Anatomy and embryology

Question 1

What are the regions of the pituitary gland?

Answer 1

anterior pituitary = adenohyphysis/pars distalis
Posterior pituitary = neurohyphysis/pars nervosa

Question 2

What is the hypophysis?

Answer 2

pituitary gland

Question 3

Describe the location of the pituitary gland

Answer 3

Outside BBB - needs to be able to communicate with bloodstream

Question 4

where does the sections of the pituitary gland develop from?

Answer 4

adenohypophysis/anterior = ectoderm from roof of mouth (Rathke’s pouch)
neurohypophysis/posterior = downgrowth of ectoderm of forebrain

Question 5

What is the embryological origin of the brain?

Answer 5

Neural folds move together and fuse => neural tube
Neural tube gives rise to tissues of CNS - brain and spinal cord

Question 6

What is the cause of pituitary dwarfism?

Answer 6

Rathke’s pouch doesn’t differentiate into glandular tissue of adenohypophysis (anterior pituitary) => no growth hormone

Question 7

What is the infundibulum of the pituitary gland?

Answer 7

connection between brain and neurohypophysis/posterior pit.

Question 8

Label the brain

Answer 8

Question 9

Describe the sections and functions of the adenohypophysis/anterior pit.

Answer 9

Pars tuberalis – monitors melatonin levels
Pars intermedia – Rathke’s pouch remnant. Produces melanocyte stimulating hormone in foetus
Pars distalis – main secretory region. Collection of cells, each secrete different hormone

Question 10

Label the sections of the adenohypophysis/anterior pit

Answer 10

Question 11

Describe the sections of the neurohypophysis/posterior pit

Answer 11

Infundibulum – “stalk” attached to hypothalamus.
Stalk only has axons (cell bodies in hypothalamus)
Neural lobe – contains projection axons from neurons in hypothalamus

Question 12

Label the neurohypophysis/posterior pit.

Answer 12

Question 13

Describe how the hypophysis/pituitary gland is linked to the hypothalamus

Answer 13

Adenohypophysis/anterior pit - hormonall linked
Neurohypophysis/posterior pit - neurologically linked via infundibulum

Question 14

Describe how the adenohypophysis/anterior pituitary is controlled by the hypothalamus

Answer 14

releasing factors from hypothalamus circulate via hypothalamo-hypophyseal portal system to adenohypophysis and act on specific target cells (BBB absent in this area)
Specific target cells release stimulating hormones which circulate to target organs

Question 15

Describe how the posterior pituitary/neurohypophysis is controlled by the hypothalamus

Answer 15

Axons from supraoptic and paraventricular nuclei in hypothalamus form supraopticohypophyseal & paraventriculohypophyseal tracts
These tracts descend into the neural lobe via the infundibulum

Question 16

what is the function of the pineal gland/epithalamus?

Answer 16

controls circadian rhythms
controls breeding seasons
mediates courtship/breeding behaviours
linked with seasonal hair/feather colour changes

Question 17

How does the pineal gland respond to light?

Answer 17

Secretes melatonin when dark

Question 18

what is the function of melatonin from the pineal gland?

Answer 18

modulates sleep patterns
inhibits or stimulates repro cycles in seasonal breeders

Question 19

How does melatonin affect repro cycles?

Answer 19

Melatonin levels monitored by pars tuberalis to coordinate reproductive hormone periodicity / seasonality by affecting release of LH & FSH.

Question 20

what are the cells found in the thyroid gland and what is there function/secretion?

Answer 20

Follicular cells:
- secrete thyroid hormones T3 and T4 by proteolysis
- metabolic effects
Parafollicular/C-cells:
- secrete calcitonin
- lowers blood calcium

Question 21

how is thyroid hormone stored in the thyroid gland?

Answer 21

stored extracellularly bound to thyroglobulin
Follicular cells surround and contain the thyroglobulin

Question 22

Label the thyroid glands of different species

Answer 22

Question 23

What are the cells found in the parathyroids and what do they secrete?

Answer 23

Chief/principal cells
Produce parathyroid hormone (PTH) => raises blood calcium

Question 24

Label the layers and secretions of the adrenal layers

Answer 24

Question 25

Describe the effects of the corticoids produced from the adrenal cortex

Answer 25

Zona glomerularis - mineralocortioids - targets kidney to control Na and water reabsorption - alter blood pressure
Zona fasciculata - glucocorticoids - effect metabolism
Zona reticularis - androgens (oestrogen, testosterone etc.) - effects metabolism

Question 26

Label the associated structures of the adrenal glands

Answer 26

Question 27

What is the secretion of the adrenal medulla?

Answer 27

catecholamines: adrenaline + noradrenaline

Question 28

Fill in the table describing the hormonal control of the hypophysis/pituitary gland by the hypothalamus

Answer 28

Question 29

Describe the blood supply to the hypophysis/pituitary gland

Answer 29

Sits in Circle of Willis - arterial supply to whole brain

Question 30

Describe the blood supply to the thyroid gland

Answer 30

Arteries:
- cranial and caudal thyroid arteries
Veins:
- thyroid veins

Question 31

Describe the blood supply to the adrenal glands

Answer 31

Branches from aorta, renal, lumbar and cranial mesenteric arteries
blood draining the cortex enters medullary sinusoids, mixes with blood in medullary cells, central medullary veins collect blood, drained into caudal vena cava