PHY3171 Lecture 4: CVS Hormones
10 Feb 2019
School
Department
Course
Professor
13/03/18
CARDIOVASCULAR RESPONSE TO STRESS L4
HORMONES
– Hormones are not just endocrine
– Any chemical messengers that are not released at the synapse of neurones
– Act in a negative feedback loop (only a few exceptions)
– Local factors are also hormones
o Autocrine - released from a cell and act on the same cell
o Paracrine – released from one cell and act on a neighbouring cell eg. NO
Endocrine
- Angiotensin II
- Aldosterone
- Atrial natriuretic peptide
- Arginine vasopressin (ADH)
- Adrenaline
Paracrine/Autocrine
- Nitric oxide
- Prostaglandins
- Endothelins
- Bradykinin
Sites at which hormonal action can be modified
1. Synthesis
2. Release
3. Activation (if a prohormone)
4. Inactivation
5. Receptors
6. Signal transduction
ANGIOTENSIN II
– Myriad of actions – all mostly increase blood pressure
Within the kidney
- Vasoconstriction (reduces blood flow)
o But favours efferent arteriole ↑ GFR
- ↑ Na+ reabsorption
Outside the kidney
- Vasoconstriction
- Stimulates aldosterone secretion from adrenal cortex
o Both act together to promote reabsorption of salt + water
o Ang II acts on proximal part of tubule, aldosterone acts on distal part
- Stimulates sympathetic nervous system ↑BP
- ↑ thirst and salt appetite
Renin
– Renin is the rate limiting step for release of aldosterone
– Renin is found in cells that line afferent arteriole
– 3 stimuli that cause release of renin:
1. If BP in afferent arteriole falls
2. Released by juxtaglomerular cells if SNS activated (noradrenaline acts on beta adrenoceptors
to stimulate release of renin)
3. Signalling from distal tubule – if there is ↓Na+ to distal tubule, renin is released
Document Summary
Any chemical messengers that are not released at the synapse of neurones. Act in a negative feedback loop (only a few exceptions) 13/03/18: autocrine - released from a cell and act on the same cell, paracrine released from one cell and act on a neighbouring cell eg. no. Sites at which hormonal action can be modified: synthesis, release, activation (if a prohormone, inactivation, receptors, signal transduction. Myriad of actions all mostly increase blood pressure. Vasoconstriction (reduces blood flow: but favours efferent arteriole gfr. Stimulates aldosterone secretion from adrenal cortex: both act together to promote reabsorption of salt + water, ang ii acts on proximal part of tubule, aldosterone acts on distal part. Renin is the rate limiting step for release of aldosterone. Renin is found in cells that line afferent arteriole. Sites at which hormones can influence circulatory control: blood vessels (arterial resistance vessels and veins most important)
