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What is the function of the tubuloglomerular feedback mechanism?
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Macula densa cells sense increased filtrate flow and release adenosine, causing constriction of the afferent arteriole and reducing GFR.
What is the primary function of the kidneys?
To filter blood and remove waste.
Explain the impact of Angiotensin II on renal blood flow.
Angiotensin II constricts arterioles, thereby reducing blood flow but maintaining GFR at low levels.
What is the Glomerular Filtration Rate (GFR) and how much plasma is typically filtered per minute?
GFR is about 125 mL per minute, with approximately 20% of plasma being filtered.
What role do natriuretic peptides (ANP and BNP) play in regulating renal blood flow?
They dilate afferent arterioles and constrict efferent arterioles, increasing blood flow.
How much of the cardiac output do kidneys receive per heartbeat?
Approximately 25%.
What happens to renal blood flow when systemic blood pressure is high and renal arteriolar resistance is low?
Renal blood flow increases.
How does adrenaline affect renal blood flow?
Adrenaline binds to alpha-1 adrenergic receptors in arterioles, causing constriction and decreasing blood flow.
Describe the myogenic mechanism involved in renal blood flow autoregulation.
Smooth muscle cells in arterioles contract when stretched by high blood pressure, maintaining consistent blood flow.
How does dopamine at low concentrations affect renal blood flow?
Dopamine dilates arterioles at low concentrations, increasing blood flow.
To which pressure gradient is renal blood flow proportional?
The pressure gradient between renal artery pressure and renal vein pressure divided by resistance.
Which molecules are known to slightly dilate arterioles under sympathetic stimulation?
Prostaglandins E2 and I2.
How do peritubular capillaries contribute to venous return?
The peritubular capillaries form venous vessels which eventually converge into the renal vein, which drains into the inferior vena cava.
Describe the structure and components of a nephron.
A nephron consists of a renal corpuscle (glomerulus + Bowman's capsule) and a renal tubule.
Name the sequential parts of the renal tubule starting from the Bowman's capsule.
Proximal convoluted tubule, Loop of Henle (ascending and descending limbs), Distal convoluted tubule.
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