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BODY LOGISTICS > Epithelial Cells and Surface Specialisation > Flashcards

Epithelial Cells and Surface Specialisation Flashcards

1
Q

Definition of epithelial cells

A

Epithelia are:
Sheets of contiguous cells, of varied embryonic origin, that cover the external surface of the body and line internal surfaces, including the body’s vessels

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2
Q

What are the Embryologic origins of the epithelial cells

A

Epithelial tissues are derived from all of the embryological germ layers: from ectoderm (e.g., the epidermis)
from endoderm (e.g., the inner and outer lining of the gastrointestinal tract) from mesoderm (e.g., the inner linings of body cavities)

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3
Q

What are the three surfaces with epithelial linings and give examples

A

Exterior surface:
eg, skin
Interior spaces opening to exterior:
eg, gastrointestinal tract respiratory tract genitourinary tract
Interior spaces which do not open to the exterior:
eg, pericardial sac, pleural sacs, peritoneum
blood vessels, lymphatic vessels

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4
Q

What are the two cell types of epithelial cells

A

SIMPLE and STRATIFIED / COMPOUND

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5
Q

What are simple epithelial cells and give an example

A

SIMPLE - (one cell layer thick)
SQUAMOUS
CUBOIDAL
COLUMNAR
PSEUDOSTRATIFIED

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6
Q

What are STRATIFIED / COMPOUND epithelial cells and give examples

A

STRATIFIED / COMPOUND - (more than one cell layer
thick)
SQUAMOUS
CUBOIDAL
COLUMNAR
TRANSITIONAL

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7
Q

What is the structure of transitional epithelia

A

Cuboidal cells - Bottom attached to the basement membrane
Columnar cells - Middle
Umbrella cells - Top, Stops urine coming into body

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8
Q

Do all cells make contact with basement membrane, in the Pseudostratified Columnar

A

YES,
Despite nuclei looking like they are in different levels all cells make contact with basement membrane.

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9
Q

What is the position, structure and function of the basement membrane ?

A
  • The basement membrane can be found in almost every tissue and can either lie underneath endothelial and epithelial cells, separate cells from the underlying connective tissue, or surround cells.
  • Basement membranes are thin layers of a specialized extracellular matrix that form the supporting structure on which epithelial and endothelial cells grow
  • The basement membrane acts as a filter, Thus large molecules can’t get through (eg, RBC) unless there is a hole
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10
Q

basal lamina + reticular layer =

A

Basement membrane

(Basement membrane = basal lamina + reticular layer)

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11
Q

What are endothelial cells

A

Endothelial cells form a single cell layer that lines all blood vessels and regulates exchanges between the bloodstream and the surrounding tissues

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12
Q

What are epithelial cells

A

Epithelial cells are a type of cell that covers the inside and outside of the surfaces of your body
(Organs and Body)

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13
Q

What is the function of Simple squamous epithelia
Give examples

A

Fast material exchange, Barrier to fluids and Tissue lubrication

Fast Material exchange
- vasculature and lymphatics, respiratory space in the lung
Gas exchange (Type 1 pneumocytes of pulmonary alveoli)
-Water, nutrient and waste product exchange (endothelial cells lining heart & capillaries)

Barrier
- Barrier in the brain and CNS (Without Oedema can cause swelling)
- Bowmans Capsule Barrier
skin, oesophagus, conjunctivae of eye,)

Tissue Lubrication
- Serosa of the lungs, heart, and viscera tissue lubrication
(pericardium, pleural membranes, peritoneum/viscera) - (collectively known as mesothelium)

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14
Q

What is Serosa

A

-Lining is called Serosa which produces a fluid (exudate)
-This lubricates tissue
-This ensures all is smooth when breathing ( lungs - Ribs Lubrication)

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15
Q

What is the Simple Cuboidal

A

Simple cuboidal:
a single layer of polygonal cells, whose height and width are approximately equal

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16
Q

How is metabolism regulated in the Thyroid gland

A
  • Simple cuboidal epithelium bounding thyroid gland follicles.
  • Each follicle is approximately spherical.
  • The epithelial cells synthesise thyroglobulin and store in the centre of the follicle (colloid).
  • Only organ (Thyroid Tissue) that stores its product outside of the cells.
  • Reprocess thyroglobulin to produce thyroxine and release that into the blood (hormone)
  • This hormone regulates metabolism
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17
Q

Why is there a very thick pink ring around each tubal in the collecting ducts of the kidney.

A

The very thick pink ring around each tubal = very thick basement membrane
Prevents fluid accumulation in the surrounding connective tissue layer

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18
Q

What is the function of the SIMPLE CUBOIDAL epithelium and where

A

1.Absorption & Conduit
(exocrine glands)
2.Absorption & Secretion
(kidney tubules)
3.Barrier/covering
(ovary)
4.Hormone synthesis, storage and mobilisation
(thyroid)

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19
Q

What is the Simple Columnar

A

Simple columnar:
A single layer of cells, whose heights are significantly greater than their widths

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20
Q

Where are Simple Columnar Epithelium found
(In the GI tract)

A

Simple columnar epithelium lining the crypts of Lieberkühn (intestinal glands) in the mucosa of the colon.

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21
Q

What are vacuoles used for in goblet cells

A

Vacuoles are actually secretory vesicles in the goblet cells that produce mucins and water = mucus

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22
Q

What is the main function of the GI tract

A
  • Absorption of nutrients
  • Movement of lumen contents
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23
Q

What do Microvilli do

A

They increase the surface area available for absorption

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24
Q

How can you see Microvilli and why

A

Can only be seen with Electron Microscopes
Cant be seen by light microscopes due to “limit of Resolution”

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25
Q

What is the location of SIMPLE COLUMNAR epithelium

A

Locations include:
Stomach lining & gastric glands Small intestine & colon
Gallbladder

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26
Q

What is the function of SIMPLE COLUMNAR epithelium and where do they occur

A

Functions include:
Absorption
(small intestine and colon, gallbladder)
Secretion
(stomach lining & gastric glands, small intestine and colon)
Lubrication
(small intestine and colon)

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27
Q

What is the Pseudostratified epithelia

A

Pseudostratified epithelia are tissues in which all cells make contact with the basement membrane, but not all of the cells reach the epithelial cell surface.

This results in nuclei lying at different levels giving the impression of multiple cell layers.

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28
Q

What is the mucociliary escalator/elevator

A

In the Upper repository tract there is
Pseudostratified ciliated epithelium of the trachea.
The cilia beat at 12 Hz within a watery solution exuded by the epithelium.
Above this is a viscoelastic mucous blanket, secreted by the goblet cells, which immobilises particles and lubricates their passage to the pharynx, where they are swallowed.

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29
Q

What are mucin glycoproteins

A

Mucins are glycoproteins that represent the major secreted products of the gastrointestinal tract

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30
Q

What do goblet cells do

A
  • Goblet cells lack of cilia on the apical surface
  • Instead have microvilli
  • Release of mucins through exocytocis
  • Water release increased by release of
    ions
31
Q

What is Cystic Fibrosis

A

Deficiency of chloride ion release results in very sticky and immovable mucous – characteristic of cystic fibrosis due to mutation in CFTR gene

32
Q

What is the job of the CFTR
(cystic fibrosis transmembrane conductance regulator)

A

The job of the CFTR is to put chloride ions onto the surface of the cell.
As It does this it takes water with it
Water + Mucus = less Stickiness
With Cystic fibrosis, less Chloride ions
thus less water
thus more sticky immovable mucus

33
Q

How is Cystic Fibrosis treated

A
  1. medicines to make the mucus in the lungs thinner and easier to cough up.
  2. Physiotherapists bangs on chest to move mucus up to mouth where it can be swallowed or spit out.
34
Q

Where do you find cystic fibrosis and what does it do in those areas

A

Airways
* clogging and infection of bronchial passage with thick sticky mucus obstructs breathing, progressively damages lungs – major cause of mortality in CF patients
Liver
* the small bile duct becomes blocked, disrupts digestion in 5% of CF patients
Pancreas
* zymogen secretions not released in 85% of patients (no lipid digestion)
Small intestine
* thick, non-motile stools in 10% of CF neonates - requires surgery
Reproductive tracts
* absence of fine ducts such as vas deferens renders 95% of CF males infertile. Occasionally, a thick mucous plug in cervix prevent semen transit and results in female infertility
Skin
* malfunctioning of sweat glands results in very salty sweat and crystals on the surface of the skin

35
Q

Where do you find PSEUDOSTRATIFIED epithelium

A

Locations include: Lining of nasal cavity, trachea and bronchi

36
Q

What is the function of PSEUDOSTRATIFIED epithelium

A

Functions include:
Secretion and conduit (respiratory tract, ductus deferens) Mucus secretion (respiratory tract)
Particle trapping and removal (respiratory tract)

37
Q

What is the Stratified squamous epithelia

A

Stratified squamous epithelia
contain multiple layers of cells, the outermost of which are thin squamous epithelial cells

38
Q

How are the cells held together in Stratified squamous epithelia

A

Desmisomes

39
Q

What type of area are Stratified squamous non-keratinised
epithelia are found

A

Stratified squamous non-keratinised
epithelia are found in areas that are moist and subject to varying degrees of abrasion

40
Q

How does the Stratified squamous non-keratinised
epithelia maintain a low Ph in the vagina
what is the point for the lower PH

A

The cells are rich in glycogen, a substrate for lactobacilli, which produce lactic acid and thereby maintain a suitably low pH
- helps to destroy non-native bacteria and viruses

41
Q

What are some of the locations of STRATFIED SQUAMOUS NON-KERATINISED epithelium

A

Locations include:
Oral cavity
Oesophagus
Vagina
Part of anal canal
Surface of cornea
Inner surface of eyelid

42
Q

What is the function of STRATFIED SQUAMOUS NON-KERATINISED epithelium

A

Functions include:
Protection against abrasion (all sites)
Reduces water loss but remains moist (all sites)

43
Q

What is the Stratified squamous keratinised epithelium

A

Stratified squamous keratinised epithelium
contains multiple layers of cells,
the outermost of which are squamous cells that have lost their nuclei and cornified
(i.e. become
‘squames’ of keratin).

44
Q

What is the outer most layer called ,( what is it and what is the purpose in) Stratified squamous keratinised epithelium

A

The outermost dead cells of this epithelium are collectively called the Stratum Corneum

This layer
- greatly reduces water loss and
ingress
- prevents ingress of toxins
- protects against abrasion
- reduces microbial colonisation

45
Q

what is the primary site for the stratified squamous keratinised epithelium

A

The epidermis of the skin is the primary site of stratified squamous keratinised epithelium

46
Q

Is the epidermis avascular

A

Yes, (like all epithelia epidermis contains no blood vessels – it is avascular)

47
Q

What is the structure of the dermis layer

A

Dense irregular connective tissue, consisting of collagen and elastin bundles orientated in all directions;
leather is made out of dermis

48
Q

What is the location of STRATFIED SQUAMOUS KERATINISED epithelium

A

Locations include:
Surface of skin
Limited distribution in oral cavity

49
Q

Functions of STRATFIED SQUAMOUS KERATINISED epithelium -(4)

A

1.Protection against abrasion and physical trauma 2.Prevention of water loss
3.Prevention of microbial ingress
4.Shielding against UV light damage

50
Q

What is another name for TRANSITIONAL epithelium

A

urothelium

51
Q

What is the shape of cells in TRANSITIONAL epithelium

A

surface cells vary in shape from columnar/cuboidal to flattened

52
Q

Location of Transitional epithelium (urothelium)

A

Urinary tract:
from renal calyces –> ureters –> bladder –> Proximal urethra

53
Q

Function of the Transitional epithelium (urothelium)

A

Distensibility (The capability of being distended or stretched under pressure)
Protection of underlying tissue from toxic chemicals (Urea dentures proteins)

54
Q

What is a Serous Membrane

What is its function

A

During embryonic development the heart, lungs, and gut develop next to a bag-like cavity into which they invaginate. So they each become surrounded by serous membrane that has an inner (Visceral Serosa) and
outer part (Parietal Serosa).

It allows the frictionless movement of the heart and lungs, as well as the organs of the abdominal cavity.

55
Q

What is the Visceral serosal

A

Visceral serosal membrane closest to organs in cavity

56
Q

What is the Parietal serosal

A

Parietal serosal membrane lines outer edge of cavity

57
Q

What is between the Visceral serosal and the Parietal serosal

A

The pleural cavity is a space between the visceral and parietal pleura. The space contains a tiny amount of serous fluid.
The serous fluid continuously lubricates the pleural surface and makes it easy for them to slide over each other during lung inflation and deflation.

58
Q

Comparison of mucous and serous membranes
- What are they
- Where are they found
- What do they consist of

A

MUCOUS MEMBRANES line certain internal tubes which open to the exterior, for example:
* the gastrointestinal tract
* the respiratory tract
* the urinary tract
(these mucosae bear mucus-secreting cells to varying degrees)
A MUCOUS MEMBRANE consists of:
* an epithelium lining the lumen of a tube (type depends on site)
* an adjacent layer of connective tissue often referred to as the lamina propria (literally ‘one’s own layer ’)
* a third layer consisting of smooth muscle cells, referred to as the muscularis mucosae
* (also carries blood and lymphatic vessels and nerves)
SEROUS MEMBRANES are thin, two-part membranes which line certain closed body cavities (spaces which do not open to the exterior) and envelop the viscera
They line:
* the peritoneum……which envelops many abdominal organs.
* the pleural sacs……..which envelop the lungs.
* the pericardial sac…..which envelops the heart.
These serous membranes (or serosae) exude a lubricating fluid that promotes relatively friction-free movement of the structures they surround.
A SEROUS MEMBRANE consists of:
* a simple squamous epithelium (mesothelium) that exudes the
watery lubricating fluid
* a thin layer of connective tissue that attaches the epithelium to
adjacent tissues
* (also carries blood and lymphatic vessels and nerves)

59
Q

What do these do …

Keratin
Cilia
Goblet cells
Microvilli
Club cells
Microfold cells
Stereocilia

A
  • Keratin – prevents water loss and protects against abrasion
  • Cilia – controls micro-movement of luminal contents
  • Goblet cells – mucus secretions, moistens and lubricates
  • Microvilli – increases surface area for absorption and secretion
  • Club cells – (previously known as Clara cells) protect bronchioles and acts as stem cells for respiratory epithelium
  • Microfold cells – allows rapid sampling of gut microflora
  • Stereocilia – in the auditory system coverts pressure waves into electrical signals
60
Q

Club (Clara) cell structure and location

A

On the airway side of the terminal bronchioles and have club like apical surfaces, no cilia and no basal bodies

61
Q

Function of Club (Clara) cells

A

To protect the bronchiolar epithelium
* Secretion of a small variety of products, including club cell
secretory protein uteroglobin, and a solution similar in composition to pulmonary surfactant

Detoxification of harmful substances inhaled into the lungs * Accomplish this with cytochrome P450 enzymes found in
their smooth endoplasmic reticulum

Act as a stem cell, multiplying and differentiating into ciliated cells to regenerate the bronchiolar epithelium

62
Q

Where are microfold cells found

A

Found only in the small intestine and very close to lymphatic nodules

63
Q

What is the function of microfold cells

A
  1. Trap pathogens and other molecules
  2. Present to underlying dendritic cells that
    process material and
  3. Present to lymphocytes and macrophages that
    reside in a basal ‘pocket’ that is not linked to the basement membrane to raise an immune response or digestions, respectively
64
Q

What is the strength and weakness of Microfold cells

are they attached to the basement membrane

A

Although M cells are important for the generation of a strong immune response, they also represent a weak point in the intestinal epithelium as many pathogens exploit them as a portal of entry

they are not attached to the basement membrane.

65
Q

Where is stereocilia found and what does it do

A
  • In the inner ear, stereocilia are the mechanosensing organelles of hair cells, which respond to fluid motion for hearing and balance
  • In the epididymis and vas deferens (sperm duct) , stereocilia facilitate absorption of the residual sperm body after spermiation has completed
  • Stereocilia contain actin and myosin filaments (just like cilia) and so could be involved in sperm movement along these ejaculatory ducts
66
Q

What happens in early stages of smoking

A

Early stage
1. Normal mucus layer thickens
2. Cilia die off
3. Ciliagenesis – 2 to 4 days

67
Q

What happens in the ironic stages of smoking

A

Chronic stage
1. Goblet cells and basal cells proliferate
2. Club cells (metaplasia- cancer) or die
3. Carcinogens induce mutations and malignancy
4. Pneumocytes in the alveoli die
* Remaining type II cells proliferate to make both type I and II pneumocytes
* Fibroblasts lay down scar tissue

68
Q

What are the cell renewal rates

A

Cell renewal rates:
Trachea - 1 to 2 months
Alveoli - 8 days
Goblet cells - 10 days
Club cells - never (once they die or undergo morphogenesis)

69
Q

What are 5 common respiratory conditions

A

Acute bronchitis
Chronic bronchitis
Emphysema
COPD
Asthma

70
Q

What is Acute bronchitis

A

Acute bronchitis
– cough and mucus production, breathlessness < 3 months
Reduced lung function and breathlessness due to inflammation, swelling and narrowing of the lung airways and excess mucus in the lung passages
Later stage - Increased risk of serious respiratory diseases

71
Q

What is Chronic bronchitis

A

Chronic bronchitis - chronic inflammation of the bronchi that produces a cough and mucus production that has at least 2 episodes of
cough lasting 3 months or more during a 2 year period (smoker’s cough)
* Reduced lung function and breathlessness due to inflammation, swelling and narrowing of the lung airways and excess mucus in the lung passages
* Start of or irreparable damage to the bronchioles and alveoli

72
Q

What is Emphysema

A

Emphysema – shortness of breath due to permanent widening of the airspaces distal to the terminal bronchiole without fibrosis (i.e. destruction of the air sacs)
* Damage to air sac, loss of elastic recoil and permanent changes to the size of the alveoli (fuse and enlarge)

73
Q

What is COPD

A

COPD – chronic obstructive pulmonary disease – umbrella condition that includes both emphysema and chronic bronchitis

74
Q

What is Asthma

A

Asthma - wheeze, shortness of breath, chest tightness and cough that may vary over time and in intensity, with a variable expiratory airflow limitation * often has a trigger (e.g. cold, exercise, allergens, stress, etc.)
Caused by bronchospasm (tightening of the smooth muscle layer in the bronchi and bronchioles), obstruction from mucus and narrowing of the conducting airways

BODY LOGISTICS (16 decks)

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