Chapter 16: Renal System

Question 1

Body Fluid

Answer 1

Fluid in body – 60% of body weight
Intracellular fluid (ICF) – 40% of body weight,
Extracellular fluid (ECF) – 20% of body weight,
Interstitial fluid (IF) – 15% of body weight,
Blood plasma (BP)– 5% of body weight,

If your weight is 70 Kg, your fluid is:
ICF = 70 Kg X 0.40 = 28 Liters,
ECF = 70 Kg X 0.20 = 14 Liters,
IF = 70 Kg X 0.15 = 10.5 Liters,
BP = 70 Kg X 0.05 = 3.5 Liters.

Fluid in BP – determines blood pressure!

Question 2

Renal Cortex Range

Answer 2

~ 300 mOsm

Isotonic to blood

Question 3

Renal Medulla Ranges

Answer 3

~300 - 1400 mOsm

hypertonic to blood

Question 4

Renal Corpuscle

Answer 4

Blood plasma is filtered through the glomerulus-capsule membrane, the fluid that moves into the Bowman’s space is called filtrate.

Question 5

Processes in Blood Filtration and Urine Formation

Answer 5

First step in blood processing, occurs in the renal corpuscles:
Water and solutes filter into bowman’s capsule, through glomerular-capsular membrane.

Question 6

Glomerular Hydrostatic Pressure (GHP)

Answer 6

+ 60 mmHg. Forcing filtration. Increased GHP increases filtration/fluid in urine.

Question 7

Glomerular Oncotic Pressure (GOP)

Answer 7

• 32 mmHG. Against filtration. Increased GOP decreases filtration/less fluid in urine. Albumin changes

Question 8

Bowman’s Hydrostatic Pressure (BHP)

Answer 8

-18 mmHg. Against filtration. Increased BHP decreases filtration/less fluid in urine.

Question 9

Reabsorption at Proximal Convoluted Tubule

Answer 9

First part of renal tubule nearest to Bowman’s capsule,
Follows a winding, convoluted course,
Reabsorption: movement of molecules OUT of the tubule and INTO blood. Water, electrolytes and glucose are reabsorbed through secondary active transport dependent on Na+ gradient set-up by Na+/K+-ATPase pump.

Question 10

Reabsorption in Loop of Henle

Answer 10

Water conservation process: Counter-current mechanism filtrate concentration
Separates reabsorption of water and solutes.

Descending loop
Permeable to water

Ascending loop
Permeable to NaCl, but NOT water,
Last segment hypotonic (100 mOsm/L) to ECF

Question 11

Reabsorption by Distal tubule and Collecting Duct

Answer 11

DT and CD Function in water conservation, solute and pH balance
A small amount of solute reabsorption

Question 12

Aldosterone

Answer 12

functions in Na+ reabsorption

Question 13

Antidiuretic hormone (ADH)

Answer 13

functions in water reabsorption

Question 14

Natriuretic peptides

Answer 14

function in decreasing Na+ reabsorption

Question 15

Intercalated cells

Answer 15

Function in pH balance – in acidosis secrete H+ in alkalosis conserve H+.

Question 16

Tubular Secretion in Distal tubule

Answer 16

Distal Tubule: MOST secretion by mass
Primarily K+, H+

Proximal tubule – small amount
Cellular transporters – transport blood hormones, metabolites, medications, toxins, etc

Question 17

Compensation for Hypertension

Answer 17

Atrial natriuretric hormone (ANH) - secreted by specialized cardiac atrial and ventricular muscle fibers

Promotes ↑[Na+] in urine ↑H2O in urine ↑urine volume ↑H2O loss, (opposes Aldosterone).
Secreted in response to ↑blood pressure or ↑blood volume.

Question 18

Compensation for Hypotension

Answer 18

ADH secreted by hypothalamus influences water reabsorption:
↑H2O reabsorption ↓urine volume preventing water loss.

Aldosterone: activated by the RAAS (renin-angiotensin-aldosterone system) mechanism
↑Na+ reabsorption in distal tubule ↑[Na+] in blood ↑ H2O reabsorption into blood.

Question 19

RAAS (Renin, Angiotensin, Aldosterone)

Answer 19

For hypotension. Renin (kidney) + Angiotensin-converting enzyme (ACE) (Liver) = Angiotensin 1 (Lungs) –> Angiotensin 2 –> Aldosterone –> Salt + Water Retention/Vasoconstriction

Question 20

Ethanol decreases ADH, what does that do to urine volume?

Answer 20

Increases Urine volume (it’s a diuretic)