Nervous System Tissue

Front 1

Nervous System-

Back 1

1. CNS- Consists of brain and spinal cord
2. PNS- (Peripheral) - nerves, ganglia

Front 2

What are the divisions of the PNS

Back 2

Sensory & Motor

Front 3

Sensory-Afferent-Towards
Motor-Efferent-Away from

Back 3

Sensory -picks up sensory info and delivers it to CNS
Motor-Carries signals from CNS to muscles and glands (effectors) organs that carry out the body's responses

Front 4

Divisions of the Motor Division

Back 4

1. Somatic motor division-carries info to skeletal muscles & involuntary muscle contractions known as somatic reflexes.
2. Visceral motor division-(ANS)carries info to smooth muscles, cardiac muscle & glands (AKA visceral reflexes).

Front 5

Sympathetic division
Parasympathetic division

Back 5

1. Sympathetic-"Arouse the body for action.
2. Parasympathetic-calming effect, slowing down HB but stimulating digestion. (Rest & digest).

Front 6

Functions of NS

Back 6

1. Excitability-irritability
2. Conductivity- Neurons respond to stimuli by prod signals that reach other cells.
3. Secretion-Neurotransmitter that jumps the gap & stimulates next cell.

Front 7

3. What is diff betw sensory neuron & motor neuron?

Back 7

Sensory (afferent) neurons are specialized -detect stimuli & transmit info about them *to the CNS. Motor (efferent) neurons send signals predominantly to muscle & gland cells; they are called motor neurons because most of them lead to muscle cells, and efferent because they carry signals away* from the CNS.

Front 8

4. What is diff betw somatic neuron and autonomic neuron?

Back 8

1. Somatic nerves:carries signals to skeletal muscles. This output produces muscular contractions that are under voluntary control as well as involuntary muscle contractions (somatic reflexes)
2.Visceral-motor division ("autonomic" NS) carries signals to glands, cardiac muscle, and smooth muscle over which we have no voluntary control; the responses are termed visceral reflexes. Unconscious level.

Front 9

5. What is diff betw sympathetic neuron & parasympathetic neuron?

Back 9

sympathetic-tends to arouse the body for action; for example, through accelerating the heartbeat and increasing respiratory airflow and inhibiting digestion. Parasympathetic-tends to have a calming effect; for example, slowing down the heartbeat and stimulating digestion

Front 10

6. What is another name for sensory neuron? motor neuron?

Back 10

Sensory: afferent = towards
Motor: efferent = away from

Front 11

7. Where are interneurons found, what do they do?

Back 11

(Association neurons) entirely within the CNS.
a. Receive signals from many other neurons and carry out integrative functions and “make decision” about response.
b. Most abundant (90%)

Front 12

8. Name 3 main parts of a neuron & tell what ea part does?

Back 12

Soma, dendrite, axon

Front 13

Soma-Dendrite-Axon

Back 13

1. Soma -Main nutrition & metabolic area of cell. Integration-receives info from dendrite and figures out approp. response.
2. Dendrite-Receive signals & convey them to soma. (multiple)
3. Axon-where action potentials generated. Arises from Axon hillock. This & 1st segment of axon are trigger zone, where action potential generated. Ea branch ends in synaptic knob.

Front 14

axon-

Back 14

The axon (nerve fiber) originates on a mound on the soma called the axon hillock.
a. Axon collateral-place where axon branches out.
b. Most axons branch extensively at their distal end.
c. Sends out rapid conduction of nerve signals to points remote from the soma.

Front 15

6 different support or glial cells. List each cell & it's function.

Back 15

Below:

Front 16

Oligodendrocytes

Back 16

(CNS)
a. Each process spirals around a nerve fiber like electrical tape, wrapping the fiber with the insulating myelin sheath.
b. This sheath speeds up nerve conduction.

Front 17

Ependymal cells

Back 17

Lines internal cavities of the brain and spinal cord.
a. Produce cerebrospinal fluid (CSF), which bathes the CNS and fills its internal cavities.
b. These cells have cilia that helps to circulate CSF.

Front 18

Microglia

Back 18

Microglia are small macrophages that develop from white blood cells called monocytes; they wander through the CNS, constantly probing for cellular debris or other problems. (CNS)
a. They are thought to perform a complete checkup on the brain tissue several times a day, phagocytizing dead tissue, microorganism, etc.
b. They become concentrated in areas damaged by infection, trauma, or stroke, and pathologists look for clusters in brain tissue as a clue to injury.

Front 19

Astrocytes

Back 19

1. Most abundant in CNS.
2. Helps create beneficial enviro 4 neurons.
3. Blood brain barrier-grps of cells forms physical barrier.

Front 20

Schwann cells

Back 20

Schwann cells envelope nerve fibers of the PNS. (PNS)
a. The Schwann cell winds repeatedly around a nerve fiber, producing a myelin sheath similar to the one produced by oligodendrocytes in the CNS.
b. Schwann cells also assist in regeneration of damaged fibers.

Front 21

Satellite cells

Back 21

Surround neurons. Helper cells.

Front 22

10. what is myelin and how does it affect a nerve?

Back 22

The myelin sheath is an insulating layer around a nerve fiber, somewhat like the rubber insulation on a wire. (p. 450)
1. The myelin sheath speeds up nerve conduction.

Front 23

12. Define:

Back 23

xx

Front 24

Nodes of Ranvier-

Back 24

long internodes separated by interruptions of myelin sheath.

Front 25

internodes-

Back 25

The myelin-covered segments from one gap to the next are called internodes;

Front 26

saltatory conduction-

Back 26

When the diffusing ions reach a node, these gates are opened and a new action potential is generated; this process of jumping from node to node is called saltatory conduction.

Front 27

synapse-

Back 27

A synapse exists at the end of an axon; in synapses between two neurons, the first neuron is the presynaptic neuron (releases neurotransmitter) and the second is the postsynaptic neuron (responds to neurotransmitter).

Front 28

presynaptic cell

Back 28

A presynaptic neuron may form an axodentritic, axosomatic, or axoaxonic synapse

Front 29

postsynaptic neuron

Back 29

The postsynaptic neuron has no synaptic vesicles in the synapse and cannot release neurotransmitters; the membrane does contain receptor proteins and ligand-regulated ion gates.

Front 30

13. Briefly describe what happens at a chemical synapse?

Back 30

1. Begins when nerve signal arrives at end of presynaptic neuron.
2. Triggers exocytosis of synaptic vesicles. Neurotransmitter is released into synaptic cleft, diffuses across to postsynaptic cell and binds to receptors on that cells membrane.
3. Depending on neurotransmitter & type of receptor, this may either stimulate or inhibit postsynaptic cell.
4. Postsynaptic cell decides where or not to initiate a new nerve signal based on composite effects of excitatory or inhibitory input thru the many synapses on its dendrites & axons.

Front 31

14. Describe the following types of interconnections betw neurons:

Back 31

. Neurons function in ensembles called neural pools, which may contain thousands to millions of interneurons; the functions of a neural pool are partly deteremined by its neural circuit.

Front 32

divergence- (impulses from single neuron in CNS may be amplified to activate enough motor units needed for muscle contraction.)

Back 32

In a diverging circuit, one nerve fiber branches and synapses with several post synaptic cells, so that input from one neuron may produce output through hundreds of neurons.

Front 33

convergence-(allows neuron to sum impulses from different sources.)

Back 33

1. Input from many different never fibers is funneled to one neuron or neural pool;
2. this type of circuit allows input from different sensory systems to be evaluated, such as correcting balance.

Front 34

reverberating circuits-

Back 34

In a reverberating circuit, neurons are stimulated in a linear fashion, but some have an axon collateral leading back to the initial neuron and restimulates it.

Front 35

parallel after-discharge circuits-

Back 35

In a parallel after-discharge circuit, an input neuron diverges to stimulate several neuron chains that eventually reconverge on a single output neuron; these chains different in total synaptic delay, meaning that their signals arrive on the output neuron at different time