Lecture 13 - Blood pressure regulation Flashcards
Blood pressure: what is it?
The force exerted upon vessel walls during blood flow
Capillary hydrostatic pressure
The minimum pressure needed for substances to be exchanged across the capillary wall (without pressure pushing the substance out, there would no force moving the fluid)
Short-term regulation of blood pressure: what causes it to happen, what does it do, and is it sustainable?
This occurs due to the neural system
Can change blood pressure due to altering cardiac output and doing vasoconstriction/vasodilation
Not sustainable so, if necessary, renal support will aid long term regulation
Long-term regulation of blood pressure: what causes it to happen, what does it do, and is it sustainable?
This occurs due to the renal systems
Can change blood pressure by altering blood volume and doing vasodilation/vasoconstriction
Sustainable but changing blood volume takes a while to initiate
Baroreceptors: what do they do, what does stimulation do?
Detect blood pressure levels and, if stimulated, will reduce blood pressure
Chemoreceptors: what do they do, what does stimulation do?
Detect blood oxygen (carbon dioxide) concentration by detecting the pH change in the blood
Stimulated chemoreceptors will increase the respiratory rate
Low blood volume: what does the body do
The pituitary gland produces Anti-diuretic hormone (ADH) which increases the reabsorption of water in the collecting duct of the nephron in the kidney, increasing blood volume
Low blood pressure/oxygen: what does the body do
The kidney and liver produce more erythropoietin which results in the production of more red blood cells
RAAS: what is it, what does it do?
Renin-angiotensin-aldosterone system
Angiotensinogen is produced by the liver and, if renal blood pressure falls, the kidneys produce renin which converts angiotensinogen into angiotensin I. Lungs generate an angiotensin conversion enzyme (ACE) which reacts with angiotensin I to form angiotensin II which has various effects in the body
Angiotensin II: the impact it has on arterioles, kidneys, SNS, adrenal cortex, hypothalamus
Arterioles - causes vasoconstriction
Kidneys - causes increased sodium reabsorption
SNS - increased noradrenaline release
Adrenal cortex - increased aldosterone release
Hypothalamus - increase thirst and ADH secretion
High blood pressure: what does the body do?
The cardiac muscle is stretched more in the atria and ventricles, causing natriuretic peptides to be produced which have effects on vascular and renal systems
The vascular response to natriuretic peptides
The release of noradrenaline, adrenaline, ADH, and aldosterone is inhibited which causes blood pressure to be reduced
Peripheral vasodilation causes decreased blood pressure as blood vessels expand and so blood can flow easier
The renal response to natriuretic peptides
The blood volume is decreased due to decreased thirst and more sodium and water are removed from the body through the urine
Less blood volume leads to reduced blood pressure
Haemorrhaging: what is it, and how is it solved?
The loss of blood from ruptured blood vessels
Short term solution is increasing cardiac output and vasoconstriction
Long term solution is the increase of blood volume by reabsorbing more water and salt using ADH and aldosterone and also by producing more red blood cells by having the kidney and liver produce more erythropoietin
