Chapter 12 Nervous System Lecture

what is the nervous system

communication and control ssytem

waht are the functions of the nervous system

collect information, process and evaluate information, initiate response to information

how does the nervous system collect information

receptors dectect stimuli and sen sensroy signals to spinal cord and brian

how does the nervous system process and evaluate information

brain and spinal cord determine repsonse to sensory input

how does the nervous system initate response to information

brain and spinal sen motor output vianerves to effectors (muscles or glands)

what is located in the Central Nerovus System (CNS)

brain and spinal cord

what is located in the Peripheral Nervous System (PNS)

nerves and ganglia

what are the structural organizations of the nervous systems

central vs peripheral

what are the functional organizations of the nervous system

sensory vs motor

what does sensory nervous system do

detects stimuli and transmits information from receptors to the central nervous system

what is the motor nervous system

initiates and transmits information from the central nervous system to its effectors

what is somatic sensory

sensroy input that is consciously perveived from receptors (eyes, ears, and skin)

what is visceral sensory

sensory inout that is not consciously perceived from receptors of blood vessels and internal organs (heart)

what is somatic motor

motor output that is consciously or voluntarily controlled; effector is skeletal muscle

what is autonomic motor

motor output that is not consciously or is involuntairly controlled; effectors are cardiac muscle, smooth muscle, and glands

autonomic has two two divisions

sympathetic and parasympathetic

what is a nerve

a bundle of parallel axons in the Pheripheral nervous system

nerves have what kind os tissue wrapping

connective tissue wrapping

what is an epineurium wrapping

enclouses the entire nerve with a thick layer of dense irregular connective tissue

what is an perineurium wrapping

wraps fascicle with a layer of dense irregular connective tissue

what does fascicle mean

bundle of axons in a nerve

what is an endoneurium wrapping

wraps an individual axon with a delicate layer of areolar connective tissue, seperates and electrically insulates each axon

a collection of cell bodies in ther peripheral nervous system

ganglion looks like a bulge

what are cranial nerves

extend from the brain

what are spinal nerves

extend from the spinal cord

sensory nerves contain what

snesory neurons sending signals to the CNS

what fo the motor nerves contain

motor neurons sending signals from CNS

what are mixed nerves

contain both sensory and motor neurons, most named nerves are in this category, individual axons in these nerves transmit one type of information

what are neuron characteristics

exitability, conductivity, secretion, extreme longevity, amitotic

what is excitability

responsiveness to a stimulus, stimulus causes change in a cell’s membrane potential

what is conductivity

ability to propagate electrical signal, voltage-gated channels along membrane open sequentially

what is secretion

release of neurotransmitter in response to conductive activity, messenger is released from vesicle to influence target cell

what is extreme longevity

a cell can live throughout person’s lifetime

what does amitotic

after fetak development, miotic activity is lost in most neurons

waht are the parts of a neuron

cell body, dendrites, axon

what is the cell body

plasma membrane encloses cytoplasm, contains nucleus, initates some graded potentials, receives others from dendrites; conducts these potentials to axon, contain ribsomes

waht does a cell body do

takes information in form of an electrical signal called a graded potential generated from the denrite that are then handed off to the axon

what is a chromatophillic substance

free and bound ribosomes

what are dendrites

short, unmelinated, recieve input and transfer it to the cell body

what is an axon

long process emanating from cell body, makes contact with other neurons, muscle cells,or glands

where does the axon attach to the cell body

axon hillock

what is the cytoplasm called in the axon

axoplasam

what is the plasma membrane called in an axon

axolemma

what are the branches called that an axon splits into

axon collaterals

what do axons end in

telodendria (axon terminals)

what are the tips of telodenria called

synaptic knobs (terminal boutons)

what do synaptic knobs house

snaptic vesicles containing neurotransmitter

the area where they come together is called what

synapse

axons function to conduct what

action potentials and then release neurotransmitter at synapitc knobs

an axon is also called a

nerve fiber

what is the cytoskeleton of an axon

composed of microfillaments, intermediate filaments, microtubules, aggregate to form bundles, provide tensile strength

what are neurofilaments

intermediate filaments

what are neurofibris

bundles

what is anterograde transport

from cell to body, moves newly synthesized material toward synaptic knobs

what is retrograde transport

to cell body, moves used materials from axon for breakdown and recycling in soma

what is fast axonal transport

occurs about 400 mm per day, involves movement along microtubules, powered by motor proteinsthat split ATP, anterograde or retograde motion possible

anterograde transports what

vesicles, organelles, glycoproteins

retrograde transports what

used vesicles, potentially harmful agents

what is slow axonal transport

occurs about 0.1 to 3 mm per day, results from flow of axoplasm, substances only moved from cell body toward knob

what is moved in slow axonal transport

enzymes, cytoskeletal components, new axoplasm

how are axons structurally classified

by number of processes coming off stoma

what are multipolar nuerons

many dendrites, one axon (most common)

what are bipolar neurons

one dendrite and one axon (limited number in retina of the eye)

what are unipolar neurons

one process extends from cell body, splits into two processes

what are anaxonic neurons

have denrites but no axons

what are the two processes which happen in unipolar neurons

periphral process and central process

what is the periphral process

splits into several receptive dendrites

what is the central process

leads to synaptic knobs in CNS

what are the structural classification of neurons

multipolar, bipolar, unipolar, anaxonic

what are the functional classifications of neurons

sensory, motor, interneurons

what is functional classification

according to the direction they propagate action potentials

what are sensory neurons (afferent neurons)

conduct input from somatic and visceral receptors to CNS, most are unipolar, few bipolar

waht are motor neurons (efferent neurons)

conduct output from CNS to somatic and visceral effectors, all are multipolar

what are interneurons (association neurons)

receive, process, and integrate information from many other neurons, communicate between sensory and motor neurons, located within CNS, generally are multipolar, make up 99% if our neurons

what is a synapse

place where a neuron connects to another neuron or an effector

what are the two types of synapse

chemical and electrical

which type of synapse is more common

chemical

what is electrical synapse

presynaptic and postsynaptic neurons bound together by gap junctions, fast: no synaptic delay in passing electrical signal

what does a chemical synapse require

a chemical called a neurotransmitter

what is chemical synapse

presynaptic neuron’s axon terminal produces signal, postynaptic neuron recieved signal

what is a synaptic cleft

small fluid-filled gap between the two neurons

what are the events of synaptic communication

neurotransmitter molecules released from vesicles of synaptic knob into cleft, nuerotransmitter diffuses across cleft and binds to postsynaptic receptors, binding of neurotransmitter to receptor initates postsynaptic potential (graded potential)

what is a synaptic delay

time it taked for all of these events

what are glial cells

nonexitable, support cells found in CNS and PNS, approximately same number of glial cells as there are neurons, account for about half the volume of nervous system

what are the general characteristics of glial cells

capable of mitosis, protect and noursih neurons, provide physical scaffolding for nervous tissue, critical for normal function at neurak synapses

what are the glial cells in the CNS

astrocytes, oligodendrocytes, microglial, ependymal cells

what are the glial cells in the PNS

satellite cells, enteric cells, neurolemmocytes

what are astrocytes

star shaped cells that have processes that end in perivascular feet, most abundant glial cell in CNS, help form blood-brain barrier,regualte tissue fluid composition, form structural support, assist neutrinal development, alter synaptic activity, occupy the space of dying neutrons

how do astrocytes help form blood-brain barrier

wrapping feet around brain capillaries, controls which substances have access to brain

how do astrocytes regulate tissue fluid compostion

have a chemical enviroment around neurons (regulate potassium concentration)

what are epnedymal cells

line cavities in brain and spinal cord, part of choroid plexus

what is choroid plexus

produces cerebrospinal fluid

what is microglia

small cells that wander CNS and replicate in infection, phagocytic cells of immune system, engulf infectious agents and remove debris

what are oligodendrocytes

large cells with slender extensions, extensions wrap around axons of neurons forming myelin sheath

what is myelin

increases the electrical speed which the electrical signals travel down the axons

what are satelite cells

arranged around neuronal cell bodies in a ganglion, electrically insulate and regulate the exchange of nutrients and wastes

what are neurolemmocytes

elongated, flat cells that ensheath PNS axons with myelin, allows for faster action potential propegation

what are neoplasms

tumors from unregulated cell growth, sometimes occur in CNS, orginating from the brain, primary brain tumors, typically orginate in supporting tissues

what are gilomas

glial cell tumors, may be benign, may be malignant, capable of metastasizing