Neuro

Question 1

Glial Cells

Answer 1

Non-excitable

support and protect neurons

Question 2

Excitability

Answer 2

Responsive to stimulation, binding of molecules, neurotransmitters

Question 3

Conductivity

Answer 3

Electrical charges propagated along membrane

Local/short-lived or self-propagating

Question 4

Secretion

Answer 4

1. Release neurotransmitters in response to nerve impulses
2. A given neuron releases only one type of neurotransmitter with excitatory or inhibitory effect on target (1 neurotransmitter per nerve impulse)

Question 5

Extreme longevity

Answer 5

Most formed before birth/still present in advanced age

Question 6

Amitotic

Answer 6

Mitotic activity lost in most neurons

-Hippocampus is exception

Question 7

Cell body

Answer 7

(Soma) - nucleus and other organelles

Question 8

Dendrites

Answer 8

• receive signals from other neurons
• conduct signal towards soma
• branched
• not covered by myelin sheath

Question 9

Epineurium

Answer 9

Thick layer of dense irregular connective tissue, encloses the entire nerve, provides support and protection

Question 10

Perineurium

Answer 10

Layer of dense irregular connective tissue, wraps bundles of axons (fascicles) supports blood vessels – hold them to fascicles

Question 11

Endoneurium

Answer 11

Delicate layer of areolar connective tissue, separates and electrically insulates each axon, has capillaries that supply the axon

Question 12

Astrocytes

Answer 12

• The most abundant glial cells in CNS
• Cell processes touch capillary walls and neurons
• Help form blood-brain barrier that regulates passage of substances into brain
• Regulate tissue fluid composition
• Form structural network
• Assist neuronal development
• Occupy the space of dying neurons (become larger)

Question 13

Ependymal cells

Answer 13

• In CNS, line the ventricles of brain (inside) and central canal of spinal cord, these internal cavities are filled with CSF
• These cells and nearby blood vessels together form choroid plexus, which produces CSF

Question 14

Microglia

Answer 14

• Phagocytes that engulf/destroy microorganisms & cell debris; located in CNS
• The least abundant glial cells
• Hope that we do not need these
• When there is damage = more abundant

Question 15

Oligodendrocytes

Answer 15

• Form myelin sheath in CNS
• Contain slender processes which wrap around portions of many different neurons
• Individual

Question 16

Schwann cells (neurolemmocytes)

Answer 16

Flattened cells wrap around axons to form myelin sheath in PNS

Question 17

Satellite cells

Answer 17

• Flattened cells around somas in a ganglion

- Regulate exchange of nutrients and wastes b/w neurons and their environment

Question 18

Myelin

Answer 18

1. composed of neuroglia
2. it covers
3. insulates the axon
4. increases the speed of nerve impulses
5. protects

Question 19

Myelin Formation?

Answer 19

• Formed by glial cells (Schwann cells in the PNS, oligodendrocytes in the CNS) wrapping around the axons.
• Myelin is not part of, nor produced by, the nerve cell whose axon it envelops.

Question 20

Graded potentials

Answer 20

Also known as local potential - which signal over short distance

Result From:

• The permeability of neuron membrane (determined by ligand-gated K+ and Na+ channels)
• The difference in concentration of K+ and Na+ b/w intracellular and extracellular fluid

Question 21

Action potentials

Answer 21

Long distance signals

Result From:

• The permeability of resting neuron membrane (determined by voltage-gated K+ and Na+ channels)
• The difference in concentration of K+ and Na+ b/w intracellular and extracellular fluid

-Self propagating and continues at constant velocity (called a nerve impulse) - serves as a signal to communicate

Question 22

Depolarization

Answer 22

Is the reduction in membrane potential, the inside of the membrane becomes less negative, e.g., from -70 mV to -65 mV

-Increases the probability of
producing nerve impulses

Question 23

Repolarization

Answer 23

Is the increase of in membrane potential, the inside of the membrane becomes more negative, e,g., -65 mV to -70 mV

Question 24

Hyperpolarization

Answer 24

Is the increase of membrane potential above RMP(the inside of the membrane becomes more negative than resting potential),
e,g., -70 mV to -75 mV

-Reduces the probability of
producing nerve impulses

Question 25

Characteristics of action potential:

Answer 25

1. Produced by voltage-regulated channels 2. Always begins with depolarization 3. All or none (does not occur at all, or exhibits the same peak voltage regardless of stimulus strength) 4. Irreversible 5. Self-propagating 6. Non-decremental – also goes to same peak voltage

Question 26

Axon

Answer 26

- Conducts signal away from soma - Longer than dendrites - The first part is axon hillock where axon emerges from soma, and where the action potential summates

Question 27

Axon Structure

Answer 27

- Axoplasma - inside - Axolemma - outside - Each neuron has one axon, divided into many braches, each branch is called a telodendrion or axon terminal -Each telodendrion ends in a synaptic knob, which forms a synapse with another neuron or cell of the target organ

Question 28

Multipolar neurons

Answer 28

- Many processes extend from soma, one is axon, the others are dendrites - The most abundant neuron in body - Interneurons (CNS), motor neurons

Question 29

Bipolar neurons

Answer 29

-One axon, one dendrite -Two processes extend from soma: axon dendrites -Rare, found in some special sensory organs (specific): olfactory cells neurons of retina sensory neurons of inner ear

Question 30

Unipolar neurons

Answer 30

- Sensory neurons - Single, short neuron process extends directly from soma - Axon includes peripheral process (dendrites to cell body) and central process (cell body into CNS) - Sensory neurons with soma located in ganglia - Placed where they are protected (very close to spinal cord – dorsal/posterior root ganglion)

Question 31

Sensory (afferent) neurons

Answer 31

-Transmit the signals to CNS, -Some can detect stimuli (e.g., light, heat, pressure, chemicals) as well as transmit the signals to CNS their somas are located outside the CNS in posterior root ganglia, their axons synapse with the interneurons in CNS -Most are unipolar neurons a few are bipolar neurons (in olfactory epithelium and retina)