Week 4 Flashcards
Adrenal medulla
Modified sympathetic ganglia, secreted catecholamines
Adrenal cortex
Steroid factory, it secretes steroid hormones
Main catecholamine
epinephrine, it is secreted in enough quantity to exert effects
chromaffin cell
post ganglionic sympathetic neuron
Catecholamines
Epinephrine, norepinhrine, dopamine
Stimulus for release of epinephrine
Activation of the sympathetic nervous system - fight or flight response
role of epinehrine in skin, intestine, kidney
intestine: muscle relaxation, arteriole contriction
skin and kidney: arteriole contriction
role of epinehrine in liver and fat
liver: glucose release (via glycogenolysis)
fat: fatty acid release
role of epinehrine in muscle, brain and resp
muscle: arteriole contraction (alpha receptors), arteriole relxation (beta receptors)
brain: increased alertness
resp: bronchodilator
Reactions of anaphylactic shock
bronochospasm (contriction of airways), decrease in blood pressure
How does epipen counteract symptoms of anaphylactic shock?
bronchodilation, vasoconstriction in skin, kidney, intestine and vasodilation in skeletal and cardian muscles.
Parts of adrenal cortex
Zona glomelurosa, zona facilutata, zona reticularis
what does zona glomerulosa secrete
aldosterone
what does zona fasciculata secrete
glucocorticoids - cortisol
Weak androgens
Less than 20% activity of testosterone but they are converted to more potent androgens and estrogens in peripheral tissue
what does zona reticularis secrete
sex steroids
What increases androgen production?
ACTH
physiological role of androgens in children
Male prenantal development, also contribute to andrenarche - pubic hair, body odor, oily skin, acne - for both males and females
physiological role of androgens in adult men
no physiological role - testes provide androgens for males
physiological role of androgens in women
although ovaries provide estrogen, androgens maintain pubic and axillary hair, source of estrogen after menopause
Aldosterone
its actd on the distal tubule of increase Na+ absorbtion and K+ secretion
Cortisol
Main glucocoricoid, secreted by zona fasiculata
role of cortisol
mediation long term stress
what is the control pathway of secretion of cortisol
hypothalamic-adrenal-pituatary pathway
diurnal rhythm
continious secretion of costisol
short term stress
nerve impulse –> spinal cord –> preganglionic sympathetic fibres –> adrenal medulla (secretes amino acid based hormones) –> catecholamines
short term stress response
- heart rate and blood pressure increases
- bronchioles dilate
- liver converts glycogen to glucose and releases glocse to blood
- blood flow chnages, reducing digestive system activity
- metabolic rate increases
prolonged stress
hypothalamus –> CRH released –> corticoptropic cells of anterior pituatary –> ACTH –> targets blood –> adrenal cortex –> steroid horones secreted
long term stress response
- kidneys retain sodium and water
- blood volume and blood pressure rise
- proteins and fats converted to glucose or broken down for energy
- blood glucose increases
- Immune system supressed
What is cortisol protective against?
Hypoglycemia through the permissive effect
Metabolic effect of cortisol
they primarily catabolic
1. promotes glucogenesis
2. brakdown of skeletal muscle proteins
3. enhances lipolysis
4. supresses the immune system
How is cortisol used as a drug to supress the immune system?
- inhibit inflammatory responses
specififc uses: poison ivy, allergies, asthma
cortisol regulation
it is regulated through the negative feedback loop.
cortisol supresses both CRH and ACTH production, inturn stopping its own production.
what can long term use of cortisol drugs do
inhibition of ACTH secretion and atrophy cortisol secretig cells
addisons disease (adrenal insifficiency)
hyposecretion of adrenal steroid hormones.
it causes destruction of the adrenal by autoimmunity, sometimes infection
symptoms of addisons disease
hypotension (low aldosterone –> low Na + reabsorbtion –> increased water loss –> low blood volume) , hypoglycemia. (low cortisol –> low blood glucose levels)
Cushings syndrome - excess cortisol
caused by tumours, cortisol therapy
symptoms of cushings syndrome
hyperglycemia, muscle protein breakdown, lipolysis but build up of fat on trunk and facem increased apetite, mood elevation but then followed by depression and problems with learning
What does excessive water loss do?
It can cause disease (hypotension/shock)
there is less extracellular fluid –> decreased blood pressure
How is water distributed in the body?
2/3 in intracellular fluid
1/3 in extracellular fluid - 75% interstitial and 25% plasma
Symptoms of excessive water loss
confused, chess pain, low blood pressure, no urine