BL Homeostasis, Body Fluids, pH + Temp

Question 1

Define homeostasis

Answer 1

Process in which internal environment is maintained at equilibrium despite internal/external factors

Question 2

Examples of positive feedback

Answer 2

Child birth -oxytocin
Blood clotting

Question 3

What is the range for normal body temperature?

Answer 3

36.5-37.5°C

Question 4

Body control if temp is too high

Answer 4

Vasodilation of vessels
Sweating
Pilorelaxation

Question 5

Body control if temp is too low

Answer 5

Vasoconstriction
Shivering
Piloerection - traps warm air

Behavioural - more layers, metabolic activities

Question 6

What can be used to measure body temperature?

Answer 6

• Infrared skin thermometer
• Tympathic thermometer - ear canal
• Temporal film
• Oral/rectal/axillary
• Traditional - glass rod

Question 7

What is the normal range for the body’s pH?

Answer 7

7.35-7.45

Question 8

What are the causes of acidosis?

Answer 8

• Metabolic acidosis - increased metabolic acids or inability for kidneys to excrete acids
• Respiratory acidosis - excessive build up of CO2

Question 9

Mechanisms to control pH

Answer 9

• Bicarbonate solution
• Ca2+ is alkali > ^pH
• sodium phosphate buffer system
• aluminium hydroxide is mildly alkaline but insoluble so good acid neutraliser

Question 10

A change in [H+] by a factor of ** causes a pH change of **

Answer 10

A change in [H+] by a factor of 2 causes a pH change of 0.3

Question 11

Relationship between pH and [H+]

Answer 11

pH +/- 0.3 = [H+] halves/doubles

Question 12

How many litres of water are in a 70kg man?
How much of this is extra/intracellular?

Answer 12

42 litres
Extra - 14L
Intra - 28L

Question 13

Circulating blood volume in litres

Answer 13

5L

Question 14

Define osmolality

Answer 14

Conc. of solution expressed as total no.of solute particles per kg

Question 15

How is osmolality measured?

Answer 15

Using mass of solution