Term
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Definition
Maintain fluid and electrolyte balance
Disposal of water-soluble wastes
Secondary functions:
Erythropoetin (EPO) production
Vitamin D Activation
Responsible for 20% of total glucose production |
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Term
| What is the functional unit of the kidney? |
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Definition
Nephron
1 million nephrons per kidney |
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Term
| Normal Glomerular Filtration Rate (GFR) |
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Definition
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Term
Afferent vs. Efferent arterioles:
Which one vasoconstricts to kep GFR constant?
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Definition
Aferrent arterioles vasoconstrict to keep GFR constant.
Lessens pressure felt by kidney |
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Term
| Which arteriole (afferent of efferent) is from the glomerulus? |
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Definition
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Term
| Which arteriole (afferent or efferent) is from the renal artery? |
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Definition
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Term
| How much reabsorption to blood occurs in the proximal convoluted tubule? |
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Definition
60% of Na+ and water reabsorbed
Na+/H+ exchange, glucose, AA's, bicarb, vitamins transported to interstitium
Increased ATP req. for active transport pumps. |
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Term
| What occurs at the descending loop of henle? |
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Definition
| Transportation of water and concentrated filtrate to ascending loop |
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Term
How much reabsorption occurs at the ascending loop of henle?
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Definition
30% of Na+ and water reabsorbed
Active transport of Na+, 2 CL-, K+
Starting at bottom, more water is removed from filtrate as it moves up the loop and osmolality is increased (more concentrated) in the interstitial fluid. |
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Term
| How much reabsorption occurs at the distal convoluted tubule? |
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Definition
7% of Na+ and water reabsorbed
Na+/Cl- co-transport.
Transports Na+, Cl-, water, urea
responsive to aldosterone and angiotensin II
Macula densa regulation of GFR
Secretion of H+, K+, NH3+ |
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Term
| How much reabsorption occurs at the collecting duct? |
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Definition
3% of Na+ and water reabsorbed.
Passive water transport under influence of ADH (vasopressin). ADH stimulates water reabsorption.
Collecting duct secretes H+, K+ (controlled by aldosterone) |
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Term
| How does systemic BP affect GFR? |
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Definition
Increased Systemic BP causes increased GFR
Afferent arterioles vasoconstrict to keep GFR constant; lessens pressure felt by kidney |
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Term
| The driving force of filtration in the glomerulus is _________________ |
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Definition
Hydrostatic pressure in glomerular capiillaries
Colloid osmotic/oncotic pressure: proteins are negatively charged, attract + ions which then attract water. THUS
Oncotic pressure opposes filtration by holding water, ions in capillaries. |
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Term
| What gets filtered by the kidney (moved across tubule walls) |
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Definition
Water
Electrolytes (H+, K+)
Solutes (Creatinine, urea, glucose, AAs)
Organic acids
Phosphates |
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Term
| What does NOT get filtered by the kidney? |
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Definition
Negatively charged particles (i.e., protein)
Particles too large to pass (RBCs, WBCs, platelets) |
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Term
| How does each individual nephron regulate GFR? |
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Definition
At the juxtaglomerular apparatus,
at macula densa (distal convoluted tubule)
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Term
| What is the role of JG cells? |
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Definition
JG cells are modified smooth muscle cells of afferent/efferent arterioles.
JG cells are baroreceptors.
They synthesize, store, and release renin (an enzyme)
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Term
What is Renin?
What does it do? |
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Definition
It is an enzyme
It causes conversion of Angiotensin to Angiotensin II (lungs) which leads to potent vasoconstriction of efferent arterioles (which will increase GFR) |
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Term
| What is the role of the macula densa (in GFR regulation) |
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Definition
- senses changes in NaCl delivery
- When NaCl increases, signal is sent to slow GFR
- Will also stimulate renin release from JG cells
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Term
| *What is the best indicator of how well the lungs are excreting metabolic wastes? |
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Definition
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Term
| *What is the best indicator of how well the kidneys are excreting metabolic wastes? |
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Definition
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Term
| How does the kidney excrete metabolic wastes? |
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Definition
In urine with ammonia as a buffer: NH4
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Term
| *What is the significance of NH4 and HPO4? |
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Definition
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Term
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Definition
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Term
Aldosterone:
What is its role?
Where is it excreted from? |
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Definition
It increases NaCl and water reabsorption,
K+ excretion: increases as serum K+ increases
It causes retention of Na+, thus K+ is excreted out
(Na+ IN, K+ OUT)
It is excreted from the adrenal cortex |
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Term
| On which part of the tubular system does aldosterone act? |
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Definition
Collecting duct
(where it controls excretion of K+) |
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