A + P: Chapter 10 - Nervous System (Part 1)
What are the four types of cells in the CNS?
Astrocytes, Oligodendrocytes, Ependymal cells, Microglia
electrical impulse
action potential
sympathetic
activates involuntary muscles and glands
transmits impulses into the CNS
afferent neuron
AP intensity
always the same do not decrease over time all-or-none event
most abundant and versatile glial cell
astrocyte
star-shaped cells of the CNS
astrocytes
efferent
away from the brain (motor)
synapse location names
axoaxonic axodendritis axosomatic
soma-
body
central nervous system
brain and spinal cord integration and command center
parasympathetic
calms involuntary muscles and glands
motor division
carries nerve impulses from CNS to effector organs: somatic nervous system autonomic nervous system
sensory division
carries nerve impulses from sensory organs to CNS from skin, skeletal muscles and visceral organs
motor (efferent) neurons
carry AP from CNS to muscles and glands mostly multipolar neurons
The ____ nervous system consists of the brain and spinal cord.
central
what types of signals do neurons use to communicate?
chemical and electrical
meninges
coverings around the brain and spinal cord
The nerve fibers on the nerve cell that receive signals are called ____________________.
dendrites
Valium is an example of a(n) ____.
depressant
amitotic
do not divide (neurons)
Neurons that convey information from the brain and spinal cord to muscles and glands are called ____ neurons.
efferent
The final nerve cell that receives the impulse and brings about the reaction to the original stimulus is called the motor or ____ neuron.
efferent
neurotransmitter termination
enzymes destroy neurotransmitters astrocytes presynaptic terminal (endocytosis, take back in for reuse) diffuse away from synapse (lyzosimes?)
The space that separates the meninges from the vertebrae is called the ____ space.
epidural
EPSP
excitatory postsynaptic potentials neurotransmitter causes depolarization future AP if enough EPSP (one is not enough)
need for sensory nerves in visceral organs
injury, soreness and knowing the location and limits of body parts (think yoga), sensing stomach aches, needing to use the toilet
depolarization
inside becomes less negative
hyperpolarization
inside becomes more negative
group B nerve fibers
intermediate size with some sheath 40mph small skin sensory fibers
autonomic nervous system
involuntary regulates smooth and cardiac muscles and glands includes sympathetic and parasympathetic divisions
Descending tracts of the central nervous system that conduct impulses down the spinal cord are concerned with ____ functions.
motor
Neurons that have several dendrites and one axon are called ____ neurons.
multipolar
structural neuron classification
multipolar bipolar unipolar
A bundle of fibers located outside the central nervous system is called a(n) ____.
nerve
A bundle of nerve cells or fibers is called a ____.
nerve
ganglia
nerve cells bodies outside the CNS
peripheral nervous system
nerves outside brain and spinal cord sensory receptors, cranial nerves, spinal nerves, peripheral nerves
The ____________________ of a Schwann cell contains the cell's nucleus and most of its cytoplasm, which remain outside the myelin sheath.
neurilemma
transmits nerve impulses
neuron
presynaptic neuron
neuron that conducts impulses toward the synapse (sends info)
postsynaptic neuron
neuron that transmits impulses away from the synapse (receives info)
Nerve cells known as ____ transmit nerve impulses in the form of electrochemical changes.
neurons
principle cells of the nervous system
neurons neuroglia
electrical signals
neurons have gap junctions to allow ion flow synchronize many neurons at one time two-way and faster communication less common
The chemicals that transmit signals across the synapse are called ____.
neurotransmitters
postsynaptic potentials
neurotransmitters cause a graded potential on postsynaptic neuron dendrites EPSP IPSP
Gaps in the myelin sheath are called the ____________________.
nodes of Ranvier
dendrites
numerous, short, branched processes receptive regions of the neuron convey incoming messages toward cell body via graded potential
multipolar neuron
one axon and many dendrites 99% of neurons mostly in CNS
bipolar neuron
one axon and one dendrite rare found in the eyes (retina) and ears
unipolar neuron
one axon only (has a neck that comes out of the body with two sheathed axons) rare sensory receptors
spatial summation
postsynaptic neuron receives multiple impulses at the same time (from multiple axons)
temporal summation
postsynaptic neuron receives multiple impulses in a rapid-fire fashion can "ride on top" of each other
conduction speed on an axon is determined by...
presence of a myelin sheath axon diameter temperature (cold fingers=butterfingers)
synapses types
presynaptic neuron postsynaptic neuron
oligodendroglia
produce myelin sheath on neurons in the CNS
myelin sheath function
protect axon insulate axons from one another increase nerve impulse speed 30 times!
ependymal cells
squamous or columnar shape, some with cilia line cranial and spinal cavities to form a permeable barrier for cerebrospinal fluid beating or cilia helps circulate cerebrospinal fluid
neuroglia functions
support, segregate, and insulate neurons promote health of nervous tissue guide young neurons to proper connections DO REGENERATE
satellite cells
surround cell bodies in PNS (support like astrocytes?)
somatic nervous system
voluntary controls skeletal muscles
groups of myelinated axons
white matter
tract
white matter in the spinal cord
interneurons
within CNS between sensory and motor neurons mostly multipolar neurons most common functional
Myelin sheaths surrounding nerve fibers in the peripheral nervous system are produced by ____.
Schwann cells
Most synapses in our bodies use the ____ neurotransmitter.
acetylcholine
The ____ act like the male sex hormones.
anabolic steroids
Star-shaped cells that form a supporting network in the brain and spinal cord are called ____.
astrocytes
The outermost spinal meninx is called the ____.
dura mater
Cells that line the fluid-filled ventricles of the brain, some of which produce cerebrospinal fluid, are called ____.
ependymal cells
Areas of the nervous system known as ____ consist of nerve cells bodies and dendrites.
gray matter
The spinal cord is a continuation of the ____.
medulla oblongata
The ____ system is the body's control center and communication network.
nervous
Sodium-potassium pumps restore the resting membrane potential following an action potential, a process known as ____.
repolarization
The ____ division of the autonomic nervous system stimulates and speeds up certain bodily activities.
sympathetic
Terminal branches of an axon are anchored close to the ends of the dendrites of another neuron at regions called ___
synapses
Astrocytes
Help maintain our blood brain barrier.
IPSP
inhibitory postsynaptic potentials neurotransmitter causes hyperpolarization future AP more difficult
astrocytes
"the mommies" support and anchor neurons to capillaries guide migration of young neurons control chemical environment by cleaning up released neurotransmitter
Central Nervous System
(CNS) Consists of the brain and spinal cord
Peripheral Nervous System
(PNS) Consists of all nerves and receptors that are not part of the brain or spinal cord.
Events at the Synapsis
1. The nerve impulse travels along neuron A to its axon terminal. 2. The neurotransmitter is released into the synaptic cleft. 3. Neurotransmitter travels across the synaptic cleft and binds to the receptor sites. 4. The nerve impulses travels toward the cell body and axon of neuron B.
There are ____ pairs of cervical nerves.
8
Sodium (Na+)
A lot of sodium is on the outside of our cells.
Explain how a reflex arc functions, and name its components.
A reflex arc is the pathway that results in a reflex.The components of a reflex arc include sensory receptors that pick up sensory information from sensory nerves and relay it to an integration center, which consists of singular or multiple synapses. The integration center then sends a signal to a motor nerve, which relays it to a muscle fiber, triggering a reflexive contraction.
All-or-nothing manner
Action potential does not lose strength with distance.
Refractory period
An action potential cannot take place because the axon is busy and directs the action potential to continue down the axon.
Dendrites
Branchlike part of the neuron that transmits the nerve impulse toward the cell body.
fiber tracts are axon bundles in the...
CNS
nuclei are cell body clusters in the...
CNS
consists of the brain and spinal cord
CNS
stimulus intensity
CNS determines stimulus intensity by frequency of AP transmission strong stimuli generate AP more frequently than weaker stimuli
neuronglia types
CNS: astrocytes, microglia, ependymal cells, oligodendrocytes PNS: Schwann and satellite cells
Axon
Carries impulses away from cell body to the target organ.
What are the four major parts of the brain?
Cerebrum, Cerebellum, Brain Stem, and Diencephalon
Neurotransmitters
Chemicals that send a message from the nerve to another structure. Acetylcholine (Ach) and Norepinephrine (NE)
Microglia
Cleans up the debris in the CNS.
Parts of a Neuron
Dendrites, Cell body, Ganglion (ganglia), Axon, Axon terminals (synaptic knobs), Myelin sheath (myelin), Schwann cells, and Nodes of Ranvier.
Nerve impulses
Electrical signal from a neuron to another structure.
Axon terminals (synaptic knobs)
Ends of the axon that stores neurotransmitters.
Over 60% of all brain cells are neurons.
False
The action potential moves in both directions down a nerve fiber.
False
The first nerve cell receiving an impulse directly from a receptor is called a motor or efferent neuron.
False
Nodes of Ranvier
Gaps between the myelin and is the only place that a nerve impulse can happen.
Horns
Gray matter in the spinal cord
Ganglion (ganglia)
Group of cell bodies in the PNS.
What is a Sensory Function (Afferent)?
It carries information from the PNS to the CNS.
What is a Motor Function (Efferent)?
It carries the motor commands from the CNS to the PNS.
Neurons
It transmits the nerve impulse. Does not replicate nor replace themselves when injured.
Ependymal cells
Line the cavities within the brain and contain cilia to keep the cerebral spinal fluid moving.
Cell body
Located in the CNS and contains DNA.
Receptor sites
Locations on a receptor neuron into which a specific neurotransmitter fits like a key into a lock.
Blood brain barrier
Made up of tight junctions which prevent toxic substances from entering the blood stream in our brain.
White matter
Myelinated axons
What is the difference between Myelinated axon and Unmyelinated axon?
Myelinated axons have myelin and unmyelinated axons do not contain myelin.
Action potential
Nerve impulse.
Synapses across neurons
Nerves never touch anything.
Depolarization
Sodium ions are flooding into the cell.
What are the two types of cells in the nervous system?
Neurons and Neuroglia (glial cells).
ganglia are cell body clusters in the...
PNS
nerves are axon bundles in the...
PNS
Repolarization
Potassium is leaving the cell but leaves slowly.
Schwann cells
Produce myelin in the PNS.
Oligodendrocytes
Produces myelin in the CNS, can produce enough myelin for 70 different axons
myelinating cells of the PNS
Schwann cells
What are the three functions of the nervous system?
Sensory Function (Afferent), Integrative Function, and Motor Function (Efferent)
Satellite cells
Surround neuron cell bodies in the ganglia of the PNS. Help regulate the chemical environment of the neurons.
The parasympathetic division of the autonomic nervous system uses the neurotransmitter ____ at nerve endings.
acetylcholine
Polarization
The resting state of a neuron, the inside of the cell is more negative than the outside of the cell.
Synaptic cleft
The space between the nerve and the next structure.
Name the two functions of the spinal cord.
The spinal cord's two major functions are to conduct impulses through afferent and efferent nerves, and to connect the body parts to the brain.
Neuroglia (glial cells)
They are the most abundant nerve cell that supports and nourishes the neurons.
Interneurons
Transmit nerve impulses from one neuron to another.
An unmyelinated nerve fiber conducts an impulse over its entire length with a slower rate of conduction than that of a myelinated fiber.
True
The parasympathetic division of the autonomic nervous system stimulates the body's vegetative activities such as digestion, urination, and defecation.
True
Gray matter
Unmyelinated axons
neurotransmitter
acetylcholine
Potassium (K+)
We have a lot of potassium on the inside of our cells, which can leak out.
Saltatory conduction
When the action jumps from one Node of Ranvier to the next.
What is an Integrative Function?
When the brain is processing the information.
Myelin sheath (myelin)
White fatty material that insulates the axon and speeds up nerve impulses.
schwann cells
form myelin sheath around larger axons in PNS one cell makes one segment grows and becomes longer and wider, wraps around and glues to itself
Nerve cell bodies found outside the central nervous system are called ____.
ganglia
nodes of ranvier
gaps on axon between myelin sheaths where action potentials land where axon branches emerge shorter in Schwann cells than in oligodendrocytes
neurons must be adequately stimulated in order to...
generate nerve impulses from the dendrites to the axon
neuron cell body
has nucleus and usual organelles active in synthesis of neurotransmitters (well developed rough ER, ribosome, and Golgi apparatus) focal point for outgrowth of processes
oligodendrocytes
have a few processes wrap around thick CNS nerve cells produce insulating covering myelin sheaths around large axons in CNS one cell can form up to 60 segments
microglia
immune function small cells with long spiny processes turn into macrophage when microorganisms are present monitor and maintain health of neurons
where are most neuron cell bodies are located?
in the CNS
where are most neuron processes located?
in the PNS
continuous conduction
in unmyelinated axons electrical current moves forward and depolarizes next region every part of axon generates AP
neurons
large and complex cells transmit nerve impulses long lived and amitotic
why does axon diameter affect axon conduction speed?
larger diameter conducts faster because there is less resistance
group A nerve fibers
largest fiber with thick sheaths 300mph most somatic sensory and motor nerves
5-7 minutes
length of time neurons can survive without O2 (they are highly metabolic)
myelin sheath
made of phospholipids wrapped concentric layers of plasma membranes and cytoplasm around axon
nucleus
mass of nerve cells bodies and dendrites in the CNS
phagocytic cells of the CNS
microglia
immune function in nervous system
microglia turn into macrophages when necessary lymphatic system doesn't reach brain and spinal cord
All the spinal nerves are ____ nerves.
mixed
neurotransmitters
most neurons release more than one type may have different action depending on location examples: dopamine, epinephrine, noepinephrine, serotonin and histamine
cerebrospinal fluid
provides cushion and nutrients covered by bag "meningi"
The smallest and simplest pathway able to receive a stimulus and produce a response is the ____________________.
reflex arc
repolarization
returns to resting potential
Neurons that convey information from receptors in the periphery of the body to the brain and spinal cord are known as ____________________ neurons.
sensory
Ascending tracts of the spinal cord carry ____ information from body parts to the brain.
sensory
functional classification of neurons
sensory (afferent) neurons motor (efferent) neurons interneurons
functions of nervous system
sensory input integration motor output
graded potential
short-lived, local changes in membrane potential initial intensity varies, will decrease with distance (may die down before reaching axon and nothing will happen) must be sufficiently strong enough to reach axon and prompt AP
axons
singular long processes secrete neurotransmitters from axon terminals generates and transmit action potential long axon from cell body
synapses
site where neural signal transfers from one neuron to another or an effector cell
group C nerve fibers
small and unmyelinated fibers 2mph visceral sensory and motor fibers (feeling of being full and time to start digesting) no saltatory conduction
regardless of stimulus, neuron type or location AP is always...
the same (the brain will differentiate the information)
afferent
toward the brain (sensory)
A bundle of fibers inside the central nervous system is called a ____.
tract
sensory (afferent) neurons
transmit AP from skin, muscles, or internal organs toward CNS mostly unipolar and bipolar
Most sensory neurons are ____ neurons.
unipolar
chemical signals
use neurotransmitters carried in synaptic vesicles, diffuse across synaptic cleft and received by receptor one way communication
contains motor nerve fibers only
ventral root
