Endocrine System

Question 1

Vasopressin is one of the hormones released by the __________.
What are the two actions of vasopressin hormone?

Answer 1

Posterior pituitary gland

1. Acts on the nephrons in the kidneys to retain water: in specifically, increases permeability of distal and collecting tubules to H20. (regulation of water loss, primary role)
2. causes vasoconstriction of arterioles smooth muscle throughout the body (regulation of bp, minor role)

Question 2

Under normal conditions, what is the primary endocrine factor (hormone) that regulates urinary water loss and overall water balance?

Answer 2

vasopressin

Question 3

What major factor/control is responsible for causing the hypothalamus to induce the posterior pituitary to release vasopressin?

Answer 3

1. In the hypothalamus, specialized osmoreceptors monitor the rise in plasma osmolarity. When ECF solutes concentration increases, these receptors send a signal to the brain to release vasopressin into the systemic blood to act on the kidneys to retain water.
2. Additional, specialized volume receptors in the left atria of the heart could sense a drop in pressure/ decreased in blood volume in the atria and sends a signal from the receptors to the hypothalamus in the brain to release vasopressin, thus retain water, in an attempt to stabilize blood pressure. (This is a less powerful input from the left atrial volume receptors)

Question 4

What are the two major physiological effects of oxytocin?

Answer 4

a. This hormone promotes the ejection of milk from the mammary glands during breastfeeding
b. stimulates the contraction of the uterine smooth muscle to help expel the infant during childbirth

Question 5

One of the six hormones secreted by the anterior pituitary gland is “follicle-stimulating hormone (FSH)”

In females, what are the physiological effects of FSH ?
What physiological effects does FSH have on males?

Answer 5

In females,

a. stimulates the growth & development of ovarian follicles
b. stimulates the ovaries to release estrogen

In males, FSH is required for sperm production