Test 5 Study Guide Part 6 Flashcards
How can the glomerular filtration rate be measured?
- General theory:
- Specific methods:
- General theory:
Find substance which is neither selectively secreted or reabsorbed - Specific methods:
Inulin (actively added)
Creatinine (product of creatine breakdown, measure amount in plasma, and amount in urine)
Selective reabsorption of glucose and amino acid occurs how?
In the proximal tubule, by secondary active transport (using Na+ as the favorable gradient)
Diabetes:
Mellitus:
Excessive urination
Sweet
Plasma Renal Threshold:
- Define:
- What is the number?
- Define:
The conc. of glucose at which renal Na/glucose symporters will be overwhelmed and glycosuria will occur - What is the number?
190 mg/dl of glucose
Parathyroid hormone primary effect on the kidney:
Promote reabsorption of Ca2+
Aldosterone:
- Effect:
- What is the name of the membrane next to the interstitial (peritubular) fluid?
- Effect:
Activates the ATPase 3Na+/2K+ channels into the interstitial fluid -> intracellular K+ rises, Na+ decreases -> K+ diffuses into the filtrate -> Na+ diffuses from the filtrate - What is the name of the membrane next to the interstitial (peritubular) fluid?
Basolateral membrane
How much potassium is reabsorbed before reaching the distal tubule?
How much Na+?
Is this reabsorption regulated?
90%
90%
No, it’s constant.
What combats increased plasma K+?
What combats decreased plasma Na+?
Aldosterone
Aldosterone
Aldosterone-Independent K+ secretion:
Increased blood K+ causes ‘exocytosis’ of K+ channels towards the lumen of the descending duct
Visa versa also occurs
Explain how voltage may effect K+ secretion?
Na+ reabsorption -> filtrate more negative, basolateral side positive -> K+ enters filtrate to compensate
Increased sodium concentration reaching the distal tubule will have what effect on K+ secretion?
Increase it.
distal tubules have what specialized sensor of flow rate?
Primary cilium
Primary cilium of the distal tubules:
- Potassium effect:
Cause excretion of K+ when activated by increased flow rate (like that caused by water being brought with high Na+)
Increased Na+ reaching the distal tubules means increased ______ will also reach the distal tubules:
Water
Diuretics:
- Normal mechanism of action:
- Effect on K+?
- Normal mechanism of action:
Stop reabsorption of Na+, increase water loss - Effect on K+?
Increased secretion of K+ as Na+ tries to be reabsorbed.
High levels of plasma K+ concentration:
- Self regulation:
- Direct or indirect?
- Self regulation:
High plasma K+ -> depolarizes the aldosterone secreting cells of adrenal cortex -> increased aldosterone - Direct or indirect?
Direct
Low levels of plasma Na+ concentration:
- Self regulation:
- Direct or indirect?
- Self regulation:
Low Na+ -> low H20 level -> hypotension -> rennin-angiotensin-aldosterone -> increased Na+ absorption - Direct or indirect?
Indirect
Where is the juxtaglomerular apparatus located?
Where the afferent arteriole meets with the last portion of the ascending limb of the loop of henle.
AKA: right before the distal tubule
- What cells of the juxtaglomerular apparatus excrete renin?
- What do these cells act as?
- The granular cells, which lie next to the afferent arteriole
- Baroreceptors
- Where other then the lungs is Angiotensin II produced?
- What does it do there?
- In the kidneys.
- Regulate reabsorption, renal blood flow, and embryonic kidney development
Inadequate intake of NaCl will cause what issue?
Hypotension, activation of osmoreceptors.
Beta-1 adrenergic receptors and renin secretion:
Granular cells activated to secrete renin.
When Na+ is brought into a cell in the filtrate, what must enter the filtrate to replace it?
Why?
Implication:
- K+ or H+
- Balance electrochemical gradient
- if H+ levels are high, more of it will return to the filtrate and visa versa, sparing the other ion
Acidosis will cause what effect on K+ in the collecting duct?
Increased H+ secretion will cause increased K+ reabsorption (to maintain electrochemical gradient)
Hyperkalemia
Alkalosis will cause what effect on K+ in the collecting duct?
Decreased H+ secretion will cause decreased K+ reabsorption (to maintain electrochemical gradient)
Hypokalemia
Hyperkalemia will cause what effect on H+ in the collecting duct?
Increased K+ secretion will cause increased H+ reabsorption. (to maintain electrochemical gradient)
- acidosis
Abnormally high aldosterone secretion (hyperaldosteronism) causes:
Hypokalemia
metabolic alkalosis
Abnormally lo2 aldosterone secretion (Addison’s disease) causes:
Hyperkalemia
metabolic acidosis
Why is normal urine slightly acidic?
Most bicarbonate is absorbed from the filtrate, H+ is excreted into it
How is H+ concentrated into the urine?
Which is the predominant effect??
- How is H+ concentrated into the urine? Na+ / H+ antiport (proximal tubules) H+ ATPase pumps (distal tubules) - Which is the predominant effect?? H+ ATPase
Why can bicarbonate not be directly absorbed
The nephron tubule cells are impermeable to bicarbonate
How is bicarbonate absorbed from the filtrate?
Bicarbonate and H+ -> Carbonic acid H2CO3 -> Carbonic anhydrase -> CO2 + H20 -> CO2 diffuses into tubular epithelium -> Carbonic ahydrase -> H2CO3 -> H+ + HC03- -> H+ excreted through Na+/H+ exchanger
Where is the majority of bicarbonate absorbed?
Proximal tubules 90%
In a person with alkalosis how will bicarbonate absorption be affected?
Less H+ will result in less CO2 formation by carbonic anhydrase and more bicarbonate will be excreted.
Kidney’s compensation for acidosis
- Write the reaction performed by the proximal tubules to compensate for acidosis.
- Explain how it compensates
- Write the reaction performed by the proximal tubules to compensate for acidosis:
Glutamine -> 2HCO3- + 2NH3 - Explain how it compensates:
Increased HCO3- to buffer blood. NH3 buffer H+ in the filtrate, allowing more to be excreted
Respiratory compensation for acidosis (respiratory or :
- Define:
- Define:
Chemoreceptors in medulla oblongata detect high pH -> Increased respiration -> CO2 is blown off -> less H+ free in blood
What all buffers H+ in the filtrate?
NH3
Phosphates
List the types of diuretics:
Loop diuretics Thiazides Carbonic anhydrase inhibitors osmotic diuretics Potassium-sparing diuretics
What type of diuretic is the most powerful?
Loop diuretics
Loop diuretics:
- Work by:
- One example:
- Work by:
Stopping Na+ reabsorption in ascending limb -> renal medulla is less concentrated -> Less water can be pulled into it in the collecting duct - One example:
Lasix
Thiazide diuretics:
- Work by:
- One example:
- Work by:
Inhibiting Na+ transport in the initial segment of the distal tubule -> reduced osmotic gradient for water reabsorption - One Example:
Hydrochlorothiazide
Carbonic anhydrase inhibitors:
- Work by:
- One example:
- Altitude use:
- Work by:
Stop reabsorption of bicarbonate -> stops water from coming back with bicarbonate - One example:
Acetazolamide - Altitude use:
Produce metabolic acidosis (because of low bicarbonate) -> hyperventilation to compensate -> treats altitude sickness
Osmotic Diuretics:
- Work by:
- One example:
- Work by:
Are not transported from filtrate -> pull water in by osmosis - One example:
Mannitol
What naturally occurring substances can cause osmotic acidosis:
Glucose (if past 190 mg/ml) Ketone bodies (during ketoacidosis)
- Which diuretics can cause hypokalemia?
- Why?
- How is this dealt with?
- Which diuretics can cause hypokalemia? Loop diuretics Thiazide diuretics - Why? Both inhibit Na+ excretion prior to the collecting duct -> Aldosterone upregulates as Na+ is lost -> Na+/K+ exchanger -> more K+ in urine - How is this dealt with? K+ supplement pills
Potassium Sparring diuretics:
- Work by:
- Work by:
Competitive antagonist of aldosterone, results in more Na+ excretion and less k+ excretion and loss of water through osmosis from Na+
Which two diuretics are often combined to spare potassium while having a large diuretic effect?
Potassium sparing diuretics and thiazonide diuretics (hydrochlorothiazide)
Urinary albumin excretion rate:
- Define:
- Microalbuminuria is diagnosed at what quantity of albumin:
- Define:
Measure urinary albuminin - Microalbuminuria:
30 - 300 mg protein per day
Often the first sign of renal damage is?
microalbuminuria?
Proteinuria:
- Define:
- Define:
> 300 mg of protein per day
- Define: Condition with high protein excretion - level of protein excretion: > 3.5 g of protein per day - Symptoms? Systemic edema due to lowered oncotic pressure
Nephrotic syndrome:
- Define:
- level of protein excretion:
- Symptoms?
- Define:
Drop in kidney’s ability to excrete everything over a few hours or days - Why does it occur?
Inflammation of kidneys, atherosclerosis, reduced blood flow to kidneys, some drugs
Acute Renal Failure:
- Define:
- Why does it occur?
- Cause:
Antigen antibody complexes from streptococcal infection enter systemic circulation
Antibody made against the basement membrane - Can result in:
Renal Insufficiency
Glomerulonephritis:
- Cause:
- Can result in:
- Define: Inadequate filtration by kidney - Secondary resulting conditions: All from failure to clear something Hypertension (from failure to clear ions), acidosis, hyperkalemia, high urea
Renal insufficiency:
- Define:
- Secondary resulting conditions:
- Define:
Infection of the kidney’s - Can cause:
Renal insufficiency
Pyelonephritis:
- Define:
- Can cause:
Accumulation of all your metabolic waste
Uremia:
- Define:
Diffuse blood across a semipermeable membrane so toxins can enter the dialysate - Frequency:
Three times a week, for a few hours each time
Hemodialysis:
- Define:
- Frequency:
How do you keep the good things in blood from entering the dialysate?
They are already in the dialysate. Glucose and some salts will have no concentration difference so they will be no net diffusion.
- Define: Dialysis fluid is introduced to peritoneal cavity, waste accumulates into it, it is drained. - Frequency: Several times a day - Hazards: Infection from catheter in peritoneum
Continuous Ambulatory Peritoneal Dialysis:
- Define:
- Frequency:
- Hazards:
