Urinary System Pt. 3 Flashcards
(40 cards)
How much of the total cardiac output do the kidneys receive?
About 20-25% of the cardiac output
What is the primary role of the renal arteries?
To deliver blood to the kidneys
How does the renal blood flow compare to other organs?
Renal blood flow is higher than in most other organs
What is the role of the afferent arterioles in renal blood flow?
They supply blood to the glomerulus
What do efferent arterioles do in the context of renal blood flow?
They take blood away from the glomerulus
What are the peritubular capillaries in the kidneys?
A network of tiny blood vessels surrounding the proximal and distal convoluted tubules
What is the vasa recta in the kidneys?
Specialized peritubular capillaries that supply the nephron loop
Why do the kidneys have a large amount of blood flow?
To maintain the necessary pressure and flow for filtration
What is autoregulation in the kidneys, and how does it work?
The kidneys can regulate their own blood flow by adjusting the diameter of the afferent and efferent arterioles
What is the myogenic mechanism in autoregulation?
A response to increased blood pressure, causing a constriction of afferent arterioles
What is the tubuloglomerular feedback mechanism?
A response to increased blood pressure causing a reduced GFR
What is the juxtaglomerular apparatus (JGA)?
A region in the nephron where the distal convoluted tubule contacts the afferent and efferent arterioles
What cell types are present in the JGA?
Macula densa cells, granular cells (juxtaglomerular cells), and extraglomerular mesangial cells
What is the role of macula densa cells in the JGA?
They monitor the composition of the fluid in the distal convoluted tubule, and if it has enough sodium. If it doesn’t, it releases renin.
How do granular cells (juxtaglomerular cells) respond to changes in blood pressure?
They can contract when blood pressure drops and relax when it rises
What is the role of extraglomerular mesangial cells in the JGA?
They provide structural support and can communicate with each other and other JGA cells
What triggers the release of renin by granular cells?
Low blood pressure or sympathetic stimulation
What does renin do when it’s released into the blood?
It initiates a cascade that ultimately results in increased blood pressure
What are the three processes of urine formation in the nephron?
Filtration, reabsorption, and secretion
What is reabsorption in the nephron?
The process of moving substances from the filtrate back into the bloodstream
What is secretion in the nephron?
The movement of substances from the blood into the tubular fluid
In which part of the nephron does the majority of reabsorption occur?
Proximal convoluted tubule
What substances are typically reabsorbed in the proximal convoluted tubule?
Glucose, amino acids, ions, and water
What is the descending limb of the nephron loop primarily permeable to?
Water
