Cccv

Question 1

What structures are part of the CNS?

Answer 1

Brain and spinal cord.

Question 2

How does the CNS connect to the PNS?

Answer 2

Via cranial nerves (from the brain) and spinal nerves (from the spinal cord).

Question 3

What structures are part of the PNS?

Answer 3

All nerves outside the CNS, including cranial nerves and spinal nerves.

Question 4

How is the PNS subdivided?

Answer 4

Into the somatic nervous system and autonomic nervous system (sympathetic and parasympathetic divisions).

Question 5

What are the three categories of nervous system function?

Answer 5

• Sensory (afferent): Detects stimuli and sends info to CNS. * Integrative: Processes sensory info and makes decisions in CNS. * Motor (efferent): Sends commands from CNS to effectors (muscles/glands).

Question 6

What functions are carried out by the CNS?

Answer 6

Integration and processing.

Question 7

What functions are carried out by the PNS?

Answer 7

Sensory input and motor output.

Question 8

What are the major characteristics of neurons?

Answer 8

• Excitability * Conductivity * Secretion * Extreme longevity * Amitotic (don’t divide)

Question 9

What are the parts of a neuron?

Answer 9

• Dendrites (receive signals) * Cell body (soma) * Axon (transmits impulses) * Myelin sheath (insulates axon)

Question 10

What are the types of neurons by function?

Answer 10

• Sensory neurons: Carry signals to CNS. * Motor neurons: Carry signals from CNS to muscles/glands. * Interneurons: Connect neurons within CNS.

Question 11

Define ganglion.

Answer 11

Cluster of neuron cell bodies in PNS.

Question 12

Define nucleus.

Answer 12

Cluster of neuron cell bodies in CNS.

Question 13

Define nerve.

Answer 13

Bundle of axons in PNS.

Question 14

Define tract.

Answer 14

Bundle of axons in CNS.

Question 15

What is grey matter?

Answer 15

Neuron cell bodies & dendrites.

Question 16

What is white matter?

Answer 16

Myelinated axons.

Question 17

What are the functions of astrocytes in CNS?

Answer 17

Support neurons, maintain BBB, regulate environment.

Question 18

What are the functions of oligodendrocytes in CNS?

Answer 18

Myelinate CNS axons.

Question 19

What are the functions of microglia in CNS?

Answer 19

Immune defense in CNS.

Question 20

What are the functions of ependymal cells in CNS?

Answer 20

Line ventricles, produce CSF.

Question 21

What are the functions of Schwann cells in PNS?

Answer 21

Myelinate PNS axons.

Question 22

What are the functions of satellite cells in PNS?

Answer 22

Support neuron cell bodies in ganglia.

Question 23

What are the advantages of myelination in CNS vs PNS?

Answer 23

Increases conduction speed by saltatory conduction. CNS: Myelinated by oligodendrocytes (one cell myelinates multiple axons). PNS: Myelinated by Schwann cells (one cell per axon segment).

Question 24

What is the charge distribution at resting membrane potential?

Answer 24

Inside cell is negative relative to outside, due to K+ inside and Na+ outside.

Question 25

What ions contribute to resting membrane potential?

Answer 25

* K+ (most influential) * Na+ * Cl- * Negatively charged proteins.

Question 26

What ion channels are involved in maintaining resting membrane potential?

Answer 26

Leak channels (especially K+ leak channels).

Question 27

What does it mean for a cell to be polarized?

Answer 27

Resting state, inside negative.

Question 28

What does depolarized mean?

Answer 28

Inside less negative (more positive).

Question 29

What does hyperpolarized mean?

Answer 29

Inside more negative than resting.

Question 30

What does repolarized mean?

Answer 30

Return to resting potential after depolarization.

Question 31

What is a graded potential?

Answer 31

Small, variable change in membrane potential at dendrites or soma caused by stimulus.

Question 32

What stimulates graded potentials?

Answer 32

Opening of ligand or mechanical gated ion channels due to stimuli.

Question 33

How do graded potentials influence membrane voltage?

Answer 33

Can depolarize or hyperpolarize the cell.

Question 34

What does the amplitude of a graded potential indicate?

Answer 34

Strength of the stimulus.

Question 35

What is summation in the context of graded potentials?

Answer 35

Adding multiple graded potentials to reach threshold to trigger action potential.

Question 36

What is required for a graded potential to trigger an action potential?

Answer 36

Must depolarize membrane to threshold (~ -55 mV).

Question 37

What is an action potential?

Answer 37

Rapid, all-or-none depolarization that propagates along axon, starting at axon hillock.

Question 38

What triggers an action potential?

Answer 38

Membrane depolarization reaching threshold.

Question 39

What does the frequency of action potentials indicate?

Answer 39

Intensity of the stimulus.

Question 40

What are the steps of action potential?

Answer 40

* Resting: Na+ and K+ channels closed; RMP maintained. * Depolarization: Na+ channels open; Na+ influx; membrane potential rises. * Repolarization: Na+ channels close; K+ channels open; K+ exits; membrane returns negative. * Hyperpolarization: K+ channels stay open too long; membrane more negative than resting. * Return to resting: Ion pumps restore ion concentrations.

Question 41

What is the absolute refractory period?

Answer 41

Time during which no new action potential can be generated due to inactivated Na+ channels.