hormones

Question 1

list 4 hormones produced by the hypothalamus

Answer 1

gonadotrophin releasing hormone
corticotrophin releasing hormone
growth hormone releasing hormone
thyrotrophin releasing hormone

Question 2

list 6 hormones produced by the anterior pituitary gland

Answer 2

growth hormone
prolactin
adrenocorticotrophin releasing hormone (ACTH)
thyroid stimulating hormone (TSH)
luteinising hormone
follicle stimulating hormone

Question 3

list 2 hormones released by the posterior pituitary gland

Answer 3

oxytocin
antidiuretic hormone (ADH)

Question 4

list the 3 layers of the adrenal cortex and state which hormones are released
list the hormones released by the adrenal medulla

Answer 4

adrenal cortex:
zona glomerulosa-mineralocorticoids e.g. aldosterone
zona fasciculata-glucocorticoids e.g. cortisol
zona reticularis-gonadocorticoids e.g. androstenedione and DHEA

adrenal medulla-catecholamines- adrenaline and noradrenaline

Question 5

3 classifications of hormones based on chemical structre

Answer 5

amino acid based e.g. catecholamines, thyroid hormones, ACTH, ADH, TSH, insulin, glucagon, growth hormone

steroid based e.g. gonadal hormones, adrenal hormones

eicosanoids e.g. prostaglandin

Question 6

what is a hormone?

Answer 6

a diverse collection of chemical messengers which travel through the blood and bind to specific cellular receptors at target tissues

Question 7

Describe how amino acid based hormones differ to steroid hormones in terms of their (i) solubility in water and (i) ability to cross target cell membranes

Answer 7

AA based hormones are water soluble and are therefore unable to pass through the phospholipid bi-layer of the cell membrane at target tissues *except thyroid hormone

Steroid based hormones are lipid soluble and are therefore able to cross through the phospholipid bi-layer of the cell membrane at target tissues

Question 8

4 general actions of hormones

Answer 8

1. alteration of cell membrane permeability or excitability e.g. noradrenaline acting on the SA node
2. stimulation of synthetic activity or secretion e.g. enzymes, proteins; LH acting on Leydig cells causing the production of testosterone
3. activation/deactivation of enzymes e.g. cortisol on intracellular enzymes
4. stimulation of mitosis e.g. growth hormone causing growth

Question 9

Explain the difference (at the cellular level) between a second messenger system and direct gene activation

Which class of hormones act as second messengers?

Answer 9

Second messenger system: act upon receptors embedded in cell membrane of target cells; rely on intracellular signalling (second messengers) to mediate their effects
Direct gene activation: bind to receptors within the cytosol because the hormone can diffuse through the cell membrane

Amino acid based hormones EXCEPT thyroid hormone (T3 and T4) use second messengers

Question 10

Provide some examples of molecules that are used as second messengers

Answer 10

Cyclic AMP e.g. ACTH, FSH, LH, Glucagon, PTH, Calcitonin

Tyrosine Kinase e.g. insulin

Question 11

3 main types of hormonal stimuli

Answer 11

humeral
neural
hormonal

Question 12

explain the stimulus for release and action of:
oxytocin
antidiuretic hormone

Answer 12

oxytocin-
stimulated by cervical/uterine stretching/suckling of infant on breast
uterine contractions (labour) and milk ejection

andidiuretic hormone-
stimulated by increased blood osmolarity or decreased blood volume
increases the reabsorption of water by inserting aquaporins in the DCT and CD on the kidney nephron

Question 13

all hormones released by the anterior pituitary gland, except … act by using Cyclic AMP second messenger systems

Answer 13

growth hormone

Question 14

in cases of anterior pituitary hypersecretion, which two hormones are most often produced in excess?

Answer 14

growth hormone and prolactin

Question 15

explain the stimulus for release and function of:
growth hormone
prolactin

Answer 15

growth hormone-
stimulated by GHRH due to low GH levels/ low blood sugar, fatty acids and high levels blood AA
anabolic hormone that stimulates somatic growth
mobilises fats for use as energy source

prolactin-
stimulated by low dopamine levels, enhanced by breast feeding and oestrogens
promotes mammary gland development and milk production
sexual gratification after orgasm

Question 16

explain the stimulus for release and function of:
adrenocorticotrophic hormone
thyroid stimulating hormone

Answer 16

ACTH-
stimulated by Corticotrophin Releasing Hormone in response to stress
promotes release of hormones from adrenal cortex
cleavage product is alpha-melanocyte stimulating hormone which produces Melanin for skin pigmentation

TSH-
stimulated by Thyrotropin Releasing Hormone (TRH)
stimulates thyroid gland to release thyroid hormone T3 and T4

Question 17

explain the stimulus for release and function of:
Folicle Stimulating Hormone
Luteinising Hormone

Answer 17

FSH-
stimulated by GnRH
F: Stimulates maturation of ovarian follicle and production of oetrogens
M: Stimulates production of androgen-binding protein by sustentacular cells

LH-
stimulated by GnRH
F: Triggers ovulation and converts the ruptured follicle into the corpus luteum (the corpus luteum secretes progesterone and some oestrogen)
M: Stimulates production of testosterone by interstitial (Leydig) cells

Question 18

what is the vascular supply of the adrenal glands?

Answer 18

superior, middle and inferior adrenal arteries

Question 19

differentiate Cushing’s Disease from Cushing’s Syndrome

Answer 19

Cushing’s Disease- hypercortisolism due to increased ACTH secretion from the anterior pituitary; most common cause is pituitary microadenoma.

Cushing’s syndrome= hypercortisolism has occurred independently of pituitary ACTH secretion; most common cause is iatrogenic-glucocorticoid hormone therapy.

Question 20

summarise the clinical features of hypercortisolism

Answer 20

Effects on metabolism:
o Truncal obesity, development of striae
o Lemon on toothpicks appearance vs. generalised obesity
o Moon face with flushed red cheeks, buffalo hump
o Muscle weakness/wasting, myalgia, arthralgia
o Osteoporosis, pathological #
o Hyperglycaemia=insulin resistance
Effects on blood pressure= hypertension
Effects on immunity= poor wound healing, skin infections
Involvement of Zona Reticularis may cause features of hyperandrogenism: hirsutism, menstrual irregularity

Question 21

what is another name given to primary adrenocortical insufficiency?

Answer 21

Addison’s Disease

Question 22

differentiate between primary and secondary adrenocortical insufficiency

Answer 22

Primary Adrenocortical Insufficiency:
• Due to intrinsic dysfunction of adrenal cortex
• Also referred to as Addison’s Disease
• Associated with increased ACTH levels but decreased cortisol

Secondary Adrenocortical Insufficiency:
• Causes include: Pituitary or hypothalamic dysfunction
• May also occur after glucocorticoid therapy
• Associated with decreased ACTH and decreased cortisol levels

Question 23

what is the most common cause of Addison’s Disease?

Answer 23

autoiimune attack

other causes: infection, metastatic spread, bilateral adrenalectomy

Question 24

Define the term phaeochromocytoma

list some clinical features

Answer 24

A tumour arising from the chromaffin cells of the adrenal medulla; most common cause of excess catecholamine production

HTN or complication HTN e.g. AMI, stroke, heart failure, AAA
intermittent catecholamine secretion e.g. pallor, sweating, tremours, anxiety, abdo pain, weight loss etc.

Question 25

which part of the adrenal gland is responsible for
a-long term stress response
b-short term stress response

Answer 25

a=adrenal cortex

b=adrenal medulla