reticularis
64
layers of the basement membrane
lamina lucida
lamina densa
lamina reticularis
65
lamina lucida makeup
laminin
66
lamina densa makeup
- type IV collagen
67
lamina reticularis makeup
type III collagen
68
basement membrane disorders
- alport syndrome
- diabetic neuropathy
- inflammatory bowel disease
69
alport syndrome
- mutations in type IV collagen
- defective glomerular basement membrane
70
diabetic neuropathy
chronic hyperglycaemia
-> thickened glomerular basement membrane
71
inflammatory bowel disease
- uncontrolled remodelling and degradation of collagen and laminins
- impaired epithelial barrier
72
goblet cells
- columnar
- basal nuclei
- lots of rER
- apical secretory vesicles/granules containing mucin
73
mucus primary functions
- protection
- lubrication
74
epithelial cell junction types
- tight junctions
- adherens junctions
- gap junctions
- desmosomes
- hemidesmosomes
75
ectoderm epithelia
- epidermis
- oral/nasal mucosa
- anal canal
76
mesoderm epithelia
- endothelium
- mesothelium
- reproductive tract
- kidney tubules
77
endoderm epithelia
- GI lining
- respiratory tract
78
risk factors of epithelial cells
- high renewal = high mutation rate
- exposed to environment
- colorectal cancer 2nd highest in NZ
79
epithelia through the gi tract
e: stratified squamous
s: simple columnar
i: simple columnar
a: stratified squamous
80
stomach epithelia
simple columnar
- cheif cells
- parietal cells
- goblet cells
81
intestinal epithelia
simple columnar
- enterocytes
- goblet cells
82
renal epithelia
- simple cuboidal and simple squamous in the collecting duct
- transitional in the ureter
83
how do epithelial cells get nutrients
diffusion from nearby tissue (eg. lamina propria)
84
what is a gland
a clump of secretory cells to increase SA for secretion
85
simple squamous
- allows things to pass across easily
- tiny bit of serous secretion
86
simple cuboidal
- secretory often
- absorptive
87
types of stratified squamous
keratinised
- protective
- top cells dead
non-keratinised
- softer
- moist
88
stratified squamous
- classified by shape of most of the cells
- cells become more squamous and have less organelles further from the basement membrane
- protect against abrasion
89
transitional/urothelium
- stratified round/cuboidal cells
- random shape distributions
90
umbrella cells
- cells flatten and stretch when bladder stretches
- protects renal system from urine
91
transitional epithelium features
- tight cell junction
- lots of intermediate filaments right under surface
- few transport proteins
- cells impermeable to piss
92
lumen
empty part of a hollow organ
93
dyneins
- motor proteins
- cause ATP-powered cilia movement
- swish
94
males highest cancer
prostate
95
females highest cancer
breast
96
acinar cell
- produce enzymes
