Homeostasis Flashcards
What is the series of stages that controls any self-regulating system?
The SET POINT is the desired level at which the system operates, this is monitored by a RECEPTOR which detects deviation from this set point and informs the CONTROLLER which coordinate the information from the various receptors and send instructions to the EFFECTOR which brings about the changes needed to return the system to normality and this creates the FEEDBACK LOOP which informs the receptor of the changes to the system brought about by the effector.
What are two methods of gaining heat?
Production of heat through the metabolism of food.
Gain of heat from the environment through, conduction from the ground, convection through the air or water and radiation.
What are two methods of losing heat?
Evaporation of water (during sweating)
Loss of heat to the environment by conduction, convection or radiation.
What is conduction?
Occurs mainly in solids and is the transfer of energy through a substance for particle to particle. Heat energy increases the kinetic energy of the particles and so more vibration, these vibrations are passed on to the next particle along. Therefore kinetic energy is passed through the material.
What is convection?
Occurs in fluids. The warmer areas of the fluid rise as they have a lower density (pressure) and this causes a pressure gradient and so cooler denser areas flow into the less dense areas. The movement of the fluid spreads the heat energy.
What is radiation?
This is not spread through the movement of particles but through electromagnetic waves and surfaces warm up when these waves hit it.
How do ectotherms regulate their body temperature?
Basking in the sun Taking shelter in the shade Gaining warmth from the ground Generating metabolic heat Colour variation
How do endotherms conserve heat in a cold environment?
Vasoconstriction Shivering Raising of hair Increased metabolic rate Decrease in sweating Behavioural mechanisms
How do endotherms lose heat in a warm environment?
Vasodilation
Increasing sweating
Lowering of body hair
Behavioural mechanism
What effect does vasoconstriction have?
The diameter of the arterioles near the surface of the skin is made smaller. This reduces the volume of blood reaching the skin. Most blood then passes through the capillaries below the layer of fat.
What is vasodilation?
Diameter of arterioles near the surface of the skin surface increases, so more warm blood near the surface and the heat is radiated out of the body.
What does sweating do?
Evaporation requires energy in the form of heat from the skin surface. Water is evaporated off the skin, this draws energy from the body, reducing body temperature.
What does lowering a body hair do?
It reduces the thickness of the insulating layer of air and allows more heat to be lost to the environment. The hair erector muscles relax and the skin’s elasticity pulls the hair down.
What does raises body hair do?
It increases the thickness of the insulating layer of air which reduces heat loss through convection as the air is trapped.
What does shivering do?
Involuntary contractions that produce metabolic heat.
