homeostasis

Question 1

what is homeostasis

Answer 1

the regulation of conditions in the body such as temperature, water content and CO2. this is necessary for the body and its conditions to function properly.

homeostasis works by detecting changes, controlling systems, and responding to them.

Question 2

three components of homeostasis

Answer 2

1- detector; a sensor or receptor detects change in the internal/external environment, e.g. peripheral receptors detecting pH change in blood

2- control centre; receives this information of change and initiates response to maintain homeostasis (balance), e.g. hypothalamus in the brain controls BP and temperature.

3- effector; any organ/tissue that receives information from control centre and acts upon the desired change necessary to maintain homeostasis, e.g. kidney retains water when BP is too low.

Question 3

negative feedback

Answer 3

negative feedback mechanisms reduce output or activity to return an organ or system to its normal range of functioning. E.g.

sensors within the blood vessels (baroreceptors) can detect low or high levels of BP and send a signal to the brain to increase or decrease this.

hypothalamus will send a message to effectors, in this case the heart, blood vessels and kidneys, to carry out the changes needed to regulate the BP back to normal range.

Question 4

positive feedback

Answer 4

a mechanism where an output is enhanced to maintain homeostasis. this feedback is designed to accelerate r enhance the output created by a change/stimulus that has already been activated.

positive feedback is rarely used as it may become uncomfortable, e.g. blood platelet accumulation causes blood clotting to stop bleeding from a damaged blood vessel.

Question 5

temperature regulation

Answer 5

heat conservation;

• vasoconstriction reduces blood flow in peripheral blood vessels, forcing blood towards core organs of the body and increased CBT
• piloerection is the erection of hairs on the skin due to tiny arrectores pilorum muscles which elevate hair follicles above the rest of the skin to ‘trap heat’
• shivering is a bodily function in response to coldness which is triggered when the CBT drops as a reflex triggered by homeostasis, causing skeletal muscles to shake, causing warmth by expending energy
• reducing sweating is inhibited (stopped) by homeostasis once set point is reached

heat loss;

• vasodilation- peripheral blood vessels dilating will allow more blood to flow through them and therefore more heat to be lost to the environment
• increased sweating- sweat glands in the skin will increase sweat secretion which will evaporate (liquid to vapour; gas), transferring heat out of the body and cool the skin down
• decrease in cellular metabolism, to reduce energy expendure and therefore heat generated