B10 - The Nervous System Flashcards
homeostasis
the control of conditions within the body - involves nervous pathways and hormonal/chemical pathways
conditions that need to be maintained by homeostasis
- body temperature - so enzymes don’t become denatured
- water levels - so cells don’t rupture
- glucose concentration - so cells don’t collapse due to the release of too much sugar
effectors
muscles or glands that bring about a response
receptors
cells that detect changes in the environment
stimuli
changes in the environment
coordination centres
areas that receive and process information and coordinate a response
pathway of control for body temperature
- rise and fall of body temp
- receptor - skin
- coordination centre - brain (hypothalamus)
- effectors - sweat glands, hairs on skin
nervous pathway
pathway of control for water imbalance
- rise or fall of water levels in blood
- receptor - brain
- coordination centre - pituitary gland
- effector - sweat, dehydration
chemical hormone pathway
pathway of control for blood glucose concentration
- rise or fall in blood glucose concentration
- receptor - pancreas
- coordination centre - pancreas
- effector - insulin and other hormones
chemical hormone pathway
difference between nervous pathways and chemical hormone pathways
- nervous pathways send extremely fast electrical nerve impulses through neurons
- chemical hormone pathways send hormones not as fast through the bloodstream
- effects of nerve impulses are short lasting
- effects of hormones can last much longer - sometimes permanent
what makes up the CNS
brain and spinal cord
connected to the rest of the body with the peripheral nervous system
CNS vs PNS (penis lol🤭)
- PNS - detects and carries out a response
- CNS - coordinates the response
structure of a sensory/motor neurone
- nucleus
- myelin sheath
- axon
- cell body
- dendrite
structure of a relay neurone
- cell body
- nucleus
- dendrite
myelin sheath
insulates the axon and speeds up the conduction of impulses
reflex arc
- contains three neurons (Sensory, Relay, Motor)
- allows for rapid responses to changes in environment
- does not involve the brain - reflex actions are involuntary
- effector can be a muscle or a gland
- receptors are found within sense organs
reflex actions
*crucial for survival
* involuntary actions - no involvement of the brain
what are receptors
specialised cells that detect stimuli
what happens once receptors detect stimuli
nerve impulses are sent to the CNS along sensory neurons
neurons
specialised nerve cells
synapse
junction between two neurons
sensory neuron
carries nerve impulses to the CNS from the receptor
motor neuron
carries the nerve impulse from CNS to an effector
relay neuron
connects a sensory and motor neuron
nerve
bundle of neurons
nerve impulse
electrical message that passes along a neuron
what factors affect reaction time
- distractions eg: texting, talking
- age
- illness
components of the brain
- cerebral cortex
- hypothalamus
- pituitary gland
- cerebellum
- medulla
cerebral cortex
consciousness, intelligence, memory, language
large part at the top
hypothalamus
temperature control
part in the middle
pituitary gland
produces hormones
small bean shaped part that comes off the hypothalamus
cerebellum
coordinated muscular activity and balance
second smaller brain looking thing at the back
medulla
heartbeat, movement of the gut, breathing
part that comes own, relatively thin
methods to study the brain
- MRI scan (magnetic resonance imaging)
- CT scan
components of the eye
- iris
- choreid
- retina
- sclera
- ciliary muscles
- fovea
- optic nerve
- blind spot
- vitrious humour
- aqueous humour
- pupil
- cornea
- conjunctiva
- lens
- suspensory ligaments
- rods
- cones
iris
coloured ring of muscle that controls the amount of light that goes into our eyes
choreid
black lining of the eye that stops light from being reflected inside the eye - contains the blood vessels which supply the eye with glucose and oxygen
retina
light sensitive layer on the inside of the eye containing rods and cones. light is transduced into the electrical energy of nerve impulses
sclera
tough white protective outer layer that the eye muscles attach to
ciliary muscles
- attach to the lens by suspensory ligaments
- circular muscles which change in thickness of the lens during accommodation
fovea
- small depression in centre of retina containing cones
- region with greatest concentration of sensory cells
- formes extremely sharp images
optic nerve
carries nerve impulses from the retina to the brain - a sensory neuron
blind spot
point where optic nerve attaches to the cell and no light-sensitive cells are
vitious humour
transparent jelly that maintains shape of eye
aqueous humour
transparent liquid fills the front of the eye
pupil
central hole formed by the iris that light enters through
cornea
transparent part of the sclera that allows light to focus on the retina
conjunctiva
transparent membrane that covers and protects the cornea
lens
focuses light on the retina by changing in thickness
suspensory ligaments
holds the lens in place and attaches to the ciliary muscles
rods
detect motion
cones
detect colour and precision in light
accommodation
focussing
what happens to the muscles in bright light
- ciliary muscles contact
- radial muscles relax
- pupils constrict
what happens to the muscles in dim light
- ciliary muscles relax
- radial muscles contract
- pupils dilate
how are the suspensory ligaments connected to the ciliary muscle
like spokes of a wheel
focusing on a distant object
- ciliary muscles relax
- suspensory ligaments tense
- light rays are parallel
focusing on a nearby object
- ciliary muscles contract
- suspensory ligaments loosen
- light rays are divergingmyopia
myopia
- short-sightedness
- can focus on nearby objects
- elongated eyeball means lens focuses sharpest image in front of the retina
- corrected with concave lens - pushes the focal point back
hyperopia
- long-sightedness
- can focus on distant objects
- focuses the sharpest image behind the retina
- corrected with convex lens - pulls the focal point forwards
new technology in fixing vision
- glasses
- contact lenses
- laser eye surgery
- replacement lenses
advantages of contact lenses
- reduce image distortion
- improves vision
disadvantages of contact lenses
prone to shifting and dryness
advantages of laser eye surgery
- permanent solution
- pain free surgery
disadvantages of laser eye surgery
- expensive
advantages of replacement lenses
- used to correct issues such as cataracts and presbyopia
- drastically improves vision
disadvantages of replacement lenses
- infection
- inflammation
