Homeostasis Flashcards
How is homeostasis brought about?
Negative feedback
What is negative feedback?
A control mechanism where a change from the set point is corrected by bringing about change in the opposite direction
What is the negative feedback system made up of?
- receptor> detects a change, sends info to control centre
- Control Centre> processes the information, activates corrective mechanisms
- Effector> responds and corrects change
What are some examples of negative feedback?
- Glucose (blood sugar) concentration
- Carbon Dioxide concentration
- Water and salts
What is carbon dioxide negative feedback?
- with a higher concentration of CO2, an increased amount of carbonic acid is produced
- This lowers the PH,increases the acidity, of body fluids. (lower PH affects metabolism) Therefore excess co2 must be released.
- Lower PH stimulates chemoreceptors in blood vessels in medula oblongata
- The control centre (respiratory centre of Medulla) processes information about lower pH, activates corrective mechanism
- The corrective mechanism, an increased number of impulses, sent to the effectors (respiratory muscles - diaphragm, intercostals)
- Muscles contract, breathing rate will become faster and deeper, excess co2 will be breathed out , released in the lungs
- Change in co2 concentration is corrected and conditions are returned to set point.
What is Thermoregulation?
The maintenance of a constant body temp by balancing heat production by heat loss
what is another name for heat production?
Thermogenesis
what is another name for heat loss?
thermolys
How is heat lost from the body?
body temp is higher than that of the environment heat by four physical processes
What are the four physical processes
Radiation
Conduction
Convection
Evaporation
what is radiation?
transfer of heat from a warm body to a cooler environment
what is conduction?
The transfer of heat from a hotter to a cooler object.
What is convection?
replacing of warm rising air by cooler air
What is evaporation?
loss of heat by using body heat to change sweat into water vapour.
How is the skin made up?
- Layers of skin= epidermis, dermis, subcutaneous fat layer
- sensory receptors = Ruffini corpuscle,Krause corpuscle
- glands = sweat gland
- position of capillary network.
How is skin adapted to regulate body temp?
It regulate body temperature by sweating, vasconstriction, vasodilation
What does it mean when Thermo- receptors are sensitive to environmental temp changes
Ruffini corpuscles detect incerease, while Krause detect decrease
The receptors enable body to respond to temp change. Thus adapting to environmental changes
What does the blood vessels help with?
Increase/ decrease blood flow by vasoconstriction or vasodilation
What is the purpose of the sweat glands?
Increase/decrease amount of sweat secreted?
What is the function of the subcutaneous layer of fat?
retain heat.
Fat insulate body against heat loss.
why does vasoconstriction occur in the skin when its cold?
To prevent heat loss.
Why is the hypothalamus regarded as the TEMPERATURE REGULATING CENTRE?
It constantly monitors the temp of the blood flowing through it.
what are the stimulation that occur when the temp drops below 37°C
- decrease in blood temp
- impulses from skin receptors registering cold environment e.g Krause corpuscles
How does Hypothalamus prevent heat loss?
when control measures are set up,impulses are sent to the dermal arterioles and sweat glands.
What happens when impulses are sent to the dermal arterioles?
The constriction of circular muscles which limits the flow of blood to capillary loops
what other problem is associated with Vasoconstriction?
Reduced sweating by sweat glands, less blood flow to the sweat glands, decreasing secretion of sweat.
Less heat is lost through evaporation
what is Hypothermia?
Drop in body temp to below 35°C due to uncontrolled exposure to cold
What are some of the consequences of Hypothermia?
impaired brain activity
If uncorrected, cardiac arrest and coma, death
What. The definition of homeostasis?
Ability to return to the set point
