Nervous System

Question 1

Specialized cells responsible for conduction nerve impulses

Answer 1

neuron

Question 2

List ways in which neurons communicate .

Answer 2

1. Physical Communcation (via ion exchange and generation of AP)
2. Chemical Communcation (neurotransmitter)

Question 3

List the major components of a Neuron.

Answer 3

1. Dendrites (receives signal AP)
2. Soma (Cell body, location of nucelus and mitochondria)
3. Axon Hillock (cell body transition to axon, transmission of AP to axon)
4. Axon (Long appendage down which AP travel)
5. Synaptic bouton (Nerve Terminal)
   
   1. releases neurotransmitters into synaptic cleft to allow for transmission of signal to next neuron

Question 4

List two important structures found on axon that assist in saltatory conduction.

Answer 4

1. Myelin Sheath
2. Nodes of Ranvier

Question 5

What is the purpose of the myelin sheath and and nodes of Ranvier?

Answer 5

1. Myelin Sheath
   
   1. Insulation: Prevent signal lost or crossing signals
   2. Increase AP across axon
2. Nodes of Ranvier
   
   1. Regions in which AP “jump” along axon, speeding up conduction.

Question 6

What are the major components of the synapse?

Answer 6

1. Synaptic Bouton (Pre-synaptic cell)
2. Synaptic Cleft
3. Membrane of Post-synaptic cell

Question 7

Creates myelin for CNS.

Answer 7

Oligodendrrocytes

Question 8

Creates myelin for PNS.

Answer 8

Schwann Cells

Question 9

Ganglia

Answer 9

Cluster of neuronal cell bodies if PNS.

Question 10

Nuclei

Answer 10

Cluster of neuronal cell bodies if CNS.

Question 11

Types of information a neuron can carry.

Answer 11

1. Sensory (Sensory neurons)
2. Motor (Motor Neurons)
3. Both (Interneurons)

(Nerve tracts, bundle of individual axons, carry only one type)

Question 12

Cells within nervous syste that support neurons.

Answer 12

Glial Cells

Question 13

List three types of Glial Cells.

Answer 13

1. Astrocytes
2. Microglia
3. Empendymal Cells

Question 14

Glial cells that form blood brain barrier (controlling transmission of solutes from blood to nervous system)

Answer 14

astrocytes

Question 15

Glial cells that that lines ventricles and secrete CSF.

Answer 15

Ependymal Cells

Question 16

Glial cells that are phagocytes and are responsible for breaking down pathogens and waste in CNS.

Answer 16

Microglia

Question 17

Resting membrane potential

Answer 17

-70 mV

Question 18

What two things maintains resting membrane potential?

Answer 18

1. Selective permeability of specific ions (Na/K)
2. Na+/K+ ATPase Pump

Question 19

How many sodium and potassium ions are pumped out/in respectively by Na+/K+ ATPase pump.

Answer 19

3 sodium out, 2 potassium in (reason for why cells have a higher negative charge when compared to extracellular fluid)

Question 20

Incoming signals can be either ________ or ________. What does this mean?

Answer 20

1. Inhibitory
   
   1. Depolarize neuron - contribute to AP
2. Excitatory
   
   1. Hyperpolarize neuron - Makes it harder for AP to occur

Question 21

Types of summation that refers to addition of multiple signals of a single neuron add up over a period of time to produce/inhibit and AP in the next neuron.

Answer 21

Temporal Summuation

Question 22

Types of summation that refers to addition of multiple signals of all surrounding neurons near are summed at a given moment in time to produce AP in next neuron.

Answer 22

Spatial summation

Question 23

Describe the different events prior, during, and after an AP.

Answer 23

1. Neurotransmitted bind to receptors on post-synaptic cell
2. Conformation changes occur in receptors that eventually open up channels for which sodium can flow in (working down its electrochemical gradient)
3. Threshold is reach: -55 mV.
4. Sodium Voltage gated channels open up and Na+ continues to flood in.
5. Peak of AP is at +35 mV
6. At this point, Na+ voltage gated channels imactivate and K+ voltage gated channels open up (working down electrochemical gradient)
7. K+ Floods out of cell, causing hyperpolarization
8. K+ voltage gated channels close
9. Refractory Period begins where Na+/K+ leak channels as well as Na+/K+ ATPase pump works together to allow membrane to return to resting membrane potential

Question 24

Absolute vs. Relative Refractory Period

Answer 24

1. Absolute
   
   1. No matter how strong incoming impulses are, neuron is unable to fire an AP during this time.
2. Relative
   
   1. Cell requires larger than normal stimulus to fire AP

Question 25

Are AP unidirectional or multidirectional?

Answer 25

**Unidirectional** They propagate along an axon, jumping from node to node. Because previous node is now in refractory period, it will be unable have a simultaneous AP traveling in the opposite direction.

Question 26

Explain the events that occur at the Synapse (includes nerve terminal, synaptic cleft, and post-synaptic membrane).

Answer 26

1. Once AP has reached nerve terminal, Ca+ voltage gated channels open and Ca+ floods into terminal 2. Results in the release of neurotransmitters sitting in nerve terminal (via exocytosis) 3. Neurotransmitters travel through synaptic cleft 4. Once they reach post-synaptic membrane, they bind to receptors on membrane that will change comformation to allow Na+ to flow in.

Question 27

What are the two major receptors on post-synaptic membrane.

Answer 27

1. Ligand Gated ion channels 2. G-Protein Coupled Receptors

Question 28

List the ways in which neurotransmitters can be cleared from synaptic cleft?

Answer 28

1. Enzymatically broken down 2. Absorbed back into pre-synaptic cell via reuptake carriers 3. Diffusion out of synaptic cleft

Question 29

Removes acetylcholine from post-synaptic cleft.

Answer 29

Acetyl-cholinesterase

Question 30

Which is an efferent neuron and which is a afferent neuron? 1. Sensory 2. Motor

Answer 30

1. Sensory: afferent 2. Motor: Efferent

Question 31

Myelinated axons that lie deeper in the brain.

Answer 31

White matter

Question 32

Unmyelinated axons and dendrites on the outer portion of the brain.

Answer 32

Grey Matter

Question 33

Two division of PNS. (often act in opposition to one another)

Answer 33

1. Parasympathetic/Autonomic Nervous System 2. Sympathetic/Somatic Nervous System

Question 34

Explain important details about autonomic nervous system.

Answer 34

1. Rest and Digest 1. Includes: 1. Resting and Sleeping states 2. Decreasing HR 3. Constricting Bronchioles 4. Increasing Peristalisis and Excocrine Secretions 2. Main Role: Conserving energy 3. Two neurons that work to transmit signals 1. Pre-Ganglionic and Post-Ganglionic 1. Cell body of preganglionic neuron is in CNS. 2. Pre-ganglionic neuron travels to PNS, where it meets with cell body of post-ganglionic nerve and transmits signal to target tissue

Question 35

Explain important details about Parasympathetic nervous system.

Answer 35

1. Fight or Flight 1. Increase HR 2. Redistribution of blood to Periphery 3. Increase glucose concentration (for ATP production) 4. Relaxes bronchi 5. Decrease activity of digestive organs 6. Dialation is important 7. Epinephrine is release into the blood 2. Has one neuron that goes directly from spinal cord to muscle

Question 36

How interneurons in the spinal cord relay information to the source of the stimulus while simultaneously routing information to brain. (2 types)

Answer 36

Reflex Arc

Question 37

Describe the Monosynaptic Reflex Arc

Answer 37

Sensory neuron that synapses with and fires directly onto motor neuron.

Question 38

Describe the Polsynaptic Reflex Arc

Answer 38

Sensory neuron fires onto a motor neuron as well as other interneurons that fire onto other motor neurons.

Question 39

Describe the muscle-stretch reflex.

Answer 39

1. Only occurs on side of the body 2. Stimulus: Afferent neuron (Somatosensory Neuron) 1. Excites motor neuron on the spinal cord that sends a stimulus back, causing the knee to contract 2. Excites other inhibitory inteneurons (connected to other motor neurons) that will cause the muscles in the back of the thigh to relax. If there is no inhibitory interneuron, the leg would not become straight because the hamstring would not relax. 3. Response: Efferent Neuron (Motor Neuron) 4. Together these neurons synapse 5. This is an example of reciprocal inhibition.