Lecture 11

Question 1

Water Balance

Answer 1

Medium for chemical reactions
Solvent
Thermoregulation
Blood pressure regulation

Question 2

Electrolyte balance

Answer 2

Ion Gradient concentration

Muscle contraction
Nervous system impulses
Exocytosis of vesicles

Question 3

pH balance

Answer 3

extracellular fluid - 7.35-7.45
Intracellular fluid/Blood 7

Important for enzymes to work

Question 4

Flow of materials between fluid compartments.

Answer 4

Water In –> Digestive tract –> blood –> extracellular fluid –> intercellular fluid –> lymph nodes –> blood stream

Question 5

Average Total Body Water (TBF)

Answer 5

Males 60%
Females 50%
Males are higher because more testosterone and muscle cells.
Females lower because more adipose tissue.
Easier to get off balance.

Question 6

What is the largest fluid compartment?

Answer 6

Intracellular fluid

2/3 of TBW

Question 7

What is the larges extracellular fluid compartment?

Answer 7

Intersticial Fluid- mostly your blood

Question 8

What are the other compartments in extracellular fluid?

Answer 8

• Intersticial 25%
• Blood plasma and Lymphatic fluid 8%
• SF, synovial fluid, serous fluids, eye humors, inner ear fluids, bile, respiratory and digestive secretions

Question 9

What is the main mechanism for water loss?

Answer 9

Urination 1500ml

Sensible

Question 10

Sensible Water Loss and amounts

Answer 10

Urination 1500mL
Sweating 100mL
Deification 200 mL

Question 11

Insensible water loss

Answer 11

Cutaneous transpiration 400mL

Expiration 300mL

Question 12

What is obligatory water loss?

Answer 12

The minimal amount of fluid loss from the body that can occur is referred to as obligatory water loss. For example, at least 500mL of urine daily, or 100mL of sweat.

Question 13

What is facultative water loss?

Answer 13

Facultative water loss is anything above and beyond the necessary loss to rid of waste. Examples: urine output above 500mL

Question 14

List the three main ways that you gain body water over the course of the day.

Answer 14

Metabolic water, food, drink

Question 15

Describe two ways that the body produces metabolic water.

Answer 15

Metabolic water can be made from aerobic respiration and dehydration synthesis

Question 16

How does dehydration affect blood volume and osmolarity of extracellular fluid?

Answer 16

Dehydration lowers blood volume and pressure, and increases blood osmolarity.

Question 17

List three groups of receptors (where they are located) that provide information about changes in extracellular fluid volumes and osmolarity.

Answer 17

Osmoreceptors in the hypothalamus

Baroreceptors in the carotid and aortic sinuses

Juxtaglomerular apparatus cells sense the changes of extracellular fluids

Question 18

Describe the short-term regulation of the thirst reflex. In other words, what mechanisms are in place to prevent over-consumption of water when you are thirsty?

Answer 18

Cooling and moistening of the mouth from ingested water

Distention of the stomach are temporary mechanisms to shut down the thirst reflex.

Question 19

Describe the hormonal mechanisms that help the body to maintain extracellular fluid volumes (and thus blood pressure) and osmolarity.

Answer 19

JGA will detect increases or decreases in BP, which alters the release of renin
–Increased renin release results in more angiotensin II, aldosterone, and ADH secretion

Heart- detect increases and decreases in BP
–When blood volume and pressure are high, there is increased secretion of natriuretic peptides (ANP and BNP) by cardiocytes–Blocks renin release (and therefore, aldosterone and ADH) so excess sodium and water are lost in urine

Question 20

Volume Depletion

Answer 20

Hypovolemiais - when proportionate amount of water and sodium lost without replacement

–Isotonic fluid loss is greater than isotonic fluid gain

–Vomiting, diarrhea, third degree burns, hemorrhage, and aldosterone hyposecretion (Addison disease)

Question 21

Volume Excess

Answer 21

Hypervolemia - is retention of excess isotonic ECF (water and sodium)

–Isotonic fluid loss is reduced due to a kidney problem, such as kidney failure or hypersecretion of aldosterone

Question 22

Dehydration

Answer 22

More water lost than sodium
ECF osmolarity increases
•Water shifts from ICF to balance, and volume of both compartments is decreased from set point

• Primary cause is inadequate water consumption
• Other causes: excessive perspiration, all types of diabetes, use of diuretics, alcohol, along with hot and cold weather

•Infants more susceptible to dehydration than adults because of larger surface area to volume ratio and kidneys don’t concentrate urine as well

Question 23

Hypotonic hydration

Answer 23

Occurs when more water than solute (relative to isotonic fluids) enters the ECF, and ECFs become hypotonic
•Fluid shifts from ECF to ICF
•Results in cellular swelling, cerebral edema, and loss of CNS function called water intoxication

•Primarily caused by sweating or urinating and replacing with drinking water
–Remember urine and sweat contain water and salt
–2007 radio contest
•ADH hypersecretion can also cause

Question 24

Fluid sequestration

Answer 24

When total body water is normal, but fluid accumulates in a particular compartment

•Edema is sequestration of fluid in the IF compartment (usually lost from blood)
–May result in swelling and puffiness of a body part
–Can be caused by failure of a ventricle, hypertension, loss of plasma albumins, increase in capillary permeability to proteins, and/or blockage of lymphatic vessels

•Ascites is fluid sequestration in the abdominal cavity