5.1.2: Excretion Flashcards
What is ultrafiltration in the kidney?
The process where blood enters through afferent arterioles, splits into capillaries of the glomerulus, causing high hydrostatic pressure that forces water and small molecules out to form glomerulus filtrate.
What does the basement membrane in the kidney do?
Acts as a sieve, allowing water and small molecules to pass while blocking large proteins and blood cells.
What are podocytes?
Special cells in the Bowman’s capsule wall that act as additional filters during ultrafiltration.
What percentage of glomerulus filtrate is reabsorbed in the PCT?
85%
What is selective reabsorption?
The process where specific substances, such as glucose and amino acids, are reabsorbed from the nephron back into the blood.
How are sodium ions transported in the PCT?
Sodium ions are actively transported out of the PCT cells into the blood, decreasing their concentration in the cells.
What is co-transport in the context of kidney function?
A process where sodium ions are transported along with glucose into the PCT cells.
What role does the Loop of Henle play in the kidney?
Maintains a sodium ion gradient in the medulla to enable reabsorption.
What is the function of mitochondria in the Loop of Henle?
Provide energy to actively transport sodium ions out of the ascending limb.
What is the permeability of the ascending limb of the Loop of Henle?
Impermeable to water.
What happens to water in the presence of a sodium ion gradient created by the Loop of Henle?
Water diffuses out by osmosis into the interstitial space and then into blood capillaries.
What occurs at the base of the ascending limb of the Loop of Henle?
Some sodium ions are transported out by diffusion as the solution becomes dilute due to water moving out.
What happens to the filtrate as it moves through the DCT and collecting duct?
More water diffuses out due to the high concentration in the medulla, leading to urine formation.
Fill in the blank: The Bowman’s capsule is part of the _______ in the kidney.
nephron
True or False: Large proteins and blood cells can pass through the capillary endothelium during ultrafiltration.
False
