Kidney structure and function 1 Flashcards
Describe the structure of the glomerulus and Renalcapsule.
The glomerulus is a network of capillaries from the afferent arteriole. The Renal capsule surrounds them and has an inner epithelial layer that are highly adapted (podocytes) to filter the fluid that is forced out of the capillaries.
How does ultrafiltration occur?
The lumen of the efferent arteriole is narrower than the afferent arteriole, so blood enters the glomerulus capillaries under high hydrostatic pressure. Blood is filtered through the capillary wall, a basement membrane and through filtration slits formed by the podocytes of the Renal capsule. The solution is now called filtrate and is in the lumen of the Renal capsule.
What substances does ultrafiltration remove from the blood
Water, glucose, urea, amino acids, fatty acids and ions
What remains in the blood after ultrafiltration and why?
Blood cells, platelets, proteins such as antibodies.
What part of the filtration layers prevents small proteins from leaving the blood?
The basement membrane since this is the finest filter (has the smallest gaps).
How are the epithelial cells of the proximal convoluted tubule adapted to their function?
They have microvilli to increase surface area for reabsorption, many carrier proteins to allow facilitated diffusion, infoldings at their base to increase surface area for facilitated diffusion and active transport to the blood, high density of mitochondria to provide ATP from aerobic respiration for active transport.
How does the Proximal Convoluted Tubule reabsorb substances?
Sodium ions are actively transported into the capillaries and is carried away. This lowers the concentration of sodium ions in the cells, sodium ions enter from the lumen of the Proximal Convoluted Tubule down a concentration gradient using a carrier protein (facilitated diffusion). A glucose/amino acid is also moves into the cell by co-transport. Once inside the epithelial cells glucose diffuses out by facilitated diffusion and diffuses into the blood.
What happens to the efferent arteriole?
It turns into the capillary network that surrounds the Proximal convoluted Tubule, Loop of Henle and Distal Convoluted Tubule. Reabsorption occurs into these capillaries.
How is the loop of Henle adapted to it’s function?
The descending limb is narrow, with thin walls that are highly permeable to water. The ascending limb is wider, with thick walls that are impermeable to water.
