← Test 3, Chapter 11 Test
5 Written Questions
5 Matching Questions
- How does nerve tissue respond to injury? What cells are responsible for the repair? Where can it occur?
- What is the role of the Schwann Cell in the formation of the myelin sheath. What is the neurilemma? What is a node of Ranvier? Are nodes of Ranvier in both the CNS and the PNS?
- What are the two major divisions of the nervous system? Name the three subdivisions of the PNS, and tell how they differ in functions. What are the two subdivisions of the Motor pathway system?
- Exactly what is a nerve?
- Axons are classified into 3 groups according to the relationship between diameter, myelination and propagation speed: define Type A, B and C fibers.
- a Schwann Cell wraps around the axon to form the myelin sheath.
Neurilemma is the plasma membrane of a neuron
Ranvier is the space between mylination
- b In CNS, it doesn't heal.
In PNS, if mylineation cells are still in tact, they will reform a path for the neuron to grow.
Schwann Cells or Oligodendricites
- c Type A - large-diameter, myelinated. Conduct at 15-120 m/s. Motor neurons supplying skeletal and most sensory neurons
Type B - medium-diameter, lightly myelinated. Conduct at 3-15 m/s. Part of ANS
Type C - small-diameter, unmyelinated. Conduct at 2 m/s or less. Part of ANS
- d Central Nervous System (CNS) and Peripheral Nervous System (PNS)
Autonomic (involuntary). Within this, there are Sympathetic (Fight or Flight) and Parasympathetic (Rest and digest).
- e A bundle of neurons that travel to and from the same place.
5 Multiple Choice Questions
- spatial variation of both electrical potential and chemical concentration across a membrane.
- Presynaptic - The neuron that sends the action potential to the next dendrite
Postsynaptic - Receives the message
Convergence of Neurons - First one neuron is influenced by many others, resulting in a convergence of input.
Divergence of Neurons - When the neuron fires, the signal is sent to many other neurons, resulting in a divergence of output.
- Depolarization - Potential difference becomes smaller or less polar. If extracellular concentration of K+ increases, there is less gradient between inside and outside.
Hyperpolarization - Potential difference becomes greater or more polar. If extracellular concentration of K+ decreases, steeper gradient between inside and outside
- Cell bodies found in gray matter
Because the tissue is composed of fatty tissue.
5 True/False Questions
If a neuron synapses on a second neuron and drives the resting membrane potential further from threshold, what is this called? Where does it occur? → IPSP, Inhibitory Post Synaptic Potential.
Name the 3 types of neurons (based on structure). → In the spinal cord
What is a graded potential? Can it travel a long distance? Why or why not? → A change in the membrane potential that is localized to one area of the plasma membrane. Also known as local potentials.
Cannot travel long distances because they spread in a decremental fashion. They rapidly decrease in magnitude as they spread over the surface of the plasma membrane (teacher's voice in a large lecture hall)
What is a monosynaptic reflex? Name the elements necessary in a polysynaptic reflex arc. → 3 Na out, 2 K in
Do CNS nerve fibers generally regenerate? → Not really.