Term
Why is tehre a comparatively large electrical current genereated during the sequential depol/repol cycle? |
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Definition
1. Because the heart depolarizes as 2 separate syncytial masses of cells. The potential current generated spreads throughout the body and a small amount of electrical potential (millivolts) can actually be recorded on the surface of the body. A recording of this electrical potential obtained from discrete points on the surface of the body is referred to as an EKG. Thus an EKG is a recording (or picture) of the electrical activity of the heart obtained on the surface of the body. |
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Term
| How does the EKG recording system work? |
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Definition
A. The resting heart is relatively positive on the surface (positive outside vs inside cell membrane)
B. Depolarized myocardium has a “negative surface”.
C. Note that an EKG recorder has a positive and negative lead. When the positive lead is in an area of positivity (polarized heart) compared to the negative lead, the recorder deflects positively. When the positive lead is in a negative area (depolarized cells) compared to the negative lead, the deflection is negative. When both leads are in an area of depolarization (or both in area of repolarization) no potential difference is recorded. |
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Term
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Definition
| Negative on inside, positive on outside. |
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Term
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Definition
| process of water moving from inside of capillary to outside of capillary |
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Term
| Is there a lot filtration in glomerular capillaries |
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Definition
Yes. filtration is driven by high hydrostatis pressure (P>50mmHg)
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Term
| What are glomerular capillaries permeable to? |
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Definition
Water and small molecules.
Large molecules don't get through (like proteins) |
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Term
| How much of water and small solutes get filtered? (AKA what is the Filtration Fraction) |
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Definition
| 1/3 (goes to Bowman's space). Other 2/3 ends up in efferent arteriole (post glomerular vessel) peritubular capillary. |
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Term
| Why does reabsorption occur? |
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Definition
| Most of things that are filtered must be reclaimed. |
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Term
| How are solutes handled? (3 diff ways) |
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Definition
1. Conserved solutes: AAs, glucose from digestion are conserved solutes. They get dumped into proximal tubule but they are handled in a way that reclaims them. (goal: 100% reabsorption)
2. Balanced solutes: kidney balances input with urinary excretion (goal=balance of Na, K, H, etc)
3. Excreted solutes: important to eliminate in urine, like urea, medications like antibiotics (goal=excretion) |
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Term
| In the case of medications, slower than 30,000 daltons |
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Definition
| Some is filtered, but kidney preferentially secretes penicillin to increase the amount eliminated. |
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Term
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Definition
| Nitrogenous product that's a waste product from protein breakdown. Kidney filters/secretes urea. |
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Term
| Is water freely filtered? |
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Definition
| Yes. Regulated by urine concentrating mechanism. |
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Term
| Is glucose freely filtered? |
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Definition
| Yes, because it is small it readily gets through filtration barrier. Goal is to reabsorb it all. |
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Term
| Where does reabsorption process occur for glucose? |
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Definition
| This reabsorption process occurs in proximal tubule. |
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Term
Describe the process of conserved solute reabsorption
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Definition
- Ex: glucose
- Sodium-Glucose linked transporter (SGLT) in brush border membrane
- Secondary active transport
- SGLT2 early in proximal tubule
- SGLT1 late in proximal tubule (and small intestine)
- GLUcose Transporter (GLUT2) in basolateral membrane
- Normally >99% of glu reabsorbed before end of proximal tubule
- AA reabsorption is identical except that there are diff carriers (>99% reabsorption in proximal tubule)
- Tight junctions with the adjacent cells. Basolateral membrane (which contain GLU2)-diff tranposrter. High K low Na.
- As glucose builds up, the conc grad favors movement of glucose from inside of cell into interstitial. as more glu absorbed, the conc grad gets larger in cell than interstial fluid. It goes through glu transporters via facilitated diffusion
- Secondary active transport because it depends on primary active transport of later transporter
- Glucose begins to build up in interstitium, and enters through pores back to plasma. Blood came in renal artery, glu and sodium were filtered, then became reabsorbed to back to where they started.
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Term
| Secretion is used for what |
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Definition
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Term
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Definition
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Term
| Acid base balance in carnivores and herbivores |
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Definition
If you change H+ conc, proteins will have structure altered.
Metabolizing fat/lipids, or sugar has no effect on acid/base homeostasis. However, eating animals leads to increase in H+ generation. The body defends against this in 3 ways:
Immediate: buffers spong free H+ in ECF
Short-term: Hyperventilate
Long-term: renal handling of HCO3 and H+
If you're a vegetarian and don't have enough H+ ions, buffers will release H+ to restore pH. You will hypoventilate. Kidneys will have to adjust teh way it handles bicarbonate and hydrogen ions.
Carnivorous cat's pee will have pH of 5 or 6 because body must get rid of hydrogen ions.
Horse, which is vegeterian, will have urine pH of 8 or 9 for opposite reason.Acid |
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