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BY153 - Human Physiology > Epithelia > Flashcards

Epithelia Flashcards

1
Q

Name the 4 fundamental tissue types. Name the function of each.

A
  • connective tissue = supportive/packing
  • epithelium = lining/barrier
  • muscular = contractile
  • nervous = Action potential/transmission
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2
Q

Define the term “epithelia”.

A

Epithelia is a cohesive sheet of epithelial cells that separate the external environment from the internal environment of the body.

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3
Q

What’s the term for internal facing epithelial tissue?

A

Endothelium

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4
Q

What’s the term for external facing epithelial tissue?

A

Epithelium

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5
Q

What are the 3 types of cells that epithelia are derived from?

A

ectoderm, mesoderm, endoderm

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6
Q

Connective tissue is only derived from ——.

A

Mesoderm

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7
Q

Give examples of external-facing surfaces and internal-facing surfaces made from epithelial cells.

A

Internal facing - Blood vessels
External facing - Mouth, Bladder

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8
Q

Name two surfaces found in most epithelia.

A

Free surface and Basal surface

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9
Q

What is the function of the basal membrane?

A

The function of the basal membrane is to separate the epithelia from all other tissues including its own blood supply.

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10
Q

Name the 5 functions of epithelia—name examples where each of the functions works.

A
  1. Barrier
    skin prevents water loss and entry
  2. Protection
    outer layer of skin and oral cavity
  3. secretion
    sweat glands
  4. absorption
    gut epithelia
  5. permitting the passage of substances
    Pulmonary alveoli diffusion of O2 and CO2
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11
Q

Name and describe the 3 classifications of epithelia by layers.

A
  1. Simple epithelia
    one layer of cells all in contact with the basal membrane
  2. Stratified epithelia
    two or more layers of epithelial cells where only the lowest layer is in contact with the basement membrane
  3. Pseudostratified epithelia
    simple epithelia that looks stratified but all the cells are in contact with the basement membrane.
    the nuclei are at different levels.
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12
Q

Name the 3 classifications by shape.

A
  1. squamous
  2. cuboidal
  3. columnar
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13
Q

Describe the appearance of simple squamous epithelium.

A

A single layer of very flat cells
minimal cytoplasm which is nearly invisible

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14
Q

Name 3 functions of simple squamous epithelium. Give examples.

A
  1. Diffusion
    eg: pulmonary alveoli
  2. Filtration
    eg: Bowman’s capsule in the kidney
  3. Lining
    eg: Heart (endocardium), Blood Vessels (Endothelium)
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15
Q

Describe the appearance of simple cuboidal epithelium.

A

the cell height is similar to the cell width
rounded,centred nuclei

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16
Q

Name 2 functions of simple cuboidal epithelium.

A

Active transport
Facilitated diffusion (Secretion and Absorption)

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17
Q

Name 2 features that some simple cuboidal epithelium may have. Why?
Where are the 2 named features found?

A

Cillia - To move the mucus over the surface
Microvilli - to increase surface area

Kidney tubules, Choroid plexus(CSF), Lining of ducts of many glands (salivary glands, pancreas and thyroid follicles), respiratory tract

18
Q

What is the choroid plexus?

A

A network of blood vessels in the ventricles of the brain, producing CSF.Cerebrospinal fluid).

19
Q

Name all the types of epithelium that may have cilia or microvilli. *

A

Simple cuboidal epithelium, simple columnar epithelium, pseudostratified columnar

20
Q

Describe the appearance of simple columnar epithelium.

A

Cell height is greater than cell width
(in practical at least twice the height)
Elongated (oval) nuclei towards the base of the cell

21
Q

Name 2 features of some columnar epithelium.

A

Cilia
Microvilli

22
Q

Features of simple columnar epithelium

A

Contains numerous organelles to support complex functions (secretion and absorption)

23
Q

Where is simple columnar epithelium found?

A

Found in some glands
bronchioles of lungs
fallopian tubes
small and large intestines

24
Q

What is stratified squamous epithelium?

A

Stratified squamous epithelium is a type of tissue composed of multiple layers of cells with a cuboidal base layer that gradually flattens towards the surface.

25
Q

What is the function of stratified squamous epithelia?

A

Stratified squamous epithelium protects against abrasion, caustic substances, water loss and infection

26
Q

State the features of unkeratinised stratified squamous epithelia.
Give an example

A

Moist
Oxygen is available to it
All cells are alive
eg; pharynx

27
Q

State the features of keratinised stratified squamous epithelia.
Give an example

A

Surface layer - dead, dried, scale like flakes
eg: skin epidermis

28
Q

Describe the appearance of pseudostratified columnar epithelium
Name example of where it could be found.

A

All cells in contact with BM
Not all cells have a free surface
Appear stratified because nuclei are at different levels
mostly ciliated and associated with mucus producing cells - goblet cells
it synthesises, secretes and moves mucus on the epithelium free surface
found in nasal cavity and bronchi

29
Q

Name all the types of epithelia studied in this section

A

simple squamous
simple cuboidal
simple columnar
stratified squamous
pseudostratified columnar

30
Q

What is transitional epithelium and what is its unique characteristic?

A

Transitional epithelium is a specialized stratified epithelium. It can be stretched without loss of function

31
Q

Where does transitional epithelium typically line?

A

Transitional epithelium lines cavities that expand, such as the urinary bladder.

32
Q

What is the function of transitional epithelium?

A

The primary function of transitional epithelium is to enable tissue to expand and contract.
in the case of the urinary bladder, it is to protect underlying tissue from corrosive urine.

33
Q

How does transitional epithelium appear in its unstretched state?

A

Five or more layers of cuboidal or columnar cells

Often cuboidal, with a ‘dome-shaped free surface – each cell overlaps underlying cells

Middle layers are composed of round/pear-shaped cells

Bottom layer cubical – cone-shaped cells that rest on an incomplete basement membrane

34
Q

How does transitional epithelium appear in its stretched state?

A

In its stretched state,
- the number of cell layers decreases
- the cells become more flattened, transitioning from cuboidal to squamous in shape.

35
Q

What are the two types of glandular epithelium?

A

Endocrine and exocrine glands

36
Q

What is the difference between endocrine and exocrine glands?

A

Endocrine glands are ductless and secrete their products directly into the bloodstream
Exocrine glands secrete their products to the exterior of the body through ducts.

37
Q

How are exocrine glands classified?

A

Exocrine glands can be classified based on their structure or method of secretion.

38
Q

What are the two types of secretory units in exocrine glands?

A

The two major shapes of secretory units in exocrine glands are tubular and globular shaped.

39
Q

What are some examples of modified epithelium and their functions?

A

Germinal epithelium: It produces gametes in the ovaries and testes.

Sensory epithelium: Found in the retina and taste buds, it receives and conveys stimuli.

Myoepithelium: Located in salivary glands and their ducts, these cells contain actin and myosin filaments and contract to release secretory products from the glands.

Pigmented epithelium: Present in the retina, the cells contain colored melanin pigment granules.

Ependymal epithelium: It forms the lining in the cavities of the brain and spinal cord, and the cells are ciliated.

Cuticular epithelium: It secretes the cuticle, which is the tough resistant non-cellular protective layer of the body in invertebrates.

40
Q

Define gland

A

One or more cells that synthesise or secrete an aqueous fluid.

41
Q

Exocrine glands are connected to surface epithelia by ducts. name the 2 types and how they’re connected.

A

Simple duct: each duct is connected to a single secretory unit

Compound duct: numbers of ducts from secretory unit unite to form a large duct

BY153 - Human Physiology (12 decks)

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