Term
| Primary function of the kidney |
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Definition
| maintain homeostasis of electrolytes! |
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Term
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Definition
| removal of substances from the blood |
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Term
| What is tubular secretion? |
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Definition
| removal of substances from the blood that weren't removed during ultrafiltration |
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Term
| Main 'stages' of kidney filtration |
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Definition
Ultrafiltration
Reabsorption
Secretion
Excretion to external environment |
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Term
| What does BUN stand for? How is it produced? |
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Definition
Blood Urea Nitrogen
-product of AA breakdown |
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Term
| Is the kidney an exocrine or endocrine organ? |
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Definition
both!
Primarily it excretes metabolic byproducts, toxins etc but it also evolved in Vit D metabolism, erythropoietin activity, and renin-angiotensin-aldosterone system |
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Term
| What regulates the rate of BUN, SDMA and creatinine removal from plasma? |
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Definition
| The rate of glomerular filtration / level of kidney function. |
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Term
| What are the vascular components of the nephron? |
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Definition
Glomerulus
-afferent arteriole, glomerular capillaries, efferent arteriole
Peritubular capillary |
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Term
| What are the tubular components of the nephron? |
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Definition
Bowman's capsule
Proximal tubule
LoH
Distal Tubule
Collecting Duct |
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Term
| What does the juxtaglomerular apparatus do? |
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Definition
| Involved with regulating blood pressure systemically, and glomerular filtration rate at the level of the nephron |
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Term
| Where is the macula densa found? |
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Definition
| specialized region of the distal tubule epithelium, next to JG cells |
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Term
| What structure releases renin? |
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Definition
| juxtaglomerular apparatus |
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Term
| What is glomerular filtration rate? |
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Definition
| volume of plasma filtered by all glomeruli in a given time period |
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Term
| Are glomeruli more permeable to positively or negatively charged ions? |
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Definition
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Term
| What is removed from the plasma during glomerular filtration? |
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Definition
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Term
| What is glomerulonephritis? |
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Definition
| immune-mediated pathology that leads to protein in the urine, edema in the extremities, chronic renal failure |
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Term
| What factors determine glomerular filtration rate? |
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Definition
1. Renal blood flow & perfusion pressure
2. Difference between outside blood pressure, and inside colloid oncotic pressure within the capillaries
3. Surface area available & ultrafiltration coefficient of the glomerular membrane |
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Term
| What is the filtration coefficient? |
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Definition
| the tension on the glomerular membrane |
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Term
| How can renal blood flow be controlled? (3) |
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Definition
Myogenic response
Hormones & ANS Factors
Intrinsic response (tubuloglomerular feedback) |
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Term
| What hormones cause vasoconstriction? |
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Definition
Renin-angiotensin-aldosterone system
Endothelin |
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Term
| What hormones cause vasodilation? |
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Definition
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Term
| What do ANS factors do in regards to renal autoregulation? |
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Definition
| Increase vascular resistance or promote renin release |
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Term
| How does the myogenic response work? |
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Definition
| Contraction of smooth muscle in response to adenosine, local hypoxia etc to regulate blood flow rate |
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Term
| What do adrenergic receptors do? in regard to renal autoregulation |
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Definition
| change the resistance in arterioles |
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Term
| How does tubuloglomerular feedback work? |
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Definition
1. GFR increases = increased tubular flow
2. Macula densa senses increased net flow of NaCl
3. Adenosine produced by macula densa targets mesangial cells, increasing Ca2+ in cytosol
4. Afferent arteriole constricts in response to Ca2+, increasing resistance and inhibiting renin secretion
5. Hydrostatic pressure in glomerulus decreases
6. GFR decreases |
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Term
| Where is renin primarily stored & produced? |
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Definition
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Term
| A ______ in afferent arteriole pressure causes the release of renin from the JG cells, whereas ______pressure inhibits renin release. |
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Definition
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Term
| How does NaCl influence renin release? |
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Definition
| Macula densa senses [NaCl] in tubular fluid, and if concentration is elevated then renin release will be inhibited. If concentration is low, JG cells will be stimulated to release renin. |
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Term
| How does the renin-angiotensin-aldosterone system work? |
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Definition
1. Renin released from JG cells
2. Renin acts on angiontensinogen in blood, converting it to Angiotensin I
3. ACE from lungs acts on AI, converting to to active Angiotensin II.
4. AII promotes vascular constriction, aldosterone release to increase Na & fluid reabsorption via aldosterone (adrenal cortex) and ADH (posterior pituitary) |
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Term
| What stimulates JG cells to release renin? |
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Definition
-decreased afferent arteriole pressure
-decreased [Na] detected by macula densa
-prostaglandins PGE2 & PGI2 |
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Term
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Definition
the rate at which a substance is cleared from plasma
Cl(x) = U(x) / P(x) * V |
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Term
| What is key in order for a measure of renal clearance to reflect filtration? |
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Definition
| The substance must be freely filtered, and not re-absorbed or secreted in to the tubule |
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Term
| What substances are often used to measure filtration? |
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Definition
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Term
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Definition
| Increased concentration of SDMA, inulin or creatinine in the plasma |
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Term
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Definition
| Increased concentration of SDMA/inulin/creatinine due to an issue with the kidney itself (glomeruli function is reduced, or fewer glomeruli working) |
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Term
| How can you ID whether a glomerulus is 'leaky'? |
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Definition
| look for protein in urine |
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Term
| How can ou ID whether glomeruli are filtering enough blood? |
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Definition
| look for azotemia (check the blood!) |
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