phyl4

Question 1

State the functions of endocrinology

Answer 1

• Regulate metabolism, water and electrolyte balance
• Allow body to cope with stress
• Regulate growth
• Control reproduction
• Regulate circulation and RBC production
• Control digestion and absorption of food

Question 2

3 types of hormones

Answer 2

peptides - hydrophillic
amines - Catecholamines (hydrophobic) and thyroid (lip_
steroids - lipophilic

Question 3

hydrophillic vs lipophillic

Answer 3

– Likes water
– Can’t get through plasma membrane
– Fast onset, short-acting

Question 4

Regulation of hormone activity

Answer 4

• Secretion - central or direct
– stimulation, feedback, reflexes, rhythms – central regulation, fast/slow or long term respone
direct reg: edocrine cells respod to direct changes in ECF – very rapid response for critical needs

• Transport
– binding proteins, free/bound balance

• Metabolism
– activation/inactivation, differs for hydrophilic v lipophilic due to accessibility
- Higher rate for hydrophillic

• Excretion
– unregulated (but can be affected by renal/urinary
disease)

• Target cell responsiveness
– receptor expression, amplification,
– combination with other hormones - ‘permissiveness,
synergism and antagonism’

P - need hormone A for B to work
S - when hormana A is present, hormone B works better
A - prescence of A, b doesn’t work

Question 5

In terms of actions, there are two groups of anterior pituitary hormones:

Answer 5

‘Trophic’ hormones control activity another
endocrine gland
ACTH, TSH, LH & FSH
• Hormones which have a direct effect in their
own right
Prolactin & growth hormone

Question 6

GH: actions overall

Answer 6

• Anabolic (growth):
– Increases thickness & length of long bones
– Increases size & number of cells in soft
tissue
- Promotes soft tissue and organ growth
• Metabolic (distinct from growth):
Increase muscle mass
– Increases fat breakdown/increases circulating fatty acids
– Decreases glucose uptake by muscles
- Increase metabolism

Question 7

Calcium regulation

Answer 7

Calcium – important in many physiological processes…
• Structural component of bones and teeth
• Contributes to resting membrane potential
• Maintains normal excitability of nerve &
muscle cells
• Involved in neurotransmitter & hormone
release
• Muscle contraction (skeletal & cardiac)
• Activation of many enzymes
• Coagulation of blood
• Milk production

99% found in bones and teeth

0. 9% intracellular
1. 1% in extracellular fluid

Question 8

PTH

Answer 8

PTH secreted from chief cells in direct response to changing plasma Ca++ concentrations

Bone:
Short-term – stimulates Ca++ membrane pump in osteocytes, so Ca++ moves from bone fluid to plasma in central canal
Long-term – stimulates osteoclasts, inhibits osteoblasts, so Ca++ and PO4 increase in plasma

Kidney:
Decreases Ca++ loss - increased tubular reabsorption of Ca++ and decreased tubular reabsorption of PO4

GIT:
Indirectly increases Ca++ and PO4 – increases
absorption by small

Question 9

calcitonin

Answer 9

high plasma ca+ lvls

PROTECTS AGAINST HYPERGLYCAMENIA

Question 10

PTH abnormalities

Answer 10

hyposecretion - too much calcium - causes Hypocalcemia - very dangerous too much nerve excitability and death
hypersecretion - not enough calcium - softening and fractures, increase secretion from kidneys and movmt of ca from bone fluid to plasma causes Hypercalcemia