nerves 2

Question 1

neuron classification

Answer 1

-interneurons (association neurons)

Question 2

interneurons

Answer 2

• located mostly within the CNS
• Interconnect among nerve cells
• function in processing

Question 3

nerve cells (neurons)

Answer 3

electronically active cells that process and conduct information in the form of electrical cells

Question 4

neuroglia (glial cells)

Answer 4

several kinds of support cells

Question 5

PNS glial cells

Answer 5

satellite cells, schwann cells

Question 6

CNS glial cells

Answer 6

oligodendrocytes, astrocytes,

Question 7

Satellite cells in the PNS

Answer 7

surround neuron cell bodies within ganglia

Question 8

Schwann cells in the PNS

Answer 8

• ensheath axons and dendrites in the PNS
• unmyelinated axons- Schwann cell ensheathe sections of many axons
• myelinated axon- Schwan cell ensheathe a section of a single axon
• Nodes of Ranvier-gaps between Schwann cells

Question 9

oligodendrocytes

Answer 9

surround myelinated and unmyelinated CNS axons

Question 10

Astrocytes

Answer 10

• largest and most numerous
• structural support; scar tissue formation
• regulate interstitial fluid components
• blood brain barrier

Question 11

Blood brain barrier

Answer 11

-isolates neural tissue from general circulation
-restricts migration of cells and diffusion of molecules out of capillaries of brain
- -tight junctions between endothelial cells
-astrocytes cover capillary surfaces
-restricts diffusion of CSF out of ventricles
–tight junctions between ependymal cells
-incomplete barrier in areas
parts of the hypothalamus, pituitary gland, pineal gland

Question 12

microglia

Answer 12

phagocytic cells- remove debris, pathogens, etc.

Question 13

ependymal cells

Answer 13

• line chambers w/in CNS
• circulate CSF
• produce CSF in choroid plexus regions

Question 14

Damage repair mechanisms of the CNS and PNS

Answer 14

• Damage to nerve cell soma -> neuron death
  
  • few if any germinative cells in adult brain
• damage to nerve cell axon in CNS
  
  • Oligodendrocytes reabsorb myelin
  • astrocytes fill in area forming scar tissue
  • growth inhibiting factors secreted by oligodendrocytes and astrocytes
• Damage to nerve cell axon in PNS
  
  • Schwann cell myelin pathway can guide regenerating axons and sensory dendrites

Question 15

electricity

Answer 15

flow of electrons

-force is an electrical gradient

Question 16

bioelctricity

Answer 16

flow of ions

-force is chemical gradient and electrical gradient combined

Question 17

active transport

Answer 17

maintain concentration gradients,

-sodiums ions out of cell and potassium ions into cell

Question 18

gated ion channels

Answer 18

pathway for ion flow across the cell membrane

• chemically gated
• voltage gated
• mechanically gated

Question 19

gated channels open in response to various signals (stimuli)

Answer 19

• ions flow across membrane by diffusion down their concentration gradient
• typically stay open only briefly

Question 20

local current

Answer 20

• driving force is concentration gradient created by ions coming across membrane through open channels
• ions trave a short distance through cytoplasm or interstitial fluid
• happens anytime an ion channel is opened

Question 21

local current and interstitial fluid

Answer 21

• cytoplasm and interstitial fluid have high resistance to ion flow
• depolarization or hyperpolarizaiton effect decreases with distance from open channel.

Question 22

bioelectricity of local currents

Answer 22

• Local currents (graded potentials) transmit bioelectric signals over short distances
• Typical of dendrites & cell bodies in NS

Question 23

bioelectricity of action potentials

Answer 23

Action potentials needed to transmit bioelectric signals over long distances

• Typical of axons
• Typical of long dendrites of unipolar and bipolar sensory neurons
• Unique to “excitable” cells