A + P: Chapter 10 - Nervous System (Part 1)

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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


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