B5.2 Human nervous system Flashcards
What is the role of the human nervous system?
Enables humans to react to their surroundings and to coordinate their behaviour
What is the CNS?
The central nervous system, includes the brain and spinal cord.
“To summarise the order of how the human nervous system works, fill in the missing words:
a -> b -> c -> d -> e”
“a) Stimulus
b) Receptor
c) Coordinator
d) Effector
e) Response”
Name the three types of neurone.
“1. Sensory
- Relay
- Motor”
What is a synapse?
The method by which a nervous impulse crosses the gap between neurones.
Summarise in five steps how a synapse works.
- Impulse arrives at the end of neurone A, 2. Neurotransmitter is released into the synaptic gap, 3. Neurotransmitter diffuses across the synaptic gap, 4. Neurotransmitter binds to receptors on neurone B, 5. A new electrical impulse is generated in neurone B.
Why are reflex actions rapid?
They do not involve the brain, therefore no conscious thought.
What do you use reflex actions for?
Reactions to remove your body from danger.
What is the brain made up of?
Billions of interconnected neurones.
What is the CNS?
The central nervous system, includes the brain and spinal cord.
Name the three main parts of the brain
Cerebral cortex, cerebellum, medulla
Why is investigating the function of the brain difficult?
It is a complex and delicate organ.
Name two ways scientists can investigate brain function.
1.Electrically stimulating areas in a conscious patients and recording their response OR 2. Magnetic Resonance Imaging (MRI) scans.
Name the two stimuli the eye is sensitive to.
Light intensity and colour.
Name the muscle that changes the shape of the lens in the eye.
Ciliary muscle
Name the ligaments in the eye which help to change the shape of the lens.
Suspensory ligaments
Name the part of the eye which controls how much light enters through the pupil.
Iris
Name the part of the eye which allows light to enter through it.
Pupil
Name the part of the eye which is a transparent covering of the eyeball.
Cornea
Name the part of the eye which focuses light into the eye.
Lens
Name the part of the eye which gathers information and sends it to the brain.
Optic nerve
Name the part of the eye which has no light receptor cells.
Blind spot
Name the white part of the eye which acts a protective layer.
Sclera
Name the part of the eye which is a thin layer containing millions of receptor cells.
Retina
What happens to the suspensory ligaments and ciliary muscles when the eye focuses on NEAR objects?
Suspensory ligaments LOOSEN, ciliary muscles CONTRACT
What happens to the suspensory ligaments and ciliary muscles when the eye focuses on FAR objects?
Suspensory ligaments TIGHTEN, ciliary muscles RELAX
What shape is the lens in when the eye focuses on NEAR objects?
Thicker, more curved.
How does the shape of the lens when it is thicker and more curved affect light refraction?
Refracts light strongly.
What shape is the lens in when the eye focuses on FAR objects?
Thinner, less curved.
How does the shape of the lens when it is thinner and less curved affect light refraction?
Refracts light slightly.
Name the two muscle types in the eye that control the amount of light entering.
Radial and circular.
In high light intensities, what happens to these muscles to cause the pupils to constrict?
Radial muscles RELAX, circular muscles CONTRACT.
In low light intensities, what happens to these muscles to cause the pupils to dilate?
Radial muscles CONTRACT, circular muscles RELAX.
What kind of lens (glasses or contact) would correct myopia?
Concave
What kind of lens (glasses or contact) would correct hyperopia?
Convex
What monitors and controls body temperature?
The thermoregulatory centre of the brain.
What does this monitor the temperature of?
The blood flowing through the brain.
Name two ways the body responds if the body temperature is too high.
“1. Blood vessels dilate (vasodilation)
2. Sweat is produced from the sweat glands.”
How do these responses lower body temperature?
Causes a transfer of energy from the skin to the environment.
Name three ways the body responds if the body temperature is too low.
“1. Blood vessels constrict (vasoconstriction)
- Sweating stops
- Skeletal muscles contract rapidly (shivering)”
