What is homeostasis?
Maintenance of a constant internal environment?
What is thermoregulation?
Regulation of body temperature; maintaining balance between heat loss/gain/production
What is the normal body temperature?
~37.8 degrees Celsius, usually higher than environmental temperature
What are the consequences of increased body temperature?
Nerve malfunction, change in protein structure, death
Feedback loop: rise in body temperature?
Stimulus: rise in body temperature
Receptors: peripheral(skin and mucous membrane) heat thermoreceptors and central(hypothalamus) heat thermoreceptors
Modulator: hypothalamus
Effector: skin, blood vessels, thyroid glands(long term)
Response: sweating(evaporation), vasodilation, decrease in metabolic rate due to reduced thyroxine secretion(long term)
Feedback: reduction in body temperature
What happens during heat exhaustion?
Volume of blood plasma and resistance to blood flow are reduced to extreme sweating and vasodilation, reducing blood pressure
At what temperature does hypothermia start and what are the effect on the body?
Core body temperature falls below 33 degrees Celsius, metabolic rate becomes so low that heat production is unable to replace heat loss
What is fluid balance?
Fluid loss must equal fluid gain
How are fluids obtained?
Mostly obtained from water, small amount obtained from metabolic water
Feedback loop: fall in body temperature?
Stimulus: fall in body temperature
Receptors: peripheral and central cold thermoreceptors
Modulator: hypothalamus
Effector: skin blood vessels, adrenal medulla, brain(parts increasing skeletal muscle tone),thyroid(long term)
Response: vasoconstriction, secretion of adrenaline and noradrenaline(increase cellular metabolism), shivering, increase in metabolic rate due to increased thyroxine secretion(long term)
Feedback: rise in body temperature
Where does excretion occur and what does it excrete?
Lungs: excrete water vapor
Sweat glands: secrete water containing by products of metabolism
Alimentary canal: passes out bile pigment with faeces
Kidney(principal excretory organs): maintaining the constant concentration of materials in the body fluids
Can water loss be regulated?
Water loss from the lungs and alimentary canal cannot be regulated, water lost from the kidneys can be