Week 9 Lecture 2 Flashcards
(47 cards)
What is the functional unit of the kidney?
Nephron
The nephron filters blood and modifies the filtrate to form urine.
What two main parts consist of the nephron?
Glomerulus and Bowman’s capsule
These are crucial for blood filtration.
What are the structures included in the nephron?
- Glomerulus and Bowman’s capsule
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting tubules and ducts
These structures work together in urine formation.
What are the two types of nephrons?
- Cortical nephrons
- Juxtamedullary nephrons
They differ in the depth of the Loop of Henle in the medulla.
What is the primary function of the glomerulus and Bowman’s capsule?
Site where blood is filtered through a specialized membrane, forming an ultrafiltrate
This ultrafiltrate is then modified to become urine.
What is the main role of the proximal convoluted tubule?
Reabsorb the majority of solutes and water, and all important filtered nutrients
It is also a key site for waste secretion.
What is the function of the Loop of Henle?
Crucial for concentration of urine
It utilizes countercurrent exchangers and multipliers to limit water loss.
What happens in the distal convoluted tubule and collecting system?
Urine composition is finalized based on hormonal presence
Principal and intercalated cells play roles in ion and pH homeostasis.
What does kidney clearance refer to?
The volume of plasma from which a substance is completely removed by the kidneys per unit of time
It measures the kidney’s ability to clear substances from the bloodstream.
True or False: If half of the substance is removed in one pass through the kidney, the other half will also be removed in the next pass.
False
The same proportion is removed, not the remaining half.
What are the three ways the kidney handles substances?
- Filtration
- Secretion
- Reabsorption
These processes can occur for some substances or only one of them.
What does ‘filtered’ refer to in kidney filtration?
The process by which substances are selectively removed from the blood and transported into the kidney’s tubular system
This primarily occurs in the glomerulus.
What is the role of the glomerular capillaries in filtration?
Allow for the passage of water, ions, small molecules, and waste products from blood into Bowman’s capsule
They have fenestrations that facilitate this process.
Fill in the blank: The initial filtrate formed in the glomerulus is called _______.
glomerular filtrate
This filtrate contains substances that will eventually become urine.
What is the renal blood flow in terms of cardiac output?
1 L of blood/min (about 20% of the cardiac output)
This indicates that the kidneys receive a significant portion of the heart’s output, which is essential for their function.
What percentage of renal blood flow is filtered at the glomerulus?
Approximately 20%
This means that out of the renal plasma flow, only a fraction is actually filtered into the Bowman’s space.
What is the renal plasma flow (RPF) available for filtration?
600 ml/min
This is the volume of plasma that is available for filtration after accounting for the hematocrit.
What is the glomerular filtration rate (GFR) for most people with good renal function?
120 ml/min
This is a rough approximation based on the renal plasma flow.
What does eGFR stand for?
Estimated glomerular filtration rate
This is a measure used to estimate kidney function.
What does GFR represent?
The volume of fluid filtered from the kidney’s glomerular capillaries into the Bowman’s capsule per unit time
GFR is a key indicator of kidney function.
What is considered a normal eGFR value?
Above 90 mL/min/1.73m²
Values below this indicate decreased kidney function and may suggest kidney disease.
What are the components of the filtration barrier in the glomerulus?
- Fenestrations in glomerular capillaries
- Basement membrane
- Filtration slits between podocyte pedicels
These components work together to filter blood effectively.
What is the role of charged ions in the filtration process?
Charged ions contribute to the selective permeability of the glomerular filtration barrier
Ions such as Na⁺, K⁺, Cl⁻, and Ca²⁺ pass through the barrier, while larger charged molecules like proteins are retained.
What is the equation for net filtration pressure (NFP) across the glomerulus?
NFP = Kf · (PGC – PBC – πGC)
This equation factors in the leakiness of the filtration membrane and pressures affecting filtration.
