Endocrine physiology

Question 1

What are the structural types of hormones ?

Answer 1

Steroids and non-steroids.

Question 2

What are steroid hormones ?

Answer 2

They are made from cholesterol by the glands such as the adrenal, testis and the ovaries. These are hydrophobic and easily cross the lipid cell membrane , ergo, travels protein bound through the blood to reach the target cells.

Question 3

What are non-steroid hormones ?

Answer 3

These are hydrophilic hormones that do not cross the lipid bilayer of the cell examples are insulin and glucagon.

Question 4

What are amino acid hormones ?

Answer 4

These are derived from the amino acid Tyrosine eg: thyroid hormones, adrenaline and noradrenaline.

Question 5

How does Thyroid hormones differ in their behaviour as compared to catecholamines?

Answer 5

They behave like steroid hormones and travels protein bound in the blood to reach the target cell. Whereas catecholamines travel like peptide hormones unbound and act through cell surface receptors.

Question 6

Where does the axons contained in the posterior pituitary or neurohypophysis originate ?

Answer 6

The hypothalamic supraoptic and paraventricular nuclei.

Question 7

What is the role of hypothalamo- Hypophyseal portal system ?

Answer 7

It is responsible for moving the hypothalamic hormones to pituitary .

Question 8

What are the stimulatory hormones released by the hypothalamus to the adenohyophysis ?

Answer 8

TRH, CRH, GnRH, and GHRH

Question 9

Where does negative feedback from the endocrine glands influence?

Answer 9

The adenohyophysis

Question 10

What are the hormones that are produced by the gonads?

Answer 10

FSH and LH in response to Gonadotropin released by the anterior pituitary.

Question 11

What is the hormone that peaks at the time of ovulation ?

Answer 11

Estrogen and it makes the pituitary very sensitive to hypothalmic GnRH leading to massive surge of LH and FSH which facilitate ovulation.

Question 12

What are the inhibitory hormones secreted by the hypothalamus ?

Answer 12

• Growth hormone inhibiting hormone or Somatostatin
• Prolactin inhibiting hormone or Dopamine.

Question 13

What are the hypothalamic hormones secreted by the paraventricular and supra-optic hypothalamic nuclei ?

Answer 13

ADH or vasopressin and Oxytocin which are stored in herring bodies of the neurohypophysis.

Question 14

What is the signal for the ADH to be secreted from the herring bodies of neurohyophysis into the systemic circulation ?

Answer 14

High blood osmolarity or low blood volume. ADH retains water from the urine leading to increase in BP, decrease in blood osmolarity .

Question 15

What is the action of oxytocin ?

Answer 15

• Increase uterine contraction during child birth.
• Increase the contraction of smooth muscles of the breast to release breast milk.

Question 16

What is the function of Pineal gland ?

Answer 16

The pinealocytes produces melatonin which regulates circadian rhythm.

Question 17

What is the action of T3 or trioidothyronin ?

Answer 17

To boost the metabolic rate.

Question 18

What cells produce the hormone calcitonin ?

Answer 18

The C-cell also known as the par-folicular cells of the thyroid gland produces calcitonin.

Question 19

What are the hormones produced by the adrenal glands ?

Answer 19

• The outer Zona glomerulosa produces aldosterone.
• The middle Zona fasiculata produces cortisol
• The inner Zona reticularis produces sex hormone precursors.

Question 20

What is the function of Aldosteron ?

Answer 20

To inhibit renal loss of water and sodium and increase the elimination of potassium.

Question 21

adrenalin and noradrenalin are secreted by ?

Answer 21

Adrenal medulla.