neurons and action potential

Question 1

nervous system

Answer 1

a control system that enables animals to detect stimulus and coordinates a response by using the organism sensory organs

Question 2

neuron

Answer 2

a specialized cell that uses electrical signals and the transfer of chemicals to communicate

Question 3

parts of a neuron

Answer 3

dendrite, cell body, nucleus, axon, myelin sheath, shwann cell, axon terminal, nodes of ravnier, synapse.

Question 4

dendrite

Answer 4

carry impulses from receptors toward the cell body

Question 5

cell body

Answer 5

contains the nucleus

Question 6

axon

Answer 6

carry impulses away from the cell body

Question 7

myelin sheath

Answer 7

fatty tissues suround the axon to inslulate and maintain an electrical charge

Question 8

shwann cell

Answer 8

specialized cells that creat the myelin sheath

Question 9

axon terminal

Answer 9

site of neurotransmitter release

Question 10

nodes of ravnier

Answer 10

areas between the sections of the myelin sheath

Question 11

synapse

Answer 11

the connection between two neurons (emptry space)

Question 12

what are the three types of neurons

Answer 12

sensory neurons, motor neurons, interneurons

Question 13

sensory neurons

Answer 13

carry impulses from receptors to the brain

Question 14

motor neurons

Answer 14

carry impulses from the brain to muscles or glands

Question 15

interneurons

Answer 15

found in the brain and spinal cord and link the sensory and motor neurons

Question 16

electrochemical impulses

Answer 16

• Neurons have a rich supply of positive ions both inside and outside the cell
• Potassium ions inside the nerve cells have a tendency to diffuse outside the cell
• Sodium ions outside the cell have a tendency to move into the cell
  (under normal conditions, ie- no stimulation)
• However their diffusion is unequal- the membrane is about 50 times more permeable to potassium than sodium
• The membrane loses more potassium ions (positive) than it gains
• The membrane becomes charged or polarized

Question 17

electrochemical impulse after stimulation

Answer 17

Upon excitation, the nerve cell membrane becomes more permeable to sodium than potassium
Sodium ions rush into the cell causing a charge reversal (depolarization)
This reversal of potential is called the action potential (potential to impact little sacs of chemicals inside the axon terminal)
A sodium potassium pump allows for negative feedback (repolarization)
Tidal wave of sodium (starts close to the cell body and moves away)
- the action potential forces the synaptic vesicles in the terminal knobs to migrate toward the presynaptic membrane

Synaptic vesicle are full of neurotransmitters (eg. serotonin, dopamine)
Neurotransmitters are released by exocytosis
Neurotransmitters are dumped into the synapse and travel across to the next neuron
Neurotransmitters bind to receptors in dendrites of the next neuron which stimulates a new action potential
A single neuron may branch many times at its terminal and join with many different neurons resulting in many synapses
(One neuron can activate multiple pathways meaning their could be multiple synapses involved)

Question 18

stimulants

Answer 18

drugs that excite the neural response by increasing the release of neurotransmitters, preventing the break down within the receptor, or blocking re-uptake channels
- cause the user to become energetic, talkative, and mentally alert but also anxious and paranoid
- e.g. cocaine, ecstasy, caffine

Question 19

depressants

Answer 19

drugs that reduce neural response preventing the release of specific neurotransmitters or inhibiting the binding of neurotransmitters to receptors
- causes the user to become tired, uncoordinated and unable to focus
- e.g. heroin, fentanyl, alcohol