Lecture 26 Flashcards Preview

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Flashcards in Lecture 26 Deck (40):
1

Antidiuretic Hormone:

1. Increases water permeability = regulates facultative water reabsorption
2. Stimulates the insertion of aquaporin-2 channels into the membrane

2

When osmolarity of plasma & interstitial fluid decreases,

more ADH is secreted and facultative water reabsorption increases.

3

Dilute =

having fewer solutes than plasma

4

Water reabsorbed in thin limb, but ions reabsorbed in thick limb of loop of Henle create

a filtrate more dilute than plasma
-can be 4x as dilute as plasma
-as low as 65 mOsm/liter

5

Principal cells do not

reabsorb water if ADH is low

6

Compensation is for

low water intake or heavy perspiration

7

Urine can be

up to 4 times greater osmolarity than plasma

8

It is possible for principal cells & ADH to

remove water from urine to that extent
-Long loop juxtamedullary nephrons make that possible
-Na+/K+/Cl- symporters reabsorb Na+ and Cl- from tubular fluid to create osmotic gradient in the renal medulla

9

Urea recycling causes

a buildup of urea in the renal medulla

10

Diuretics:

Substances that slow renal reabsorption of water & cause diuresis

11

Examples of diuretics:

-caffeine which inhibits Na+ reabsorption
-alcohol which inhibits secretion of ADH
-prescription medicines can act on the PCT, loop of Henle or DCT

12

Dialysis Therapy:

-Kidney function is so impaired the blood must be cleansed artificially
--separation of large solutes from smaller ones by a selectively permeable membrane

13

Artificial kidney machine performs

hemodialysis

14

Hemodialysis:

-directly filters blood because blood flows through tubing surrounded by dialysis solution
-cleansed blood flows back into the body

15

Micturition Reflex:

-urination
Stretch receptors that signal spinal cord and brain
-when volume exceeds 200-400mL

16

Impulses sent to

micturition center in sacral spinal cord & reflex is triggered

17

parasympathetic fibers cause

detrusor muscle to contract, external & internal sphincter muscles to relax

18

Filling causes a

sensation of fullness that initiates a desire to urinate before the reflex actually occurs

19

Filling also causes

-conscious control of external sphincter
-cerebral cortex can initiate micturition or delay its occurrence for a limited period of time

20

Urinary Incontinence:

Lack of voluntary control over micturition

21

Incontinence is normal in 2 or 3 year olds because

neurons to sphincter muscle is not developed

22

Stress incontinence in adults caused by

increases in abdominal pressure that result in leaking of urine from the bladder
Ex. coughing, sneezing, laughing, exercising, walking

23

Stress incontinence in adults =

injury to the nerves, loss of bladder flexibility, or damage to the sphincter

24

Body fluid:

all the water and dissolved solutes in the body’s fluid compartments

25

Mechanisms regulate

total volume
distribution
concentration of solutes and pH

26

Regulation of Water Gain:Formation of metabolic water is

not regulated
-function of the need for ATP

27

Main regulator of water gain is

intake regulation

28

Stimulators of thirst center in hypothalamus:

dry mouth, osmoreceptors in hypothalamus, decreased blood volume causes drop in BP & angiotensin II

29

When Drinking occurs

body water levels return to normal

30

Elimination of excess water or solutes occurs through

urination

31

Consumption of very salty meal demonstrates

function of three hormones

32

Demonstrates how:

-“water follows salt”
-excrete Na+ and water will follow and decrease blood volume

33

Intracellular and interstitial fluids normally have the same

osmolarity,so cells neither swell nor shrink

34

Swollen cells of water intoxication because

Na+ concentration of plasma falls below normal

35

Swollen cells happen because =

-drink plain water faster than kidneys canexcrete it
-replace water lost from diarrhea or vomitingwith plain water
-may cause convulsions, coma & death unless oral rehydration includes small amount salt in water intake

36

Functions of electrolytes

-control osmosis between fluid compartments
-help maintain acid-base balance
-carry electric current
-cofactors needed for enzymatic activity

37

Concentration expressed in

mEq/liter or milliequivalents per liter for plasma, interstitial fluid and intracellular fluid

38

Plasma contains proteins, but interstitial fluid

does not
-producing blood colloid osmotic pressure

39

Extracellular fluid contains

Na+ and Cl-

40

Intracellular fluid contains

K+ and phosphates