5. Glands

Question 1

What is the definition of a gland?

Answer 1

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

Question 2

What is secretion?

Answer 2

Production and release by a cell or aggregate of cells

Question 3

Where do glands receive their stimuli from?

Answer 3

From the brain (CNS) and chemicals in blood and from neighbouring cells

Question 4

What are endocrine glands?

Answer 4

Ductless
Secrete directly into the blood
Release hormones

Question 5

Describe the pituitary gland

Answer 5

Endocrine
Anterior - produces hormones that regulate most glands of endocrine, prolactin which stimulates milk production, somatrophin regulates body and tissue growth
Posterior - produces vasopressin that prevents water loss from kidneys oxytocin signals uterus for delivery

Question 6

Describe the thyroid gland

Answer 6

Produces thyroid hormones T3 and T4 that control metabolism
Produces calcitonin involved in calcium homeostasis
Endocrine

Question 7

Describe the parathyroid gland

Answer 7

Produces parathyroid hormones, calcium homeostasis

Endocrine

Question 8

What are exocrine glands?

Answer 8

Ducted

Secrete into a location or region of body through a duct, secretions are mostly enzymes or lubricants

Question 9

Describe the salivary gland

Answer 9

In buccaneers cavity secrete saliva
Function of saliva include partial digestion of food and lubrication
Exocrine

Question 10

Describe the pancreas

Answer 10

Secretes enzymes - amylase, trypsin and lipase - that digest carbs, proteins and fats
Exocrine

Question 11

Describe the mammary glands

Answer 11

Produces colostrum and milk in response to prolactin and oxytocin to nourish neonates
Exocrine

Question 12

Describe the sweat glands

Answer 12

Secrete sweat which regulates body temp and excretion

Exocrine

Question 13

Describe the sebaceous gland

Answer 13

Secretes sebum onto skin an in ear to protect tissues from pathogens
Exocrine

Question 14

Describe the lachrymal glands

Answer 14

In eyes, secrete water to moisten cornea
Produces lysozyme
Exocrine

Question 15

Which cells in the gland secrete products?

Answer 15

Epithelial cells

Only cells at apex of duct

Question 16

When does the generation of glands begin in utero development?

Answer 16

Week 4-5

Question 17

Describe the 5 stages of generation of glands in utero development

Answer 17

1. Growth signal received
2. Proliferation of daughter cells occurs and extracellular protein degradation enzymes produced
3. Epithelial cells invade space created
4. Exocrine gland: central cells die off to produce duct
5. Endocrine gland: produce angiotensin factors to stimulate blood vessel growth in and around epithelial cells, link to mother cells broken by apoptosis

Question 18

What are the 2 types of epithelial cells in exocrine glands?

Answer 18

Cells lining ducts

Cells that make secretory products

Question 19

What happens to some cells at secretory end of ducts?

Answer 19

Change into myoepithelial cells

Question 20

What are myoepithelial cells?

Answer 20

Have features of both epithelial cell and smooth muscle cell

Help to eject secretions from duct

Question 21

What are the 2 types of secretion from salivary glands?

Answer 21

Mucous

Serous

Question 22

What are merocrine glands?

Answer 22

Fusion of vesicles with apical membrane (form of exocytosis)

E.g. pancreas

Question 23

What re the 2 pathways of merocrine glands?

Answer 23

Regulated secretion (needs Ca2+ ions to work), e.g. beta cells of pancreas
Constitutive secretion (secretory product in vesicles and released continuously)

Question 24

What are apocrine glands?

Answer 24

Partial loss of cytoplasm

E.g. lactating mammary gland, sweat glands in axilla (armpit), external genitalia

Question 25

What are the holocrine glands?

Answer 25

Complete loss of cytoplasm or cell | E.g. sebaceous gland in skin and tarsal glands in eyelid

Question 26

How do holocrine glands work?

Answer 26

Secretory cell gradually fills with secretory granules, cell organelles degenerate, cell dies, plasma membrane breaks and contents empty, dead cells replaced by mitotic division of basal cells

Question 27

What is the role of Golgi in secretion?

Answer 27

Proteins move from RER to cis face of Golgi Golgi modifies the protein and glycosylation takes place where sugars are added Glycoproteins leave the trans face of Golgi via vesicles

Question 28

What is the definition of glycosylation?

Answer 28

Covalent attachment of sugars by enzymes to proteins and lipids to form glycoproteins and glycolipids

Question 29

What is the role of glycosylation?

Answer 29

Aid protein folding Prevent protein/lipid digestion by intracellular proteases/lipase Cells recognition (blood groups) Cell to extracellular matrix attachment

Question 30

What is glycation?

Answer 30

Covalent attachment of sugars to proteins and lipids to form glycoproteins and glycolipids without the use of enzymes

Question 31

What is the definition of exocytosis?

Answer 31

Secretion of molecules outside the cell via a vesicle fusing to a membrane

Question 32

What is the definition of endocytosis?

Answer 32

Engulfing of molecules inside the cell via vesicle formation

Question 33

What is the definition of phagocytosis?

Answer 33

Process by which cells envelop or engulf other cells or particles

Question 34

What is the definition of pinocytosis?

Answer 34

Process in which liquid droplets are ingested by cells, used especially by smooth muscle cells

Question 35

What are the 4 types of transepithelial transport (transcytosis)?

Answer 35

- Molecules can move through aqueous channels in intercellular junction - Can move through lipid cell membranes - Molecules with appropriate characteristic may be transported by carrier proteins - Pit system

Question 36

Describe the pit system

Answer 36

Molecules that are impermeable may bind to cell surface receptors, be engulfed by cell membrane, then released inside cells or expelled via membrane-limited vesicles

Question 37

What are the 4 types of glandular control

Answer 37

Humoral stimulus through feedback loops Hormonal stimulus Neural stimulus (adrenaline and noradrenaline) Neurocrine communication (hypothalamus to pituitary)