Tissues and epithelial cells Flashcards
(96 cards)
1
Q
Define a tissue
A
a group or collection of similar cells that work together to perform a specific function or set function within an organism
2
Q
What are the four types of tissue
A
- connective
- epithelial
- muscle
- nervous
3
Q
define an organ
A
an organ is the organisation of two or more tissues that have specific functions within an organism
4
Q
what is a system
A
created when several organs work together to form organ systems that perform complex functions necessary for the survival and functioning of the entire organism
5
Q
what are the three membranes of epithelial cells
A
- apical (upper)
- lateral (sides)
- basal (lower)
6
Q
What is often found on the apical surface
A
- specialisations
e.g. microvilli, stereovilli, cillia
7
Q
what features can be found on the lateral membrane
A
- tight junctions
- adherens junctions
- desmosomes
- gap junctions
- cell adhesion molecules
8
Q
describe where and what tight junctions are
A
where: always at top of cell near apical surface in lateral border
role: prevent movement of larger molecules through lumen into deeper tissues
9
Q
describe where and what adhesion junctions are
A
- always found 1/3 distance from luminal surface
- found in pairs
- role: stabilising factor and additional transport barrier
10
Q
describe where and what desmosomes are
A
- found 1/2 way between top and bottom of cells
- found in tissues that experience mechanical stress (heart, bladder, uterus)
- role: prevent mechanical strength and prevent destruction
11
Q
describe where and what gap junctions are
A
- found close to base of epithelial cells in cardiac and muscle cells
role: quickly communicate changes intercellular molecular composition - allow free movement of small molecules from one cell to another
12
Q
describe where and what cell adhesion molecules are
A
- found on cell surface
role: adhere to extracellular matrix, other cells and surroundings
13
Q
what features are found on the basal membrane
A
- hemi-desmosome
- focal adhesions
- integrins
- proteoglycans
- cell adhesion molecules
14
Q
describe where and what hemi-desmosomes are
A
-found only on basal surface
role: attach not to cells but extracellular matrix (fibronectin, collagen, laminin fibres) attaches b connective tissue layer through elastin, fibrillin
anchors epithelial cells to basal lamina and prevents loss to external surface
15
Q
describe what focal adhesions are
A
similar to hemidesmosomes
binds to fibronectin which causes a conformational change resulting in the binding to collagen
16
Q
describe what integrins are
A
cohesive forces
work as alpha beta dimer
weak binders of extracellular matrix but phosphorylation produces heterotetramer that has greater binding capacity
17
Q
describe what proteoglycans are
A
- support hydration of extracellular matrix of normal skins (elasticity)
- support scaffolding for proper alignment of fibrous and elastic components of skin
- have the ability to control availability of growth factors in ECM
18
Q
what is the function of mucosal membrane
A
- stop pathogens entering
- prevents dehydration
- lubricates surface
19
Q
define mucosal membrane
A
moist, inner lining of some organs and body cavities
20
Q
where is mucosal membrane found where it lines all moist hollow internal organs
A
- GI tract
- urinary
- respiratory
- urogenital
21
Q
where is mucosal membrane found where it is continuous with skin at body openings
A
eyes, ears, nose, mouth, lips, vagina, anus
22
Q
what are the GI tract layers
A
- serosa
- muscularis
- submucosa
- muscularis mucosa
- mucosa
23
Q
what are the functions of the mucosa in GI tract
A
- absorb substances from the lumen
- prevent ingress of pathogens
- move contents and expel waste
24
Q
what are the layers in the oesophagus
A
- epithelium
- submucosa
- muscularis externa
25
what are the parts of the conducting portion of the respiratory system
- nasal cavity
- pharynx
- larynx
- trachea
- primary bronchi
- secondary bronchi
- bronchioles
- terminal bronchioles
26
what parts are in the respiratory portion of the resp system
- respiratory bronchioles
- alveolar ducts
- alveoli
27
what epithelial cells are found from the nasal cavity to largest bronchioles and cilia and goblet cells
psuedostratified epithelium
28
what epithelial cells are found in terminal bronchioles and cillia and clara cells
simple columnar epithelium
29
what epithelial cells are found in resp bronchioles and alveolar ducts and clara cells
simple cuboidal epithelium
30
what respiratory cells are found in the alveoli and septal cells
simple squamous
31
describe the layers in the trachea
- mucosa
- submucosa
- C- shaped hyaline cartilage
32
What are the treacheal and bronchial secreations
- mucins and water
- serum proteins
- lysosomes
- anti-proteases
33
What is the mucociliary escalator
when the cilia wave mucus towards oral cavity where material can be swallowed
34
what is the difference between primary and secondary/ tertiary bronchi
secondary and tertiary no longer have full rings of cartilage
35
what adaptations are in the alveoli epithelium
- fold in basal lamina allow for expansion
- at junction small amount of collagen provide with many layers of elastin provide elastic recoil to return sac to empty state
36
define an epithelial tissue
thin, continuous protective layer of cells that covers both the inside and outside of the body including blood vessels
37
what is the embryological origin of epithelial tissues
from all embryological germ layers
- ectoderm --> epidermis
- mesoderm --> inner and outer GI tract
- endoderm --> inner linings of body cavities
38
what does it mean that epithelial tissues are avascular and how do they get nutrients
- do not have their own blood supply
- nutrients via diffusion
39
how are epithelial cells classified
- how many layers
- cell shape
- any specialisations on free apical surface
40
what makes epithelial cells simple
one cell layer thick
41
what are the different simple epithelial cells
- squamous
- cuboidal
- columnar
- psuedostratified
42
what makes epithelial cells stratified/compound
many cell layers
43
what are the different stratified epithelial cells
- squamous
- cuboidal
- columnar
- transitional
44
what epithelial cells facilitate gas exchange and where are they found
- simple squamous epithelium
- found in mesothelial alveoli of lungs and lining of blood vessels (endothelium)
45
what are they special features of simple squamous epithelia
- thin (thin diffusion layer)
- permeable (exchange surface)
- smooth surface (reduces friction)
46
what are the functions of simple squamous epithelia
- lubrication (meothelium)
- gas exchange (alveoli)
- product exchange (water, nutrients, CO2)
- barrier (bowmans capsule, skin, oesophagus, eye, brain)
47
what epithelial cells are absorptive epithelium
- simple columnar epithelium
- simple cuboidal epithelium
48
describe the shape of simple cuboidal and where nucleus is located
single layer of polygonal cells, height and width are equal
nucleus: central
49
describe shape of simple squamous and where nucleus if located
single layer of flat cells
nucleus: risen in middle
50
where are simple cuboidal cells found
- kidney tubules
- thyroid gland
- glands and ducts
- ovaries
51
what are the functions of simple cuboidal cells in kidney tubules
function: filtration, reabsorption and secretion to form urine
adaptation: efficient reabsorption of water and ions
52
what are the functions of simple cuboidal cells in thyroid gland
function: synthesis and secretion of thyroid hormones
adaptations: follicles that store thyroid hormone precusors
53
what are the functions of simple cuboidal cells in glands and ducts
e.g. salivary glands, pancreatic ducts, sweat glands
function: secretions
adaptation: efficient transport of secretions
54
what are the functions of simple cuboidal cells in ovaries
function: cover surface of ovary and involved in production of hormones
adaptation: protection and secretion
55
describe shape of simple columnar and position of nucleus
single layer whose height greater than width
nucleus all one level at bottom
56
where are simple columnar epithelium found
lining of crypts of Lieberkuhn (intestinal glands) in mucosa of the colon
57
what are the protective epithelium cells
- stratified squamous epithelium
- transitional epithelium
58
describe shape of stratified squamous epithelia
contain multiple layers of cells, the outermost are thin squamous epithelial cells
59
where are stratified squamous cells found
-oral cavity
- oesophagus
- vagina
- part of anal cavity
- cornea
- surface of eyelid
60
what are the function of stratified squamous epithelial cells
- protect against abrasions
- reduce water loss
61
how do stratified squamous cells maintain low pH in vagina
rich in glycogen, a substrate for lactobacilli which produces lactic acid and thereby maintain a suitable low pH to destroy non-native bacteria and viruses
62
describe shape or transitional epithelium
surface cells vary in shape from columnar (non-distended) and cuboidal (distended)
63
where are transitional epithelial cells found
urinary urothelium
64
what are the functions on transitional epithelial cells
distensibility
protection of underlying tissue from toxic chemicals
65
what are microvilli
hair like projection that increase surface area available for absorption
66
what cells are microvilli found on
simple columnar
67
where are simple columnar with microvilli found
- stomach lining and gastric glands
- small intestine and colon
- gall bladder
- cervix
68
what are the function of simple columnar epithelial cells with microvilli
- absorption
- secretion
- protection
- lubrication
69
describe the structure of stratified squamous keratinised epithelium
multiple layers of cells which outermost are squamous cells that have lost their nuclei and cornified (become squames of keratin)
70
what are the outermost layers of stratified squamous keratinised epithelium called
stratum corneum
71
where are stratified squamous keratinised cells found
- surface of skin
- limited distribution
72
what are the functions of stratified squamous keratinised
- protection against abrasion and trauma
- prevent water loss
- prevent microbial ingress
- shielding against UV damage
73
describe structure of pseudostratified epithelia and position of nuceli
all cells make contact with basement membrane but not all reach epithelial cell surface (varying heights)
nuclei lying at different levels giving impression of multiple layers
74
where are pseudostratified found
- lining of conducting airway
- lining of male reproductive tract
75
what are the functions of pseudostratified epithelia
- secretion and conduit
- mucus secretion
- particle trapping
- absorption of excess fluid
76
what speacialisation are found on goblet cells
microvilli
release mucins through exocytocis
77
what gene is mutated in cystic fibrosis
CFTR ( cystic fibrosis transmembrane conductance regulator)
78
what does the mutation of the CFTR gene cause
deficiency of chloride ion causing sticky immovable mucus
79
how does CF affect airways
clogging and infection of bronchial passage with thick sticky mucus
obstructs breathing and damages lungs
80
how does CF affect liver
small bile duct becomes blocked and disrupts digestion
81
how does CF affect pancreas
zymogen secretion not released
82
how does CF affect small intestine
thick nonmotile stools
83
how does CF affect reproductive tract
absence of fine ducts so male infertility
female infertility: thick mucous plug in cervix prevents semen transit
84
how does CF affect skin
malfunction sweat glands very salt crystalline sweat
85
what is a serous membrane
bag like cavity which organs invaginate so become surrounded by outer and inner part of serous membrane ( like fist in ballon)
86
what organs are surrounded by serous membrane
heart, lungs, and gut
87
what is the visceral serosa of serous membrane
membrane closest to organ in cavity
88
what is the parietal serosa of serous membrane
membrane lines outer cavity
89
what do serous membranes line
- peritoneum
- pleural sacs
- pericardial sac
90
compare serous membrane and mucous membrane
mucous: lines internal tubes which open to exterior
serous: thin two part membrane which line closed body cavities
91
what are club cells
protect bronchioles and act as stem cells for respiratory epithelium
92
what are the functions of club cells
- protect bronchiolar epithelium (secretion of many products including uterglobin)
- detoxification of harmful substances inhaled
- act as stem cells
93
what are microfold cells and where are they found
cells with folded extension
found in small intestine and very close to lymphatic nodules
94
what are the functions of microfold cells
- trap pathogens and present them to:
- present to underlying dendritic cells that process materials
- present to lymphocytes and macrophages
95
what are stereocilia and where are they found
convert mechanical movement to electrical signal
found in inner ear
96
