Hypothalamus

Question 1

Overall role of hypothalamus?

Answer 1

Integrates information about internal and external environments

Question 2

Hypothalamus endocrine output

Answer 2

Via the pituitary gland

• hypothalamic neurones stimulate pituitary portal circulation
• also direct the endocrine function via release of oxytocin and vasopressin

Question 3

Autonomic output?

Answer 3

Control centre of para/sympathetic divisions

1. Reciprocally innervated with amygdala to covey innate and learnt significance of environmental stimuli
2. Cingulate cortex for perception of internal body states such as pain
3. Control of body via of autonomic and endocrine systems via output to brain stem motor control systems such as PAG

Question 4

Role in feedback loops

Answer 4

1. Hypothalamus controls both +/- feedback loops
2. • Such as uterine contraction> stretch receptors > hypothalamus > oxytocin release
3. • (homeostatic) increased blood osmolarity > osmoreceptors in hypothalamus > release of ADH > increased water reabsorbed in kidney/ thirst

Question 5

How does the hypothalamus measure blood fluid balance

Answer 5

1. Circumventricular organs found in ventricular system lack BBB.
2. Such as OVLT (located in anterior wall of third ventricle)

Question 6

What is a satiety response

Answer 6

1. • feedback loops have a delay (such as between drinking water till absorption) causing oscillation in controlled variable (would over/undershoot)
2. Sensory information of water being drank/ stomach stretch receptors inhibit hypothalamus

Question 7

Hypothalamus and hunger?

Answer 7

1. Arcuate nucleus bottom of 3rd ventricle contains neurones excited by medulla when glucose are low
2. Same neurones existed by hormone ghrelin- secreted when stomach is empty
3. These have output to paraventricular nucleus which controls autonomic energy conservation- low body temp, decreased insulin
4. Hunger also caused