me: ch 11: water/eletrolyte balance

Question 1

What is the process of urine formation and what does glomerular filtrate

Answer 1

Urine formation involves filtration, where glomerular filtrate (similar to plasma) is produced. It contains glucose, amino acids, albumins (100% reabsorbed)

Creatinine is filtered but not reabsorbed.

Question 2

What regulates sodium reabsorption and calcium/magnesium reabsorption in the kidneys?

Answer 2

Sodium reabsorption is regulated by Aldosterone, while calcium/magnesium reabsorption is regulated by Parathyroid Hormone (PTH).

Question 3

What are the three steps of urine formation?

Answer 3

Filtration: Passive transport, no energy, down concentration gradient

Reabsorption: 99% of filtrate reabsorbed

Tubular Secretion: Substances added to filtrate include:

K⁺

H+

PO₄³⁻

SO4

Antibiotics/ Degraded hormones

Question 4

What is the function of principal cells in dct

Answer 4

involved in sodium and water reabsorption under aldosterone through ena channels

Question 5

ADH affect

Answer 5

With ADH: water reabsorbed (water retention)

Without ADH: water not reabsorbed → diuresis (high urine volume)

Condition without ADH = Diabetes insipidus

Question 6

What substances go back into the blood during reabsorption?

Answer 6

Na⁺

Ca²⁺

Bicarbonate (HCO₃⁻)

Question 7

What is transport maximum and the glucose limit?

Answer 7

Tm = limit of how much substance can be reabsorbed due to transporter availability

Glucose Tm = 375 mg/min

Question 8

What is renal clearance and how does it apply to glucose?

Answer 8

Volume of plasma cleared of a substance per minute

Glucose is 100% reabsorbed → 0% clearance

Question 9

What is the total blood flow through the kidneys per minute?

Answer 9

1250 mL/min total blood flow
55% is plasma, 125 ml is glomerular filtrate

^ called filtrate fraction 16-18%

Question 10

Where are Na⁺, K⁺, Cl⁻, and Ca²⁺ more concentrated? ecf or icf has more ions?

Answer 10

Na⁺: More outside the cell

K⁺: More inside the cell

Cl⁻: More outside the cell

Ca²⁺: More outside the cell

ECF (extracellular fluid) has more ions

Question 11

How is water distributed in the body?

Answer 11

60% of body weight is water

40% intracellular fluid

20% extracellular fluid

15% interstitial fluid

5% plasma

Question 12

What does Atrial Natriuretic Peptide (ANP) do if BP is too high?

Answer 12

Blocks ADH, aldosterone, and angiotensin II → lowers BP

Question 13

What keeps the bladder relaxed when it’s filling?

Answer 13

Sympathetic input via β2 receptors relaxes detrusor

α1 receptors keep internal sphincter closed

Question 14

What nerve is involved in voluntary urination and which spinal levels?

Answer 14

Pudendal nerve (S2–S4)

Question 15

What happens during urination?

Answer 15

Parasympathetic activation → detrusor contracts, internal sphincter opens

External sphincter opens voluntarily

Question 16

What nerve is responsible for opening the external urethral sphincter?

Answer 16

pudendal nerve

Question 17

What happens during the Storage Phase of urination?

Answer 17

Detrusor muscle is relaxed

Internal urethral sphincter is closed

Controlled by sympathetic nervous system

Question 18

What happens during the Voiding Phase of urination?

Answer 18

Bladder stretch receptors activated

Parasympathetic input contracts detrusor muscle

Internal sphincter opens

External sphincter opens voluntarily

Question 19

How is urination controlled?

Answer 19

Bladder fills:

Detrusor muscle relaxed via β2 receptors

Internal urethral sphincter closed via α1 receptors

Urination:

Parasympathetic nerves → bladder contracts

Pudendal nerve (S2-S4) relaxes external sphincter

Internal sphincter (smooth muscle) opens

External urethral sphincter (skeletal muscle) opens

Question 20

The transport for glucose is ___secondary active, facilitated, both, none?

Answer 20

both

Question 21

There are more total ions in the ECF than in the ICF. T or F

Answer 21

F