Homeostasis

Question 1

define homeosatsis

Answer 1

~ is the maintainence of a constant internal environment

Question 2

explain the basic principles of homeostasis

Answer 2

• a receptor detects a stimulus caused by a change to the internal environment
• sends signals/info to the self-regulatory corrective mechanism to restore the conditions to normal
• as conditions return to normal, a feedback is sent to the receptor which causes the corrective mechanism to stop. This is negative feedback

Question 3

structures of the skin involved in temperature regulation

Answer 3

• hairs: helps to trap air which is a poor conductor of heat to prevent heat loss
• sweat gland: secrete sweat which, when the water in sweat is evaporated, latent heat of vaporisation is lost, thus help to lose heat
• temperature receptors: detect temperature changes
• blood vessels (capillaries & arterioles): changes in blood volume to control heat loss
• fatty tissue/adipose tissue: fat in adipose cells serves as an insulting layer, reducing heat loss

Question 4

describe the maintenance of a constant body temperature in humans

receptors, sweating, shivering, blood vessels, hypothalamus

Answer 4

• an increase or decrease in blood temperature from normal is detected by hypothalamus
• nerve impulses - sent out to different organs to help lose or retain heat

An increase in body temp results in:
- vasodilation in skin & constriction of shunt vessels (allow more blood flow to blood capillaries in skin) so that more heat is lost through skin by radiation, convection & conduction
- sweat glands: more active, increasing sweat production, more water in sweat evaporate, more latent heat of vaporisation lost, thus helping to lose heat

A decrease in body temp results in:
- vasoconstriction & dilation of shunt vessels (less blood blow) to reduce heat lost by convection conduction & radiation
- sweat glands: less active, decreased sweat production, less water in sweat evaporates, less latent heat of vaporisation lost
- when ^not sufficient, shivering (a reflex contraction of body muscles) occurs which increases amount of heat released & helps to raise body temp to normal