U6 Nervous System I

Question 1

Multiple Sclerosis (MS)

Answer 1

A potentially disabling disease of the brain and spinal cord (CNS) - the immune system attacks the protective sheath (myelin) that covers nerve fibers and causes communication problems between your brain and the rest of your body

Question 2

CNS

Answer 2

central nervous system; down axial skeleton (brain & spinal cord)

Question 3

PNS

Answer 3

peripheral nervous system; nerves leading to and from the CNS (12 cranial nerves + 31 spinal nerves)

Question 4

Sensory Integrative Responsive

Answer 4

detection of internal or external changes to “decide” on a course of action for motor neurons

Question 5

Afferent Neurons

Answer 5

carry information from sensory receptors of the skin and other organs to the central nervous system

Question 6

Efferent Neurons

Answer 6

carry motor information away from the central nervous system to the muscles and glands of the body

Question 7

Diff b/tw NERVOUS SYSTEM and ENDOCRINE SYSTEM

Answer 7

NERVOUS SYSTEM - transmits messages very fast (1-10 msec) using impulses and neurotransmitters; response stops when stimulus stops; prolonged stimulation = adaptation

ENDOCRINE SYSTEM - sends hormones into the bloodstream; takes more time to act; slow to adapt; last long after stimulation

Question 8

Neurons (+ their structure)

Answer 8

masses of nerve cells that transmit information – dendrite, cell body, axon, myelin, node of ranvier

Question 9

Neuroglial Cells

Answer 9

Provides support for neurons

Question 10

Microglial Cells

Answer 10

Immune function; digests debris, kills bacteria

Question 11

Oligodendrocytes

Answer 11

Makes myelin sheath that provides insulation around the axons (CNS ONLY)

Question 12

Astrocytes

Answer 12

Connects blood vessels to neurons

Question 13

Ependymal Cells

Answer 13

Forms membranes around tissue - produces cerebrospinal fluid (aka CSF)

Question 14

Schwann Cells

Answer 14

Used to create the myelin sheath (same function as oligodendrocytes but found in the PNS ONLY)

Question 15

Demyelination + MS

Answer 15

Nerves affected by MS lose their myelin sheath (called demyelination); messages not sent properly

Question 16

White v Grey matter (brain)

Answer 16

White = myelinated
Grey = unmyelinated

Question 17

Lesions

Answer 17

evidence of nerve cell damage in the brain or spinal cord - symptoms vary depending on the location of lesion (spinal cord = motor problems; back of brain = balance problems)

Question 18

What happens during MS (auto-immune disorder)?

Answer 18

The immune system attacks and causes damage to oligodendrocytes. This makes it harder for the CNS to replace the damaged myelin. All of this leads to a loss of myelin, or demyelination. Without the myelin insulation, the axons, or nerve fibers, also get damaged.

Question 19

Neuron Facts

Answer 19

• Longevity
• Do not divide
• High metabolic rate
• Newborns have unmyelinated nerve fibers (stimuli is coarse)

Question 20

Action Potential Explained (Steps)

Answer 20

1. Neuron membrane maintains resting potential
2. Threshold stimulus is received
3. Sodium channels open
4. Sodium ions diffuse inward, depolarizing the membrane
5. Potassium channels open
6. Potassium ions diffuse outward, repolarizing the membrane
7. The resulting action potential causes a local bioelectric current that stimulates the membrane.
8. Wave of action potentials travel the length of the axon as a nerve impulse

Question 21

Depolarization

Answer 21

Away from resting state (sodium ions moving inwards)

Question 22

Repolarization

Answer 22

Towards resting state (potassium ions moving outwards)

Question 23

Resting Membrane

Answer 23

Neg. potassium ions on the inside; Pos. sodium ions on the outside

Question 24

Communication b/tw Neurons

Answer 24

Synapse = junction between 2 communicating neurons; Nerve Pathway = nerve impulse travels from neuron-neuron

Question 25

How is a signal retrieved during neuron-neuron communication?

Answer 25

A neurotransmitter is released at the synaptic cleft to signal the next neuron -- receptors on the other neuron's dendrite receives info.

Question 26

Excitatory Neurotransmitter

Answer 26

increase membrane permeability, increases chance for threshold to be achieved

Question 27

Inhibitory Neurotransmitter

Answer 27

decrease membrane permeability, decreases chance for threshold to be achieved

Question 28

Types of Neurotransmitters

Answer 28

ACH (muscle contraction), Dopamine (happy), Serotonin (sleep), Endorphins (pain reduction)

Question 29

Agonist

Answer 29

molecule that has the same effect on the postsynaptic neuron as the neurotransmitter itself does; substances that act as neurotransmitters and attach to certain receptors in the brain (e.g. Heroin)

Question 30

Antagonist

Answer 30

molecule that blocks the effect that the neurotransmitter normally has on the postsynaptic neuron; attach to certain receptors in the brain but do not produce a response (e.g. Naltrexone)

Question 31

Resting Membrane Potential

Answer 31

-70 millivolts

Question 32

Voltage-Gated Channels

Answer 32

open and close in response to changes in membrane potential

Question 33

Ligand-Gated Channels

Answer 33

open when a neurotransmitter latches onto its receptor

Question 34

Mechanically-Gated Channels

Answer 34

open in response to the physical stretching of the membrane

Question 35

Graded Potential

Answer 35

graded potentials are temporary changes in the membrane voltage

Question 36

Threshold for Action Potential

Answer 36

-55 mV

Question 37

Refractory Period

Answer 37

time where no other signals can happen

Question 38

3 ways neurotransmitters can be inactivated:

Answer 38

1. Degradation - enzyme changes the way the neurotransmitter looks so it cannot be recognized/remembered by receptors 2. Diffusion - neurotransmitter moves away from the receptor 3. Reuptake - neurotransmitter is sucked back up by the axon of the neuron that let it out

Question 39

Modulatory Neurotransmitters

Answer 39

diffuse across a large area and are slow-acting

Question 40

Issues w/ neurotransmitters:

Answer 40

- Neurons unable to create enough of a neurotransmitter - Neurotransmitters reabsorbed too fast - Too many neurotransmitters deactivated by enzymes - Too much of a neurotransmitter is released

Question 41

Direct Effects

Answer 41

mimics the neurotransmitter/similar in chemical structure

Question 42

Indirect Effects

Answer 42

works by acting on synaptic receptors

Question 43

What are ways we can manipulate an action potential to change the frequency of a signal?

Answer 43

When the intensity of the stimulus is increased, the action potential’s frequency of a signal increases