Nervous system Flashcards
What does the nervous system do?
coordinate behaviour
respond to surroundings
Use of neurons
carry electrical impulses
Neurones adaptations
many dendrites: connect to more, pass more msg
myelin sheath: insulates impulses, speeds up impulse conduction
what are synapses, how do they work
gap between neurones
neurotransmitters are released to pass electrical impulses in a chemical way
post- receptors synapse membrane doesn’t allow backflow of impulses
electric current triggered and is transmission is continued
possible problems with synapses
interfered by other imitating or blocking chemicals
v drugs to deal
3 types of neurones
sensory, relay, motor
components and uses of CNS
brain + spinal cord
take in sensory info, instruct body to work
flow chart from stimulus to response
stimulus → receptor cells → sensory neurone → CNS (relay neurone) → motor neurone → effector → respons
spine isnt the same as spinal chord
types of receptors
eyes (light), ears (sound), nose (chemical), pain, pressure (KE / chem), temperature (thermal)
what’s a reflex arc
it’s the nerve pathway that underlies our unconscious reflexes
rapid and automatic, involuntary
avoid danger, protect
how is a reflex arc different from a normal reaction
a reflex arc doesn’t involve the brain, only spinal cord
What is homeostasis
Maintenance of a constant internal environment
Body temp & water content
What does co-ordinated response require
Stimulus, receptor, effector
Function of lens
Change shape to bend light onto retina
Lens vs cornea in terms of light refraction
Cornea: refracts light in the same amount, x flexible
Lens: adjust amount of light refracted
Function of optic nerve
Neurones to carry impulse
Suspensions ligament isn’t a muscle
What’s special about the blind spot
There aren’t any cones or rods, x image forms
What is the fovea (spelling!)
Place where light should bend to
What are the 2 types of cells the retina contain
- Cone cells: works in bright light, sensitive to red, green, blue, found in fovea only
- Rod cells: works in dim light, only black and white, found all over the retina
A: vitreous humour
B: lens
C: cornea
D: pupil
E: iris (control pupil size)
F: sclera
G: optic nerves
H: choroid (spelling!)
I: aqueous humour
J: ciliary muscle
K: suspensory ligament (fibre)
L: fovea
M: blind spot
A: vitreous humour
B: lens
C: cornea
D: pupil
E: iris (control pupil size)
F: sclera
G: optic nerves
H: choroid (spelling!)
I: aqueous humour
J: ciliary muscle
K: suspensory ligament (fibre)
L: fovea
M: blind spot
Circulatory muscles and radial muscles are found in the iris,
Which one is the inner muscle
Circulatory muscle is the inner one
Iris reflex under bright light
Circulatory muscles contract
Radial muscles relax
Constricted / smaller pupil to prevent too much light entering which may bleach the eye
Iris reflex under dim light
Circular muscles relax, radial muscles contract
Dilated pupil, allow more light in
Where are the suspensory ligament and ciliary muscles located
Suspensory ligaments (fibres) and attached to the lens and the ciliary muscles
Focusing on near object
Ciliary muscle contract, suspensory ligament slackens
Fat lens, curve, more refraction
Focusing on distant objs
Ciliary muscles relax, suspensory ligament becomes taut
Thin lens, slight light refraction
Suspensory ligament can’t contract
