PED1003/L19 Endocrine System

Question 1

Define a hormone.

Answer 1

A chemical/protein synthesised by specific tissues and secreted into the bloodstream whereby it is carried to non-adjacent sites in the body and exerts its actions

Question 2

What is regulated by the pineal gland?

Answer 2

Melatonin release

Question 3

What are steroid hormones synthesised from?

Answer 3

Cholestrol

Question 4

Give 2 features of steroid hormones.

Answer 4

Lipophilic
Hydrophobic

Question 5

By which action do steroidal hormones work?

Answer 5

Intracellular receptors

Question 6

What are non-steroid hormones synthesised from?

Answer 6

Polypeptides
Modified amino acids
Tyrosine & tryptophan

Question 7

Give 2 features of non-steroid hormones.

Answer 7

Lipophilic
Hydrophobic

Question 8

By which mechanism do non-steroid hormones work?

Answer 8

Cell surface receptors

Question 9

Give 3 examples of steroid hormones.

Answer 9

Cortisol & aldosterone (AC)
Oestrogen & progesterone (O&P)
Testosterone (testes)

Question 10

Give an example of a tyrosine derived hormone.

Answer 10

Catecholamines - adrenaline & noradrenaline
Thyroid hormones - triiodothyronine & thyroxine
Dopamine

Question 11

Give an example of a tryptophan derived hormone.

Answer 11

Melatonin (PG)
5-HT

Question 12

Give an example of a protein derived hormone.

Answer 12

TRH, GnRH & GHRH
TSH, FSH, LH, GH, ACTH, ADH, Oxytocin
Insulin, Glucagon

Question 13

Describe feedback control of cortisol. (6)

Answer 13

Physical or emotional stress
Hypothalamus produces corticotropin-releasing hormone (CRH)
Anterior pituitary produces Adrenocorticotropic hormone (ACTH)
Adrenal cortex produces cortisol
Adrenal medulla produces adrenaline

Question 14

What is the effect of cortisol? (2)

Answer 14

Increased fat & protein metabolism
Slowing increasing glucose

Question 15

What is the effect of adrenaline?

Answer 15

Rapidly increased HR, BP and glucose

Question 16

Describe the cascade of events that occurs when there is a low blood volume/pressure/high osmolarity. (6)

Answer 16

Low BP/vol detected by baroreceptors
High osmolarity detected by osmoreceptors in hypothalamus
Posterior pituitary releases ADH
ADH acts on distal tubule of V2 receptors in kidney
Increased water reabsorption
ADH acts on V1 receptors in SM to cause vasoconstriction (increase BP)

Question 17

Describe the cascade of events that occurs when high blood sugar is detected. (2)

Answer 17

High blood sugar detected by beta cells which secrete insulin
Insulin acts on tissue and liver to decrease blood sugar

Question 18

Describe the cascade of events that occurs when low blood sugar is detected. (2)

Answer 18

Low blood sugar detected by alpha cells which secrete glucagon
Glucagon acts on liver which performs glycogenolysis and increases blood sugar

Question 19

Describe substrate controlled hormone release in beta cells. (4)

Answer 19

Glucose enters cell and enters Krebs cycle
Increased ATP blocks ATP-sensitive K+ channel
Calcium channel opens and Ca2+ enters cell
Insulin storage vesicles fuse with cell membrane

Question 20

Define neuronal control and give an example.

Answer 20

Hormone is released directly in response to neuronal stimulation
ADH & CRH

Question 21

Define tropic control and give an example.

Answer 21

Hormone is released in response to stimulation from another hormone
ACTH & cortisol

Question 22

Define substrate control and give an example.

Answer 22

Hormone is directly influenced by circulating blood levels of substrate that hormone itself controls
Glucagon & insulin

Question 23

Define feedback control.

Answer 23

Exceeding a certain level of hormone inhibits further hormone release