Chapter 10 - NS

Question 1

Cells in the NS

Answer 1

• Neurons: respond to neural stimulus
• Neuroglia: protect, support, insulate and nourish neurons
• Don’t conduct electrical impulses but are much more numerous

Question 2

Sensory:

Answer 2

• afferent neurons
• Detects sensory information, converts it into impulses and conducts it to the CNS

Question 3

Motor

Answer 3

• Efferent Neurons
• Receives information from the CNS, transmits the message to effectors and causes action

Question 4

Migranes

Answer 4

Occurs due to a period of excitation followed by unresponsiveness in particular neurons which stimulates the production of pain sensation in areas at base of the brain
- Signs: pounding head, nausea, light or sound sensitivity
- Can be caused by bright light, certain foods, lack of sleep, stress
Treatment:

Question 5

Neuron Structures

Answer 5

• Cell body(soma): contains nucleus, cytoplasms
  
  • Dendrites: branched receptor surfaces
  • Axon: s
    ○ Axon hillock: cone shaped area of cell body from which axon arises
    ○ Collaterals: branches of axon
    ○ Axon terminal
    - Synaptic knob: rounded ending

Question 6

Schwann Cells

Answer 6

neuroglia of the PNS that wrap around some axons in layers
○ Myelin: mixture of fats and proteins
○ Myelin sheath
- Nodes of ranviers: gaps of nonmyelinated axons

Question 7

Myelinated Axons

Answer 7

• Coated by a myelin sheath
  
  • Makes up white matter in the CNS
    
    • Produced by oligodendrocytes(brain) and Schwann cells(spinal cord)

Question 8

Multiple Sclerosis

Answer 8

autoimmune disease in which the destruction of myelin sheaths leave scars(scleroses) behind which stop neurons from conducting impulses

Question 9

2 types of Classifications of Neurons

Answer 9

Structural Classification: how many
- Multipolar
- Bipolar
- unipolar

Functional Classification: direction of impulse transfer
- Sensory
- Interneurons: link neurons within the CNS
- motor

Question 10

Functions of Neuroglia

Answer 10

• Provide support for neurons
  
  • Guide neurons into position
  • Produce GF to nourish neurons
    
    • Help support synapsis building

Question 11

Types of Neuroglia

Answer 11

• Astroctyes: connect neurons to blood vessels
  ○ Part of the blood brain barrier
  
  • Oligodendorcytes: myelinate axons in the CNS and provide structural support
  • Microglia: phagocytic cells which also provide structural cells
  • Ependyma: help regyulate and circulate spinal fluid
  • Schwann cells: produce myelin sheath and speed up nerve signal transmission
    
    • Ganglia: support clusters of neuron cell bodies

Question 12

Neuron Regeneration in the CNS

Answer 12

• Do not regenerate as there is no neurilemma acting as a guiding sheath
  - Oligodendrocytes do not regenerate

Question 13

Neuron Regeneration in the PNS

Answer 13

• Peripheral nerons can regenerate due to the presence of shwann cells and neurilemma which can provide the guiding sheath for a regrowing axon

Question 14

Action Potential

Answer 14

a sequence of electrical events in an excitable cell involving changes in membrane potential to allow communication between cells

• cell membrane is normally polarized or internally negatively charged

Question 15

Process of ACtion Potential

Answer 15

Resting membrane potential:
- About -70mV
Due to greater potassium inside the cell and greater sodium outside the cell

Depolarization:
- Stimulus of some sort opens up sodium channels, allowing a flood of Na into the cell
As NA moves into the cell, it stimulates nearby channels to open up, creating a moving action potential down the axon

Repolarization:
- Flood of Na into the cell stimulates K to move to the outside of the cell
- Creates a positive membrane potential inside the cell temporarily

Hyperpolarization:
- Na/K pump restores resting membrane potential back to a negative charge inside the cell, allowing the cell to be restimulated again
- Does this by moving 3Na outside the cell for every 2K moved inside

Question 16

Types of Axon Transmition

Answer 16

Saltory Conduction: action potentials jump from node to node down the axon which is faster

impulse conduction: Unmyelinated axons transmit impulses over the entire length of the axon which is slower

Question 17

Neurotransmitters

Answer 17

• Acetylcholine: stimulatory transmitter which controls skeletal muscle contraction
  
  • Norepinephrine: creates a sense of well being
  • Dopamine: creates a sense of well being
  • Serotonin: primary inhibitor which leads to sleepiness
    
    • Histamine: promotes alertness