Chapter 27

Question 1

Body fluid

Answer 1

Consists of water and dissolved solute constitutes between 55 and 60% of total body mass

Question 2

What are the parts of extra cellular fluid?

Answer 2

80% is interstitial fluid and 20% is blood plasma

Question 3

What are the two general barriers that separate intracellular fluid, interstitial fluid and blood plasma?

Answer 3

Plasma membrane and blood vessel walls

Question 4

Thirst center

Answer 4

Found in the hypothalamus governs the urge to drink

Question 5

What’s the main factor that determines body fluid volume?

Answer 5

Urinary salt (NaCl) loss

Question 6

What’s the main factor that determines body fluid osmolarity?

Answer 6

The extent of urinary water loss

Question 7

What is antidiuretic hormone also known as?

Answer 7

Vasopressin

Question 8

What are the two most important hormones that regulate the extent of renal sodium reabsorption and thus how much is lost in the urine?

Answer 8

Aldosterone and atrial natriuretic peptide

Question 9

Aldosterone

Answer 9

Increases sodium reabsorption in the late distal tubules and collecting ducts of the kidneys which relieves the sodium deficiency in the plasma

Occurs after a decrease in blood pressure

Question 10

Atrial natriuretic peptide

Answer 10

Occurs with an increase in blood volume

Stretching of the atria of the heart promotes the release

Promotes natriuesis; elevated excretion of sodium into the urine

Question 11

What can increase the osmolarity of extra cellular fluid?

Answer 11

A salty meal

Question 12

A decrease in the osmolarity of extra cellular fluid can occur from what?

Answer 12

Drinking a large volume of water

Question 13

Water intoxication

Answer 13

A state in which excessive body water causes cells to swell dangerously

Question 14

What are the four general functions in the body when electrolytes dissolve and dissociate?

Answer 14

1. Because they are largely confined to particular fluid compartments then non-electrolytes certain ions help control the osmosis of water between fluid compartments
2. Ions help maintain the acid base balance required for normal cellular activities
3. Ions carry electrical current which allows production of action potentials and graded potential’s
4. Several ions serve as co-factors needed for optimal activity of enzymes

Question 15

Sodium

Answer 15

Most abundant ion in extracellular fluid

Accounts for half of the osmolarity an extra cellular fluid

Necessary for generation and conduction of action potentials in neurons and muscle fibres

Kidneys excrete and conserve sodium as necessary

Sodium is controlled in the blood by aldosterone, antidiuretic hormone, and atrial natriuretic peptide

Question 16

Chloride

Answer 16

Most prevailant anion in extra cellular fluid

Moves easily between extra cellular fluid and intracellular fluid because most plasma membranes contain many chloride leakage channels and Antiporters

Helps balance the level of an ions in different fluid compartments

ADH helps regulate chloride balance through the urinary system

Processes that increase or decrease renal absorption of sodium ions also affects direction of chloride ions

Question 17

Potassium

Answer 17

Most abundant cation in intracellular fluid

Key role in establishing the resting membrane potential and then repolarization phase of action potentials in neurons and muscle fibres

When potassium moves into or out of cells it is often exchange for hydrogen and thereby helps regulate the pH of body fluids

Increase potassium causes more aldosterone secreted into the blood which stimulates principal cells of the renal collecting duct to secrete more potassium through the urine

Needed in repolarization phase of action potentials

Question 18

Bicarbonate

Answer 18

Second most prevailant extra cellular anions

Concentration increases when blood flows through systemic capillaries because carbon dioxide released by metabolically active cells combines with water to form carbonic acid

When it flows through pulmonary capillaries concentration’s decrease because carbon dioxide is exhaled

Question 19

Calcium

Answer 19

Stored in bone and is the most abundant mineral in the body

Please important rules in blood clotting, neurotransmitter release, maintenance of muscle tone, and excitability of nervous and muscle tissue

Main regulators are parathyroid hormone and calcitonin

Question 20

Phosphate

Answer 20

85% of phosphate in adult his present is calcium phosphate salts which is structural components of bones and teeth

Governed by parathyroid hormone and calcitriol

Question 21

Magnesium

Answer 21

54% of the total body magnesium is part of bone matrix is magnesium salt the remaining 46% occurs is magnesium ions in ICF

Question 22

The removal of hydrogen from body fluids and it subsequent elimination from the body depends on what three major mechanisms?

Answer 22

1. Buffer systems
2. exhalation of carbon dioxide
3. kidney excretion of hydrogen

Question 23

Buffer systems

Answer 23

Consist of a weak acid and the salt of that I said which functions as a weak base and prevent rapid drastic changes in pH of body fluids by converting strong acids and bases into weak acids and bases

Question 24

Protein buffer system

Answer 24

Most abundant buffer in intracellular fluid and blood plasma

Proteins are composed of amino acids organic molecules that contain at least one carboxyl group and at least one amino group which function as components of the protein buffer system

Question 25

Carbonic acid bicarbonate buffer system

Answer 25

Bicarbonate ion acts as a weak base and carbonic acid acts as weak acid Doesn’t protect against respiratory problems

Question 26

Phosphate buffer system

Answer 26

Is it important regulator of pH in the cytosol can also buffer acids in urine One way that the kidneys excrete hydrogen to control blood pH

Question 27

Volatile acid

Answer 27

Because H2CO3 can be eliminated by exhaling CO2 it is a volatile acid

Question 28

Nonvolatile acids

Answer 28

Metabolic reactions that produce acid such as sulphuric acid and is excreted through the urine

Question 29

Acidosis

Answer 29

Condition in which blood pH below 7.35 Causes depression of the central nervous system through depression of the synaptic transmission Can cause individuals to become disoriented, comatose, and die

Question 30

Alkalosis

Answer 30

Condition in which blood pH is higher than 7.45 Causes overexcitability in both the central nervous system and peripheral nerves Neurons conduct impulses repetitively even when not stimulated resulting in nervousness, muscle spasms, convulsions, and death

Question 31

Respiratory compensation

Answer 31

Occurs within minutes and reaches its maximum within hours

Question 32

Renal compensation

Answer 32

Begins in minutes but it can take days to reach maximum effectiveness

Question 33

Respiratory acidosis

Answer 33

Abnormally high PCO2 In systemic arterial blood In adequate exhalation of CO2 causes the blood pH to drop Conditions such as emphysema, pulmonary edema, injury to respiratory centre of the medulla, airway obstruction, or disorders of muscles involved and breathing Reversed by exhalation of CO2

Question 34

Respiratory alkalosis

Answer 34

Systemic arterial blood PCO to falls below 35 mmHg Cause of drop in PCO to and resulting increase in pH is hyperventilation Conditions like oxygen deficiency due to high altitude or pulmonary disease, cerebrovascular accident, or severe anxiety Can be treated by breathing through a paper bag

Question 35

Metabolic acidosis

Answer 35

The systemic arterial blood HCO3 levels drop below 22mEQ per litre Caused by loss of bicarbonate like in diarrhea or renal disfunction accumulation of an acid other than carbonic acid such as with ketosis failure of the kidneys to excrete hydrogen from the metabolism of dietary proteins

Question 36

Metabolic alkalosis

Answer 36

Systemic arterial blood bicarbonate concentration is above 26mEq per litre A non respiratory loss of acid or excessive intake of alkaline drugs causes a blood pH to increase above 7.45