Nervous system physiology pt 1

what is electrochemical exclusion?

channels along the membrane have pores that are charge-specific

what are nonspecific channels?

ion channels that are selective for charge & not for size

what are gated channels?

ion channels that can only open by certain events

what is a ligand-gated channel/ionotropic receptor?

ligand/neurotranmitter binds to the extracellular region of the channel & the ions crossing the membrane changes the charge

what is a mechanically gated channel?

physical distortion \[pressure/touch\] of the cell membrane opens it & is associated w. somatosensation

what are voltage-gated channels?

responds to changes in electrical properties of the embedded membrane, opens when voltage is less negative

what is a leakage channel?

opens & closes at random & contributes to resting transmembrane voltage of an excitable membrane

what initiates action potential?

neurotransmitter binding to a receptor protein or sensory stimulus activates a sensory receptor cell

what occurs during the refractory period?

another action potential does not start while one is already in progress

what is continous conduction?

propagation along an unmyelinated axon

what is saltatory conduction?

propagation along the length of a myelinated axon

what is generator potential?

unipolar cell graded potentials in dendrites that influence the generation of an actin potential in the axon of the same cell

what is receptor potential?

taste/photoreceptor cells graded potentials result in the release of neurotransmitters at synapses w/ sensory neurons

what is postsynaptic potential?

graded potential in the dendrites of a neuron that is receiving synapes from other cells & can be depolarizing or hyperpolarizing

what is excitatory postsynaptic potential?

depolarization in postsynaptic potential that causes membrane potential to move toward threshold

what is inhibitory postsynaptic potential?

hyperpolarization in a postsynaptic potential that causes membrane potential to move away from threshhold

what happens when voltage changes summate?

additive effect of several electrical impulses on a neuromuscular junction which can either be spatial or temporal

what is spatial summation?

activity of multiple inputs to a neuron w/ each other

what is temporal summation?

multiple action potentials from a single cell resulting in a significant change in membrane potential

what is a chemical synapse?

neurotransmitter is released from 1 cell & it affects the other cell

what is an electrical synapse?

direct connection between 2 cells so ions can pass directly from 1 cell to the next & is a chain reaction current

what are the common characteristics of neuromuscluar junction synapses?

axon terminal, acetylcholine, synaptic cleft, nicotinic acetylcholine receptor, muscle cell sarcolemma, acetylcholinesterase

what is a synaptic cleft?

small gap between the cells that neurotransmitters go through

what are the neurotransmitter systems?

cholinergic, amino acid, biogenic amines, neuropeptides

what is the problem w/ the blood brain barrier?

protects the CNS from exposure to toxic/pathogenic substances, but keeps out cells & pharmaceuticals that could protect the brain & spinal cord from disease/damage

what are the ventricles of the nervous system?

cavities that are remnants of the hollow center of the neural tube

what is the choroid plexus?

specialized structure in ventricles where ependymal cells make contact w/ blood vessels & filter & absorb components of the blood to produce cerebrospinal fluid

what are the satellite cell?

glial cell in the peripheral nervous system in sensory & autonomic ganglia that surround the cell bodies of neurons

what does the satellite cell do?

provides nutrient support & protection

what is a thermoreceptor?

sensory receptor sensitive to temp

what is graded potential?

the amt of change in electrical state is dependent on the strength of the stimulus

what is propagation?

axon potential travels along the axon from the axon hillock to the terminals & into the synaptic end bulbs

what are neurotransmitters?

signaling molecule

what is the 1st step of sensory receptor-motor response?

sensory neuron senses a stimulus & the signal triggers the graded potential from sensory endings to initiate an action potential

what is the 2nd step of sensory receptor-motor response?

action potential causes the axon of the peripheral sensory neuron to enter the spinal cord, contact a synapse in the gray matter

what is the 3rd step of sensory receptor-motor response?

synapse to synapse contact makes a graded potential to release a chemical signal from axon terminals to send to the brain thalamus

what is the 4th step of sensory receptor-motor response?

signal reaches cerebral cortex & sensory pathway ends, neurons in cortex sends a motor command from precentral gyrus of the frontal cortex

what is the 5th step of sensory receptor-motor response?

upper motor neuron sends action potential down to spinal cord to dendrites in lower motor neuron in gray matter

what is the 6th step of sensory receptor-motor response?

axon of lower motor neuron emerges from spinal cord in a nerve & connects to a muscle though neuromuscluar junction & contracts muscle

what is the soma?

cell body w/ process extensions

what is the axon?

process on a neuron that connects it w/ the target

what are dendrites?

a process that brances from the soma that receives most of the input from other neurons

what contains the localized collection of neuron cell bodies in the CNS?

nucleus

what is the ganglion?

a cluster of neuron cell bodies in the peripheral nervous system

what is the bundle of axons/fibers in the CNS?

tract

what is the bundle of axons/fibers in the PNS?

nerve

how is the nervous system divided functionally?

sensation/integration/response & somatic/autonomic control

what is the enteric nervous system?

part of the PNS responsible for functions w/in the autonomic control of gastrointestinal functions

what is the role of sensory functions \[sensation\]?

receiving info ab the environment to gain input ab what is happening outside or w/in the body

which senses are chemical substances?

taste & smell

which senses are physical/mechanical substances?

touch, sight, hearing

what is the role of motor functions \[response\]?

movement of muscles or neural control of glands from stimuli

what is the role of cognitive functions \[integration\]?

processed info from stimuli are compared w/ memories of previous stimuli to produce a specific response

what are synapses?

specialized areas of contact for dendrites

what are the synapses of the ANS?

cholinergic \[acetylcholine release\] & adrenergic \[norepinephrine release\]

what are the receptor types that bind to acetylcholine & causes changes in the target cell in the cholinergic system?

nicotinic receptor \[ligand-gated cation channel\] & muscarinic receptor \[G protein-coupled receptor\]

what is the same as adrenaline & norepinephrine?

norepinephrine & noradrenaline

what is the axon hillock?

initial segment between the soma & axon start

what is the axoplasm?

a type of cytoplasm w/ limited components

what is the role of myelin sheaths?

insulation & facilitation of the transmission of electrical signals along the axon that also includes integral proteins that hold the layers of the glial cell membrane closely together

what is on the axon?

axon segments are wrapped w/ myelin & the node of ranvier is the gap between each segment

what is the axon terminal?

the end of an axon where several branches extend towards the target cell

what are the synaptic end bulbs?

the connection w/ the target cell at the synapse

what are the types of neurons?

unipolar, bipolar, multipolar

what are unipolar cells?

1 process w/ an axon & dendrite which exclusively receives sensory info & are found in ganglia

what are bipolar cells?

2 processes w/ an axon & dendrite which are mainly found in the olfactory epithelium & retina

what are multipolar cells?

has more than 2 process w/ an axon & 2+ dendrites which function based on the conditions

what is a pyramidal cell?

a multipolar cell w/ a cell body that is shaped like a pyramid located in the cerebral cortex

what is the purkinje cell?

multipolar neuron in the cerebellar cortex of the brain

what is microglia?

immune surveillance & phagocytosis

what is the blood brain barrier?

physiological barrier restricts what can cross from circulating blood into the CNS

what are the 2 divisions of the nervous system?

central \[cns\] & peripheral \[pns\]

what is in the central nervous system?

brain & spinal cord

what is in the peripheral nervous system?

crainial nerves, spinal nerves, eneteric plexuses, sensory receptors

what are the pathway divisions of the peripheral nervous system?

efferent & afferent

which pathway controls motor neurons?

efferent pathway

which pathway controls sensory neurons?

afferent pathway

what are the 2 efferent pathways?

somatic nervous system & autonomic nervous system

what is the somatic nervous system?

voluntary control of motor responses & conscious perception \[skeletal muscles\]

what is the autonomic nervous system?

involuntary control for the sake of homeostasis such as organ control \[cardiac & smooth muscle\]

what are the 2 types of cells in nervous tissue?

neuroglial & neurons

what are glial cells?

provides a framework of tissue that supports the neurons & their activities

which nervous tissue cells are responsible for electrical signals that communicate info ab sensations, produce movements in response to stimuli & induce thought processes?

neuron

what are the 5 types of glial cells?

astrocytes, phagocytes, ependymal, oligodendrocytes, schwann cells

what are astrocytes?

star shaped cells that wrap & grab blood vessels in the brain & used for support

what are phagocytes?

nervous & resident immune glial cells

what are ependymal cells?

it lines the cavities of the central nervous system \[dorsal/cranial\] & creates cerebral spinal fluid

what are oligodendrocytes?

glial cells that make the myelin sheath for insulation for multiple axon segments in the central nervous system

what are schwann cells?

glial cells that make the myelin sheath to insulate 1 axon segment for peripheral nervous system

what is myelination?

mylelinating glia wraps several layers of cell membrane around an axon segment & a schwann cells insulates part of a peripheral nerve

what are myelin sheets made of?

phospholipid bilayer/fat

what does gray matter consist of?

formed from unmyelinated nerves & has many cell bodies & dendrites

what does white matter consist of?

formed from mylinated nerves & has many axons

where is gray matter located?

superficial on brain & deep in spinal cord

where is white matter located?

superficial on spinal cord & deep in brain

why is there an area of the brain that is not myelinated?

efficiency & energy distribution of energy bc action potential flows only in the cortex

which type of neuron does energy travel fast?

myelinated neuron

which type of neuron does energy travel slow?

unmyelinated neuron

what is this part of the neuron? \[1\]

dendrite

what is this part of the neuron? \[2\]

soma