BL Homeostasis, Body Fluids, pH + Temp Flashcards
Define homeostasis
Process in which internal environment is maintained at equilibrium despite internal/external factors
Examples of positive feedback
Child birth -oxytocin
Blood clotting
What is the range for normal body temperature?
36.5-37.5°C
Body control if temp is too high
Vasodilation of vessels
Sweating
Pilorelaxation
Body control if temp is too low
Vasoconstriction
Shivering
Piloerection - traps warm air
Behavioural - more layers, metabolic activities
What can be used to measure body temperature?
- Infrared skin thermometer
- Tympathic thermometer - ear canal
- Temporal film
- Oral/rectal/axillary
- Traditional - glass rod
What is the normal range for the body’s pH?
7.35-7.45
What are the causes of acidosis?
- Metabolic acidosis - increased metabolic acids or inability for kidneys to excrete acids
- Respiratory acidosis - excessive build up of CO2
Mechanisms to control pH
- Bicarbonate solution
- Ca2+ is alkali > ^pH
- sodium phosphate buffer system
- aluminium hydroxide is mildly alkaline but insoluble so good acid neutraliser
A change in [H+] by a factor of ** causes a pH change of **
A change in [H+] by a factor of 2 causes a pH change of 0.3
Relationship between pH and [H+]
pH +/- 0.3 = [H+] halves/doubles
How many litres of water are in a 70kg man?
How much of this is extra/intracellular?
42 litres
Extra - 14L
Intra - 28L
Circulating blood volume in litres
5L
Define osmolality
Conc. of solution expressed as total no.of solute particles per kg
How is osmolality measured?
Using mass of solution
