B3 Flashcards
What do receptor cells do?
Detect the change in the environment and send this information as nervous impulses
Where are receptor cells found?
In the sense organ
Role of sensory, relay and motor neurones?
Carry the electrical impulses from the receptor cells to CNS
Carry the electrical impulses from CNS to effector
Carry the information from the sensory to motor neurones
What is an effector?
A response:
- glands secrete hormones
- muscles contract
What is a synapse?
The electrical impulses trigger a release of transmitter chemicals, which diffuse across the gap of two neurones and attach to the receptor molecules - setting off a new chemical impulse
Adaptions of neurones to speed transmission
- long neurones
- myelin sheath: insulator less energy wasted
How does the lens change to focus on nearby
objects
- lens becomes fatter (more convex)
- ciliary muscle contracts
How are images formed?
When light is focused on the retina, photoreceptors in the retina produce a nervous impulse that travels down the optic nerve, to the brain, where it is interpreted as a visual image
Cornea Pupil Iris Lens Ciliary body
C - protects the eye, refracts light
P - allows light to enter the eye
I - controls how much light enters the eye by contracting / relaxing
L - refracts light onto the retina
CB - controls lens shape, by contracting / relaxing
Short sightedness
- eyeball to long, lens too strong
- bends light too much
- light focuses in front of the retina
- concave
Long sightedness
- eyeball too small, lens to weak
- doesn’t refract light enough
- focus behind the retina
- convex
What are the types of receptor cells?
Rods
- dim light
Cones
- colours
Cerebrum Cerebellum Medulla Hypothalamus Pituitary gland
C - milc , consciousness, language, intelligence, memory
C - posture, balance
M - involuntary actions, breathing, heart rate
H - controls temperature and water levels, produces hormones that regulate the pituitary gland
P - stores and releases hormones
Damage to peripheral nervous system
Tissue can be regrafted over damaged tissue. Restoring neurone pathway.
What is it hard to repair the CNS?
Spinal cord - 1.5cm diameter
- 31 pair of nerves
Repairing damage is hard to do without damaging others