Chapter 6 - Neuronal Signaling and The Structure of The Nervous System

Question 1

Central Nervous System (CNS)

Answer 1

Brain and spinal cord

Question 2

Peripheral Nervous System (PNS)

Answer 2

Nerves that connect the brain or spinal cord with the body’s muscles, glands, and sense organs

Question 3

Neurons (characteristics)

Answer 3

• also known as “nerve cells”
• amitotic (do not divide)
• high metabolic rate
• clusters of cell bodies in the CNS is called nuclei.
• NOT the most numerous cell in CNS. Flush Cells are

Question 4

What are the 4 Glial Cells of CNS?

Answer 4

Astrocytes, microglia, ependymal cells, and oligodendrocytes

Question 5

Astrocytes

Answer 5

Support cells and control extracellular environment of neurons. They remove potassium ions and neurotransmitters around synapses. It also stimulates the formation of tight gap junctions. They also provide glucose and remove the secreted metabolic waste product ammonia.

Question 6

Microglia

Answer 6

Immune system of the CNS, contribute to synapse remodeling and plasticity

Question 7

Ependymal cells

Answer 7

Ciliated and involved with production of CSF and CSF movement

Question 8

Oligodendrocytes

Answer 8

Responsible for the myelin formation

Question 9

What are the two types of Glial cells of the PNS?

Answer 9

Satellite cells and Schwann cells

Question 10

Satellite cells

Answer 10

Surround neuron bodies located in the PNS

Question 11

Schwann cells

Answer 11

Surround and form myelin sheaths around the large nerve fibers. This is vital to regeneration and proper never signal conduction

Question 12

What are the three classes of neurons?

Answer 12

Afferent, efferent, and interneurons

Question 13

Afferent neurons

Answer 13

• transmit information into the central nervous system from receptors at their peripheral endings
• cell body and the lob peripheral process of the axon are in the PNS. Only the shirt central of the axon enters the CNS

Question 14

Efferent neurons

Answer 14

• Transmit information out of the CNS to effector cells, particularly muscles, glands, or other neurons
• cell body, dendrites, and a small segment of the axon is in the PNS

Question 15

Interneurons

Answer 15

• Function as integrators and signal changers
• integrate groups of afferent and efferent neurons into reflex circuits
• lie entirely within the CNS
• account for >99% of all neurons

Question 16

Synapses

Answer 16

• can use both chemical and electrical stimuli to pass information
• can be inhibitory or excitatory depending on the signal/neurotransmitter being transmitted

Question 17

Neuron

Answer 17

individual cells that make up the nervous system

Question 18

Cell Body (structure of neuron)

Answer 18

Contains the nucleus and ribosomes that make proteins. Contains most of the genetic information needed for the secretion of proteins,

Question 19

Neurotransmitters

Answer 19

Chemical messengers that help communicate with other cells

Question 20

Glial Cell

Answer 20

a non-neuronal cell. Not cell-cell communication, but functions as support for neurons.

Question 21

Dendrites (structure of neuron)

Answer 21

receive the incoming information

-branching dendrites and dendritic spines increase the surface area

Question 22

Axon

Answer 22

also known as nerve fiber, sends out the information (signals) to its target cells

Question 23

Initiated Segment

Answer 23

propogated electrical signals are generated

Question 24

Axon Collateral

Answer 24

greater the degree of branching, the greater the sphere of influence

Question 25

Axon terminal

Answer 25

releases neurotransmitters from axon

Question 26

varicosities

Answer 26

bulging areas in axon

Question 27

kinesin

Answer 27

a motor neuron;transport from cell body to axin terminals mainly(ANTEROGRADE). It moves nutrient molecules, enzymes, mitochondria, neurotransmitter filled vesicles, and other organelles.

Question 28

Dynein

Answer 28

motor neuron; (RETROGRADE) carries signals, recycled membrane vesicles, and growth factors that can affect the neruon connectivity, etc.

-Retrograde is the way in which some harmful agents can attack the CNS

Question 29

Synapse

Answer 29

Is a junction between two neurons where one neuron alters the chemical signal and electrical activity of another

Question 30

Presynaptic neuron

Answer 30

neuron conducting signal TOWARD a synapse

Question 31

postsynaptic neuron

Answer 31

neuron conducting signals AWAY from a synapse

Question 32

Transmission of neuronal activity

Answer 32

1) Afferent neurons in PNS receive input at sensory receptors
2) Efferent components of the PNS may terminate on muscle, gland, neuron, or other effector cells

Question 33

Blood-brain barrier

Answer 33

selective filter for exchanged substances than is present between the blood and most other tissues.

Question 34

Resting Membrane Potential

Answer 34

inside of the cell is negatively charged with respect to the outside

Question 35

excitatory synapse

Answer 35

membrane potential of a postsynaptic neuron bought closer to threshold(hyperpolarized)

Question 36

inhibitory synapse

Answer 36

membrane potential stabilized to resting potential

Question 37

Convergence

Answer 37

Many presynaptic neurons affecting a single postsynaptic cell. Allows information from many sources to influence a cell’s activity.

Question 38

Divergence

Answer 38

A single pre-synaptic neuron affects many of the post-synaptic cells. One cell affects many pathways

Question 39

How do you determine the level of excitability of a post synpatic cell?

Answer 39

depends on the number of synapses active at any one time and the number that are ecitatory and inhibitory.

If the membrane of the post-synpatic neuron reaches threshold, it will generate action potentials that are propogated along its axon to the axon terminals, which in turn influence the excitability of other cells.

Question 40

Electrical synapse

Answer 40

plasma membrane of the presynaptic and postsynaptic cells are joined by gap junctions

Question 41

chemical synapse

Answer 41

specialized junctions through which cells of the nervous system signal to one another and to non-neuronal cells such as muscles or glands.

Question 42

Mechanisms of signaling at a chemical synapse (6 steps)

Answer 42

1) action potential reaches terminal
2) volatage gated ion channels open
3) calcium enters the axon terminal
4) neurotransmitter is released and diffuses into the cleft
5) neurotransmitter binds to postsynaptic receptors
6) neurotransmitter removed from synaptic cleft

Question 43

ionotropic receptors

Answer 43

activated receptors that are ion channels

Question 44

metabotropic receptors

Answer 44

receptors may indirectly infleunce ion channels through a G-protein receptor and/or a second messenger

Question 45

EPSP (excitatory postsynaptic potential)

Answer 45

temporary depolarization of postsynaptic membrane caused by the flow of positively charged ions into the postsynaptic cell as a result of the opening of ligand-sensitive channels.

The EPSP increases the neurons membrane potential.

Question 46

IPSP (inhibitory postsynaptic potential)

Answer 46

hyperpolarzing graded potential; open to Cl and K channels. the Na permeability is not an

Question 47

synaptic functions of drugs (eight of them)

Answer 47

1) increase leakage of neurotransmitter from vesicle to cytoplasm, exposing it to enzyme breakdown
2) increase transmitter release into the cell
3) block transmitter release
4) block cleft or intracellular enzymes that metabolize transmitter
5) bind to receptor on postsynaptic membrane to block (antagonist) or mimic(agonist) transmitter action
6) inhibit transmitter synthesis
7) block transmitter reuptake
8) inhibit or stimulate second messenger activity within postsynaptic cell