bio 210 chapter 11

Six steps for information transfer across chemical synapses

1. Action potential arrives at axon terminal 2. Volted-gated calcium channels open and enters 3. Calcium entry causes synaptic vesicles to release neurotransmitters 4. Neurotransmitter diffuses across the synaptic cleft and binds to receptors 5. Binding of neurotransmitter opens ion channels, creating graded potentials 6. Neurotransmitter effects are terminated

Generating an action potential are

1. All gated sodium and potassium channels are closed(Resting stage) 2. Depolarization (sodium channels open) 3. Re-polarization (sodium channels inactivate and potassium gates open 4. Hyperpolarization (Some potassium stay open and sodium channels reset

The structural classification of neurons is

1. Multipolar 2. Bipolar 3. Unipolar

The functional classification of Neurons are?

1. Sensory 2. Motor 3. Interneurons

The three functions of the nervous system are?

1. Sensory input 2. Integration 3. Motor output

Each cell can wrap up to ______axons at onces

60

Sensory is also known as

Afferent Division

The all-or-none phenomenon is

An Action potential either happens completely or not at all

Four main neuroglia that support the Central Nervous System neurons are?

Astrocytes, Microglial cells, ependymal cells, and oligodendrocytes

Graded potentials are?

Brief, short distance signals

In the neuron process tracts are?

Bundles of neuron processes in CNS

In the neuron process nerves are?

Bundles of neurons in PNS

The two types of neuron processes are?

Dendrites and axon

The resting membrane potential depends on?

Differences in ion concentration and permeability

Four types of circuits

Diverging, Converging, reverberating, and Parallel after-distcharge

Catecholamines

Dopamine, norepinephrine and epinephrine

Motor is also known as

Efferent division

Current

Flow of electrical charges between two points

In myelin sheaths in the CNS the _________ matter is neuron cell bodies and nonmyelinated fibers

Gray

An insulator has a _________ electrical resistance

High

Resistance

Hindrance to charge flow

99% of Body's neurons are________?

Interneurons

A conductor has a ________ electrical resistance

Low

Voltage

Measure of potential energy generated by separated charge

Temporal summation

One or more presynaptic neurons transmit impulses in rapid-fire order

Circuits

Patterns of synaptic connections in neuron pools

Spatial summation

Postsynaptic neuron is stimulated by large number of terminals simultaneously

Ependymal Cells

Range in shape from squamous to columnar and line central cavities of the brain and spinal column

Synaptic potentiation

Repeated use of synapse increases ability of presynaptic cell to excite postsynaptic neuron

All neurons have a ___________membrane potential

Resting

The peripheral nervous system has two functional divisions known as?

Sensory and motor divisions

Continuous Conduction

Slow conduction that occurs in nonmyelinated axons

Group C fibers

Smallest in diameter

Excitatory Postsynaptic potential

Sodium influx greater than potassium efflux resulting in local graded potential depolarization

The peripheral nervous system is composed of?

Spinal and cranial nerves

Astrocytes

Support and brace neurons

Satellite cells

Surround neuron cell bodies in PNS

In the autonomic nervous system there are two functional subdivisions. What are they?

Sympathetic and Parasympathetic subdivisions

Acetylcholine

Synthesized from acetic acid and choline by enzyme choline

The central nervous system is composed of?

The brain and spinal cord of the dorsal body cavity

The nervous system is?

The master controlling and communicating system of the body

Absolute refactoring period

Time from opening of sodium channels until resetting of the channels

In myelin sheaths in the CNS the _________ matter is regions of the brain and spinal cord with dense myelinated fibers

White

Two types of refractory periods

absolute refractory period and relative refractory period

Endocannabinoids

act at same receptors as THC (active ingredient in marijunana)

The motor output function

activates the effector organs (muscles and glads) and produces the appropriate response

propagation

allows Action potential to be transmitted from origin down entire axon length toward terminals

inhibitory postsynaptic potential

allows entrance and exit of ions that cause hyper- polarization

Group A fibers

are the largest in diameter

Anterograde

away from the cell body

Oligodendrocytes are

branched cells that insulate myelin sheaths in thicker nerve fibers

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

The somatic nervous system

conducts impulses from the Central Nervous System to Skeletal muscle

Autonomic Nervous System

consists of visceral motor nerve fibers, and regulates smooth and cardiac muscles, and glands

Depolarization

decreases in membrane potential

Neurons or nerve cells are

excitable cells that transmit electrical signals

relative refractory period

follows the absolute refractory period; depends on the action potential as if it needs to occur again

Myelination in the PNS is

formed by Schwann cells that wrap the axon in a jelly roll fashion

Myelin sheaths in the PNS are

formed by processes of oligodendrocytes NOT WHOLE CELLS

Neuron pool

function groups of neurons

The sensory input

gathers information by the internal and external sensory receptors

Hyper-polarization

increase in membrane potential

Group B fibers

medium or intermediate diameter

Astrocytes are?

most abundant and versatile glial cells

Chemical synapses

most common type that release and receive chemical neurotransmitters

Saltatory conduction

occurs only in myelinated axons and is 30 times faster

The integration function

processes and interprets the sensory input

The ruction of myelin is to

protect and electrically insulate axons

Neuroglia cells

small cells that surround and wrap delicate neurons

Microglial cells are

small, ovoid cells with thorny processes that touch and monitor neurons

Neurons are

structural and functional units of the nervous system

Schwann cells

surround all Peripheral nerve fibers and form myelin sheaths in thicker nerve fibers

Neurons are functionally connected by?

synapses

Retrograde

toward cell body