Week 9 - The endocrine System Cont

Question 1

What does Growth Hormone do?

Answer 1

Acts on liver to promote release of somatomedins, e.g Insulin like growth factors (IGF) which:
-stimulate tissue growth (skeletal muscle and cartilage in particular)
- Inc amino acid uptake/protein synthesis

Growth hormone acts directly on tissues to:
- stimulate cell division in epithelial and connective tissues
- stimulate triglyceride breakdown in adipocytes
- stimulates liver glycogen breakdown

Question 2

Role of ADH and OXT

Answer 2

ADH is used for water reabsorption in the kidneys and elevation of blood pressure.
OXT in males is used in smooth muscle in ductus deferens and prostate gland.
in females Uterine smooth muscle (labour contractions) and mammary glands (lactation)

Question 3

Describe the pineal glands

Answer 3

Contains: Neurons - collaters from visual pathways
-Pinealpcytes secrete melatonin - lowest production during daytime

functions of melatonin - influence circadian rhythms, antioxidant.

Question 4

Describe the thyroid gland

Answer 4

Anterior to thyroid cartilage of larynx
Two lobes connected by narrow isthmus
Stores and secretes thyroid hormones thyroxins (T4) and triiodothyronine (T3)
Thyroid hormones increase sodium potassium ATPase production

Question 5

What are the effects of thyroid hormones?

Answer 5

Inc oxy and energy consumption
Inc HR
Inc sensitivity to sympathetic stimulation.
Stimulates RBC formation
Affects activity of other endocrine tissues
Increases bone turnover.

Question 6

Thyroid follicles and C cells

Answer 6

Hollow spheres lined by cuboidal epithelium, surrounded by capillaries
contain colloid (protein rich fluid)
follicle cells synthesise tyrosine rich thyroglobulin
Iodine incorporated to form thyroxine (T4) and triiodothyronine (T3)

C Cells produce calcitonin, important in calcium homeostasis. Reduces serum calcium
Deposition in bone, inc excretion by kidney.

Question 7

What happens with a Iodine Deficiency?

Answer 7

Derbyshire neck also called Goitre is a swelling of the thyroid gland and is now known to be caused by lack of iodine. It is almost unknown today because iodine is added to drinking water ( and salt)

Question 8

What are the parathyroid glands?

Answer 8

-Small glands (1.6g) on
posterior of thyroid
- Parathyroid (chief) cells
produce parathyroid hormone
(PTH)
- PTH is released to increase
serum calcium when levels
decline

Question 9

Describe the adrenal glands

Answer 9

Medulla - catecholamines, fight or flight, inc blood gluc, inc HR
Zona retic -Androgens (steroid hormones) anabolic affects
Zona Fascic- glucocorticoids, e.g cortisol, promote glucose synthesis, fat and protein catabolism, anti inflammatory effects.
Zona glgomerulosa - mineralocorticoids, e.g aldoserone, affect electrolyte composition

Question 10

describe pancreas

Answer 10

Islets of langerhans - alpha cells, produce glucagon, inc BG
Beta cells produce insulin, lowers BG

Question 11

what is diabetes melitus?

Answer 11

Abnormally high glucose (hyperglycaemia)
if untreated could result in:
kidney damage, retinal damage, peripheral nerve damage, inc cv disease risk.

Type 1- often diagnosed in childhood, pancreatic insulin production inadequate
insulin injection needed

Type 2 - most common, middle age
reduced tissue response to insulin
often managed w diet and exercise.

Question 12

what are the 4 patterns of hormone interaction?

Answer 12

Antagonistic - opposing e.g PTH and calcitonin
Synergistic (additive) effects - e.g GH and glucocorticoids
Permissive - One hormone is necessary for another to produce effect
Integrative effected - hormones produce different but complementary results.

Question 13

Hormones and growth