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26 Cards in this Set

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Why is it important to regulate the temperature in our body?
If the temperature is too low the reactions in our body will happen slowly due to slow enzyme activity and if the temperature is too high the enzymes might be denatured so the organism will cease to function completely.
Methods of gaining heat:

1.Production of heat by the metabolism of food during respiration


2.Gain of heat from the environment, by conduction from the ground and convection from surrounding air or water and radiation

Methods of losing heat :

1.Evaporation of water (during sweating)


2.Loss of heat to the environment by conduction and conversion from surrounding air and water and radiation.

What is Conduction?
Transfer of energy through matter of particle to particle (atom to atom). Heat causes the particles to vibrate and gain kinetic energy. These particles cause adjacent particles to vibrate so kinetic energy is transferred.
What is Convection?
Occurs in fluid (gases and liquids) and the transfer of heat as a result of the movement of the warmed water its self. The heat causes the fluid to expand and move , carrying with it the heat that it has absorbed.
What is radiation?
Energy is not transferred from particle to particle but by electromagnetic waves. When these waves hit an object they heat them up.
How do animals conduct heat?
Animals such as birds conduct heat from their metabolic activities that take place inside their body so their called endotherms (inside heat). The other animals conduct heat outside of their body and therefore called ectotherms (outside heat)
How does animals gaining their heat from the environment (ectotherms)affect them?
Their body temperature fluctuates with that of the environment. Therefore they control their body temperature by adapting their behaviour to changes in the external temp e.g. exercise.

Reptiles cannot exercise to generate heat so how do they control their body temp?

1. Exposing themselves to the Sun


2. Taking Shelter (prevent overheat and losing heat at night)


3. Gaining warmth from the ground (press against the ground and retain heat)


4. Generating metabolic heat ( from respiration)


5. Colour variations- Darker colours absorb more heat)

Summarise the regulation of heat in endotherms?
They get heat from their internal metabolic activities and the temp ranges from 35-44 degrees and this is the optimum temp for enzyme and this is a compromise as there is need for high energy needed to maintain that higher temp. Unlike ectotherms they use physiological mechanisms to regulate their temp
Animals who live in cold climates have adapted to retaining heat, how do they do this?
By having a small surface area ,it is easier to maintain a higher body temp in a cold environment.
What do mammals in cold climates do to keep up with daily temperature 1:
Vasoconstriction: the diameter of the arterioles in the skin is made smaller , this reduces the volume of the blood reaching the skin surface through the capillaries, so therefore most of the blood entering the skin passes beneath the insulating layer of fat , so little heat is lost to the environment.
What do mammals in cold climates do to keep up with daily temperature 2:
Shivering: the muscle of the body undergo involuntary rhythmic contractions that produce metabolic heat.
What do mammals in cold climates do to keep up with daily temperature 3:
Raising hair- the erector muscles in the skin contract, thus raising the hairs on the body. This enables thicker layer of still air , which is a good insulator, to be trapped next to the skin thus improving insulation
What do mammals in cold climates do to keep up with daily temperature 4:
Increased Metabolic rate: In cold conditions more of the hormones that increase metabolic rate are produced . As a result metabolic activity including respiration is creased and more heat is generated.
What do mammals in cold climates do to keep up with daily temperature 5:
Decrease in sweat: Sweating is reduced.
What do mammals in cold climates do to keep up with daily temperature 6:
Behavioural mechanisms: Sheltering from the wing, basking in the sun and huddling together all helps animals maintain their core temperature.
Losing heat in response to a warm environment 1:
Vasodilation, the diameter of the arterioles near the surface of the skin become larger, this allows warm blood to pass close to the skin surface through the capillaries. The heat from the blood is then radiated away from the body.
Losing heat in response to a warm environment 2:
Increasing sweating, to evaporate water from the skin surface requires energy in the form of heat. In hairless mammals , such as humans , sweating is highly effective means loosing heat. In mammals with fur , cooling is achieved by evaporation of water from the mouth and tongue which occurs when air is rapidly passed over these surfaces.
Losing heat in response to a warm environment 3:
Lowering of body hair, the hair erector muscles in the skin relax and the elasticity of the skin causes them to flatten against the body. This reduces thickness of insulating layer and allows more heat to be lost to the environment when the internal temperature is higher than the external temp
Losing heat in response to a warm environment 4:
Behavioural mechanisms avoiding the heat of the day by sheltering in burrows and seeking out help to prevent the body temperature from rising.
What is an example of homeostasis in endotherms?
Regulation of core body temperature.
Summarise the Homeostasis in Endotherms

1. Stimulus (change in body temp)


2. Thermo receptors (detect the change in temp)


3. Coordinator( the information is passed from the receptor to the coordinator in the brain called the hypothalamus)


4. Effector ( the skin produce the appropriate response whether its increasing or decreasing temp)



What is a hypothalamus?
A coordinator in the brain that triggers the right response from effectors
What does the hypothalamus consist of?

A thermoregulatory centre which consist of two parts :


1. A heat gain centre, activated by a fall in blood temperature ( This increases body temp)


2. A heat loss centre, activated by a rise in blood temp (this decreases body temp)

Role of thermo receptors in the skin?
Measure of skin temp and these thermo receptors send impulses along the autonomic nervous system to the hypothalamus. They provide info on the environment temp and give advanced warnings of potential changes in the core temp. The animal can therefore take measures to conserve or lose appropriate heat.