B1.2 Responses to a changing environment
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What is homeostasis?
Homeostasis is maintaining a constant internal environment.
Name 3 things that your body must keep constant.
- Blood Glucose
What is osmoregulation?
Keeping a balance of water in the body.
Which area of the brain controls body temperature?
What happens when the body is too hot?
- Sweats - evaporation of sweat transfers heat from the body to the environment
- Hairs lie flat
- Blood vessels close to the skin dilate (widen) to let more blood near the surface so it can lose more heat.
What happens when the body is too cold?
- Hair erector muscles make hairs stand on end - this traps air and insulates you.
- Blood vessels near the skin constrict (narrow) reducing blood flow to the skin and reducing heat loss.
- Shivering - muscle contraction produces heat energy
What are the gaps between neurones called?
What is the function of the myelin sheath?
Insulates the nerve axon stops the impulse getting lost and speeds up the electrical impulse.
Name the chemical that is released across a synapse.
What is a stimulus?
A change to your enviroment which your body can detect.
Name the 5 sense organs which contain receptors.
- Eyes - have light receptors
- Ears - Sound receptors
- Nose - Smell receptors - detect chemical stimuli
- Tongue - Taste receptors - detect chemical stimuli
- Skin - detect touch, pressure and temperature change
Which neurone sends impulses from the receptors to the CNS.
Which neurone carrys impulses between the sensory neurone and the motor neurone?
Which neurone carries impulses to effectors?
Give two examples of effectors.
Muscles and Glands.
What does the central nervous system consist of?
The brain and the spinal cord.
What is a reflex?
A fast involuntary response
Why do we have reflexes?
The are protective. They ensure we react quickly to minimise the chance of harm.
Outline the reflex arc.
Stimulus --> receptor --> sensory neurone --> relay neurone (in CNS) --> motor neurone -->effector --> response
Where are hormones produced?
How do hormones get around the body?
In the bloodstream
Name the hormone which reduces blood sugar levels.
Which type of diabetes is caused by a lack of insulin?
Which type of diabetes is due to resistance to insulin?
How would a type I diabetic control their blood sugar?
- Diet - not eating foods with lots of sugar in them
- Injecting insulin
How would a type II diabetic control their blood sugar?
- Diet - not eating foods with lots of sugar in them.
- Regular exercise.
Which type of diabetes is linked to obesity?
Name a plant growth hormone that allows it to respond to light.
Name 3 things plants respond to.
- Light (phototropism)
- Gravity (Gravitropism/Geotropism)
- Water (osmotrophic/hydrotrophic)
How does a root respond to gravity?
Grows downwards as auxin accumulates in the roots causing cells in the roots to elongate
Where in a plant is auxin produced?
Tips of shoots and in roots.
What does gibberellin do?
Makes seeds grow faster and plants flower.
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