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Neurons
the functional units of the nervous system that respond to physical and chemical stimuli
glial cells
the cells that support and nourish the neurons (also known as schwaan cells)
Sensory neurons
relay information about the environment to the CNS (five senses)
Interneurons
link sensory neurons and motor neurons in the body
Motor neurons
carry nerve impulses from CNS to the effectors (muscles and glands)(movement)
cell body
contains the nucleus and where all the metabolic reactions occur within the cell
Dendrites
branching terminals that carry information to the cell body (both sensory and motor)
Axon
extension of the cytoplasm that carries nerve impulses from the dendrites to the effectors
Myelin sheath
A layer of fatty tissue that covers the axon and protects it from losing charged ions formed by schwonn cells
Nodes of Ranvier
the gaps in between the myelin sheath
true or false: unmyelinated nerve fibres transmit nerve fibres faster because of salitory conduction
false
white matter
myelinated neurons
grey matter
unmyelinated neuron cell bodies and short, unmyelinated axons
How is a electrochemical signal formed?
unequal concentration of positive ions across a membrane
electrical current
a faster current that diminishes near the end and uses external source to generate energy
Nerve impulse
a slower process that remains strong at the end and uses cellular energy(ATP) to move ions across a cell membrane
membrane potential
when one is more positive than the other
resting membrane potential
-70mV
Polarization
The process where the inside of the membrane is negative and the outside is positive. Occurring due to a sodium potassium pump that moves potassium to the inside and the sodium to the outside
Action potential
the all or non electrical signal that has a domino effect across the membrane in the axon
threshold potential
-55mV
Depolarization
the process where the sodium channels open up and the sodium ions flood into the inside of the membrane turning the inside of the membrane positive and the outside negative
repolarization
the process where the potassium channels open up again and the potassium ions move from high to low and go to the outside of the axon
hyperpolarization
where the potential dips too low and both the sodium and potassium channels are opened and the process of polarization occurs again
refractory period
the recovery time before a neuron can produce another action potential
synapse
the connection between two neurons (also synaptic cleft)
Neuromuscular junction
synapse between a motor neuron and muscle cell(not in direct contact)
Synaptic terminal
where one impulse will travel from one end to the opposite end
synaptic cleft
the space between synaptic terminals
neurotransmitters
chemicals that move from one neuron to the next that carry signals
acetylcholine
most common neurotransmitter that causes depolarization
presynaptic neuron
the neuron that releases the neurotransmitters
postsynaptic neuron
the neuron that accepts the neurotransmitters
Excitatory effect
a process that lowers the threshold and causes depolarization in the postsynaptic neuron
Inhibitory effect
increases the threshold and prevents the postsynaptic neuron from depolarizing using potassium ions
cholinesterase
the enzyme that hunts down and breaks down acetylcholine and stops the depolarization
Norepinephrine
helps control alertness and arousal
dopamine
controls body movements and linked to sensations of pleasure
serotonin
regulates temperature and sensory perception(involved in mood control)
endorphins
Acts as a natural pain killer in the brain ( also affects emotional areas of the brain)
GABA
an inhibitory neurotransmitter in the brain
Summation
when one postsynaptic neuron is excited/inhibited by more than one presynaptic neuron. Thus several neurons converge and release their neurotransmitters towards one neuron
spinal cord
a primary part of the CNS that branches out from the centre of your body through nerves
Brain
a primary part of the CNS that is the main centre for homeostasis, intelligence, consciousness and emotion
hindbrain
composed of the cerebrum, medulla oblongata, and pons
cerebellum
a walnut-shaped part of our brain that controls balance, fine voluntary motor skills, and unconscious coordination of posture
medulla oblongata
responsible for the continuous rate control within our body like heart and blood rate (automatic)
Pons
infront and above the medulla oblongata and is considered the relay centre in the brain for neurons
Midbrain
a part of the brain that above the pons and controls the relay of visual and auditory information between the hindbrain and the forebrain
Forebrain
composed of the cerebrum, thalamus, and hypothalamus
Thalamus
the base of the forebrain that consist neurons that provide connections mainly in the forebrain and hindbrain
Hypothalamus
below the thalamus and regulates the body's internal environment, emotions, hormones and coordination of the pituitary gland
cerebrum
largest part of the brain which controls intellect, memory conciousness and language
cerebral cortex
the covering of grey matter on the outside of each half of the cerebrum that controls language, memory personality, vision and conscious thought
left brain
the intellectual and logical side
right brain
the more creative and imaginative side
occipital lobe
receives and analyzes visual information
temporal lobe
responsible for auditory learning (wernickes)
pareital lobe
responsible for sensory information (pain,pressure,position,touch temperature)
frontal lobe
integrate info from other parts of the brain and control reasoning, critical thinking, memory and personality.
somatic system
voluntary control in the PNS
autonomic system
involuntary control
sympathetic nervous system
your fight or flight reaction that releases norepinephrine when the body is put in a stressful situation
parasympathetic nervous system
your rest or digest reaction that activates when the body is resting
impulse-transmission pathway
sensory input->integration-> motor output
reflex arc
the involuntary reaction that our body has to protect us from potential danger (sensory receptor->sensory input->integration->brain+SC->motor output->effector
Sclera
external white layer of the eye
cornea
the transparent part of the eye that bends light rays into the eye
choroid
the intermediate layer of the eye that absorbs stray light not detected by the photoreceptors
iris
regulates the amount of light entering the eye by expanding or constricting the eye
pupil
the opening of the eye( black circle)
Ciliary muscles
changes the shape of the lens in order to focus
retina
internal layer made up of rods,cones and the fovea centralis
rods
photoreceptors that are sensitive to dim light and movement
cones
photoreceptors that and different to different wavelengths of light or colour
fovea centralis
contains a high density of cones and rods and provides acute vision
ganglion cell
the projection neurons of the retina
bipolar cell
a cell that has two extensions that act as pathways
amacrine cell
interneurons in the retina that are responsible for 70% of input to ganglion cells
lens
focuses light rays onto the fovea centralis
vitreous humor
helps maintain the shape of eyeball and supports the surrounding cells
aqueous humour
maintains the shape of the cornea and providing oxygen and nutrients
optic nerve
sends auditory info to the brain for it to process it and to interpret it
blindspot
where the ganglion cells merge to the optic nerve where there are no photoreceptors
acutity
sharpness of vision(like our resolution)
Accomodation
charges optical power to maintain a clear image or focus on an object (the changing of our lens shape)
adaptation
ciliary muscles that will flatten or thicken the lens the focus the image on the retina(what causes accommodation)
binocular vision
using two lenses to view one image
peripheral vision
seeing an image that is in our periphery(3D image)
image focussing
how our eye flips an image within our brain
myopia
nearsightedness where the eyeball is elongated and you need and concave lens to correct
hyperopia
farsightedness where the eyeball is shortened and you need a convex lens to correct
astigmatism
uneven curvature of the cornea
outer ear
an air filled part of the ear that consists of the pinna and the auditory canal
pinna
the outer flap of the ear that enhances sound vibrations and sends them to the auditory canal
auditory canal
the canal that leads to the tympanum and amplifies sound waves also where ear wax and hairs are found to block foreign things from entering
middle ear
an air filled part of the ear that contains the tympanum, ossicles and eustachian tube
tympanum
a round elastic structure that vibrates in response to sound waves that are later passed onto the ossicles(eardrum)
ossicles
three tiny interconnected that pass from one to another the names for these names are the hammer/malleus, anvil/incus, stapes/stirrups
Eustachian tube
where the middle ear connects to the throat and when there is a pressure change in our surroundings then the pressure changes in our middle ear (popping of our ears)