Homeostasis and Response Flashcards
(28 cards)
What is Homeostasis?
The regulation of the conditions inside your body to maintain a stable internal environment, in response to changes in both internal and external conditions.
Why is Homeostasis important?
Cells and enzymes inside the body need the right conditions in order to function properly
What is negative feedback?
When the level of something gets too high or too low, your body uses negative feedback to bring it back to normal.
What is a stimulus?
A change in the environment
What do receptors do?
Receptors are the cells that detect a stimulus
What does the coordination centre do?
It receives and processes the information, then organises a response.
What does the effector do?
Produces a response, which counteracts the change and restores the optimum level
What does the nervous system do?
It means that humans can react to their surroundings and coordinate their behaviour.
What are some examples of receptors?
- Taste receptors on the tongue
- Sound receptors in the ears
What are some examples of effectors?
Muscles and glands - They respond in different ways
What are sensory neurones?
The neurones that carry information as electrical impulses from the receptors to the CNS
What are motor neurones?
The neurones that carry electrical impulses from the CNS to the effectors
What are relay neurones?
They connect sensory neurones to motor neurones
What is the Central Nervous System?
It is a coordination centre - it receives information from the receptors and then coordinates a response (decides what to do about it). The response is carried out by effectors.
What is a synapse?
The gap between two neurones is called a synapse
How is information transferred through the synapse?
The nerve signal is transferred by chemicals which diffuse across the gap. These chemicals then set off a new electrical signal in the next neurone.
What are reflexes?
They are rapid, automatic responses to certain stimuli that do not involve the conscious part of the brain
What are some examples of reflexes?
- I someone shines a bright light in your eyes, your pupils automatically get smaller so that less light gets into your eye, to stop it from getting damaged
- If you get a shock, your body releases the hormone adrenaline automatically
What does the body do when you are too hot?
1) Sweat is produced by sweat glands and evaporates from the skin
2) Blood vessels supplying the skin dilate so more blood flows close to the surface of the skin
What does the body do when you are too cold?
1) Hairs stand up to trap an insulating layer of air
2) No sweat is produced
3) Blood vessels supplying skin capillaries constrict to close off the skin’s blood supply. This is called vasoconstriction
4) Shivering contracts your muscles. This needs respiration which transfers some energy to warm the body
What are hormones?
Hormones are chemical molecules released directly into the blood. They only affect particular cells in particular organs.
What is the pituitary gland?
Produces many hormones that regulate body conditions
What is the Thyroid?
This produces thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature
What is the adrenal gland?
This produces adrenaline, which is used to prepare the body for a ‘fight or flight’ response
