Chapter 5 - Endocrine System

Question 1

Where are steroid hormones primarily produced?

Answer 1

Gonads and adrenal cortex

Question 2

What is the difference between a peptide hormone and an amino acid derivative

Answer 2

AA derivatives are derived from one or two amino acids and usually have a few additional modifications.

Think of dérivantes of carboxylic acids…you can swap out atoms

Ex: thyroid hormones made from tyrosine with the addition of several iodine atoms

Question 3

Where do catecholamines and thyroid hormones bind?

Answer 3

Catacholamines (épi, nor epi)
- gcoupled receptors

Thyroid:
- intracellularly

Question 4

What’s the difference between direct and tropic hormones?

Answer 4

Direct: secreted and then act directly on a target tissue

Tropic: required an intermediary to act
- GnRH stimulates release of LH and FSH, LH acts on gonads to produce estrogen in females and testosterone in males

Question 5

Which pituitary has a blood vessel system that directly connects it to the hypothalamus and what is this system called?

Answer 5

Hypophyseal portal system connects the anterior pituitary to the hypothalamus

Question 6

List the hormones released by the hypothalamus and the hormones released by the anterior pituitary in response

Answer 6

GnRH -> FSH and LH
GHRH -> GH
CRF-> ACTH
TRH-> TSH

Exception:
PIF (which is dopamine)causes a decrease in prolactin secretion

Question 7

What do ‘axes’ refer to in terms of hormones , give some examples

Answer 7

Three- organ systems

Hypothalamic - pituitary-adrenal (HPA) axis

Hypothalamic-pituitary-ovarian (HPO) axis

Essentially, these axes need receptors on all organs to be able to recognize increase or decrease in concentration of molecules produced up and down stream

Question 8

What hormones are released by the posterior pituitary ?

Answer 8

Oxytocin and ADH

Question 9

What are the products of the anterior pituitary?

Answer 9

FLAT PEG

Tropic:

• FSH
• LH
• ACTH
• TSH

Direct:

• prolactin
• Endorphins
• Growth hormones

Question 10

Two major functions of the thyroid

Answer 10

1) setting basal metabolic rate
- releases T3 and T4

2) calcium homeostasis
- calcitonin

Question 11

;What are T3 and T4?

Answer 11

Triiodothryonine (T3)

Thyroxine (T4)

• 3 and 4 refer to # of iodines attached to the tyrosine

Increased T3, T4 = Increased cell respiration

Question 12

What is hypothyroidism ?

Answer 12

Deficiency of iodine or inflammation of the thyroid may result in less hormones being secreted by the thyroid

May result in mental retardation and developmental delay (cretinism)

Question 13

What is hyperthyroidism?

Answer 13

Excess thyroid hormone

• can result from a tumour or thyroid over stimulation

Question 14

Vas eez calcitonin?

Answer 14

Calcitonin “tones” down calcium levels in the blood

• produced by C-cells (prafollicular cells)

Question 15

List four important functions of calcium?

Answer 15

1) bone structure and strength
2) release of neurotransmitters from neurons
3) Regulation of muscle contraction
4) clotting of blood (Ca is a cofactor)

Question 16

What vitamin is activated by parathyroid hormone?

Answer 16

Vitamin D

• page 173, fig 5.8.
  If you have time learn this figure

Question 17

What does the adrenal cortex secrete and what are the three functional classes of them?

Answer 17

Corticosteroids:

1) glucocorticoids
- cortisol and cortisone

2) Mineralcorticoids:
- aldosterone

3) Cortical sex hormones

Question 18

Draw out the RAAS pathway

What is its purpose?

Answer 18

Page 175, fig 5.9

Increases BP

Question 19

Adrenal medulla secretes:

What larger class of molecules are they?

Answer 19

Epi and nor epi

They are catecholamines

Question 20

What are the three cells contained in islets of langerhans?

Answer 20

Alpha: glucagon
Beta: insulin
Gamma: somatostatin