24 Questions
What is the main function of cortical nephrons?
Absorption of sodium
What percentage of nephrons are juxtamedullary nephrons?
14%
What is the function of the glomerulus?
To filter waste from the blood
What is the structure that encloses the glomerulus?
Bowman's capsule
What is the rate of blood flow to the kidneys?
1200 ml/min
What is peculiar about the renal circulation?
Very high blood supply
What is the term for the thin segment of the loop of Henle?
Thin segment
What is the main function of the proximal convoluted tubule?
Reabsorption of useful substances
What is the primary function of the kidneys in regulating the body's electrolyte balance?
To maintain a balance between intake and output of water and electrolytes
Which of the following waste products is excreted by the kidneys?
Urea
What is the name of the hormone produced by the kidneys that stimulates the production of red blood cells?
Erythropoietin
What is the term for the process of removing waste products from the body?
Excretion
What is the main function of cortical nephrons?
To form urine
Which of the following organs is responsible for excreting carbon dioxide?
Lungs
What is the role of the kidneys in regulating blood pressure?
To maintain a stable blood pressure
What is the purpose of the nephron, the structural and functional unit of the kidney?
To form urine
What is the main function of the efferent arteriole in the nephron?
To break into the peritubular capillary network around the tubules of cortical nephrons
What is the characteristic of blood flow through the vasa recta?
It is sluggish and has a low pressure
What is the main function of the afferent arteriole in the nephron?
To provide a short, straight branch of the interlobular artery
What is the purpose of autoregulation in the kidneys?
To maintain a constant renal blood flow despite changes in blood pressure
What is the pressure in the glomerular capillary bed?
60 mmHg
What is the function of the distal convoluted tubules?
To open into initial arched collecting ducts
What is the name of the ducts that open into the papilla of minor calyces?
Papillary ducts
What is the percentage of blood flow through the vasa recta?
1-2%
Study Notes
Role of the Kidneys in the Body
- Regulate the volume and composition of the ECF by maintaining a balance between intake and output of water and electrolytes in the body.
- Excrete and eliminate waste products of metabolism, such as urea, creatinine, and uric acids, as well as various toxins like drugs and food additives.
- Act as endocrine glands, producing hormones like erythropoietin and renin.
- Play a dominant role in the long-term and short-term regulation of arterial blood pressure.
- Contribute to acid-base regulation along with the respiratory system.
- Synthesize glucose from amino acids and other precursors.
Excretion
- Defined as the removal of waste products from the body.
- Organs involved in excretion:
- Kidneys: excrete water and water-soluble waste products.
- Lungs: excrete carbon dioxide, water vapor, and other volatile substances.
- Skin: excretes water and salts mainly in the form of sweat.
- Gastrointestinal tract: excretes undigested food.
Structure of Nephron
- Nephron is a structural and functional unit of the kidney.
- Each nephron is capable of forming urine.
- Two types of nephrons:
- Cortical nephrons (86%): glomeruli are present near the surface of the kidneys; main function is absorption of sodium.
- Juxtamedullary nephrons (14%): glomeruli lie at the junction of cortex and medulla; main function is to increase concentration of medullary interstitial fluid.
- Two major parts of a nephron:
- Glomerulus: a tuft of capillaries that connect afferent arteriole with an efferent arteriole.
- Renal tubule: consists of three parts - proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
Blood Flow to Kidneys
- Rate of blood flow to kidneys: 1200 ml/min.
- Peculiarities of renal circulation:
- Very high blood supply (21% of cardiac output).
- Two sets of capillaries: glomerular capillaries and peritubular capillaries.
- Glomerular capillary bed has a high hydrostatic pressure (60 mmHg) due to a smaller diameter of the efferent arteriole compared to the afferent arteriole.
- Peritubular capillary bed is a low-pressure bed (13 mmHg).
- Vasa recta (loop-shaped vessels) in juxtamedullary nephrons receive only 1-2% of blood flow, which is very sluggish.
- Renal blood flow shows remarkable constancy in the face of blood pressure changes due to autoregulation.
- The kidneys regulate the hydrostatic pressure in both capillary beds by adjusting resistance of the afferent and efferent arterioles.
This quiz covers the functions of the kidney, morphology of the typical nephron, and the concept of clearance. It also explores the role of the kidneys in regulating the body's ECF volume and composition.
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