A&P NERVOUS

two major regions of nervous system

central and peripheral nervous systems

the nervous system region composed of the brain and spinal cord

central nervous system (CNS)

the nervous system region composed of everything except the brain and spinal cord

peripheral nervous system (PNS)

nervous tissue contains which two basic types of cells:

neurons and glial cells

one of a variety of cells that provide a framework of tissue that supports the neurons and their activities

glial cell

the more functionally important cell in terms of the communicative function of the nervous system

neuron

cell body of a neuron

soma

extension of the neuron

process

a specific extension of a neuron, which is the fiber that connects a neuron with its target

axon

a type of process that branches off from the soma of the neuron

dendrite

responsible for receiving most of the input from other neurons

dendrite

region within the nervous system largely composed of cell bodies and dendrites

gray matter

region within the nervous system largely composed of axons

white matter

lipid-rich substance that gives white matter its color

myelin

a localized collection of neuron cell bodies in the CNS

nucleus

a cluster of neuron cell bodies in the PNS

ganglion

a bundle of axons, or fibers, found in the CNS

tract

a bundle of axons, or fibers, found in the PNS

nerve

the three basic functions of the nervous system

sensation, integration, and response

receiving information about the environment around us

sensation

generating responses to sensory input

motor responses

combines sensory perceptions and higher cognitive functions such as memories, learning, and emotion to produce a response

integration

a change from homeostasis or a particular event in the environment that is registered by the sensory functions of the nervous system

stimulus

how can responses be divided

voluntary or involuntary

______ responses are governed by the somatic nervous system

voluntary

_______ responses are governed by the autonomic nervous system

involuntary

the processing of stimuli that are received by sensory structures

integration

the nervous system can be divided into two parts on the basis of a functional difference in responses:

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

this division of the nervous system is responsible for conscious perception and voluntary motor responses

SNS

which kind of motor response would reflexes be considered

somatic

this division of the nervous system is responsible for involuntary control of the body, usually for the sake of homeostasis

ANS

this third division of the nervous system is responsible for controlling the smooth muscle and glandular tissue in your digestive system

enteric nervous system (ENS)

specialized areas of contact between two neurons, where information is passed onwards

synapses

why are neurons considered to have a polarity

they flow in one direction: dendrites, cell body, axon

where the axon emerges from the cell body; tapering of the cell body toward the axon fiber

axon hillock

within the axon hillock, the cytoplasm changes to…

axoplasm

the axon hillock narrows and transitions into the beginning of the axon, called the…

initial segment

action potentials are generated in the trigger zone, which is a combination of…

the axon hillock and initial segment

many axons are wrapped by this insulating substance

myelin

what type of cell is myelin made from

glial cells

the gaps in the myelin covering an axon; important to the way that electrical signals travel down the axon

node of Ranvier

the length of the axon between each gap (nodes of Ranvier), which is wrapped in myelin

axon segment

the end of the axon, where there are usually several branches extending toward the target cell

axon terminal

the extensions of the axon terminal each end in an enlargement called a ________; these bulbs make the connection with the target cell at the synapse

synaptic end bulb

supporting cells with functions directed at helping neurons complete their function for communication

glial cells, or neuroglia, or glia

list the 6 types of glial cells and where they are found

CNS: astrocyte, oligodendrocyte, microglia, ependymal cell

PNS: satellite cell, schwann cell

the astrocyte is to the CNS what the ________ is to the PNS

satellite

the oligodendrocyte is to the CNS what the _____ is to the PNS

schwann cell

star-shaped glial cell that provides support to the neurons of the CNS; has many processes extending from main cell body, which extend to interact with neurons, blood vessels, or the connective tissue covering the CNS (pia mater)

astrocyte

a physiological barrier that keeps many substances that circulate in the rest of the body from getting into the central nervous system, restricting what can cross from circulating blood into the CNS

blood-brain barrier (BBB)

what kind of molecules can pass through the BBB

nutrient molecules, such as glucose or amino acids

the glial cell type that insulates axons in the CNS; there are a few processes that extend from the cell body, and each one reaches out and surrounds an axon to insulate it in myelin

oligodendrocyte

also referred to as CNS-resident macrophages; smaller than most other glial cells; act like macrophages: ingest and digest diseased or damaged cells

microglia

a glial cell that filters blood to make cerebrospinal fluid (CSF); ciliated; can be considered a component of the BBB

ependymal cell

a specialized structure in the ventricles where ependymal cells come in contact with blood vessels and filter and absorb components of the blood to produce cerebrospinal fluid

choroid plexus

one of two types of glial cells found in the PNS; found in sensory and autonomic ganglia, where they surround the cell bodies of neurons; provide support, performing similar functions as astrocytes

satellite cell

one of two types of glial cells found in the PNS; insulates axons with myelin; wraps around a portion of only one axon segment and no others; nucleus and cytoplasm of this cell are on the edge of the myelin sheath

schwann cell

facilitates the transmission of electrical signals along the axon

myelin sheath

a type of sensory receptor that is sensitive to temperature

thermoreceptor

the change in membrane potential; dependent on the strength of the stimulus

graded potential

the voltage at which an electrical signal is generated

threshold

the electrical signal resulting from crossing the threshold

action potential

the process of the action potential traveling along the axon from the axon hillock to the axon terminals and into the synaptic bulb

propagation

the sodium/potassium pump moves sodium ions (NA+) ________ the cell

out

the sodium/potassium pump moves potassium ions (K+) ________ the cell

into

is the concentration of NA+ higher outside or inside the cell

outside

this type of gated protein channel opens because a signaling molecule, a ligand, binds to the extracellular region of the channel

ligand-gated channel

this type of gated protein channel opens because of a physical distortion of the cell membrane

mechanically gated channel

this type of gated protein channel responds to changes in the electrical properties of the membrane in which it is imbedded; when the voltage becomes less negative, the channel begins to allow ions to cross the membrane

voltage-gated channel

this type of gated protein channel is randomly gated, meaning it opens and closes at random

leakage channel

what is the resting membrane potential value

-70 mV

what is the membrane potential once fully depolarized

+30 mV

what is the membrane potential during hyperpolarization

< -70 mV

what is the membrane potential once fully repolarized

-70 mV

in this type of synapse, a chemical signal (neurotransmitter) is released from one cell and it affects the other cell

chemical synapse

in this type of synapse, there is a direct connection between the two cells so that ions can pass directly from one cell to the next

electrical synapse

all synapses have these common characteristics:

• presynaptic element

• neurotransmitter (packaged in vesicles)

• synaptic cleft

• receptor proteins

• postsynaptic element

• neurotransmitter elimination or re-uptake

briefly explain the release of a neurotransmitter

• action potential reaches axon terminals, voltage-gated CA2+ channels in the membrane of the synaptic end bulb open

• concentration of CA2+ increases inside the end bulb, and the CA2+ associates with proteins in the outer surface of neurotransmitter vesicles

• CA2+ facilitates merging of the vesicle with the presynaptic membrane so the neurotransmitter is released through exocytosis into the synaptic cleft

• travels to the postsynaptic membrane where it interacts with neurotransmitter receptors (fit together lock and key)

the small gap between two cells where the neurotransmitter is released

synaptic cleft