Central Nervous System & Neurophysiology

ASCI 240

the central nervous system’s main parts are

the brain and the spinal cord

what are the two anatomic sections of the nervous system?

the central nervous system and the peripheral nervous system

the two types of nerves in the peripheral nervous system are..

afferent and efferent

the peripheral nervous system has _ cranial nerves

12

the peripheral nervous system has _ spinal nerves

31

afferent neurons are..

sensory neurons that transmit impulses from external/internal to the central nervous system

efferent neurons are..

motor neurons carry impulses from the central nervous system to muscle cells

examples of efferent neurons are..

smooth, cardiac, and some skeletal muscles

interneurons neurons are…

association, relay/local circuit neurons that are found in neural pathways in the central nervous system

interneurons neurons are what kind of neuron? .

connect sensory and motor neurons

the two subdivisions of the peripheral nervous system are...

somatic division and the autonomic division

the somatic division is the…

voluntary movement of skeletal muscles

the autonomic division is the…

involuntary movement of smooth muscles (organs) and glands (endocrine)

the three subdivisions within the autonomic divisions are…

the sympathetic system, parasympathetic system, and the enteric system

the sympathetic nervous system is..

the system that stimulates the body’s response to stress, fight or flight

the parasympathetic nervous system is…

the system that controls the homeostasis of the system, rest and digest, feed, reproduction

neuroglia cells are..

cells classified as support cells for neurons, they hold neurons together and sustain regeneration post-birth.

neurons are..

cells also known as nerve cells and are specialized cells with the ability of transmitting messages

regeneration happens where?

within the PNS

can regeneration take place in the CNS?

no

Astrocytes are..

star-shaped cells that brace neurons that form a barrier between capillaries and neurons, and control the chemical environment of the CNS

microglia are…

spider-like phagocytes that dispose of waste and debris

ependymal are…

tissue that line cavities of the brain and spinal cord and circulate cerebrospinal fluid

oligodendrocytes are..

cells that produce myelin sheath around the nerve fibers in the central nervous system. only in the CNS

satellite cells are..

cells that sit outside or on top of the cell line are rather calm and do not move much. they are capable of differentiation to repair neurons and involve efferent nerves within the PNS

Schwann cells

form the myelin sheath in the PNS

what are the four primary segments of neurons?

soma, axon, dendrites, and the axon terminal

the soma is…

a cell body that contains a single, large nucleus and all the organelles of a typical cell

the axon is…

a long slender extension of the neurons that conduct electrical across the neuron

what are the three aspects of the axon?

the axon hillock, myelin sheath, and the nodes of Ranvier

the axon hillock is..

a conical mound of cytoplasm that gives rise to an axon

the myelin sheath is the..

sheath of fatty acids ( plasma membrane) that serves as an electrical insulator

the nodes of ranvier are..

gaps on the axon that allows the exchange of ions for regeneration of the action potential

dendrites are..

nerve processes that transmit action potential toward the neuron cell body that receives chemical signals from adjacent neurons

the axon terminal is..

the nerve processes that transmit the action potential away from the neuron cell body, they signal to adjacent neurons and to the target tissue and terminates at the synapsis

pre-synapses is..

synapses at the neuron transmitting electrical impulses

post-synapses is..

synapses at the neuron/effector tissue receiving the electrical impulse, through the dendrite of adjacent neuron and the target tissue

synaptic vesicles are..

vesicles containing neurotransmitters, and releases when it reaches the membrane

the synaptic cleft is..

the gap between pre and post-synapse/ effector tissue

the three general morphologies of neurons are

unipolar, bipolar, and multipolar neurons

unipolar neurons are..

single short process emanating from the cell body and are rare, being in the vertebrate nervous system

bipolar neurons are..

two processes extending from the cell body and are common in vestibular cochlear, and olfactory pathways. such as the ear, eye, and nose, and are fast so it doesn’t have a myelin sheath

multipolar neurons are..

two or more processes and are the most abundant type of neuron. it is a motor neuron within the ventral horn of the spinal column and contains a large soma with a sizable receptive dendrite tree

projection neurons are..

connection with relatively distance structures

interneurons are..

restricted projection with only local influence on neurons within the same structure

depolarize =

excitatory, mostly motor neurons

hyper-polarize =

inhibitory, GI tract, smooth muscle contractions

What is the function of all neurons?

to transmit info to and from the CNS

The action potential is..

all communication that is a biochemical generate impulse

action potential can originate from the PNS to the CNS from..

afferent neurons to interneurons

action potential can originate from the CNS to the PNS from..

interneurons to efferent neurons

is a neuron a single cell?

yes it is a single cell

is a nerve a bundle of numerous neurons?

yes it is a bundle of numerous neurons

action potential is crated and transmitted through the..

neuron plasma membrane

the transmission of the action potential is regulated by..

ion concentration gradient (CG) between two environments

the concentration gradient is..

the difference in levels between the inside and outside of the cell

the regular state of a neuron CG is..

negative or at rest

negative CG =

resting membrane potential

Extracellular =

> Na+

Intracellular=

>K+

what chemicals are sending positive charges?

K and Na

what chemicals are sending negative charges?

Cl

the ion channel potential..

controls the rate of transportation of specific molecules

the two important ion channel types of the ion channel potential are the..

voltage-gated ion channels and the signal proteins

the voltage-gated ion channels are..

Na+,K+,Cl-

the signal proteins are…

Active transporters, (cellular energy, ATP) and Na+ , K+

They go against the concentration gradient

the AP starts..

with the arrival of a signal (neurotransmitters) to the dendrites to the neuron

Biochemical signals are known as..

neurotransmitters

Physical signals are known as

specialized or stretch receptors such as pressure or pain

the signal of AP is transmitted form one neuron or the next with

biochemical or physical signals

the order of the signal transmitted from neurons is…

Afferent→Interneuron, Interneuron→Efferent, or Afferent→Efferent

the signal of the AP is transmitted via the..

synaptic cleft

Signal protein receptors..

restarts the action potential

What is the resting membrane potential?

its how much potential there is for a change

voltage-gated ion channels regulate what?

membrane potential

what is the resting voltage?

\-70 mV

what is the threshold state?

\-55mV

what is the action state?

\-45mV

to create an action potential there must be…

a stimulus transmitted to the dendrites

a weak signal is..

a failed initiation

post-synapsis receives stimulus or a biochemical signal to activate..

signal protein channels

steps of action potential

1. post-synapsis receives signal
2. soma integrates signal
3. the axon transmits action potential
4. AP spreads across the axon terminal
5. AP is transferred to the target tissue or the next neuron

afferent nerves are..

sensory nerves, send nerve impulses form the body to the CNS

efferent nerves are..

motor nerves, send nerve impulses to effector tissue

what are the two divisions of the peripheral nervous system?

somatic nervous system (SNS) and the autonomic nervous system (ANS)

the somatic nervous system is also known as..

the SNS

the somatic nervous system is..

straight forward, regulates the voluntary contraction of skeletal muscles

the autonomic nervous system is also known as..

the ANS

the autonomic nervous system is..

complex, it regulates the involuntary control of smooth, cardiac muscles and glands Ex: fight or flight, and homeostasis

the two main ideas of the ANS are..

fight or flight and homeostasis

what system does the ANS work with?

the endocrine system

what is the endocrine system fuction?

hormones

the ANS is comprised of central control of the CNS and receives feed back from what?

Sensory receptors, peripheral effectors and reflex conduction pathways

The ANS controls what?

the circulation of blood, activity of the GI tract and regulation of the body temperature.

does the ANS work with voluntary or involuntary muscles?

involuntary muscles (smooth muscles, heart, glands)

what are the two nerve fibers within the ANS?

preganglionic and postganglionic

what is a preganglionic fiber pathway?

its the first fiber pathway that originates within the CNS

what is the postganglionic fiber pathway?

it is the second fiber pathway that originates in the ganglia outside the CNS

what are ganglia?

they are massive nerve tissue

what are the 3 branches of the ANS?

Sympathetic, parasympathetic and enteric