Long Term Control of Blood Pressure Flashcards
Which organ is responsible for long term control of blood pressure?
control of plasma volume by kidney
What are the functions of the kidney?
Excretion of waste products
Maintenance of ion balance
Regulation of pH
Regulation of osmolarity
Regulation of plasma volume
What are the following areas labelled on this nephron?
What is the effect of the renal counter current system?
Creates very high osmolarity outside collecting duct
How is control over how much water is lost with urine acheived?
- Osmotic gradient between collecting duct and outside collecting duct
- Na+ transport determines this gradient
- Control over the permeability of the collecting duct to water will determine if water follows that osmotic gradient or not
Where is sodium pumped?
outside of distal tube - concentration of solute decreases significantly before it reaches collecting duct
What is the affect of varying the permeability of the collecting duct?
- Making collecting duct very permeable to water will result in lots of water reabsorption, little urine, and conserve plasma volume
- Making collecting duct very impermeable to water will result in little reabsorption, lots of urine (= diuresis), and reduction in plasma volume
What are the three main hormones that regulate water reabsorption?
Renin - angiotensin - aldosterone system
Antidiuretic factor (ADH, vasopressin)
Atrial natriuretic peptide
Where is the renin produced?
Juxtaglomerular (= granule cells) of kidney
What triggers renin production?
- Activation of sympathetic nerves to juxtaglomerular apparatus
- Decreased distension of afferent arterioles (“renal baroreflex”)
- Decreased delivery of Na+/Cl- through tubule
What is responsible for detecting a reduced delivery of sodium and chlorine ions?
Macula densa
Where do you find the macula densa?
Ascending loop of henle
(distal convoluted tubule)
What does renin do?
- Converts angiotensinogen to angiotensin 1
- Angiotensin converting enzym to Angiotensin 2
How does angiotensin increase MAP?
Stimulates release of aldosterone from adrenal cortex
(this increases amount of sodium reabsorption in loop of henle - less diuresis and increased plasma volume)
Increases release of ADH from pituitary
(increases permeability of collecting duct, reduces diuresis. Increases sense of thirst)
Vasoconstrictor
(increases total peripheral resistance)
How is the formation of angiotensin 2 a form of negative feedback?
- Multiple mechanism detect any decrease in MAP
- Stimulates release of renin
- Evokes multiple mechanisms which increase MAP
