homeostasis

Question 1

what is homeostasis

Answer 1

Homeostasis is the maintenance of a relatively stable internal environment in the body despite changes in the external environment

• The external environment is continually changing.
• Homeostasis allows our bodies to deal with this change.
• It means that our internal environment is stable and unchanging.
• Homeostasis is about coping with external change.

Question 2

what is the importance of homeostasis

Answer 2

As organisms that are able to regulate our internal environment, homeostasis allows us to live in extreme conditions and to extend our geographic range.

The loss or prevention of homeostasis in humans is life-threatening.

Question 3

key variable maintained by homeostasis

Answer 3

• temperature
• blood glucose
• waters
• ions
• blood ph

Question 4

what body systems contribute to homeostasis

Answer 4

• The most important systems are:
• The nervous system through communication via electrochemical signals
  -The endocrine system through hormones released from the endocrine glands that travel via the blood

Question 5

feedback response model for homeostasis

Answer 5

• Homeostatic variables are monitored
• If a variable goes outside the normal range this is detected and adjustments are made to bring it back within the normal range.
• Homeostasis is controlled by a stimulus-response model
• The model starts with a stimulus and ends with a response.

Question 6

stimulus response model in homeostasis

Answer 6

Stimulus – a change Increase or decrease in variable level
Receptor – structure that detects the change and sends a message to the modulator/control center
Modulator/control center Central nervous system brain and spinal cord – compares change to set point and sends a message to effector
Effector – structure that adjusts output to make the correction
Response – the corrective action taken

Question 7

receptors of homeostasis

Answer 7

Structures that detect stimuli and send signals to the brain
* Chemoreceptors –chemical changes (pH, CO2 in blood)
* Mechanoreceptors – touch, pressure, stretch changes
* Photoreceptors – light changes (eyes)
* Thermoreceptors – temperature (nerve endings in skin)
* Osmoreceptors – water (osmotic concentration of fluids)

Question 8

what is a negative feedback loop

Answer 8

• When the response counteracts the change in the variable it is known as negative feedback loop
• The change to a variable is detected and mechanisms are put in place to reverse the change
• Receptors are constantly monitoring the variables under homeostatic control and effectors are constantly making corrections to keep the variables within the narrow range around the set point.
• If the stimulus is an increase in a variable the response is a decrease to that variable, hence negative feedback.
• in negative feedback, the response leads back to the stimulus

Question 9

negative vs positive feedbacks

Answer 9

• Feedback can also be positive – the original change is increased
• Causes more of that action to occur.
• When the original stimulus is removed then the positive feedback loop stops
• Positive feedback is not used in homeostasis