neurophysiology and cns

Central nervous systejm (cns)

brain and spinal cord

peripheral nervous system (pns)

cranial/ spinal nerves and their branches

sensory neurons (afferent)

carry signals from sensory receptors towards the cns

motor neurons (efferent)

carry signals away from the cns to muscles and glands

interneurons

relay messaged within the cns

nuclei

clusters of cell bodies in the cns

ganglia

clusters of cell bodies in the ins

tracts

bundles of axons in the cns

nerves

bundles of axons in the pns

white matter

areas of myelinated axons, which appear white due to myelin

gray matter

areas of cell bodies and dendrites

membrane potential

elecrtical gradient exists across plasma membrane

resting membrane potential

-70 mV

absolute refractory period

time during which no additional stimulus can produce an additional action potential

relative refractory period

time during which only a strong stimulus will produce an action potential

local potentials

travel short distances, decremental, reversible, vary in the extent to which they alter the membrane potential, occur in dendrites and cell bodies

action potentials

travel entire length of an axon, non decremental, irreversible, alter the membrane potential in a characteristic way, occurs along axons

synapse

location where a neuron meets its target cell

neuronal synapse

synapse in which the target cell is another neuron

can be chemical or electrical

presynaptic neuron

neuron sending the message from its axon terminal

postsynaptic neuron

neuron that is receiving the message

synaptic transmission

transfer of chemical or electrical signals between neurons at a synapse

postsynaptic potentials

local potentials in the membrane of the postsynaptic neruon

excitatory postsynaptic potential (epsp)

moves the membrane potential of the postsynaptic neuron closer to threshold, making an action potenital more likely

inhibitory postsynaptic potential (ipsp)

moves the membrane potential of the postsynaptic neuron further from the threshold, making an action potential less likely

neural integration

all input from presynaptic neurons combines to have one cumulative effect on the postsynaptic neuron

summation

the input from several postsynaptic potentials is added in order to affect the membrane potential at the trigger zone

temporal summation

occurs when neurotransmitters are released repeatedly from the axon terminal of a single presynaptic neruon

spatial summation

occurs during the simultaneous release of neurotransmitters from the axon terminals of multiple presynaptic neurons

diffusion

some neurotransmitters diffuse away from the synaptic cleft and are absorbed by other neurons or astrocytes

degradation

some neurotransmitters are broken down by enzymes in the sunaptoc cleft

reuptake

some neurotransmitters are taken back into the presynaptic neuron to be reused

iontropic receptors

part of a ligand gated ion channel

cause rapid and short lived effects on the postsynaptic neuron

metabotropic receptors

in the plamsa membrane and connected to a separate ion channel

slower to elicit a change, but the changes are longer lasting and more varied

acetycholine

utilized at the neuromuscular junction

norepinephrine

influences heart rate, blood pressure, digestion, sleep/wake cycle, attention, feeding behaviors

epinephrine

utilized similarly to norepinephrine

dopamine

modulates movement coordination, emotion, and motivation

serotonin

modulates mood regulation, attention, and other cognitive funcations

glutamate

excitatory neurotransmitter

gaba

inhibitory neurotransmitter

cerebrum

performs higher mental functions

interprets sensory stimuli

plans and initiates movement

diencephalon

processes, integrates, and relays information

maintaines homeostasis

regulates biological rhythms

cerebellum

monitors and coordinates movement

brainstem

maintains homeostasis

controls certain reflexes

monitors movement

integrates and relays info

commissural fibers

connect the left and right cerebral hemispheres

projection fibers

connect the cerebral cortex of one hemisphere with other areas of the same hemisphere

internal capsule and corona radiata connect the brainstem with gray matter in each hemisphere

association fibers

connect cortical gyri with each other within one hemisphere

functional brain system

groups of gray matter that share the same function and the white matter connects them

fornix

primary white matter output tract of the limbic system

limbic lobe

gray matter cortex involved in memory formation and retrieval, emotion, and learning

hippocampus

nucleus involved in learning and memory

amygdala

nucleus involved in behavioral expressions of emotion, particulary fear

thalamus

receives input from many sources and sends output to the cerebral cortex

hypothalamus

regulates the autonomic nervous system, sleep/wake cycle, thirst, hunger, and body temp

secretes various horomones that affect the pituitary gland and other hormones that do not affect the pituitary gland

connects to the limbic system via mammillary bodies

epithalamus

contains the pineal gland, which secretes the hormone melatonin

subthalamus

connects to the basal nuclei and works with them to control movement

lobes of the cerebellum

anterior, posterior, flocculonodular

crus cerebri

descending tracts of white matter that originate in the cerebrum

tegmentum

middle region of the midbrain containing many nuclei

substantia nigra

works with the basal nuclei to control movement

tectum

posterior region of the midbrain

superior colliculus

recieves visual signals, which are then sent to the thalamus

inferior colliculus

recieves auditory signals, which are sent to the thalamus

primary motor cortex

plans and executes movement

primary sensory cortices

recieve and process different types of sensory input

multiple task association areas

integrate sensory and motor info from a variety of different cortices

caudate nuclei putamen globus paddllidus

regulates movement

amygdala

plays a role in behavioral expression and emotion

hippocampus

memory and learning

cerebellum

coordinates ongoing voluntary movement to reduce motor error

midbrain

processes and routes visual and auditory stimuli to the thalamus

carries motor fibers from the cerebral cortes and monitors movement with the basal nuclei

pons

regulates breathing and the sleep/wake cycle

medulla oblongata

contains tracts of white matter involved with movement and sensation

regulates many autonomic functions

reticular formation

involved in sleep and arousal, pain transmission, mood regulation

cranial meninges

a set of three membranes that surround the brain

cerebrospinal fluid (csf)

protective fluid that bathes the brain and fills its cavities

blood brain barrier

prevents many substances in the blood from gaining access to the cells of the brain

dura mater

outermost meninx, thick and tough

periosteal dura

attached to the bones of the cranial cavity

meningeal dura

attached to the periosteal dura

falx cerebri

partition between the right/left cerebral hemispheres and lies in the longitudinal central fissure

tentorium cerebelli

partition between the cerebellum and occipital lobe

falx cerebelli

partition between the right and left cerebellar hemispheres

arachnoid mater

middle meninx, which looks like a spiders web

pia mater

innermost meninx, which is very thin

touches brain directly and follows all of its gyri and sulci

posterior (dorsal) horn

snesory input

anterior horn

motor output

posterior (dorsal) root ganglia

where all the cell bodies of the senory nerves are housed

posterior columns - fasciculus gracilis

carry somatosensory stimuli including fine touch, vibration, and propioception from the lower limbs

posterior columns- fasciculus cuneatus

carry somatosensory stimuli including fine touch, vibration, and propioception from the trunk, neck, and upper limbs

spinocerebellar tracts

carry proprioceptive stimuli to the cerebellum

anterolateral system- apinothalamic tracts

carry stimuli about pain ,temp, and certain types of touch

corticospinal tracts

carry motor stimuli from the motor areas of the cerebral cortex

reticulospinal tracts

carry motor stimuli from the brainstem

maintines posture and proper orientation of the limbs during movement

tectospinal tract

carries motor stimuli from the superior colliculu of the brainstem

reflexive movement of the head and eyes

vestibulospinal tract

carries motor stimuli from the vestubular nuclei in the brainstem

maintance of posture and balance