Lecture 26

Question 1

Antidiuretic Hormone:

Answer 1

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

Question 2

When osmolarity of plasma & interstitial fluid decreases,

Answer 2

more ADH is secreted and facultative water reabsorption increases.

Question 3

Dilute =

Answer 3

having fewer solutes than plasma

Question 4

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

Answer 4

a filtrate more dilute than plasma

• can be 4x as dilute as plasma
• as low as 65 mOsm/liter

Question 5

Principal cells do not

Answer 5

reabsorb water if ADH is low

Question 6

Compensation is for

Answer 6

low water intake or heavy perspiration

Question 7

Urine can be

Answer 7

up to 4 times greater osmolarity than plasma

Question 8

It is possible for principal cells & ADH to

Answer 8

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

Question 9

Urea recycling causes

Answer 9

a buildup of urea in the renal medulla

Question 10

Diuretics:

Answer 10

Substances that slow renal reabsorption of water & cause diuresis

Question 11

Examples of diuretics:

Answer 11

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

Question 12

Dialysis Therapy:

Answer 12

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

Question 13

Artificial kidney machine performs

Answer 13

hemodialysis

Question 14

Hemodialysis:

Answer 14

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

Question 15

Micturition Reflex:

Answer 15

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

Question 16

Impulses sent to

Answer 16

micturition center in sacral spinal cord & reflex is triggered

Question 17

parasympathetic fibers cause

Answer 17

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

Question 18

Filling causes a

Answer 18

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

Question 19

Filling also causes

Answer 19

• conscious control of external sphincter

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

Question 20

Urinary Incontinence:

Answer 20

Lack of voluntary control over micturition

Question 21

Incontinence is normal in 2 or 3 year olds because

Answer 21

neurons to sphincter muscle is not developed

Question 22

Stress incontinence in adults caused by

Answer 22

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

Question 23

Stress incontinence in adults =

Answer 23

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

Question 24

Body fluid:

Answer 24

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

Question 25

Mechanisms regulate

Answer 25

total volume
distribution
concentration of solutes and pH

Question 26

Regulation of Water Gain:Formation of metabolic water is

Answer 26

not regulated

-function of the need for ATP

Question 27

Main regulator of water gain is

Answer 27

intake regulation

Question 28

Stimulators of thirst center in hypothalamus:

Answer 28

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

Question 29

When Drinking occurs

Answer 29

body water levels return to normal

Question 30

Elimination of excess water or solutes occurs through

Answer 30

urination

Question 31

Consumption of very salty meal demonstrates

Answer 31

function of three hormones

Question 32

Demonstrates how:

Answer 32

• “water follows salt”

- excrete Na+ and water will follow and decrease blood volume

Question 33

Intracellular and interstitial fluids normally have the same

Answer 33

osmolarity,so cells neither swell nor shrink

Question 34

Swollen cells of water intoxication because

Answer 34

Na+ concentration of plasma falls below normal

Question 35

Swollen cells happen because =

Answer 35

• 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

Question 36

Functions of electrolytes

Answer 36

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

Question 37

Concentration expressed in

Answer 37

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

Question 38

Plasma contains proteins, but interstitial fluid

Answer 38

does not

-producing blood colloid osmotic pressure

Question 39

Extracellular fluid contains

Answer 39

Na+ and Cl-

Question 40

Intracellular fluid contains

Answer 40

K+ and phosphates