Term
| What is on top of the kidneys? |
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Definition
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Term
| What is draining into and out of the kidney? |
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Definition
The renal artery into the kidney
Renal vein and renal pelvis --> ureters out of the kidney
All enter/leave at the hilus |
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Term
| At one point is urine made? |
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Definition
| When fluid enters the ureters, it is called urine. Until that point, it is called filtrate. |
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Term
| What are major functions of the kidney? |
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Definition
Excretion of waste
Electrolyte balance
Acid-base balance
Arterial pressure regulation
Hormone regulation
Gluconeogenesis |
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Term
| What volume is filtered by the kidneys every day? |
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Definition
| 650 ml/min of plasma, 125ml/min is filtered |
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Term
| What are the 3 coverings of the kidney? |
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Definition
The posterior renal fascia anchors to the peritoneal cavity
The adipose capsule gives protection
The renal capsule holds the kidney in place. |
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Term
| How many different vertebrae are there of each type? |
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Definition
7 cervical vertebrae
12 Thoracic vertebrae
5 Lumbar vertebrae
5 fused Sacral vertebrae
4 fused Coccyx vertebrae |
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Term
| What are the 2 major layers of the kidney and their features? |
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Definition
- Outer layer - Cortex. All Glomeruli and 85% of nephrons in the cortex
- inner layer - medulla. Medullar nephrons concentrate or dilute urine |
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Term
| What is the anatomy of a pyramid, and how do they drain into a ureter? |
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Definition
| Pyramids are separated by renal columns. Outer cortex layer and inner medulla, emptying into collecting duct. Minor and major Calyces --> Renal pelvis --> ureter |
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Term
| Where does the majority of blood go in the kidney, and how does it flow? |
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Definition
Because nephrons are in the cortex, blood flows into the cortex.
Renal artery --> Segmental artery --> Lobar --> Arcuate --> Afferent --> Glomerulus --> Efferent --> peritubular capillaries --> Arcuate --> Interlobar --> Renal vein.
Note there is no Lobar vein |
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Term
| What are the 2 kinds of nephrons and their differences? |
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Definition
- Cortical nephron - completely in the cortex, smaller loop of henle
- Juxtamedullary nephron - next to the medulla, vasa recta capillaries on the longer loop of henle concentrate and dilute urine |
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Term
| How do you calculate whether reabsorption or secretion takes place in the capillary? |
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Definition
(HPc - HPif) - (OPc - OPif)
If net is inward flow, reabsorption occurs
if net is outward (positive) flow, secretion occurs |
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Term
| What are the 3 processes that take place between the capillaries and the renal tubule? |
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Definition
- Filtration - in the glomerulus/bowman's capsule, blood is filtered. As filtrate is removed, osmotic pressure goes up and opposes filtration
- Absorption - filtered molecules reabsorb back into the capillaries
- Secreted - molecules cross from the peritubular capillaries to be secreted out with the urine |
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Term
| What is the function of the Bowman's Capsule? |
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Definition
| To collect the filtrate and send it into the proximal tubule. Continuous with proximal tubule |
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Term
| What fills up the space between the capillaries and the arterioles? What is their function? |
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Definition
Mesangial cells. Synthesize matrix material, phagocytic. Can contract, which constricts blood flow in the capillaries
Podocytes also cover the capillaries |
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Term
| What is the juxtaglomerular apparatus? |
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Definition
| The afferent and efferent arterioles, and the distal tubule which juts up against the arterioles. |
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Term
| What is the function of macula densa and J-G cells in the Juxtaglomerular apparatus? |
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Definition
| Macula densa sense the presence or absence of sodium, signal the J-G cells to release renin |
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Term
| What is the purpose of podocytes? |
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Definition
| On the capillaries, to regulate the size of molecules that can pass into the filtrate. Contain fenestrated capillaries, then basement membrane, then slit diaphragm. Protein and RBC, myoglobin and albumin cannot be filtered |
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Term
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Definition
Site 1 - proximal convoluted tubule
Major site of reabsorption, contains mitochondria (basal) and microvilli (apical).
No drugs target here, would have too many side effects. |
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Term
| What sites are between site 1 and site 2? |
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Definition
- Descending limb of the loop of henle (DTL) - only permeable to water
- Ascending thin limb - loses permeability to water |
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Term
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Definition
| Thick Ascending Limb - site of Na/K/Cl pump. Impermeable to water, site of loop diuretics |
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Term
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Definition
| Distal Convoluted tubule - contains the macula densa cells which also have the Na/K/Cl pump. Some mitochondria/atp |
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Term
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Definition
The collecting tubule and collecting duct. Call be permeable to water depending on the presence of ADH. If ADH is present, Na/water reabsorbed and urine is concentrated.
Contains principal cells (site of aldosterone) and intercalated cells (for acid-base balance). More principal cells than intercalated cells, and less intercalated cells moving down collecting duct |
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Term
| Where does the SNS innervate? |
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Definition
The J-G cells (Beta 1)
Afferent/efferent arterioles
Proximal tubule |
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Term
| What are secretory functions of the kidney? |
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Definition
- Renin - increase BP
Erythropoietin - stimulate RBC synthesis
PgE2 and prostacyclin - from the cortex, excretion of sodium and water/dilation
Calcitriol - active D3 |
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Term
| What is the role of erythropoietin? |
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Definition
| If there is a decrease in oxygen from hypoxia or an increase in oxygen demand --> HIF-1 in the kidney induced release of EPO --> red bone marrow produces RBC |
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Term
| What is the kidney's role is Vitamin D and calcium regulation? |
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Definition
| Kidney converts D2 to active D3 (calcitriol), as well as reducing the excretion of calcium. Calcitriol stimulates the small intestine to absorb dietary calcium and calcium release from bone. Parathyroid hormone increases calcitriol synthesis as well as calcium/phosphorus release from bone. |
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Term
| What is the drug Zemplar used for? |
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Definition
| In chronic renal disease, too much parathyroid hormone is produced. Prevents secondary parahyperthyroidism |
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Term
| How is Urinary excretion rate calculated? |
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Definition
| Urinary excretion rate = filtration rate - reabsorption + secretion --> What goes into the renal tubule - what goes back into the capillary + what goes back into the tubule |
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Term
| How are inulin and creatine cleared in the kidney? |
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Definition
| Freely filtered, neither secreted nor absorbed. So as plasma inulin increases, urine inulin increases linearly and has NO EFFECT of GFR ie. clearance is independent of concentration. |
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Term
| How are sodium, Chlorine, and Bicarbonate cleared in the kidney? |
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Definition
| Freely filtered, but some of what is filtered is reabsorbed |
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Term
| How are glucose and amino acids cleared in the kidney? |
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Definition
| Freely filtered, but all of what is filtered is then reabsorbed. |
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Term
| How is penicillin cleared in the kidney? |
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Definition
| Freely filtered, and some of what is not filtered is then secreted into the tubule to be excreted. Probenecid interferes with this. |
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Term
| How is Para-aminohippuric acid cleared in the kidney? |
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Definition
| Freely filtered, but ALL of what is not filtered is then secreted into the tubule to be excreted. Was used to determine RBF/renal plasma flow |
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Term
| How are Potassium and Uric acid cleared in the kidney? |
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Definition
| Freely filtered, but then both reabsorbed AND secreted |
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Term
| What is filtration fraction, and how is it calculated? |
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Definition
| FF = Plasma filtered (GFR) / Renal plasma flow --> 125/650 = 19.2% |
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Term
| Why is the glomerulus better at filtration than other capillaries? |
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Definition
- anatomy of the membrane
- Higher hydrostatic pressure - Hydrostatic pressure drives filtrate OUT of the capillary into the Bowman's capsule |
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Term
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Definition
| GFR = filtrate formed each minute by all nephrons = net filtration pressure * constant (Kf) --> 10 mmHg * 12.5 = 125ml/min |
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Term
| What is renal clearance and how is it calculated? |
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Definition
If a material is filtered and neither absorbed nor secreted,
GFR = (Urine conc. *Volume formed per min) / plasma concentration
Always make sure units are the same. ie 3.5 g/dl = 3500 mg/100 ml = 35mg/ml |
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Term
| How could Kf, normally a constant, be changed? |
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Definition
- Contraction of the mesengial cells lowers Kf, releases constricting hormones that retain Na/water --> Decrease GFR
- Renal damage and disease can decrease Kf and GFR |
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Term
| If hydrostatic pressure in the Bowman's capsule were increased, what affect would that have on GFR? |
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Definition
| Pushes back into the capillaries, so deceases GFR (less filtrate) |
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Term
| How would increasing renal blood flow affect GFR? |
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Definition
| Blood flow is more rapid and less is being filtered. As less filtrate is pushed out, osmotic pressure in the blood is lower, which increases GFR |
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Term
| What would happen if osmotic pressure in the glomerulus were to increase? |
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Definition
| Proteins in the capillary drawing filtrate back in --> decrease GFR |
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Term
| What would happen if there were an increase in glomerular hydrostatic pressure? |
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Definition
| More pressure pushing filtrate out of the capillaries --> increased GFR. |
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Term
| If there is resistance/constriction in the afferent arteriole, how is GFR affected? |
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Definition
| renal blood flow into the glomerulus is decreased, decreasing Hp and GFR |
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Term
| If there is resistance/constriction in the efferent arteriole, how is GFR affected? |
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Definition
Renal blood flow decreases because it can't get out.
Hydrostatic pressure in the glomerulus increases due to backup, which increases GFR at first. As blood backs up, it slows down and protein concentration increases (Op), and GFR goes back down |
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Term
| What is the overall relationship between GFR, RBF, and Op? |
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Definition
| Increasing renal blood flow increases GFR. Because blood flows faster, less is being filtered and osmotic pressure is slower to increase. |
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Term
| What is the function of the peritubular capillaries? |
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Definition
| reabsorption of materials absorbed in the proximal tubules and delivery of nutrients |
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Term
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Definition
| RBF = renal artery pressure - renal vein pressure / total resistance --> Flow = P/R |
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Term
| What is tubuloglomerular feedback? |
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Definition
Used to keep GFR at 125ml/min
GFR too fast - materials filtered very quickly and not reabsorbed. Macula densa senses high sodium levels in the filtrate and tries to bring GFR down
- GFR too slow - Material is reabsorbed more than normal. Macula densa sees a decrease in sodium, brings GFR up. |
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Term
| What are 3 intrinsic mechanisms for autoregulation of GFR? |
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Definition
- tubuloglomerular feedback - macula densa cells control afferent arteriole based on sodium concentrations in filtrate
- intrarenal baroreceptors - if pressure decreases, prostaglandins and renin increased.
- myogenic response - an increase in pressure leads to smooth muscle stretch and calcium release --> contraction of afferent arteriole and decreased GFR |
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Term
| What are extrinsic mechanisms to affect GFR? |
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Definition
-SNS - constricts arterioles, increases renin release when GFR decreases, and stimulates B1 on J-G cells
- Renin
-ADH
-ANF
-NO
-PgE2, prostacyclin
- Kinins |
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Term
| How does the macula densa react to low blood pressure and a decreased GFR? |
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Definition
Less sodium reaches the Na/K/Cl pump on the macula densa. If less Na is taken up, nitrous oxide is produced --> pgE2/prostacyclin --> dilation of the afferent arteriole to increase GFR
Prostaglandins or B1 stimulate release of renin from J-G cells via cAMP. |
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Term
| How does the macula densa react to high blood pressure and increased GFR? |
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Definition
Na/K/Cl pump on macula densa brings in ions, adenosine acts on the A1 receptor (different than local blood flow) which constricts the afferent arteriole via and IP3 mechanism
Release of renin decreases. |
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Term
| In the RAAS system, what are effects of bradykinin? |
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Definition
Vasodilation
also pain, inflammation, and cough |
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Term
| What are the effects of angII? |
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Definition
- AngII increases BP. Increases afterload, preload, constriction. Releases NE/epi and ADH for constriction and increased BV. Aldosterone also reabsorbes Na/water.
Constricts both arterioles for less filtration and promotes more reabsorption.
Because Op is higher distal to the efferent arteriole, increases reabsorption. |
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