Hypothalamic-Pituitary-Axis Flashcards
What cells are glucagon and insulin made in?
Glucagon= alpha cells of pancreas ilets of langerhans Insulin = beta cells of pancreas
How is calcium levels in the blood controlled?
If ca level high, thyroid gland releases calcitonin
If levels low, parathyroid gland releases parathyroid hormone (PTH)
Linked -ve feedback, work antagonistically
What are the hypothalamus inputs?
- nervous
Light= reg circadian + seasonal rhythms
Olfactory= pheromones
Autonomic= neural input from heart, digestive, reprod - Plasma borne signals
Endocrine: pituitary H + steroids
Conc glucose + ions (osmolarity)
What are the hypothalamus outputs?
- Neuropeptide hormones
Release/inhib hormones secreted, nerve endings in blood 🩸
Hypo axons form posterior pituitary, release H direct to systemic circ - Nervous signals- reg para- + sympathetic
Posterior pituitary= neural/axonal
Anterior= glandular tissue
What are the three forms of capillary?
most to least incomplete basement membrane
Continuous
Fenestrated
Sinusoid
What is the function of the liver (metabolism) ?
BG buffer system- glycogen store, gluconeogenesis
Ketone body former
what is the response to low glucose levels ?
ketosis
too much ketosis= Low pH, causing osmotic diuresis
What is the response to high blood glucose levels? long and short term
Short term high BG
- glucose lost in renal filtrate (overcomes resorptive capacity of kidney)
- causes water loss as well
Long term
cells become glycated
deposition of cholesterol
What is the structure of insulin?
A + B chains held by disulphide bonds
Where is mineralocorticoids- aldosterone produced ?
zona glomerulosa (adrenal cortex)
what do mineralocorticoids- aldosterone do ?
lose K/ retain NA+/ increase BP
no carrier proteins so cleared from plasma quick- shorter action than cortisol
Name the two sections of the Arenal gland
Medulla [ produce adrenaline]
Cortex [produce steroids]
