Epithelia Flashcards Preview

Tissues of the body > Epithelia > Flashcards

Flashcards in Epithelia Deck (26)
Loading flashcards...
0
Q

Name the external surface of the body

A
  • Skin

- Cornea of the eye

1
Q

Define Epithelia

A

A sheet of contiguous cells of varied embryoinic origin which cover the external surface of the body and line the internal surfaces

2
Q

Name the interior spaces of the body which open to the environment

A
  • Gastrointestinal tract
  • Respiratory tract
  • Genitourinary Tract
3
Q

Name the interior spaces of the body which do not open to the environment

A
  • Pericardium
  • Pleural Sacs
  • Peritoneum
  • Blood Vessels
  • Lymphatics
4
Q

Which epithelia are of ectodermic origin?

A
  • Skin

- Cornea

5
Q

Which epithelia are of mesodermic origin?

A
  • All the interior spaces closed to the environment and the genitourinary tract
6
Q

Which epithelia are of endodermic origin?

A
  • Respiratory tract
  • GI tract
  • liver
  • Many glands
7
Q

What is the structure and function of the basement membrane?

A
  • A thin, flexible, acellular layer consisting of basal lamina and reticular fibres
  • It lies between epithelia and the underlying connective tissue and serves as a cellular and molecular filter as well as for adherence of epithelia
8
Q

Describe simple squamous epithelia, indicating their function and a named example

A
  • One layer thick flattened squamous cells
  • Allow diffusion in the alveoli
  • Line the body cavities and aid lubrication
  • Line the blood and lymph vessels and allow gas exchange and cell migration
  • Bowmans capsule - allow exchange
9
Q

Describe simple cuboidal epithelia, including their function and named example

A
  • Centrally located nuclei
  • Main function is for secretion
  • Small ducts of exocrine glands, eg pancreatic duct
  • Many glands, eg thyroid
  • collecting duct of nephrons
10
Q

Describe simple columnar epithelia, including its function and a named example

A
  • Basally located nuclei
  • main function is for absorption
  • GI tract, eg small intestine, colon, crypts of Lieberkhun, gall bladder
  • Fallopian tube, ciliated
  • Microvilli increase surface area
11
Q

Describe Pseudostratified epithelia, including its function and named example

A
  • One layer thick, however looks like many layers
  • Found in upper respiratory tract - ciliated to assist movement of mucus to immobilise particles and lubricate larynx. Goblet cells present
  • Form mucocillary esculator to eliminate trapped particles and pathogens
12
Q

Are epithelia vascular or avascular?

A

Avascular - receive nutrients via diffusion

13
Q

Describe Stratified Squamous non-keratinised epithelia, including its function and a named example

A
  • Multiple layers of squamous cells
  • Resist abraision
  • Reduces water loss
  • Found in Buccal Cavity and Oesophagus
  • Vagina and Anal Canal
14
Q

What is special about epiglottis epithelia?

A

-Lined with Stratified squamous on one side and Pseudostratified on the other

15
Q

What is special about the epithelia of the cornea?

A

-Lined with stratified squamous on the outside and simple squamous on the inside

16
Q

Why is it important that the vagina has a high source of glycogen?

A

Helps maintain the pH balance in the vagina as lactobacilli thrive under rich glycogen conditions. This maintains the pH and controls other bacteria

17
Q

Why are there no goblet cells in the narrower tracts of the respiratory tract?

A
  • Goblet cells produce mucus
  • If mucus was secreted in these narrow lumens they would become blocked
  • cells secrete surfactant instead
18
Q

Describe keratinised stratified squamous epithelia, including its function and a named example

A
  • Skin
  • Multiple layers of cells. Cells at the apical membrane loose their nucleus and die due to lack of nutrients, water loss and keratin
  • Resists abrasion
  • Prevents water loss
  • Barrier to microbes
  • Curved edge on basolateral side of epidermis stops shearing
19
Q

Describe transitional epithelium, including its function and a named example

A
  • Multiple layers
  • Distensibility
  • Protection from toxic chemicals
  • Urothelium (found only in urinary tract), eg ureter, urethra, renal calyces
20
Q

How often is the epithelia of the skin renewed?

A
  • From the basal layer through differentiation, migration, keratinisation and shedding it is approximately 28 days
21
Q

How often is the epithelia of the small intestine renewed?

A
  • Every 4-6 days by regenerative cells in the base of the crypts
22
Q

What are cilia?

A
  • Actin extensions which protrude from the cell and are use to mobilise particles for extrusion
23
Q

What are microvilli?

A
  • Apical extensions which greatly increase surface area for selective absorption
  • Also known as ‘brush border’
24
Q

What is metaplasia?

A
  • Epithelia which are under stress undergo a change from one cell type to another in order to better cope with its surroundings
  • eg pseudostratified to stratified squamous in heavy smokers
25
Q

What is neoplasia?

A
  • Tumour formation, specifically known as carcinoma in epithelia
  • Benign tumours represent cellular origin
  • Malignant tumours have an altered cellular structure