Revision lecture Hypothalamic pit axis

Question 1

What is the function of the posterior pit?

Answer 1

storage of hormones synthesised in the hypothalamus and transported to the posterior pit via the inferior hypophyseal artery.
Ready for later release

Question 2

Give two examples of hormones released from the posterior pit?
Also a bit on what each hormone does

Answer 2

Oxytocin- Aids lactation, sexual excitement, uterine contractions etc..
ADH: Increased reabsorption of water from the collecting ducts of the kidneys
Also vasoconstriction

Question 3

What is the stimulus for ADH release

Answer 3

High blood osmolality

Question 4

Why does alcohol lead to increase urine output

Answer 4

Inhibits ADH release, so less water reabsorption

Question 5

Name 4 hormones synthesised and released from the anterior pit?

Answer 5

TSH- Stimulates thyroid hormone release
Prolactin- Increased breat milk production
ACTH- Cortisol release from the adrenals
GH- Stimulates inssulin release ad growth factor release from the liver. Also growth effects

Question 6

From where is growth hormone secreted? and what stimulates growth hormone release? What inhibits growth hormone production

Answer 6

Anterior pituitary
GHRP from the hyppothalamus stimulates
Somatostatin inhibits its production

Question 7

What causes the release of growth hormone?

Answer 7

Deep sleep
Stress (trauma, surgery)
Exercise
fall in glucose or FAs

Question 8

4 actions of growth hormone?

Answer 8

Hypertrophy and hyperplasia
increased protein synthesis
increased lipolysis
decreased glucose uptake

Question 9

Describe the negative feedback of GH secretion

Answer 9

Long loop-
IGFs, secreted in the liver have three effects, two on hypothalamus one on anterior pit gland
inhibit release of GHRH+stimulate release of somatotropin
inhibit release of GH from ant pit

Short loop- GH from the ant pit causes stimulation of somatostatin release from the hypothalamus

Question 10

What is the result if in childhood you are GH deficient?

Answer 10

pituitary dwarfism

delayed sexual development

Question 11

What is the result of growth hormone excess? in childhood and adulthood

Answer 11

Gigantism in childhood

acromegaly in adults

Question 12

How do GHs exert their effects on cells?

Answer 12

GH receptors activate Janus kinases–>activation of signalling pathways–>transcription factor activation and IGF production

Question 13

What four things does Insulin like growth factor cause?

Answer 13

Hypertrophy
Hyperplasia
Increased rate in protein synthesis
Increased rate of lipolysis in adipose tissue

Question 14

What is the name of the bony socket that the pit glands sit in?

Answer 14

Sella turcica

Question 15

how is the hypothalamus connected to the pit glands

Answer 15

the infundibulum

Question 16

where in the hypothalamus are oxytocin and ADH produced?

Answer 16

supraoptic nuclei

paraventricular nuclei

Question 17

Describe how the hormones that are synthesised in the hypothalamus and stimulate the anterior pit gland travel from the hypothalmus to the ant pit gland

Answer 17

hormones synthesised in the hypothalamus–>transported down axons–>stored in median eminence–>released into the hypophyseal portal system–>stimulation of endocrine cells in the ant pit gland

Question 18

Define tropic hormone

Answer 18

A hormone that affects the release of another hormone from a target tissue

Question 19

name 5 tropic hormones that are released from the hypothalamus and stimulate the ant pit gland and what each stands for

Answer 19

TRH- thyrotropin releasing hormone
GnRH- Gonadotropin releasing hormone
CRH-Corticotropin releasing hormone
GHRH- GH releasing hormone
GHIH- Growth hormone inhibiting hormone (Somatostatin)

Question 20

Define trophic hromone

Answer 20

hormone that affects growth

Question 21

name 6 hormones released by the ant pit

Answer 21

TSH- Thyroid stimulating hormone
ACTH-Adrenocorticotropic hormone
LH
FSH
PRL-Prolactin
GH

Question 22

How does growth hormone mainly have its effects via?

Answer 22

Insulin like growth factors

Question 23

where are insulin like growth factors produced and secreted?

Answer 23

liver and skeletal muscle

Question 24

in children, what effects do IGF and GH have?

Answer 24

GH- Long bone growth

IGF- Bone and cartilage growth

Question 25

In adults what do IGF and GH do?

Answer 25

help maintain muscle and bone mass and heal and repair and also modulate metabolism and body composition