Nephron Function and Structure

Study Notes

Nephron Function

The nephron is the functional unit of the kidney, responsible for filtering waste and excess fluids from the blood.
Each nephron consists of:
- Renal corpuscle (glomerulus and Bowman's capsule)
- Proximal convoluted tubule (PCT)
- Loop of Henle
- Distal convoluted tubule (DCT)
- Collecting duct
The nephron's main function is to:
- Filter blood to remove waste and excess ions, water, and nutrients
- Regulate electrolyte and water balance
- Maintain acid-base balance

Tubular Reabsorption

Tubular reabsorption is the process by which the kidney reabsorbs water and solutes from the filtrate back into the bloodstream.
Types of reabsorption:
- Passive reabsorption: occurs through diffusion and osmosis
- Active reabsorption: requires energy and involves transport proteins
Reabsorption occurs in different segments of the nephron, including:
- PCT: reabsorbs majority of glucose, amino acids, and other nutrients
- Loop of Henle: reabsorbs sodium, chloride, and potassium
- DCT: reabsorbs sodium and water

Renal Blood Flow

Renal blood flow is the amount of blood that flows through the kidneys per minute.
The kidneys receive approximately 20-25% of the total cardiac output.
Regulation of renal blood flow is critical for maintaining blood pressure and kidney function.
Factors that influence renal blood flow:
- Sympathetic nervous system activity
- Renal artery pressure
- Hormonal regulation (e.g., vasopressin)

Urine Concentration

Urine concentration is the process by which the kidneys regulate the amount of water in the urine.
The kidneys can concentrate or dilute the urine depending on the body's needs.
Mechanisms of urine concentration:
- Antidiuretic hormone (ADH) regulates water reabsorption in the collecting duct
- Osmotic gradient in the medulla of the kidney
- Urea recycling

Glomerular Filtration

Glomerular filtration is the process by which the kidneys filter the blood to remove waste and excess fluids.
The glomerular filtration rate (GFR) is the rate at which the kidneys filter the blood.
Factors that influence GFR:
- Blood pressure
- Renal blood flow
- Glomerular capillary permeability
- Bowman's capsule pressure
The glomerular filtration barrier consists of:
- Glomerular endothelial cells
- Glomerular basement membrane
- Podocytes

Nephron Function

Nephron is the functional unit of the kidney, responsible for filtering waste and excess fluids from the blood.
Each nephron consists of renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.

Nephron's Main Function

Filter blood to remove waste and excess ions, water, and nutrients.
Regulate electrolyte and water balance.
Maintain acid-base balance.

Tubular Reabsorption

Process by which the kidney reabsorbs water and solutes from the filtrate back into the bloodstream.
Types of reabsorption: passive reabsorption (occurs through diffusion and osmosis) and active reabsorption (requires energy and involves transport proteins).
Reabsorption occurs in different segments of the nephron.
PCT reabsorbs majority of glucose, amino acids, and other nutrients.
Loop of Henle reabsorbs sodium, chloride, and potassium.
DCT reabsorbs sodium and water.

Renal Blood Flow

Amount of blood that flows through the kidneys per minute.
Kidneys receive approximately 20-25% of the total cardiac output.
Regulation of renal blood flow is critical for maintaining blood pressure and kidney function.
Factors that influence renal blood flow: sympathetic nervous system activity, renal artery pressure, and hormonal regulation (e.g., vasopressin).

Urine Concentration

Process by which the kidneys regulate the amount of water in the urine.
Kidneys can concentrate or dilute the urine depending on the body's needs.
Mechanisms of urine concentration: antidiuretic hormone (ADH) regulates water reabsorption in the collecting duct, osmotic gradient in the medulla of the kidney, and urea recycling.

Glomerular Filtration

Process by which the kidneys filter the blood to remove waste and excess fluids.
Glomerular filtration rate (GFR) is the rate at which the kidneys filter the blood.
Factors that influence GFR: blood pressure, renal blood flow, glomerular capillary permeability, and Bowman's capsule pressure.
Glomerular filtration barrier consists of glomerular endothelial cells, glomerular basement membrane, and podocytes.

Description

Learn about the nephron, the functional unit of the kidney, and its components, including the renal corpuscle, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. Understand the main functions of the nephron, including filtering blood, regulating electrolyte and water balance, and maintaining acid-base balance.