11: Physiology 7 Flashcards Preview

Renal Week 2 2017/18 > 11: Physiology 7 > Flashcards

Flashcards in 11: Physiology 7 Deck (31)
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1

What is the equation for pH?

pH = 1 / [H+]

or

pH = -log[H+]

2

What is the average pH of blood?

7.4

3

Why is the pH of venous blood slightly more acidic than the pH of arterial blood?

Venous blood has more CO2

4

A pH of 7.4 is equal to which concentration of H+?

40 x 10-9 M

5

Small changes in pH reflect (small / large) changes in [H+].

large changes in [H+]

6

Acidosis causes ___ of the CNS.

Alkalosis causes ___ of the CNS.

acidosis - depression

alkalosis - excitability

7

What

a) sensory

b) motor

symptoms are caused by alkalosis?

a) Pins and needles

b) Spasticity

8

Which important proteins do changes in [H+] have an effect on?

Enzymes

9

What happens to potassium ion concentration in acidosis?

Why?

[K+] increases

As [H+] is secreted by kidneys to compensate, Kis reabsorbed

10

What is constantly added to the blood by metabolism?

H+

11

What endocrine disease can cause a metabolic acidosis?

What endocrine disease can cause a metabolic alkalosis?

Diabetes

Conn's syndrome

12

What solutions in the blood resist changes in pH

Buffers

13

What is the equation for the pH at which a buffer system is at equilibrium?

Henderson Hasselbalch

go over principles

14

What does carbon dioxide form when it combines with water?

Carbonic acid

15

Is carbonic acid a strong or weak acid?

Weak acid

so dissociates in solution

16

Which organs regulate

a) [CO2]

b) [HCO3-]?

a) Lungs

b) Kidney

17

For Henderson Hasselbalch

pH = pK + log (kidneys/lungs)

i.e bicarbonate over carbon dioxide

i.e base over acid

18

Which organs regulate bicarbonate concentration?

Kidneys

19

How do you calculate rate of filtration?

ROF = [substance]plasma x GFR

20

Which enzyme converts carbon dioxide and water to carbonic acid?

Carbonic anhydrase

21

How is bicarbonate reabsorbed by the proximal tubules?

Bicarbonate ions in filtrate combine with hydrogen ions pumped out of tubular cells to form CARBONIC ACID

Carbonic anhydrase converts carbonic acid to CARBON DIOXIDE and WATER

That enters cell, carbonic anhydrase converts it back to CARBONIC ACID

Carbonic acid dissociates into HYDROGEN AND BICARBONATE

H+ pumped out, HCO3- reabsorbed into capillaries

22

What effect does an increase in CO2 have on

a) H+ secretion

b) HCO3 reabsorption?

Increases both

23

The rate of ___ ___ is greater than the rate of ___ ___.

Rate of hydrogen secretion

is GREATER THAN

Rate of bicarbonate reabsorption

24

What does H+ bind with in the absence of bicarbonate?

When might this occur?

Phosphate

Metabolic acidosis

25

In severely acidotic patients, where all bicarbonate and phosphate has been used up, what combines with H+ ions?

Ammonia

to form ammonium ions

26

In a patient who is severely acidotic, what is excreted in their urine?

Ammonium ions (NH4+)

27

What can be measured in the urine when a patient's H+ is combining with

a) phosphate

b) ammonia?

a) Titratable acid

b) Ammonium ions

 

28

Why is bicarbonate ion reabsorption described as unorthodox?

Because the bicarbonate ion found in the filtrate isn't the one being reabsorbed at the end

Converted to carbonic acid > carbon dioxide water and back again first

29

reabsorption of bicarbonate

THEN

excretion of acid phosphate

THEN

excretion of ammonium

as acidosis worsens

30

H+ secretion drives ___ ___ to prevent acidosis.

bicarbonate reabsorption