Overview
This lecture explains glomerular filtration rate (GFR), focusing on how filtration occurs in the nephron’s glomerulus and what regulates the rate.
Glomerulus and Filtration Basics
- The nephron is the kidney’s functional unit, responsible for filtration, reabsorption, secretion, and elimination.
- Blood enters the nephron via the afferent arteriole and leaves via the efferent arteriole.
- The glomerulus is a permeable structure that allows small waste molecules to pass but prevents larger molecules, like proteins and blood cells, from filtering out.
- Filtration in the glomerulus produces filtrate that moves into the Bowman's capsule and continues through the nephron.
- If large molecules do pass through, it indicates a kidney problem.
Regulation of Glomerular Filtration Rate (GFR)
- GFR is the rate at which blood is filtered through the glomerulus.
- Increasing pressure in the glomerulus raises the GFR, while decreasing pressure lowers it.
- Constricting the efferent arteriole (outflow) increases glomerular pressure and GFR.
- Constricting the afferent arteriole (inflow) decreases blood entry, lowers pressure, and reduces GFR.
- The smooth muscle in arteriole walls adjusts diameter, thus regulating GFR.
Key Terms & Definitions
- Nephron — the kidney’s microscopic functional unit that filters blood and forms urine.
- Glomerulus — a network of capillaries within the nephron where filtration occurs.
- Afferent arteriole — blood vessel bringing blood into the glomerulus.
- Efferent arteriole — blood vessel carrying blood out of the glomerulus.
- Glomerular Filtration Rate (GFR) — the rate at which the kidneys filter blood through the glomeruli.
- Bowman's capsule — structure that collects filtrate from the glomerulus.
Action Items / Next Steps
- Review the previous video on nephron structure for further clarification.
- Study how changes in arteriole diameter affect GFR for upcoming assessments.