Homeostasis - Topic 1 Flashcards
What is Homeostasis?
The ability to maintain internal biological stability while adjusting to external changes
What does homeostasis allow?
Allows the body to control a number of variables within an optimal range (set point) for survival
List examples of what the body needs to control in order to survive.
Temperature
pH
Blood-glucose
Salt/water balance
Blood pressure
What is a regulated variable and give an example
Variable that is directly sensed by the body and controlled.
Eg: arterial pressure (blood pressure)
Blood pH
Blood pO2/pCO2 (partial pressure)
What is a nonregulated variable and give an example
Variable indirectly sensed by the body but still controlled.
Eg: heart rate (changed to regular blood p)
Breathing rate (changed to regulated blood pCO2/pO2)
What is a nonregulated variable and give an example
Variable indirectly sensed by the body but still controlled.
Eg: heart rate (changed to regular blood p)
Breathing rate (changed to regulated blood pCO2/pO2)
What are the 3 things homeostasis needs to do to keep the body close to a set point (optimum)?
Detect change = receptor/sensor
Process these signals = control centre
Change body state via output = effector
What are the 3 things homeostasis needs to do to keep the body close to a set point (optimum)?
Detect change = receptor/sensor
Process these signals = control centre
Change body state via output = effector
What is negative feedback?
The primary mechanism of homeostasis. Sensors, control centre and effective work together to reverse effects of change in condition to bring body back to a set point.
What does negative feedback allow?
Fine-tuning of conditions through small conditions. Then it “turns itself off” when conditions are back to the set point.
Describe a basic negative feedback loop
- Deviation from a set point caused by stimulus
- Change detected by receptor
- Info (as electrical impulse or hormones) is sent to a CONTROL CENTRE
- Change counteracted by an EFFECTOR
What is the most common control centre in the negative feedback mechanism?
The brain. (CNS = brain and spinal cord)
Give an example of effectors
Glands (eg sweat glands)
Muscles (eg erector pili muscles that raise body hair/muscles in iris)
What are the 2 different categories for the effects of negative feedback?
Behavioural and physiological changes
Give an example of a behavioural effect when body temp falls
Add clothes
Have a hot drink
Give an example of a physiological effect when body temp falls
Decrease blood flow to skin
Start to shiver
Give an example of a behavioural change when body temp rises
Remove clothes
Have a cold drink
Give an example of a physiological change when body temp rises
Increase blood flow to skin
Start to sweat
What is positive feedback?
An uncommon mechanism generally not involved in homeostasis that works to amplify the response to changes in condition.
Give an example of positive feedback
Uterus stretched during labour - needed so cervix stretches more to birth baby
What can prevent homeostasis, leading to extreme conditions like hyper/hypothermia, heatstroke or even death?
Neurological diseases or damage to nerves. This interrupts communication, so signals are disrupted. Effector cannot carry out response to counteract the original stimuli if it doesn’t receive an impulse.
How is homeostasis implemented?
Communication via signalling systems - nervous and endocrine.
What is the nervous system?
A network of connected nerve cells (neurons) that allow communication of information and control throughout the body. This allows targeted signalling between body and brain.
Finish the sentence (hint:DPP)
“nervous systems allow information from the environment to be…”
Detected
Processed
Produce behavioural output.
