Homeostasis

Question 1

Define homeostasis

Answer 1

A state of dynamic equilibrium that responds to changes in the external environment to maintain constant internal conditions

Question 2

What percentage of water is an average man?

Answer 2

60%

Question 3

State the body compartments where fluids accumulate

Answer 3

?

Question 4

Compare and contrast water balance in males and females and infants

Answer 4

Infants have the highest % of TBW
Adults have the least
Higher % of body fat = lower % of TBW
Males have more TBW than females

Question 5

Physiological effect of dehydration

Answer 5

Cells + tissues absorb water from interstitial space
Then from each other
Tissues die -> water absorbed from organs
Organs die -> water absorbed from brain, liver, kidneys, heart
Die

Question 6

Physiological effects of water toxicity

Answer 6

Osmotic pressure is high
Cells absorb water + burst
Enzymes + proteins stop working

Question 7

What is osmolality?

Answer 7

Concentration of a solution expressed as the total number of solute particles per kilo

Question 8

What happens to osmolality when dehydrated/water toxicity?

Answer 8

Dehydrated = osmolality incr.
Water toxicity = osmolality decr.

Question 9

Explain the concepts behind negative and positive feedback loops

Answer 9

Negative: works to return internal conditions back to normal after change, stops when the effector stops
Positive: works to reinforce/enhance the stimulus, ceases when stimulus/initiator stops

Question 10

Why is acid-base balance important?

Answer 10

If below 7.35, acidosis
If above 7.45, alkalosis
If below 6.8 or above 8 for period of time = death

Question 11

Causes + symptoms of acidosis

Answer 11

Metabolic acidosis- build up of metabolic acids (lactic)
Respiratory acidosis- build up of CO2 due to hypoventilation

Headache confusion, tiredness, tremors, coma

Question 12

Mechanisms to warm up/cool down body

Answer 12

+shivering
+piloerection
+vasoconstriction

-Pilorelaxation
-vasodilation
-sweating
-stretching out

Question 13

Process of oedema

Answer 13

Body fluids diluted, reductions of sodium concentration in extracell. fl., shift in osmotic pressure, causes cells and tissues to swell

Question 14

Buffering systems in the body + what is a good antacid?

Answer 14

• carbonic acid
• sodium phosphate buffering
• calcium is an alkali that raises pH

Aluminium hydroxide: mildly alkaline + insoluble