Human nervous system Flashcards
Nerve cells properties
- long
- thin
- branched connections
Synapse
- connection between two neurons
- Chemicals diffuse across to the next
neurone to trigger an electrical
impulse
Central nervous system
- contains the brain and spinal cords
- connected to the body by sensory and
motor neurones
Sensory neurones
Carries information as electrical impulses from receptors to CNS
Motor neurones
Carries electrical impulses from CNS to effectors
Benefits of relex arcs
- rapid
- automatic
avoid getting hurt
Nervous system in order
- stimulus
- receptors
- sensory neurones
- CNS
- motor neurones
- effectors
- response
Reflex arc in order
- stimulus
- receptors
- senory neurones
- relay neurones
- motor neurone
- effector
Parts of the brain
- cerebal cortex
- cerebellum
- medulla
- hypothalamus
3 main reasons why treating the brain is difficult
- hard to access due to skull
- fragile
- brain is complicated so hard to target
with medications - many things can go wrong from
mental illness to infections
How is the cornea adapted
- transparent
- no blood vessel
Cornea purpose
to refract the light
iris purpose
controls how much light can pass through to the lens
lens purpose
refract light by changing its shape so light reaches the retina
What are the functions of the 2 receptor cell in the retina
Cone cells - helps see colour in light
rod cells - more sensitive to light but
only allows us to see in black
and white
optic nerve
takes all the impulses generated by the receptor cells and transmit then to the brain
Iris reflex purpose
controls size of pupil to avoid damage to the retina from bright light
What is it called when the pupils shrink
contricted
What is it called when the pupil enlarges
dilated
How is the iris reflex controlled?
- circular and radial muscles
- when constricted circular muscles
contract - when dilated radial muscles contracts
Whats the fovea
The point where light focuses on the retina
accomodation
A reflex that changes the refractive power of the lens
What part of the eyes control the shape of the lens
- ciliary muscles
- suspensory muscles
