Section 4

Question 1

General func. of the nervous system, their branches, and examples (4)

Answer 1

1. controls internal environment; parasympathetic (autonomic nervous system); ex. altering hormone release
2. voluntary movement; somatic nervous system; ex. direct movement
3. spinal cord reflexes; afferent division (sensory); ex. yanking hand away when touched something HOT
4. memory and learning; autonomic;

Question 2

Components of periphery: stimulus, nerve sig. pathway, response of spindles and GTO; include stretch reflex

Answer 2

Stimulus: muscle over-stretching
Nerve sig. path: annulospiral neve fiber; sends impulse to thru dorsal root to spinal cord producing a shortening reflex of muscle
Resp. spindles: detects and responds by shortening length of extrafusal muscle fibers
Resp. GTO: sensors discharge to depress motor neuron activity to reduce force output

Question 3

Org. of nervous system

Answer 3

CNS
Afferent (sensory)
PNS
Efferent (motor)
Autonomic (involuntary)
Sympathetic
Parasympathetic
Somatic (voluntary)

Question 4

CNS descrip.

Answer 4

consists of the brain and spinal cord

• brain (incl. retinas)
• spinal cord
• integrative/control centers

Question 5

Afferent (sensory)

Answer 5

division of CNS
somatic and visceral neurons
conducts impulses from receptors to CNS

Question 6

PNS

Answer 6

Consists of nerves that transmit information to and from the CNS

• cranial nerves 3-12
• spinal nerves

Question 7

Efferent (motor)

Answer 7

division of PNS
motor neurons
conducts impulses from CNS to effectors

Question 8

Autonomic

Answer 8

division of efferent
involuntary
conducts impulses from CNS to cardiac muscle, smooth muscle, and glands
ex. sweating

Question 9

Somatic

Answer 9

division of efferent
voluntary
conducts impulses from the CNS to skeletal muscle
ex. flexing

Question 10

Sympathetic

Answer 10

division of autonomic
prepares fro excitement (HR increase)
“fight or flight”

Question 11

Parasympathetic

Answer 11

division of autonomic

relax and digest (HR decreases)

Question 12

Unipolar

Answer 12

a neuron that only has one neurite extending from the cell body

Question 13

Are sensory neurons uni or multipolar?

Answer 13

Unipolar b/c sensory neurons only carry sensory processes and conduct impulses from receptor toward CNS.

Question 14

Multipolar

Answer 14

a neuron that possesses a single axon and many dendrites to allow info from other neurons to be received.

Question 15

Are somatic motor neurons uni or multipolar?

Answer 15

Multipolar b/c they conduct impulses from CNS to multiple receptors (skin, skeletal muscles, joints, tendons)

Question 16

Describe what is meant by excitability

Answer 16

-ability to receive and respond to a stimulus.
Impulse (stimulus) arrives at NMJ
ACh releases saclike vesicles in terminal axons w/in synaptic cleft.
ACh changes elec. neural impulse into chem. stimulus and combines w/ transmitter-receptor complex in postsynaptic membrane.
This change in elec. property of postsynaptic membrane triggers end-plate potential that spreads from motor end-plate to extrajunctional sarcolemma of muscle.
This causes AP to travel to muscle fibers for contraction

Question 17

Key components of neuron controlling skeletal muscle (6)

Answer 17

Cell body
Dendrites
Axon
Myelin Sheath
Schwann cells
Nodes of Ranvier

Question 18

Cell body

Answer 18

aka Soma
Contains the nucleus
Connect dendrites
Found in spinal cord grey matter

Question 19

Dendrite

Answer 19

brings info TO cell body

consists of short neural branches that receive impulses through numerous connections and conduct them toward cell body

Question 20

Axon

Answer 20

takes info AWAY from cell body

extends from cord to deliver the impulse to muscle

Question 21

Myelin Sheath

Answer 21

bilayer lipoprotein membrane that wraps around axon, encasing larger nerve fibers
Acts as an electrical insulator that encloses the axon
ex. plastic coating elec. wires

Question 22

Schwann Cells

Answer 22

produce the myelin sheath

covers bare axon and spirals around it

Question 23

Nodes of Ranvier

Answer 23

a 1-2mm gap between the myelin sheath
placed between adjacent Schwann cells
allows impulses to jump from node to node
permits depolarization of axon

Question 24

Polarized

Answer 24

the electrical difference across a membrane resulting in resting membrane potential (cell is in active at -70 mV)

Application: a cell at rest has more Na+ ions inside than K+ outside ions

Question 25

Depolarized

Answer 25

loss of polarization; process of reversing the charges across the cell membrane (inside turns +, outside turns -), causing AP. occurs during Na+ influx into cell Application: Na+ channels open causing rapid influx of Na+ into cell, changing the charge inside cell to -55 mV (threshold for AP), which causes AP.

Question 26

Influx

Answer 26

movement of substance (ions) INTO cell Application: Na+ channels open and Na+ rushes into cell (depolarization)

Question 27

Efflux

Answer 27

movement of substance (ions) OUT of cell Application: Na+ channels close and K+ open (overshoot). K+ moves OUT of cell, restoring charge inside cell to -70mV (repolarization).

Question 28

Electrochemical gradient

Answer 28

electrical difference between inside and outside of cell. can be viewed as a source of potential energy. ions move across membrane (up and down gradient) depending on their gradient level (chemical) and charge (electrical).

Question 29

Graded Potential

Answer 29

change in membrane potential by EPSP or IPSP. Few Na+ channels open so small amt. of Na+ rushes in resulting in slight depolar. (EPSP) or hyperpolar. (IPSP). Size of GP depends on strength of EPSP or IPSP.

Question 30

Threshold

Answer 30

membrane voltage that graded potential becomes action potential.

Question 31

Action Potential

Answer 31

begins as a graded potential. when enough stimulus from EPSP occurs, depolar. of +15 to +20 mV, increasing RMP (-70mV) to threshold -50mV to -55mV. Ex. Na+ influx = depolarize cell to +40mV > repolar. begins: Na+ ch. close, K+ ch. open; efflux of K+ and RMP -70mV is restored.

Question 32

What is the role of Na/K exchanger?

Answer 32

maintain RMP by shuttling Na+ in/out and K+ in/out of cell

Question 33

Temporal SUMmation

Answer 33

adding together graded potentials (GP) in TIME. if 2 GP separated by enough time, they won't have any effect on each other and will decay. If they happen at similar times, they add to each other (SUMmation), which eventually can add up enough for depolar.

Question 34

Spatial SUMmation

Answer 34

adding together GPs in SPACE. if 2 GPs happen far enough away from each other, they may have no effect on each other and decay. If happen closer, they add to each other (SUMmation), which eventually can add up enough for depolar. Ex./In. input from synapse closer to axon will create larger GP than input from synapse further from axon.

Question 35

Excitatory Postsynaptic Potential (EPSP) on target cell

Answer 35

graded potential that pushes postsynaptic neuron toward threshold (increase charge inside cell; depolarization), making AP more likely

Question 36

Inhibitory Postsynaptic Potential (IPSP) on target cell

Answer 36

GP that push postsynaptic neuron further from threshold (hyperpolarization), making AP harder to achieve

Question 37

Propagation (2)

Answer 37

how an impulse travel down neuron. Myelin sheath Diameter of neuron

Question 38

Propagation during AP: Myelin sheath

Answer 38

axons with myelin sheaths conduct impulses (AP) faster than non-myelinated (nodes of ranvier) by leaping from one myelin to the next (saltatory conduction)

Question 39

Propagation during AP: Diameter of neuron

Answer 39

speed of neuron down axon is also determined by the diameter of the neuron. Larger = faster because there's less resistance to local current flow

Question 40

Voltage

Answer 40

potential energy available by separate charges

Question 41

Current

Answer 41

flow of electricity

Question 42

Resistance

Answer 42

ability to resist current. | ex. membrane w/ closed channels = more resistance; membrane w. open channel = less resistance

Question 43

3 types of channels. Which includes the Na and K channel and ACh receptor?

Answer 43

Ligand-gated: neurotransmitter/hormone (ACh receptor channel) Mechanically gated: stretching/pressure Voltage-gated: voltage change (Na and K channel)

Question 44

Impact exercise has on nervous system while aging (4)

Answer 44

Improved cognitive function Improved blood flow to brain Increases brain levels of growth factors that promote optimal function of neurons Protection against various diseases and stroke

Question 45

Disorders that effect the NS (5)

Answer 45

``` Multiple Sclerosis Amyotrophic Later Sclerosis Parkinson's Disease Dystonia Spinal Muscle Atrophy ```

Question 46

Multiple Sclerosis

Answer 46

Immune system attacks myelin and destroys sheath. Results in general fatigue, muscle weakness, poor motor control, loss of balance, and depression. Exercise improves functional capacity, qual. of life, lower depression

Question 47

Amyotrophic Later Sclerosis

Answer 47

motor neurons die. Starts in hands, feet, legs and continues into chewing, swallowing, and breathing; impacts body until paralysis. No cure, rapid progression, total paralysis and death.

Question 48

Parkinson's Disease

Answer 48

Results in decreased dopamine which inhibits muscular activity to aid in control of muscular activity (tremors, shaking). Treated by drugs that stimulate dopamine production.

Question 49

Dystonia

Answer 49

involuntary muscle contractions that cause repetitive twisting movements. Cause not fully understood, but believed to have something to do with the basal ganglia in the brain

Question 50

Spinal Muscle Atrophy

Answer 50

genetic disease affecting the part of the nervous system that controls voluntary muscle movement. Caused by a deficiency of motor neuron protein SMN.

Question 51

What happens when slow and fast muscles are cross innervated?

Answer 51

Cross innervation can change the characteristics of fast and slow twitch muscles (i.e. fast twitch very slowly being turned to slow twitch, vis versa).