5.3 - thermoregulation

behavioural & physiological

what is the body’s core temp?

36.8 Celsius

define thermoregulation

the maintenance of body temperature at approximately 36.8°C by balancing heat loss and gain.

what is the purpose of thermoregulation? Why do we need to balance our heat loss & gain

to maintain a constant internal body temperature (keep body core temp within tolerance limits) independent of the environmental temperature

How does thermoregulation occur?

occurs by the control of heat exchange & metabolic activity through physiological & behavioural mechanisms

what causes body heat to increase?

increase in metabolism (e.g. due to exercise, stress, etc) or heat absorbed from our surroundings

• conduction

• convection

• radiation

define metabolic rate

The rate at which energy is released by the breakdown of food

what is the temperature cycle?

our core body temp is the lowest in the morning, but the highest in the evening

what can a constant increased body temp cause?

• nerve malfunction

• change in structure of proteins

• death

complete the following:

___ reactions in ___ are very ___ sensitive

chemical reactions in cells are very heat sensitive

complete the following:

most of the time ___ body temp is higher than ____ _____ temp

most of the time internal body temp is higher than surrounding environmental temp

what causes heat loss?

conduction, convection, radiation & evaporation

define radiation

The transfer of energy in the form of waves - no direct contact with source

define convection

The transfer of heat by the movement of liquids or gases e.g. when hot or cold air passes over a body

define conduction

The transfer of heat by direct contact between particles - direct contact

define evaporation

The process of a liquid forming a gas, which absorbs heat energy

identify, define & explain the 2 thermoreceptors

Peripheral thermoreceptors: A temperature receptor in the skin and in some mucous membrane

• detect changes in external environment & send info to the hypothalamus

Central thermoreceptors: A thermoreceptor located in the hypothalamus, spinal cord & organs

• detect changes in temp of internal environment, sends info to the hypothalamus

there are cold & heat receptors - how are they stimulated & what does the hypothalamus initiate due to the stimulation of these receptors?

name the 2 ways that the body does to prevent body temp from falling

• increasing heat production

• reducing heat loss

how does the body increase heat production to prevent body temp from falling?

identify & define how the body reduces heat loss to prevent body temp from falling

vasoconstriction of cutaneous blood vessels (sympathetic nervous system): A decrease in the diameter of arterioles, restricting the flow of blood through them

explain vasoconstriction

Blood vessels located in the dermis of the skin carry heat to the skin from the core of the body. The diameter of these arterioles is controlled by autonomic nerves. If the diameter of the arterioles is reduced by vasoconstriction, less blood is transported to the capillaries in the skin and the rate of heat loss decreases

name the 2 ways the body prevents body temp from rising?

• reducing heat production

• increasing heat loss

explain how the body reduces heat production

explain how the body increases heat loss

What body temp is considered dangerous & what body temp can cause death

• temps around 42 Celsius is considered dangerous

• death usually occurs around 45 Celsius

what causes high body temps?

fever & certain environmental conditions

define/explain heat stroke & include a treatment

Heat stroke: The failure of a person’s temperature-regulating mechanisms when exposed to excessive heat

define/explain heat exhaustion

Heat exhaustion: The collapse of a person after exposure to heat, during which their body’s heat-regulating mechanisms continue to function normally

define/explain hypothermia

Hypothermia: Abnormally low body temperature; the temperature drops below the level required to maintain normal body functions