Communication and homeostasis Flashcards
What is homeostasis
The maintenance of a constant internal environment via physiological control systems
Involves both negative and positive feedback loops
What does homeostasis control
Body temperature
Blood pH
Blood glucose concentration
Blood water potential
What is negative feedback
When a deviation from the set limits is detected in the body by a receptor, mechanisms are put in place to restore the conditions back within the set limit
Involved in the nervous system and endocrine system
What is positive feedback
When a deviation from set limits triggers a respond to increase the deviation further
Example: in childbirth when the baby’s head presses on the cervix, oxytocin is released which causes the uterus to contract, this leads to more oxytocin being released.
Why is thermoregulation necessary
If body temperature dropped too low there would be insufficient kinetic energy for enzyme controlled reactions
If body temperature increased too high, enzymes would denature
(either way) Metabolic reactions slow to the point that cells die
What is an ectotherm
Cannot regulate their internal temperature, can only control it through changing their behaviour
Examples: fish, amphibians, reptiles and invertebrates
Temperature in water stays relatively constant due to high specific heat capacity so endotherms with aquatic environments do not have much need to regulate their temperature
Ectotherms on land often bask on hot rocks to absorb radiating heat energy from the sun
What is an endothermic
Regulate body temperature through a nervous response, peripheral temperature receptors in the skin detect a change in external temperature , this sends an impulse to the brain to the hypothalamus which coordinates an impulse which is responded to by glands in the skin and muscles
Example of reactions by endotherms
Producing more sweat- sweat evaporates from the skin which means heat from the skin is lost (cooling effect)
Vasodilation- arterioles near skin surface dilate and blood flows through the arteries near skin surface so more heat energy radiates from skin surface
Vasoconstriction- arterioles near skin surface restrict so blood flows through capillaries further away from skin surface so less energy is radiating from the skin.
Shivering- Increases rate of respiration so more heat energy is released
Animals can raise fur or feathers to trap air/insulate or lower fur and hair to prevent insulating layer forming (controlled by erector pili muscles in skin)
Modify behaviour- huddle for warmth, move to shade etc
