Homeostasis ADDITIONAL

Question 1

Why does the variable oscillate around the set point?

Answer 1

The value of a controlled variable will oscillate around a set point because of the time delay between sensing a change and its correction.

Question 2

What is released by the posterior pituitary?

Answer 2

vasopressin (ADH) and oxytocin

Question 3

How do some neurosecretory cells in the hypothalamus release their hormones? (not to the posterior pituitary)

Answer 3

Other neurosecretory cells in the hypothalamus release their hormones into the portal capillaries in which they are transported directly to endocrine cells of the anterior pituitary gland

Question 4

What stimuli causes the pituitary to release ADH?

Answer 4

• Angiotensin II
• Hyperosmolarity
• Decreased atrial receptor firing
• Sympathetic stimulation

Question 5

Diseases for too much cortisol and too little cortisol.

Answer 5

• Too much cortisol = cushions disease

* Too little cortisol = Addison’s disease

Question 6

What regulates cortisol?

Answer 6

• circadian rhythm, (biological clock

- increased stress increases cortisol

Question 7

EDIT: What is the difference between negative feedback control and positive feedback control?

Answer 7

With negative feedback, if there is an increase in a controlled variable, the body will put in motion processes that will eventually decrease that variable. This happens for the majority of cases in our body.

However, some cases involve positive feedback control. Here, if there is an increase in a controlled variable, the body will instead amplify that to further increase that variable. Essentially, the response of the effector output reinforces the stimulus. E.g. blood clotting, ovulation, childbirth