Adrenal And Pituitary Glands

Question 0

What hormones are secreted from the anterior pituitary gland and in which cells?

Answer 0

TSH - thyrotrophs
ACTH - corticotrophs
Growth hormone - somatotrophs
LH and FSH - gonadotrophs
Prolactin - lactotrophs

Question 1

Where is the pituitary gland located?

Answer 1

From the base of the brain suspended from a stalk.

Lies in a deep recess of the sphenoid bone.

Question 2

Where are the adrenal glands found?

Answer 2

Cap the upper poles of the kidneys and lie against the diaphragm

Question 3

What is produced in the cortex?

Answer 3

Mineralocorticoids eg aldosterone

Glucocorticoids eg cortisol and corticosterone

Androgens

Question 4

What is produced in the medulla of the adrenal glands?

Answer 4

Adrenaline

Question 5

What are the three zones of the cortex in the adrenal glands called and what do the hormones they secrete regulate?

Answer 5

Zona glomerulosa - mineralocorticoids regulate sodium and potassium levels

Zona fasciculata - glucocorticoids regulate carbohydrate metabolism

Zona reticularis - androgens

Question 6

Which family is cortisol a member of?

Answer 6

C21 steroid family

Question 7

How are the steroids synthesised?

Answer 7

From cholesterol via progesterone in a series of enzyme catalysed reactions

Question 8

How is cortisol secretion controlled?

Answer 8

CRF (corticotrophin releasing factor) is released from the hypothalamus
This stimulates the release of ACTH in the anterior pituitary gland
This stimulates the release of cortisol

Question 9

How is CRF secretion regulated?

Answer 9

Negative feedback by glucocorticoids

Response to stressors

• physical (temperature, pain)
• chemical (hypoglycaemia)
• emotional

Question 10

From which protein is ACTH derived?

Answer 10

POMC

Question 11

What can be produced from POMC?

Answer 11

ACTH
Alpha-MSH
Endorphins

Question 12

When is the peak plasma level of ACTH?

Answer 12

Early morning

Question 13

What enzyme does ACTH activate and how?

Answer 13

Cholesterol esterase

Binds to receptors on the surface of the zona fasciculata and reticularis

Question 14

What does cholesterol esterase do?

Answer 14

Increases the conversion of cholesterol esters to cholesterol

Question 15

What effects does over secretion of ACTH have?

Answer 15

Increased pigmentation due to partial MSH activity

Adrenal hyperplasia and over production of cortisol

Question 16

What type of symptoms does under secretion of ACTH cause?

Answer 16

Those related to a lack of glucocorticoids only

Question 17

What is the type of receptor for ACTH?

Answer 17

Melanocortin or corticotrophin receptor

Question 18

What is the major transport protein of cortisol?

Answer 18

Transcortin/CBG

Question 19

What is the mechanism of action of cortisol upon its target cells?

Answer 19

Crosses plasma membrane
Binds to cytoplasmic receptors
Hormone/receptor complex enters the nucleus
Interacts with specific regions of DNA which alters the rate of transcription of specific genes

Question 20

What effects does cortisol have?

Answer 20

Decreased amino acid up take and protein synthesis
Increased proteolysis (except in the liver)

Increased hepatic gluconeogenesis and glycogenolysis

Increased lipolysis, high levels of cortisol increase lipogenesis

Decreased peripheral uptake of glucose (anti-insulin)

Question 21

What does the adrenal medulla synthesise?

Answer 21

Catechol amines including adrenaline and the neurotransmitters noradrenaline and dopamine

Question 22

How are catecholamines synthesised?

Answer 22

Enzyme catalysed steps

Tyrosine -> dopamine -> noradrenaline -> adrenaline

Question 23

What effects does adrenaline have?

Answer 23

Cardiovascular system - increased cardiac output and blood supply to muscle

CNS - increased mental alertness

Carbohydrate metabolism - increased glycogenolysis in muscle and liver

Increased lipolysis

Question 24

What is over secretion of adrenaline normally caused by?

Answer 24

A tumour

Question 25

What effects does over secretion of adrenaline have?

Answer 25

Hypertension
Anxiety
Palpitations
Pallor
Sweating
Glucose intolerance