Shared Flashcard Set

Details

Nervous system
Nerve notes
121
Anatomy
Undergraduate 1
04/14/2009

Additional Anatomy Flashcards

 


 

Cards

Term
What are the functions of the nervous system?
Definition

1. Sense changes in environment

2. Interpret changes

3. Respond to changes in environment

Term

What are the 2 divisions of the nervous system?

Definition

I. Central Nervous System (CNS)

 

II. Peripheral Nervous System (PNS)

Term

Central Nervous System (CNS)

Definition

control center composed of brain and spinal cord

Term

Peripheral Nervous System (PNS)

Definition

cranial nerves from brain

 

and spinal nerves from spinal cord

Term
Structure of Peripherial Nervous System
Definition

Afferent

Efferent

Term

Afferent

Definition

(sensory) takes impulses to CNS

Term

Efferent

Definition

(motor) takes impulses away from CNS

Term

Somatic

Definition

goes to voluntary muscles

Term

Autonomic nervous system

Definition

goes to involuntary muscles and glands

Term

Autonomic nervous system

Definition

a. Sympathetic

 

b. Parasympathetic

Term

NERVOUS SYSTEM COMPOSED OF TWO TYPES OF CELLS

Definition

Neuroglia cells

 

Neurons

Term

Functions of Neuroglia cells

Definition

support

 

protection

Term

Neuroglia cells

Definition

Schwann cell

Oligodendrocytes

Microglia

Astrocytes

Ependyma cells

Satellite cells

Term

Neurons

 

Definition

basic structural and functional units of nervous system.

 

Can not divide mitotically, but some can regenerate a severed portion.

Term

Three Principal Components of Neurons

Definition

Cell body or perikaryon

Dendrites

Axon

Term
Cell Body or Perikaryon
Definition

 enlarged portion of neuron that contains nucleus and nucleolus surrounded by cytoplasm.

 

Cytoplasm characterized by Nissl bodies and neurofibrils

Term

Dendrites

Definition

branched processes that extend from cytoplasm of cell body.

 

Receive stimulus and conduct impulse to cell body

Term

Axon

Definition

Single, relatively long, highly branched process that conducts impulses away from cell body.

 

Term

Axon Hillock

Definition

 

originates from the cell body is axon hillock. Conical region where it

Term
What is the length of an Axon?
Definition
axons vary from a few millimeters to over a meter
Term
What does the cytoplasm of the axon consist of?
Definition
many mitochondria, microtubules and neurofibrils
Term
What is not in the cytoplasm?
Definition
Nissl Bodies
Term
what are the Special Structures?
Definition

Axon colaterals

axoplasm

axolemma

telodendria

synaptic end bulbs

Term
Axon Colaterals
Definition
side branches that extend short distance from axon
Term
Axoplasm
Definition
cytoplasm
Term
axolemma
Definition
plasma membrane
Term
Telodendria
Definition
end branches of axon
Term
synaptic end bulbs
Definition
sac-like structures at the end of teledendria that contain transmitter substance
Term
Peripheral nerve fibers may be surrounded by?
Definition
myelin sheaths
Term
Myelinated
Definition
 axons containing a myelin sheath
Term
unmyelinated
Definition
axons not containing a myelin sheath
Term
What does Schwann cells produced?
Definition
Myelin sheath
Term
What is Neurilemma or Sheath of Schwann made of ?
Definition
cytoplasm, a nucleus, and cell membrane
Term
Neurilemma or Sheath of Schwann may assist in
Definition
regeneration of injured axons
Term
Nodes of Ranvier
Definition
gaps in sheath
Term
smallest axons are enclosed by what?
Definition
Schwann Cells
Term
the smallest axons are not wrapped around the axon;
Definition
therefore no myelin sheaths
Term
Myelin in the CNS is produced by?
Definition
oligodendrocytes rather than Schwann cells
Term
A single oligodendrocyte may provide myelin myelin for up to
Definition
40 axons
Term
what is the white matter?
Definition
groups of myelinated fibers appear white and are responsible for white matter in the brain and spinal chord
Term
Regeneration
Definition
A damaged axon may regenerate
Term
Steps for Regeneration of injured axon
Definition

1. distal portion degenerated

 

2. proximal end of injured nerve sprouts and regenerates into tube of sheath cells

 

3. sheath cells proliferate and axon grows 3 to 4 mm per day

Term

Structural classification of neuron

 

classified by number of processes

Definition

1. multipolar

 

2. bipolar

 

3. unipolar

Term
Multipolar
Definition

several dendrites and 1 axon. 

 

 Brain and spinal cord

Term
bipolar
Definition

1 dendrite and 1 axon

 

Brain and spinal cord

Term
unipolar
Definition

1 process which divides to form branches that function as axon and dendrite

 

dorsal root ganglia

Term
Functional classification
Definition
classified according to direction impulse flows
Term
Functional Classification
Definition

1. afferent or sensory - impulse travels toward CNS.

 

2. efferent or motor - impulse travels away from CNS.

 

3. association - connections from sensory to motor.

Term
What are nerves?
Definition
bundles of affarent and efferent processes and can be grouped
Term
Nerves
Definition

1. General somatic afferent fibers

 

2. General somatic efferent fibers

 

3.  General visceral afferent fibers

 

4. General visceral efferent fibers 

Term
Cell Membrane Potential
Definition
Cell membrane is electrically charged or polarized so that the outside is positively charged with respect to the inside
Term
What is the distribution of ions determined by?
Definition
the presence of pores or channels in the membrane.  some channels are always open, while others open or close like gates.
Term
Resting potential
Definition
nerve cell is not conducting impulses
Term
There is a greater concentration of what on the outside of the cell?
Definition
Na
Term
There is a greater concentration of what on the inside of the cell?
Definition
K
Term

The ouside of the membrane is __________

 

charged and the inside is ____________ charged

Definition

positively

 

negatively

Term
Potential Difference
Definition
difference in the electrical charge between the measured in volts.
Term
The resting potential is ______  mv
Definition
-70
Term
Depolarization
Definition
membrane becomes less negative
Term
What affects the neurons in a localized region of the membrane?
Definition
Stimulation
Term
What happens during depolarization?
Definition
sodium channels open and Na passes in
Term
The amount of change in potential is directly related to ?
Definition

Intensity of Stimulation

 

such changes are graded

Term
Summation
Definition
if another stimulus of the same type is received before the effect of the first stimulus subsides, the change in the local membrane is greater
Term
What is the additive effect called?
Definition
Summation
Term
Threshold stimulus
Definition
the very least amount of stimulus necessary to start an action potential
Term
Stimulus
Definition
any condition capable of altering membrane potential
Term
action potential
Definition
sequence of electrical changes occuring when nerve cell membrane is exposed to stimulus that exceeds its threshold
Term
Repolarization
Definition
Channels open at almost the same time as Na channels to allow K to pass out and membrane becomes negatively charged again.
Term
What is the time it takes for the action potential of repolarization to take place?
Definition
1/1000 second or less
Term
What happens when too may ions pass through the membrane?
Definition
the action potential ceases and active transport mechanism returns membrane to the resting period
Term
What causes the ions to flow from adjacent portions of the membrane?
Definition
action potential
Term
This stimulates membrane to the threshold level and a __________________
Definition
wave of action potentials pass through
Term
Nerve Impulse
Definition
propagation of action potential along nerve
Term
Events leading to nerve impulse conduction:
Definition

1.  Nerve fiber membrane developes resting potential

2. threshold stimulus received

3. Na channels open

4. Na diffuses toward

5. K channels in membrane open

6. K diffuses outward

7. Ion channels close and membrane becomes less permeable to Na and K

8. wave of action potential travels length of nerve fiber as nerve impulse

Term
Refractory Period
Definition
time following stimulation during which neuron will NOT respond
Term
Absolute Refractory Period
Definition
membrane changing in Na permeability and cannot be stimulated
Term
Maximum rate of nerve impulse conduction
Definition
1 impulse per millisecond
Term
All or None Response
Definition
if nerve resonds at all, it responds completely
Term
Impulse conduction
Definition

a.  unmyelinated fiber

 

b.  myelinated fiber

Term
Unmyelinated fiber
Definition
conducts impulse over entire membrane
Term
myelinated fiber
Definition
nerve impulse jumps from node to node. 
Term
saltatory conduction
Definition
nerve impulse jumps from node to node
Term
Why do the nerve impulses jump from node to node?
Definition
the myelin is composed of largely of lipids which act as an insulator
Term
Speed of the nerve impulse is related to what?
Definition

diameter of the fiber

 

the greater the diameter, the faster the impulse.

Term
speed is determined by
Definition

1. size of fiber

2. type of fiber

3. physiological conditions

Term
types of fibers
Definition

Type A

 

Type B

 

Type C

Term
Type A fiber
Definition
130 m/sec greatest diameter, myelinated, saltatory, conduction, connects with sensors detecting danger.
Term
Type B fibers
Definition
10 m/sec - longer refractory period, myelinated.  Visceral efferent fibers
Term
Type C fibers
Definition
slowest.  .5 m/sec. thin, longest refractory period, no saltatory conduction.  Impulses for pain form skin, and all motor from ganglion to smooth muscle and visceral organs
Term
Synapse
Definition
junction between 2 neurons or neuron and muscle
Term
Presynaptic Neuron
Definition
neuron located before synapse
Term
Postsynaptic neuron
Definition
neuron located after synapse
Term
Synaptic transmission
Definition
process of crossing gap
Term
Synaptic Vesicles
Definition
located in synaptic end bulb and release transmitter substance substance.  Causes one-way impulse conduction
Term
The body produces over 30 transmitter substances which are made from what?
Definition
amino acids
Term
what are examples of the transmitter substances made from amino acids?
Definition
acetylcholine, norephinephrine, dopamine, glycine, glutamic acid, histamine and serotonin
Term
Where is the transmitter substance produced?
Definition
cytoplasm
Term
Where is the transmitter substance stored?
Definition
synaptic vesicles
Term
What causes the release of Ca from the knob and stimulates the vesicles to release the contents into the synaptic cleft?
Definition
An action potential
Term
What is destroyed by enzymes
Definition
neurotransmitters
Term
divergence
Definition

synaptic knobs from a single presynaptic neuron synapse with several post-synaptic neurons

 

spread out

Term
convergence
Definition

several presynaptic neurons synapse with a single post-synaptic neuron

 

comes together

Term
Excitatory Transmission
Definition
excitatory transmitter receptor interaction lowers post synaptic neuron's membrane potential
Term
Oligodendrocytes
Definition
form myelin sheaths around axons in CNS
Term
axon hillock
Definition
cone-shaped elevation
Term
Excitatory postsynaptic potential (EPSP) is always ________  _________ than the resting potential but ______ ________ than the threshold.
Definition

less negative

 

more negative

Term
Facilitation
Definition
the effect of lower the membrane potential by using sub-threshold stimuli
Term
sub-threshold stimuli
Definition
Term
What increases the odds that the next stimulus will reach the threshold?
Definition
Facilitation - the effect of lowering the membrane potential by using sub-threshold stimuli
Term
2 Types of Summation
Definition

Spatial summation

 

Temporal summation

Term
Spacial Summation
Definition
summation is result of accumulating transmitter substance from several presynaptic knobs.
Term
Temporal Summation
Definition

summation from one neuron firing several times

 

additive effect from acetylcholine

Term
Inhibitory Transmission
Definition
inhibitory transmitter receptor interaction raises post synaptic neuron's membrane potential.  This causes hyperpolarization of the post-synaptic membrane
Term
What synapse with many presynaptic neurons, some excitatory and some inhibitory
Definition
post synaptic neurons
Term
Effects of PSN
Definition

1.  Facilitation

 

2. Initiation of impulse

 

3. inhibition of impuse

Term
Acetycholine
Definition
usually excitatory, but inhibitory with respect to the heart
Term
Norepinephrine
Definition
excitatory
Term
Seratonin
Definition
excitatory
Term
Gamma Aninobutyric Acid
Definition
inhibits CNS
Term
Glycine
Definition
inhibits spinal cord
Supporting users have an ad free experience!