Long term control of blood pressure Flashcards
How do the kidneys regulate plasma volume?
The kidneys adjust sodium and water excretion to control blood volume, which directly influences blood pressure.
What happens when plasma volume decreases? (in the kidneys)
The kidneys retain sodium and water to restore volume and blood pressure.
What happens when plasma volume increases? (in the kidneys)
The kidneys increase sodium and water excretion to reduce volume and blood pressure.
What receptors detect changes in plasma volume?
Cardiopulmonary baroreceptors (in atria and pulmonary vessels) detect blood volume changes.
Arterial baroreceptors (in carotid sinus and aortic arch) detect pressure changes.
Juxtaglomerular cells (in kidneys) detect renal perfusion pressure and regulate renin release.
What triggers the renin-angiotensin-aldosterone system (RAAS)?
Low blood pressure, low sodium levels, or sympathetic stimulation.
What is the role of renin?
Renin (from juxtaglomerular cells) converts angiotensinogen (from liver) into angiotensin I.
What enzyme converts angiotensin I into angiotensin II?
Angiotensin-converting enzyme (ACE) in the lungs.
What are the effects of angiotensin II?
- Vasoconstriction → increases blood pressure.
Stimulates aldosterone release from adrenal cortex → increases sodium & water retention.
Stimulates ADH release → promotes water retention.
What is the role of aldosterone?
Increases sodium (Na⁺) reabsorption and potassium (K⁺) excretion in the kidneys, increasing water retention and blood volume.
Where is antidiuretic hormone (ADH) released from?
The posterior pituitary gland in response to low plasma volume or high blood osmolality.
What is the function of ADH?
Increases water reabsorption in the kidneys (collecting ducts), reducing urine output and increasing blood volume.
How does ADH affect blood pressure?
It increases blood pressure by raising plasma volume and causing vasoconstriction.
Where are ANP and BNP released from?
ANP: Released from atrial myocytes in response to atrial stretch (high blood volume).
BNP: Released from ventricular myocytes during heart failure or excessive stretch.
What is the function of ANP and BNP?
Increase sodium and water excretion in kidneys → lower blood volume.
Inhibit renin, aldosterone, and ADH → reduce fluid retention.
Vasodilation → decreases blood pressure.
What are the key hormones involved in plasma volume control?
Renin-Angiotensin-Aldosterone System (RAAS): Increases blood volume and BP.
Antidiuretic Hormone (ADH): Retains water to increase BP.
Atrial Natriuretic Peptide (ANP) & Brain Natriuretic Peptide (BNP): Reduce blood volume and BP.
