Thermoregulation and Homeostasis Flashcards
(24 cards)
Physical means of heat gain/loss
Radiation, conduction, convection, evaporation of water
Biological means of heat gain/loss
Basal metabolism, sweating, shivering, skeletal muscle activity, subcutaneous fat insulation, vasoconstriction, vasodilation, eating to increase liver activity, eliminating/urinating
Temperature to be considered hyperthermia
Over 38 degrees
Temperature to be considered hypothermia
Below 35 degrees
Why is the core temperature of the body often different to that of the skin?
When capillary pads of the dermis are flushed with blood heat can be lost through convection, conduction, radiation or evaporation.
Vasoconstriction causes the skin temp to approach that of ones surroundings.
Insulation from adipose tissue keeps the core temperature higher.
What is conduction?
Objects of a higher temperature pass heat to something of a lower temperature through touch
Why do metals often feel cool to the touch
Things that are good conductors take up heat from the body more efficiently, leaving the area touching the object feeling cool even if it is at room temperature
What is convection?
Flow of heated particles from one place to another at a lower temperature
What factors determine how much heat is lost through convection?
Temperature difference between skin and air and area of exposed skin
What is an example of forced convection?
Blood flow around the body - energy is released at one part and travels to an are that is potentially cooler
Explain radiation
All objects emit infrared electromagnetic radiation due to their temperature - about half of human body heat is lost through radiation
What factors determine how much heat is lost through radiation?
Degree of vasodilation of blood vessels in the dermis, temperature difference between skin and surroundings, surface area of the body, how good the object is at conducting heat
Human sensations of hot and cold depend on…
Local skin temperature, temperature of the object being touched, how good the object is at conducting heat
How does evaporation of sweat effect heat loss
Water molecules on the skin continually gain kinetic energy from the blood passing through the dermis, eventually gaining enough kinetic energy to evaporate. Water vapour takes more than the average amount of kinetic energy as it leaves the skin, hence cooling skin temp
What outside factor can impact the effectiveness of sweat evaporation?
Humid environments where the air is saturated with water makes it difficult for water to evaporate
How much of our heat is lost through breathing
10-15% is lost through breath and water vapour in breathing
What is homeostasis?
The body’s automatic tendency to maintain a relatively constant (within a narrow range) internal environment through response to stimuli
What factors are maintained through homeostasis
Temperature, cardiac output, ion concentrations, pH, hydration, CO2 concentration in the blood, blood glucose concentration, waste accumulation
Homeostasis maintains a ______ state of equilibrium
Dynamic
What is the function of receptors in homeostasis?
Monitor changes in a variable/ receive stimulus
The afferent pathway to the integrating system
What is the function of the integrating system in homeostasis?
Determines the normal level of the variable
Efferent pathway to the effector organ
What is the purpose of the effector in homeostasis?
Produces a response that moves the variable value back to the set point (to normal range)
What is negative feedback?
A response that opposes a stimuli
What is positive feedback?
A response that enhances a stimuli
