5) Glands

Question 1

Define a gland

Answer 1

An epithelial cell or aggregate of epithelial cells that are specialised for the secretion of a substance

Question 2

Define secretion

Answer 2

The production and release of material from epithelial cells or an aggregate of epithelial cells

Question 3

How are glands typically classified?

Answer 3

1) Structure

2) How they secrete their product

Question 4

What are endocrine glands?

Answer 4

Glands that secrete hormones directly into the blood flowing through them into distant parts of the body

Question 5

What are exocrine glands?

Answer 5

Glands that secrete substances, typically lubricants and enzymes, into ducts

Question 6

What is a benefit of a gland secreting it’s product directly into the bloodstream?

Answer 6

This allows the secretion to function at distant parts of the body

Question 7

Which cells secrete hormones?

Answer 7

All epithelial cells in endocrine glands

Question 8

Which cells secrete enzymes and lubricants ?

Answer 8

Cells at the apex of the duct in exocrine glands

Question 9

What types of epithelial cells are present in endocrine glands?

Answer 9

Simple cuboidal epithelial cells

Question 10

What type of epithelial cells are present in exocrine glands?

Answer 10

Simple cuboidal epithelial cells

Complex epithelial cells

Question 11

How are endocrine glands generated?

Answer 11

1) Mesenchymal cells under the epithelium produce fibroblast profactors (typically 7 & 10), which causes the epithelial cells to grow towards the mesenchymal
2) As the epithelial cells grow they produce multiple enzymes that breakdown the extracellular matrix (connective tissue) that surrounds the mesenchymal, allowing the cell room to grow
3) Central cells and surface cells die during programmed cell deat or apoptosis, forming a duct i the middle
4) As the duct elongates the apical cells differentiate and change function, allowing them to begin secreting substances

Question 12

How are exocrine glands generated?

Answer 12

1) Mesenchymal cells under the epithelium produce fibroblast profactors (typically 7 & 10), which causes the epithelial cells to grow towards the mesenchymal
2) As the epithelial cells grow they produce multiple enzymes that breakdown the extracellular matrix (connective tissue) that surrounds the mesenchymal, allowing the cell room to grow
3) Aniogenic factors are produced (growth factor 1), which causes the development of blood vessels between and around the epithelial tissue
4) Apoptis occurs, causing thduct cells to dissapear and the gland to separate from the epithelial tissue.
5) The tissue moves away from the epithelial surface and proliferates

Question 13

What are mesenchymal cells?

Answer 13

Cells that we dont know the function of

Question 14

How do limbs form?

Answer 14

Mesenchymal cells produce epidural profactors qhich caus ethe epithelial cells to grow away from the mesenchymal

Question 15

What enzymes are produced by the epithelial cells during the generation of glands?

Answer 15

Lipase - breaks down lipids
Elastase - breaks down elastin
Collagenase - breaks down collagen
Plasmin - breaks down fibrin

Question 16

What are the 4 ways of gland secretion?

Answer 16

Merocrine
Apocrine
Holocrine
Cytocrine

Question 17

What is merocrine secretion?

Answer 17

The fusion of vesicles with the apical membrane which is then released by epithelial cells or glands

Question 18

What is apocrine secretion?

Answer 18

The partial loss of the top of the cell or the cytoplasm which is lost into the duct (therefore exocrine secretion)

Question 19

What is holocrine secretion?

Answer 19

The complete loss of the cell cytoplasm

Question 20

What is cytocrine secretion?

Answer 20

The release of the entire cell

Question 21

Define exocytosis

Answer 21

The secretion of molecules outside of the cell via a vesicles fusing to a membrane

Question 23

Define endocytosis

Answer 23

The engulfing of molecules inside of the cell via vesicle formation

Question 25

Why is exocytosis important?

Answer 25

To prevent the cell from bursting after endocytosis

Question 25

What is phagocytosis and which cells use this process?

Answer 25

The process by which cells envelop or engulf other cells or particles
Mainly used by cells of the immune system

Question 25

What is pinocytosisis and which cells use this process?

Answer 25

The process in which liquid droplets are ingested by cells

Used by all cells but particularly smooth muscle

Question 26

How does branching and/or elongation of glands occur?

Answer 26

1) Basic growth factors (FGF10) are released by mesenchymal cells
2) The epithelial cells move towards the signal
3) Different growth factors are active or inactive resulting in tubule elongation and branching