Ch.10

Long-distance signals of axons

action potentials

Always open

leakage (non gated) channels

What are the two main types of ion channels?

leakage channels and gated channels

What pigment do you see in most elderly brain cells?

lipofuscin

What is the destruction of myelin sheaths in CNS by an immune response?

multiple sclerosis

99% of neurons, many processes, most neurons of CNS

multipolar neurons

What are the three classifications of neurons by structure?

multipolar, bipolar, unipolar

What is the sodium potassium pump important for?

muscle contraction and nerve conduction

Whitish, protein-lipid substance

myelin

Protects and electrically insulates axon, increases speed of nerve impulse transmission

myelin functions

Concentric layers of Schwann cell plasma membrane around axon

myelin sheath

Gaps between adjacent Schwann cells, sites where axon collaterals can emerge, formerly called nodes of Ranvier

myelin sheath gaps

Myelinated/Unmyelinated axons in the PNS have a series of Schwann cells lined up along the axon, each having a wrapped coating of myelin insulating the axon.

myelinated

Segmented sheath around most long or large-diameter axons

myelinated fibers

Where do neurons communicate?

synapses

What separates the two neurons?

synaptic cleft

What do axons do?

transmit nerve impulses along membrane to axon terminal

What does the motor (efferent) division do?

transmits impulses from CNS to effector organs

True or False: Axons lack rough ER and Golgi apparatus.

true

True or False: Mature neurons do not divide.

true

True or False: many chemical & electrical factors affect opening & closing of gated channels

true

True or False: neurons vary in size and shape.

true

True or False: non-myelinated fibers conduct impulses more slowly.

true

True or False: they may differ in length and size of their axons and dendrites.

true

True or false: If cell body is injured, the neuron usually dies.

true

True or false: neurons are highly excitable.

true

One process, cell bodies are in ganglia, sensory

unipolar neurons

Myelinated/Unmyelinated axons are encased by Schwann cell cytoplasm, but there is no wrapped coating of myelin surrounding the axons

unmyelinated

Where is cerebral spinal fluid produced?

ventricles of the brain

Mostly soma and unmyelinated fibers

gray matter

What serve as selective membrane ion channels?

large proteins

How many cranial nerves are there?

12

How many spinal nerves are there?

31

What are the types of neuroglia in the PNS?

Schwann cells and satellite cells

Contains both neuron cell bodies and their processes Processes see as white matter Cell bodies as grey matter

CNS

What are the two divisions of the nervous system?

CNS and PNS

A "nerve" is a collection of axons. Where would it be found?

PNS

Contains mainly neuron processes (few cell bodies)

PNS

Produce myelin sheath found on some peripheral axons. Speed up speed of nerve impulse transmission.

Schwann cells

What cell makes up the myelin in the PNS?

Schwann cells

Away from the cell body

anterograde

Support and brace neurons. Play role in exchanges between capillaries and neurons. Guide migration of young neurons. Control chemical environment around neurons. Respond to nerve impulses and neurotransmitters. Influence neuronal functioning (participate in information processing in brain).

astrocyte functions

Connect neurons to blood vessels; exchange nutrients and growth factors. Aid metabolism of certain substances. Regulate ion concentrations, such as K+. Part of Blood Brain Barrier.

astrocytes

Which type of cell are the most abundant CNS neuroglia?

astrocytes

Transmits impulses and releases neurotransmitters to another neuron or effector (another neuron, a muscle cell or a gland cell); a neuron may only have 1 axon

axon

Action potentials are generated at the

axon hillock

Two processes - eyes, ears, nose

bipolar neurons

What does the central nervous system contain?

brain and spinal cord

How can membrane potential changes be produced?

by changes in membrane permeability to ions

How are molecules moved along axons?

by motor proteins and cytoskeletal elements

Contains nucleus, cytoplasm, organelles, neurofilaments, chromatophilic substance (Nissl bodies)

cell body (soma)

What do ependymal cells line?

cerebrospinal fluid-filled cavities

Ions flow along their ___________________ when they move from an area of high concentration to an area of low concentration.

chemical gradient

What are the three types of gated channels?

chemically gated, voltage gated, mechanically gated

What does the peripheral nervous system do?

connects the central nervous system to other body parts (or the rest of the body)

What do dendrites do?

convey incoming messages toward cell body as graded potentials (short distance signals)

What does the peripheral nervous system contain?

cranial nerves and spinal nerves

What are microglia in the CNS?

defensive cells

What part of the cell is the "receiving" end?

dendrite, cell body

Branched receptive surfaces; a neuron may have many

dendrites

What generates a resting potential?

differences in ions across the membrane (due to sodium and potassium pump) and differential permeability of the plasma membrane

What are treatments of multiple sclerosis?

drugs that suppress immune activity

Ions flow along their __________________ when they move toward an area of opposite charge.

electrical gradient.

The electrical and chemical gradients taken together

electrochemical gradient

Line central canal of spinal cord & ventricles of brain, cover choroid plexuses. Help regulate composition of cerebrospinal fluid. Cuboidal or columnar cells; ciliated.

ependymal cells

True or False: "Neuron" and "nerve" can be used interchangeably.

false

True or False: Neurons experience a high rate of cell division.

false

True or False: myelin is found on axons and dendrites.

false

Is multiple sclerosis more common in males or females?

females

What do the processes on oligodendrocytes do?

form myelin sheaths around CNS nerve fibers

Motor (efferent) information travels TO/FROM the brain.

from

Part of protein changes shape to open/close channel

gated channels

Ions diffuse quickly across membrane along electrochemical gradients

gated channels are open

Incoming signals operating over short distances

graded potentials

What two types of signals do changes produce?

graded potentials and action potentials

What can a buildup of tissue in the ventricles of the brain cause?

hydrocephalus

Processing and interpretation of sensory input (create sensations, add to memory, produce thoughts)

integration

Association neurons, link neurons, multipolar, located in CNS

interneurons

What is the central nervous system responsible for?

interpreting sensory input and dictating motor output (integration and control center)

Formed by membrane proteins, help regulate passage of specific ions into or out of the cell

ion channels

What creates an electrical current and voltage changes across membrane?

ion flow

What is the sodium potassium pump important in?

maintaining a resting potential

What do neurons use as a way to communicate with other cells?

membrane potential changes

Phagocytic cell; also provides structural support

microglia

Small, ovoid cells with thorny processes that touch and monitor neurons. Migrate toward injured neurons. Can transform or "activate" to phagocytize microorganisms and neuronal debris.

microglial cells

Multipolar, efferent, carry impulses away from CNS, carry impulses to effectors

motor neurons

Activation of effector organs (muscles and glands) produces a response

motor output

What disease is associated with destruction of myelin?

multiple sclerosis

A cell membrane is usually electrically charged, or polarized, so that the inside of the membrane is __________ charged with respect to the outside of the membrane. This is a result of __________________________ on the inside and the outside of the membrane.

negatively, unequal distribution of ions

A grossly visible anatomic structure, and is a bundle of axonal processes from many different neurons, wrapped in a connective tissue sheath.

nerve

Bundles of neuron processes in PNS

nerves

Detects changes, makes decisions, stimulates muscles and glands to respond, and maintains homeostasis

nervous system

Highly cellular; little extracellular space, tightly packed

nervous tissue

Small cells that surround and wrap delicate neurons

neuroglia

Surround and support neurons, help maintain blood-brain barrier

neuroglia

Provide structural support for neurons. In embryo, guide neurons into position, may stimulate specialization. Produce growth factors to nourish neurons and remove excess ions and neurotransmitters. Aid in formation of synapses.

neuroglia functions

A cell, one part of which is included in a nerve.

neuron

Arm-like extensions from the soma (cell body) of all neurons There are two main types: dendrites and axons

neuron processes

CNS axons lack neurilemma to act as guiding sheath. Oligodendrocytes do not proliferate after injury. Regeneration is unlikely.

neuron regeneration in the CNS

If a peripheral axon is injured, it may regenerate. Axon separated from cell body and its myelin sheath will degenerate. Schwann cells provide guiding sheath for growing axons. If growing axon establishes former connection, function will return; if not, function may be lost.

neuron regeneration the PNS

React to change and communication

neurons

Structural units of nervous system Large, highly specialized cells that conduct impulses Extreme longevity (100 years or more) Amitotic (with few exceptions) High metabolic rate (requires continuous supply of oxygen and glucose) All have cell body and one or more processes

neurons

Excitable cells that transmit electrical signals

neurons (nerve cells)

What two types of cells does neural tissue contain?

neurons and neuroglia

Thin fibers not wrapped in myelin; surrounded by Schwann cells but no coiling

non-myelinated fibers

Myelinate CNS axons; also provide structural support.

oligodendrocytes

What are some examples of sensory (afferent) information?

pain, vision, hearing

Receives impulse

postsynaptic neuron

Major intracellular positive ions (cations)

potassium (K+) ions

Sends impulse

presynaptic neuron

What are dendrites?

receptive region of neuron

Resting neuron is one that is not being stimulated. Sodium and potassium ions follow rules of diffusion, and move from area of high concentration to area of low concentration. 70 mV potential difference from inside to outside of cell. Membrane of the neuron is a polarized membrane, with more potassium ions inside the cell, more sodium ions outside the cell, and more negatively charged ions & proteins inside. Inside of cell is negative relative to the outside of the cell. RMP = -70mV, due to unequal charge distribution. If resting potential changes, sodium and potassium pump restores it.

resting membrane potential (RMP)

Approximately -70 mV in neurons (cytoplasmic side of membrane negatively charged relative to outside). Membrane termed polarized.

resting potential

Toward cell body

retrograde

Support clusters of neuron cell bodies (ganglia).

satellite cells

What are the two functional divisions of the peripheral nervous system?

sensory (afferent) and motor (efferent)

Information gathered by sensory receptors about internal and external changes

sensory input

What are the general functions of the nervous system?

sensory input, integration, motor output

Afferent neurons, carry impulse to CNS, most are unipolar, some are bipolar

sensory neurons

What are the three classifications of neurons by function?

sensory, interneurons, motor

Major extracellular position ions (cations)

sodium (Na+) ions

Transports Na+ ions out of cell and K+ ions into cell

sodium potassium pump

What are the two divisions of the motor (efferent) division?

somatic nervous system and autonomic nervous system

Convey impulses from skin, skeletal muscles, and joints to CNS

somatic sensory fibers

What does the sensory (afferent) division contain?

somatic sensory fibers and visceral sensory fibers

One-way transfer of information. Impulse travels down axon of presynaptic neuron to axon terminal. When impulse reaches synaptic knob, causes influx of Ca+2 ions. This leads to release of neurotransmitters from synaptic vesicles by exocytosis. Neurotransmitter will exert either excitatory or inhibitory effect on postsynaptic neuron.

synaptic transmission

Sensory information travels TO/FROM the brain.

to

Bundles of neuron processes in CNS

tracts

Convey impulses from visceral organs to CNS

visceral sensory fibers

In a gross brain specimen, myelin appears gray/white.

white

Dense collections of myelinated fibers

white matter