End 2 - Pituitary Hormones And Their Control By The Hypothalamus

Front 1

What is another name for the pituitary gland?

Back 1

Hypophysis?

Front 2

What is another name for the posterior pituitary gland?

Back 2

Neurohypophysis

Front 3

What is another name for the anterior pituitary gland?

Back 3

Adenohypophysis

Front 4

What is the median eminence?

Back 4

Communicator between the hypothalamus and pituitary gland

Front 5

What is the name of the thin stalk that connects the pituitary gland to the rest of the brain?

Back 5

Pars tuberalis

Front 6

Why is it difficult to remove the brain still with the pituitary gland attached?

Back 6

Because the stalk is covered with dura

Front 7

How may the size of the pituitary gland vary?

Back 7

Depending on physiological state
e.g. it is bigger during pregnancy and lactation

Front 8

How would you get surgical access to the pituitary gland?

Back 8

Upwards through sphenoid bone

Front 9

Where does the posterior pituitary gland originate from?

Back 9

Down growth of brain tissue from hypothalamic floor
Neural in origin

Front 10

Where does the anterior pituitary gland originate from?

Back 10

Up growth of the roof of the oral cavity
Epithelial in origin

Front 11

What is the anterior pituitary divided up into?

Back 11

Pars distalis
Pars intermedia (much smaller)

Front 12

How is the posterior pituitary gland supplied with blood?

Back 12

Directly through inferior hypophyseal artery

Front 13

How is the anterior pituitary gland supplied with blood?

Back 13

Indirectly by the hypophyseal portal veins and superior hypophyseal artery

Front 14

Describe where the arteries come from

Back 14

Internal carotid artery -> branch from the circle of Willis and form capillary bed in median eminence before going into portal hypophyseal veins and a second capillary network in the anterior pituitary

Front 15

Describe the venous drainage of the pituitary gland

Back 15

Both parts of the gland drain into venous sinuses and into the systemic circulation

Front 16

Describe what the posterior pituitary gland is composed of and where the cell bodies are found

Back 16

Composed mostly of axons with large cell bodies originating in the supraoptic nucleus and paraventricular nucleus in the hypothalamus

Front 17

Where do the axons in the posterior p.g. terminate?

Back 17

In close association to the capillary network so that when an action potential passes down the axon a hormone is released into the circulation

Front 18

Which hormones are released by the posterior pituitary gland?

Back 18

Oxytocin
Vasopressin

Front 19

What is the role of oxytocin?

Back 19

Parturition - uterine contractions, placental ejection
Milk ejection reflex
Ejaculation - acts on smooth muscles of the prostate
Released during orgasm
Acts on the hippocampus to help you remember who you have had sex with
Central effects: maternal behaviour, memory, social and sexual behaviours

Front 20

What is the role of vasopressin?

Back 20

Also known as ADH
Acts to increase water reabsorption in the kidneys
Also social behaviour (aggression) and memory

Front 21

Describe how the median eminence acts as an interface between the brain and the anterior p.g.

Back 21

Neuroendocrine cells have axons that terminate in the median eminence capillary bed
Hormones released from the hypothalamus are released in median eminence and transported in the portal veins to the anterior p.g. where they act on receptors of anterior pituitary cells

Front 22

Name the hypothalamic-releasing hormones

Back 22

CRH - corticotrophin
TRH - thyrotrophin
GnRH - gonadotrophin
GRH - growth hormine
releasing hormones

Front 23

Name the hypothalamic inhibiting hormones

Back 23

GIH - growth hormone inhibiting - somatostatin
Dopamine - prolactin inhibiting
GnIH - gonadotrophin inhibiting hormone

Front 24

What are the secretory cell types of the pituitary

Back 24

Chromophils - acidophils (orange) and basophils (pale blue)
Chromophobes - don't take up colour

Front 25

What are the 5 secretory cell types of the adenohypophysis?

Back 25

Somatotrophs
Lactotrophs
Corticotrophs
Thyrotrophs
Gonadotrophs

Front 26

How many somatotrophs are there and what do they release?

Back 26

40-50% of adenohypophysis cell population
Growth hormone -> acts on liver to produce somatomedins

Front 27

How many lactotrophs are there and what do they release?

Back 27

20%
Prolactin - milk production and development of mammary tissue

Front 28

How many corticotrophs are there and what do they release?

Back 28

20%
POMC (pro-opiomelanocortin) -> adreno-corticotrophic hormone
ACTH controls cortex activity and secretion of glucocorticoids in response to stressor

Front 29

How many thyrotrophs are there and what do they release?

Back 29

5%
TSH - thyroid stimulating hormone

Front 30

How many gonadotrophs are there and what do they release?

Back 30

5%
Luteinising hormone (LH) and follicle stimulating hormone (FSH)

Front 31

What is the main cell type of the pars intermedia of the anterior pituitary?

Back 31

Melanotrophs - synthesises POMC -> ACTH + alpha-MSH - important for controlling skin colour

Front 32

What does dopamine inhibit?

Back 32

The release of prolactin

Front 33

Which cells of the anterior pituitary gland stain orange?

Back 33

Somatotrophs
Lactotrophs

Front 34

Which cells of the anterior pituitary stain blue?

Back 34

Corticotrophs
Thyrotrophs
Gonadotrophs