Co-ordination and response Flashcards
What are Receptors?
Receptors detect stimuli. Receptors in sense organs are cells which detect external stimuli.
What are Effectors?
Cells that bring about a response to stimuli. They include muscle cells and cells found in glands. Muscle effectors contract and gland effectors secrete hormones
What is a Synapse?
The connection between two neurones is called a synapse.
What is the Central Nervous System (CNS)
The Brain and Spinal cord only.
What is the Nervous Cystem
All the neurones (nerve cells) in your body.
What are the three types of neurone?
- Sensory
- Relay
- Motor
What is a neurotransmitter?
Chemicals which transfer nerve signals across the synapse through diffusion across the gap
What is a reflex arc?
Reflexes are automatic responses to certain stimuli which reduce the chance of an injury.
What part of the CNS does a reflex arc go through?
Typically the spinal cord but it can go through the unconcious part of the brain.
Why are reflex arcs faster than a normal one?
Because you don’t need to think about the response (which takes time).
What does a relay neurone do?
Relays the impulse to a motor neurone from a sensory neurone.
What is the order of neurones receiving the impulse?
Sensory -> Relay -> Motor
What is the function of the Conjunctiva?
Lubricates and protects the eye
What is the function of the Cornea?
Refracts light into the eye
What is the function of the Iris?
Controls the diameter of the pupil.
What is the function of the Lens?
Focuses light onto the retina
What is the function of the Retina?
Converting light into neural pictures
What is the function of the Optic Nerve?
Transports information to the brain
What is the function of the Sclera?
Tough outer layer that protects the eye
Function of the pupil?
The iris changes pupil size to allow varying light levels into the eye
What is accommodation of the eye?
Changing the shape of the lens to focus light onto the retina.
How is the eye changed when looking at distant objects?
1) The cilary muscles relax, allowing the suspensory ligaments to tighten.
2) This thins the lens (less curved).
3) So it refracts less light.
How does the eye accommodate to close objects?
1) The cilary muscles contract, which slackens the suspensory ligaments.
2) The lens becomes more fat.
3) So it increases the refracted light.
What are 3 main differences between nerves and hormones
Nerves Hormone
1) Very Fast message / Slower message
2) Short time response / Long time response
3) Act on a precise area / Act on a more general area
Where are Hormones produced?
Glands
What carries hormones round the body?
They are carried in the blood plasma but only effect target cells.
What is human body temp kept at?
Fluctuating around 37*C
Define Homeostasis:
The maintenance of a constant internal environment
How does the body cool itself down when it is too hot?
- Sweating
- Vasodilation
- Hairs lie flat
How does the body heat itself up when it is too cold?
- Little sweat produced
- Shivering
- Vasoconstriction
- Hairs erect
Which organisms can lose or gain heat very quickly
- Large or Small ones?
Small, this is because they have a huge SA:V ratio and there is more area for heat to transfer across.
Why do plants grow towards light?
To maximise the light intensity and absorption of light for maximised photosynthesis.
What is Auxin?
The plant growth hormone
What is Auxin’s effect on the root and on the shoot?
Root = Inhibits growth Shoot = Promotes growth
Where is Auxin produced?
In the tip of the plant
Which organ produces bile?
Liver
Where is bile stroed?
Gall Bladder
