Nervous System Flashcards
axon hillock
- summation
- where most voltage gated Na+ channels are located
soma
- neurotransmitter synthesis
- cell body
- normal cell activity
meylin
- speeds up the AP
- PNS = schwann cells. Schwann is a bike brand that hurts your penis when you sit on it.
- CNS = oligodendrocytes
axon terminus
- axon terminals
- synaptic knobs
- many per axon
- release 1 type of NT
nodes of ranvier
- saltatory conduction
- allow impulse to jump from node to node
unipolar neurons
- sensory neurons
bipolar neurons
- eye nerves
rest potential
- Na+/K+ ATPase pumps out one net positive ion
- Na+/K+ ATPase establishes Na+ and K+ concentrations gradients
- many positive ions are lost through K+ leak channels
- end result is that the inside of cell is more negative inside than the outside
- all graphs track what is happening inside the cell
pump 2K+ in and 3 Na+ out
what ions can enter the cell?
- Na+/Cl-/Ca2+
- the salty C surrounds our cells
depolarization
- move away from RMP in a positive direction
- summation and the axon hillock pushes membrane potential past threshold and opens the voltage gated Na+ channels. Allows influx of Na+ depolarizing the cell membrane.
hyperpolarization
- move away from RMP in a negative direction
- the voltage gated K+ channels close slowly allowing extra K+ to leave the cell
repolarization
- move towards RMP in either direction
equilibrium potential
- potential at which there is no net force driving the movement of an ion
absolute refractory period
- absolutely impossible to fire a second action potential
- Na+ channels are inactivated
- cell is too positive.
- near Na+ equilibrium potential
relative refractory period
- possible but difficult to fire a second action potential
- Na+ channels are now reset to closed
- cell is too negative
- further from threshold
- near K+ equilibrium potential
electrical synapses
- physical connection - gap junctions
- always excitatory - always causes AP in postsynaptic cell
- bidirectional - either cell can be pre/post synaptic
- unregulated
- VERY IMPORTANT IN CARDIAC MUSCLE CELLS
chemical synapse
- AP arrives at axon terminal
- triggers an influx of Ca2+
- vesicles of NT anchored to microtubules are released due to synapsin activated by Ca2+
- NT diffuses across the synaptic cleft binds to receptors on postsynaptic cell (ligand gated ion channels)
- allows ions to flow into or out of post synaptic cell
- NT must be removed to stop the effects on the post synaptic cell
neurons and NT
- neurons only make one type of NT, but can respond to many
response of postsynaptic cell
- depends on receptors and the ion channels they are hooked up to
- not NT
to have a significant effect on the postsynaptic cell
- takes more than one vesicle of NT
excitatory postsynaptic potential
- EPSP
- depolarize
- Na+/Ca2+
inhibitory postsynaptic potential
- IPSP
- hyperpolarize
- Cl-/K+
summation
- occurs at the axon hillock
- the closer the presynaptic neuron is to the axon hillock, the greater its effect on summation
spatial summation
- adding up all inputs from multiple sources
temporal summation
- adding up frequency impulses from a single source
sensory input
- PNS
- info coming in
- sensory neurons
- afferent neurons
- approaching CNS
integration
- CNS
- decision making
- interneurons
motor output
- PNS
- send commands out to the body
- motor neurons
- efferent neurons
- exiting CNS
- not always motion
simple reflex
- very rapid integration to avoid potential injury
telencephalon
- cerebral cortex
- forebrain
limbic system
- emotion
midbrain
- visual and auditory startle reflexes
- wakefulness
cerebellum
- eye-hand coordination
- smooths and coordinates body movement
- gets inhibited by alcohol intoxications
spinal cord
- simple reflexes
medulla oblongata
- 3 Bs
- breathing, BP, barfing
- basic vital functions
- special respiratory/digestive functions
pons
- balance
- facial movement
diencephalon
- epithalamus
- hypothalamus
- thalamus
epithalamus
- pineal gland
- secrete melatonin
- sleep/wake cycles
thalamus
- sensory relay station
hypothalamus
- maintain homeostasis
- control the pituitary gland
white matter
- myelinated axons
- cell to cell communication (send action potential)
CNS-brain white matter
- tract
CNS-spinal cord white matter
- tract/column
PNS white matter
- nerve
grey matter
- unmyelinated cell bodies and dendrites
- very few unmyelinated axons
- integration (decision making)
CNS-deep brain grey matter
- nucleus
CNS- brain surface grey matter
- cortex
CNS-cord grey matter
- horn
PNS gray matter
- ganglion
frontal lobe
- voluntary motion
- problem solving
temporal lobe
- smell
- emotions
- memories
- language
occipital lobe
- vision
parietal lobe
- general sensation and taste
CNS
- brain and spinal cord
PNS
- all nerves and sensory structures outside of the brain and spinal cord
- somatic and autonomic
somatic
- voluntary control of skeletal muscle
- acetylcholine
- excitatory only
- single neuron from CNS to the effector organ
autonomic
- involuntary control of glands and smooth (cardiac) muscle
- all other organs
- Ach (on ganglion) then Ach/NE (to organ)
- excitatory or inhibitory
- 2 neurons from CNS to effector organ
- sympathetic and parasympathetic
sympathetic
- fight or flight
- 4 Fs: fear, fight, flight, fuck
- general increase in body activity
- increase in HR, BP, resp rate
- increase blood flow to skeletal muscles
- inhibit digestive acitivity
- increase blood flow to many organs
- use NE at the effector organ
- direct stimulation of adrenal medulla - EXCEPTION TO 2-NEURON RULE
- release epinephrine into the blood
- prolong and enhance effects of the sympathetic nervous system
parasympathetic
- rest and digest
- general decrease in body activity
- reduce HR, BP, resp rate
- stimulate digestive activity.
- increase blood to digestive system
- use ACh at the effector organ (NOT FULLY INHIBITORY)
mechanoreceptors
- physical shape changes
- pressure, tension, hearing receptors, Golgi tendon organs
chemoreceptors
- responds to chemicals
- pH, pO2, pCO2, taste, smell
nociceptors
- pain
- respond to chemicals released during injury or to direct stimulation
thermoreceptors
- temperature changes
- different receptors for cold and hot
- respond to different temperature ranges
photoreceptors/electromagnetic receptors
- light, electromagnetic waves
- rods and cones,
iris
- colored part of the eye
- regulates diameter of the pupil
lens
- biconvex structure that focuses light on the retina
cornea
- external transparent layer of the eye
pupil
- black opening in the middle of the eye
ciliary muscle
- muscles that regulate the curvature of the lens
fovea centralis
- responsible for extreme visual acuity
- contains only cones
retina
- layer at the back of the eye sensitive to light
optic disc
- blind spot
- place on retina where the optic nerve forms
optic nerve
- bundle of axons leaving the eye towards the brain
cone cells
- high threshold to be activated
- color vision
- blue, green, red
- only cell type in the fovea
- fewer in the periphery
rod cells
- low threshold, low light intensity
- black and white vision
- most abundant type in the periphery
no light
- rods/cones Na+ channels are open
- Na+ is entering the cell
- cell is depolarized
- no optic ganglion activation
- rods/cones release glutamate onto bipolar cells
- bipolar cells are hyperpolarized
- retinal and opsin keep a sodium channel open and the cell remains depolarized.
- rods and cones synapse on bipolar cells and release glutamate onto the bipolar cell to inhibit it from firing
light
- inhibition of Na+ channels
- Na+/K+ pump polarizes cell
- stops release of neurotransmitter
- optic ganglion is activated
- no Na+ influx so no release of glutamate
- bipolar cell fires
- Light converts cis-retinal → trans-retinal.
- trans-retinal then causes hyperpolarization of photoreceptor cell
- the photoreceptor stops releasing glutamate and the bipolar cell can now depolarize.
- Sends signal to brain via a bundle of nerves on the back of the retina (where the blind spot is)
mechanism of hearing in the cochlea
- sound waves down auditory canal where they bound on the tympanic membrane
- vibrations in the ossicles
- stapes contacts membrane filled with fluid. move oval window back and forth.
- pressure causes waves in the perilymph and endolymph
- vibration of the basilar membrane
- stereocilia of hair cells dragged across the tectorial membrane
- hair cells get compressed, depolarize and release NT
- auditory neuron transmits the signal to the brain
high frequency
high pitch
- vibrate the thicker portion
- closer to apex
low frequency
low pitch
- can only vibrate thinner area
- further from apex
loudness
- amplitude
- soft - low amplitude
- loud - high amplitude
vestibular complex
- balance and equilibrium
- semicircular canals - rotational equilibrium
saccule and utricle
- stationary/balance
action potential
- all or none event
absolute threshold
- the minimum level of stimulation required to activate a receptor
difference threshold
- the smallest difference that can be detected
bottom-up processing
- sensory receptors register information
- information is sent to the brain
- brain interprets information
top-down processing
- prior knowledge and expectations applied
- brain interprets information
sensory adaptation
- sensory receptor becomes unresponsive to unchanging stimulus and no longer send action potentials to brain
- can be retriggered if stimulus intensifies
outer ear
- pinna
- auditory canal - don’t stick your finger in
- tympanic membrane - ear drum
middle ear
- malleus
- incus
- stapes - end connects to membrane in inner ear
inner ear
- semicircular canals
- cochlea
Eustachian tube
- auditory tube
- connects throat to middle ear
- allows pressures to be equalized between outside and inner ear.
