2.4 Flashcards
What is a conformer?
A conformers internal environment is directly dependent upon it’s external environment.
How do conformers maintain optimum metabolic rate?
Behavioral responses
What are the advantages of conformers?
Low metabolic costs
What are the disadvantages as a conformer?
The animal is restricted to a narrow range of ecological niches and is less adaptable to environmental change.
What do behavioral responses allow conformers to do?
Tolerate variation
What is a regulator?
Regulators can maintain their internal environment regardless of the external environment.
How do regulators control their metabolic rate?
Physiological Homeostasis
Advantages of a regulator?
Can exploit a wider range of ecological niches.
Disadvantages of regulators?
Has to expend energy to achieve homeostasis, this increases metabolic costs.
What is physiological homeostasis and how is it brought about?
It is the maintenance of the body’s internal environment within certain tolerable limits despite changes in the body’s external environment.
It it brought about by negative feedback control and requires energy
The principle of negative feedback control
A factor can increase or decrease from it’s norm or set point. This is sensed by receptors for that factor. Messages are sent from the receptors to the effectors which bring about a corrective response to lower or raise the factor back to it’s norm or set point.
What is an ectotherm?
An animal which is unable to regulate it’s heat by physiological means, they obtain most of their body heat by absorbing it from their surroundings.
What is an endotherm?
An animal which is able to maintain it’s body temperature at a relatively constant level irrespective of external temperature changes. Heat generated by their high metabolic rate.
What is the importance of temperature regulation?
Thermoregulating is important for optimal enzyme activity and high diffusion rates to maintain metabolism.
What is the hypothalamus?
It is the body’s temperature monitoring center
How does the hypothalamus work?
It receives information communicated by electrical impulses through nerves from the heat and cold receptors of the skin and sends information to the effectors.
The hypothalamus itself also contains thermoreceptors which detect changes in blood temp which reflect changes in body core temp.
What is vasodilation?
The capillaries near to the skin surface dilate, increasing blood flow to the skin increases heat loss by radiation.
What is vasoconstriction?
The arterioles constrict which allows only a small volume of blood to flow to the surface capillaries, this decreased blood flow to the skin decreases heat lost by radiation.
Corrective response to overheating
Vasodilation
Increased rate of sweating (evaporate the water in sweat, cooling skin)
Metabolism (decrease in metabolic rate reduces heat produced)
Corrective response to overcooling
Vasoconstriction
Hair erector muscles contract (raised hairs trap a layer of insulating air to reduce heat loss)
Metabolism - increase in metabolic rate
Shivering - muscles contract to generate heat
