Endocrine System

Question 1

What is the purpose of the hypothalamus?

Answer 1

Hypothalamus controls the link between the nervous and endocrine systems. A small region of the brain, below the thalamus. Hypothalamus - the “Master of the pituitary”. Hypothalamus has releasing and inhibiting hormones.

Question 2

What is the pituitary?

Answer 2

The pituitary attached to the hypothalamus via the infundibulum. It has anterior and posterior lobes

Question 3

What hormones does the hypothalamus release?

Answer 3

Oxytocin and ADH are released to the posterior pituitary gland.
XXXXXX released to the anterior pituitary gland.

Question 4

How many hormones does the posterior pituitary release and what are they called?

Answer 4

Oxytocin and ADH are secreted by the posterior pituitary, however these are produced in the hypothalamus, who signals the posterior pituitary to store and then release ADH and oxytocin, as required. The posterior pituitary doesnt actually produce any hormones - the posterior pituitary simply stores and released two hormones produced by the hypothalamus - oxytocin and ADH.

Question 5

How does the anterior pituitary work with the hypothalamus?

Answer 5

The anterior pituitary gland produces tropic hormones

Question 6

How are the hypothalamus and the anterior pituitary linked?

Answer 6

By blood

Question 7

How are the hypothalamus and the posterior pituitary linked

Answer 7

By nerves

Question 8

What are the anterior pituitary hormones called “trophic”?

Answer 8

“Trophic” as they stimulate glands in the body.

Question 9

hGH = ?

Answer 9

Human Growth Hormone is released by the anteior pituitary gland and it stimules growth and metabolism. hGH is also known as “somatropin”.
hGH stimulates tissues to release IGFs (Insulin Growth Factors) in the liver, then released into the blood.

Question 10

PRL = ?

Answer 10

PRL = Prolactin, released by the anterior pituitary gland, to initiate and maintain milk secretion. PIH ing=hibits this hormone most of the time (Prolactin Inhibiting Hormone, released by the hypothalamus.

Question 11

What is PIH also known as?

Answer 11

Dopamine. Can cause erectile dysfunction if large amounts in men.

Question 12

ACTH = ?

Answer 12

Adnrenocorticotropin or Corticotropin is released by the anterior pituitary and stimulates the adrenal cortex to release glucocorticoids (such as cortisol).

Question 13

What is ACTH simulated by?

Answer 13

Stress, low glucose, physical trauma and CRH stimulate ACTH. CRH =

Question 14

The hypothalamus has only inhibiting and releasing hormones - true or false?

Answer 14

True - the releasing hormones stimulate the release of hormones from the AP, the inhibiting hormones stimulate the inhibition of AP hormones.

Question 15

What is the suffix for Growth Hormone Releasing Hormone?

Answer 15

GHRH

Question 16

Do the number of hormone receptors remain consistent?

Answer 16

No, receptors constantly change through up or down regulators of receptors, depending on how available the hormone is. If the hormone is low the receptors will upregulate, for example.

Question 17

How do circulating hormones act?

Answer 17

Circulating hormones linger in the blood and exert their effects, then they get deactivated in the liver and excreted in the kidneys.

Question 18

What are the two different types of local hormones?

Answer 18

Autocrine hormones - act locally on the same secreting cell.

Paracrine hormones - act locally on a nearby/neighbouring cell.

Question 19

How do water soluble hormones bind to receptors?

Answer 19

Water soluble hormones can not travel into the cell (across lipid bilayer) so they bind to receptors on surface of the cell’s plasma membrane

Question 20

How do lipid soluble hormones bind to receptors?

Answer 20

Lipid soluble hormones can travel through the plasma membrane and thus can have action within the cell itsekf - in the cytoplasm or in the nucleus.

Question 21

Where is calcitonin released by and what does it do?

Answer 21

Calcitonin is released by the parafollicular cells in the thyroid. It inhibits the activity of osteoclasts and reduces the blood-calcium level (as the bones do not break, osteoclast activity pushes calcium out of the bones and into the blood).

Question 22

The parathyroid hormone is from the parathyroid and when secreted it increases blood calcium levels, by:

Answer 22

• BONE: increases the number of and activity of osteoclasts, releasing calcium and phosphate into the blood.
• KIDNEYS: reduces the amount of calcium and magnesium lost in the urine.
• GI TRACT: promote the formation of calcitriol (vitamin D) which increases calcium absoprtion from the GI tract. Vitamin D also helps put calcium back in the bones.

Question 23

What does the parathyroid gland and osteoclasts do to calcium?

Answer 23

Osteoclasts (stimulated by the parathyroid gland) promotes calcium resorption from bones.

Question 24

How much does the adrenal cortex make up the adrenal gland?

Answer 24

80-90%

Question 25

Main hormones from testes & responsibilities

Answer 25

Testosterone - stimulates drop of testes
development & maintenance of secondary characteristics in male.
Inhibins - which inhibits FSH, controlling spermatogenesis

Question 26

What do the ovaries produce and secrete?

Answer 26

Ovaries - oestrogen, pogesterone, relaxin, inhibin. Regulates menstruation, prepares breasts for lactation, maintains pregnancy, develops and maintains secondary sexual characteristics.

Question 27

What does inhibin do?

Answer 27

Inhibin inhibits FSH from the anterior pituitary - on both males (spermatogenesis) and in females (follicular development).

Question 28

GnGH (Gonadotropin Releasing Hormone) stimulates the anterior pituitary to release which hormones?

Answer 28

FSH - to stimulate follicles to grow, which in turns promotes follicles to secrete oestrogen.
LH - to stimulate ovulation (release of secondary oocyte into uterine tubes) & formation of corpus luteum.
Corpus Luteum secretes oestrogen, progesterone, relaxin, inhibin.
- progesterone prepares uetrus for implantation. Also mammory glands for milk secretion
- relaxin facilitates implantation in relaxed uterus
- inhibin inhibits FSH