Lecture 27 Flashcards Preview

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Flashcards in Lecture 27 Deck (60):
1

Sodium most abundant

extracellular ion
-accounts for 1/2 of osmolarity of ECF

2

Sodium Average daily intake

exceeds normal requirements

3

Sodium Hormonal controls: aldosterone causes

-increased reabsorption Na+
--acts on Principle cells

4

Sodium Hormonal controls: ADH release ceases if

Na+ levels too low--dilute urine lost until Na+ levels rise

5

Sodium Hormonal controls: ANP increases

Na+ and water excretion if Na+ levels too high

6

Sodium retention causes

-water retention

7

edema is

abnormal accumulation of interstitial fluid
(water swelling)

8

Causes of sodium retention

renal failure
hyperaldosterone

9

Excessive loss of sodium causes

-excessive loss of water (low blood volume)
--due to inadequate secretion of aldosterone
--too many diuretics

10

Chloride is the most

prevalent extracellular anion

11

Chloride Moves

easily between compartments due to Cl- leakage channels

12

Chloride Helps

balance anions in different compartments

13

Chloride Regulation:

-passively follows Na+ so it is regulated indirectly by aldosterone levels
-ADH helps regulate Cl- in body fluids because it controls water loss in urine

14

Chloride shifts and

hydrochloric acid of gastric juice

15

Potassium the most

abundant cation in intracellular fluid

16

Potassium helps

establish resting membrane potential & repolarize nerve & muscle tissue

17

Potassium is Exchanged for

H+ to help regulate pH in intracellular fluid

18

Potassium Control is mainly by

aldosterone which stimulates principal cells to increase K+ secretion into the urine

19

abnormal plasma K+ levels do what?

adversely affect cardiac and neuromuscular function

20

Bicarbonate Common for

extracellular anion
Major buffer in plasma

21

Bicarbonate Concentration increases as blood flows through

systemic capillaries due to CO2 released from metabolically active cells

22

Bicarbonate Concentration decreases as blood flows through

pulmonary capillaries and CO2 is exhaled

23

Kidneys are main

regulator of plasma levels
-intercalated cells form more if levels are too low
-excrete excess in the urine

24

Calcium Most abundant

mineral in body (skeleton & teeth)

25

Calcium has what cation?

Abundant extracellular cation in body fluids

26

Important role in calcium

blood clotting, neurotransmitter release, muscle tone & nerve and muscle function

27

Calcium Regulated by

parathyroid hormone

28

Calcium in parathyroid hormone stimulates

osteoclasts to release calcium from bone

29

Calcium in parathyroid hormone increases

production of calcitriol
-cannot absorb calcium from food

30

Phosphate Present as

calcium phosphate in bones and teeth, and in phospholipids, ATP, DNA and RNA

31

HPO4 -2 is important

intracellular anion and acts as buffer of H+ in body fluids and in urine

32

What act as buffers in the blood

mono and dihydrogen phosphate

33

Plasma levels are regulated by

parathyroid hormone & calcitriol

34

resorption of bone

releases phosphate

35

in the kidney, PTH

increase phosphate excretion

36

calcitriol increases

GI absorption of phosphate

37

Magnesium Found in

bone matrix and as ions in body fluids

38

***Magnesium has the

intracellular cofactor for metabolic enzymes, heart, muscle & nerve function

39

Magnesium is first thing that is dumped due to these problems:

Urinary excretion increased in hypercalcemia, hypermagnesemia, increased extracellular fluid volume, decreases in parathyroid hormone and acidosis

40

Homeostasis of H+ concentration is

vital

41

proteins 3-D structure sensitive to

pH changes

42

normal plasma pH must be maintained between

7.35 - 7.45

43

diet high in proteins tends to

acidify the blood

44

***3 major MECHANISMS to regulate pH:

1. buffer system
2. exhalation of CO2
3. kidney excretion of H+

45

Actions of Buffer Systems Prevent

rapid, drastic changes in pH

46

Actions of Buffer Systems work in how much time?

fractions of a second

47

Buffers Found in

fluids of the body

48

Buffers do what to strong acid or base?

change either into weak ones

49

***3 principal BUFFER systems

1. protein buffer system
2. carbonic acid-bicarbonate buffer system
3. phosphate buffer system

50

Protein Buffer System:

1. Abundant in intracellular fluids & in plasma
2. Amino acids contains at least one carboxyl group (-COOH) and at least one amino group (-NH2)
3. Hemoglobin acts as a buffer in blood by picking up CO2 or H+

51

1. PBS: hemoglobin very good at

buffering H+ in RBCs

52

1. PBS: albumin is main

plasma protein buffer

53

2. PBs: carboxyl group acts like

an acid & releases H+

54

2. PBS: amino group acts like a

base & combines with H+

55

Carbonic Acid-Bicarbonate Buffer System:

1.Acts as extracellular & intracellular buffer system
2. At a pH of 7.4, bicarbonate ion concentration is about 20 times that of carbonic acid
3. Can not protect against pH changes due to respiratory problems

56

CAB: 1. bicarbonate ion (HCO3-) can act as

a weak base
-holds excess H+

57

CAB: 1.

carbonic acid (H2CO3) can act as weak acid
-dissociates into H+ ions

58

Phosphate Buffer System: Most important

intracellularly, but also acts to buffer acids in the urine

59

Phosphate Buffer System: Dihydrogen phosphate ion acts as a

weak acid that can buffer a strong base

60

Phosphate Buffer System: Monohydrogen phosphate acts a

weak base by buffering the H+ released by a strong acid