Renal A&P

Question 1

What are the different functions of the kidney?

Answer 1

-Excreting metabolic wastes
-Maintaining extracellular fluid
-Maintain electrolytes
-Maintain acid-base balance
-Hormonal functions

Question 2

What is the anatomy of the kidney?

Answer 2

-Cortex and Medulla
-25% of CO
-Medial margins are concave/indented
-Retroperitoneal with right kidney lower than left (due to liver)
-Hilus (L1): where structures enter and leave
-Renal vessels lie anterior to kidney (Some branches may be posterior)

Question 3

What is the innervation to the kidney?

Answer 3

-PNS: Vagus Nerve
-SNS: T8-L1 preganglionic

Ureters: S2-S4

Question 4

What is the innervation to the bladder?

Answer 4

-PNS: S2-S4 (stretch, motor)
-SNS: T11-L2 (pain, touch, temp)

Question 5

What is the functional unit of the kidney?

Answer 5

The Nephron.

Question 6

Where does Acetazolamide function?

Answer 6

In the PCT.
-Carbonic Anhydrase Inhibitor

Question 7

Where does Mannitol function?

Answer 7

Descending Loop of Henle

Question 8

Where do Loop Diuretics function?

Answer 8

Ascending Loop of Henle

Question 9

Where does Spironolactone function?

Answer 9

Collecting Ducts.
-K+ sparing

Question 10

How do things enter the glomerulus?

Answer 10

Via the AFFERENT Arteriole.
-Production of urine begins with water and solute filtration from plasma flowing into the glomerulus via the AFFERENT arteriole

Question 11

What are the major determinants of GFR?

Answer 11

-Glomerular capillary pressure (arterial pressure)
-Glomerular oncotic pressure (renal blood flow)

Question 12

What is the Efferent Arteriole?

Answer 12

How flow exits Bowman’s capsule.
-Not exiting fast enough = pressure buildup in the capsule

Question 13

What causes pressure changes in the Afferent Arteriole?

Answer 13

-Increases with intense SNS activity. Filtration and GFR decrease
-Dilation with nitric oxide and prostaglandins. Increases blood flow and GFR.

Question 14

What causes pressure changes in the Efferent Arteriole?

Answer 14

-Increase with mild SNS or angiotensin activity. Increases filtration pressure and GFR.

Question 15

Why does the renal system autoregulate blood flow?

Answer 15

-Renal autoregulation of blood flow and filtration modulated by the glomerular arterial tone
-Protects glomeruli from excessive perfusion pressures
-Maintain over a wide range

Question 16

What is the Myogenic Reflex?

Answer 16

Due to arteriolar wall stretching and constricting.
-Increase in arterial pressure causes afferent arteriolar wall to stretch and then constrict by reflex (constriction decreases capsular pressure due to dec flow, protective mechanism)
-Decrease in arterial pressure cause reflex afferent arteriolar dilatation (increases flow)

Question 17

What is Tubuloglomerular Feedback?

Answer 17

-Composition of distal tubular fluid influences glomerular function involving juxtaglomerular apparatus
-When RBF falls, GFR decreases resulting in less chloride delivery to apparatus
-Causes afferent arteriole to dilate
-When GFR falls, JGA triggers release of renin which causes formation of angiotensin II
-Efferent arteriolar constriction increases glomerular pressure and GFR

Question 18

What is Renal Autoregulation?

Answer 18

The body’s mechanism of maintaining constant flow.
-GFR relatively constant with changes in MAP from 80-200 mmHg.
-Below 80, will see changes in flow and can be dramatic based on what MAP is.
-Between 80-200, body maintains constant RBF and filtration rate.

Question 19

Describe the filtration/reabsorption of sodium

Answer 19

-Actively reabsorbed almost immediately as the glomerular filtrate enters proximal tubule
-Proximal tubule reabsorbs 2/3 of filtered sodium
-No active Na transport in loop of Henle until medullary thick ascending limb

Question 20

Describe the filtration/reabsorption of H2O.

Answer 20

-Passively reabsorbed that is osmotically driven
-Depends on peritubular capillary pressure
-High capillary pressure opposes H2O reabsorption and increases urine output
-Proximal tubule reabsorbs about 65% of filtered water

Question 21

Describe the role of ADH and the kidney.

Answer 21

-Secreted by pituitary gland
-Released in response to increase extracellular Na concentration or osmolality
-Increases water permeability of collecting ducts and allows passive diffusion of sodium and water back into circulation

Question 22

Describe the role of Baroreceptors and kidney function.

Answer 22

Arterial baroreceptors are activated when hypovolemia leads to a decrease in blood pressure.
-atrial receptors are stimulated by a decline in atrial filling pressure

Question 23

What can stimulate the release of Renin?

Answer 23

-Hypotension
-Decreased tubular chloride concentrations
-Severe SNS stimulation

All lead to the release of Renin from the J-G Apparatus

Question 24

What does Angiotensin 2 cause?

Answer 24

-Renal Efferent Arteriole vasoconstriction (inc pressure in the glomerulus, things are reabsorbed, increasing volume in circulation)
-ADH release (inc Na/Water permeability in the CD)
-Aldosterone release (inc Na reabsorption, water following passively in the distal CT/beginning of CD)

Question 25

When is ANP released and what does it do?

Answer 25

-Released by atrium in response to increased stretch
-Inc GFR, systemic vasodilation, inhibit renin release, opposes production and action of angiotensin II, decreases aldosterone secretion
Nagelhout:
-Inc urine flow and Na excretion
-Inc RBF and GFR
-Decreases renin, aldosterone, and ADH

Question 26

What does N2O do to the renal system?

Answer 26

-Produced in kidney
-Opposes renal vasoconstrictor effects of AngII and the adrenergic nervous system
-End up with decreased circulating volume

Question 27

What are Prostaglandins?

Answer 27

-Produced in the kidney in response to stress, renal ischemia, and hypotension
-Cause dilation of renal arterioles
-Distal tubular effects result in an increase in sodium and water excretion

Question 28

What are the S/Sx of Hyponatremia?

Answer 28

-Symptoms rarely unless < 125mEq/L
-S&S - anorexia, nausea, and lethargy to convulsions, dysrhythmias, coma, and even death due to osmotic brain swelling
-If acute, risk of neurological complications higher
-Treat to prevent cerebral edema and seizures

Question 29

What are the S/Sx of Hypernatremia?

Answer 29

-Serum level > 145mEq/L
-Generally due to sodium gain or water loss (usually the latter)
-Can cause dehydration of brain
-Symptoms from confusion to convulsions and coma

Question 30

What are the causes and S/Sx of Hypokalemia?

Answer 30

Causes:
-Vomiting, diarrhea, drugs, hormones, renal abnormalities, insulin therapy, inadequate intake

Symptoms:
-electrocardiogram (ECG) changes (flattened T waves “no pot, no T,” U waves) and skeletal muscle weakness

Treatment:
-replacement (IV or PO)

Question 31

What are the causes of Hyperkalemia?

Answer 31

> 5.5mEq/L
Causes:
-abnormal kidney excretion, abnormal cellular potassium release (i.e. cell lysis), or abnormal distribution between the intra- and extracellular space.
-Chronic far better tolerated than acute rise

Question 32

What is acid-base balance?

Answer 32

The balance between plasma HCO3- and PCO2 in the extracellular space.