DONE Homeostasis Flashcards
Homeostasis
Physiological process by which internal systems of body maintained at eqm despite variations in intrinsic and extrinsic factors on system
‘Homeo’
Sameness
‘Stasis’
Standing still
Variable
Temperature, pH
Sensor
Monitors current value of variable
Control centre
Retains desired value of variable
Effector
Change value of variable as determined by control centre
Negative feedback
Effector opposes change, sensor/control centre inhibits further action by effector, stops when effector ceases
Response when hot
Sweating, pilorelaxation, vasodilation, stretching out
Response when cold
Shivering, piloerection, vasoconstriction, metabolism of white fat
Positive feedback
Change in one direction, stops when variable ceases
Positive feedback example
Coagulation, Ferguson reflex
Normal range for temp.
37 +-0.5
Temp in menstrual cycle + pregnancy
37.4
Where is core body temp?
Thorax, abdomen, head, neck
Hypothermia temp
Below 36.5
Ph range
7.35-7.45
Blood pH
7.4
Arteries pH
7.45
Vein pH
7.35
Acidosis pH
Below 7.35
Alkalosis/alkylosis pH
Above 7.45
What are the 2 main organs that maintain acid-base balance?
Lungs and kidneys
What is the volume of blood in a standard male (70kg)?
5 litres
What is the total body water of a standard male?
42 litres
What does hypotonic mean?
Less water outside cell as transported in
What does hypertonic mean?
Less water inside cell as transported out
What does isotonic mean?
Same amount of water both sides of plasma membrane
What is greater in oedema, hydrostatic pressure or osmotic pressure?
Hydrostatic pressure
