Chapter 1.3 (page 7) Flashcards
What are whitish, fatty, segmented sheaths that many nerve fibres are covered with?
Myelin sheaths
What are the 2 cells that produce myelin sheaths in the body?
Schwann cells
Oligodendrocytes
Schwann cells along with the axon do not touch and leave gaps called ________________.
Nodes of Ranvier
What is an electrical signal or disturbance that carries a message that travels along the surface of neurons in a tract (CNS) or a nerve (PNS)?
This has to be started or initiated by a stimulus such as pressure, temperature or chemical changes.
Nerve impulse
A nerve impulse travels in one direction, either toward the CNS over sensory nerves or away from the CNS over motor nerves, toward effector organs; muscles or glands.
Nerve impulses travel along ___________ faster than along _____________ neurons.
Myelinated
Unmyelinated
A ________________ (nerve impulse) occurs on the dendrite or cell body of a neuron.
While an ________________ (nerve impulse) only occurs on the axon of a neuron.
Graded potential
Action Potential
The outside of the neuron’s plasma membrane and the inside of the cell are positively charged due to the presence of ___________.
Sodium ions (Na+)
____________________ is a type of action potential that occurs when an impulse encounters myelin on the whole length of the axon. This type is simply a ‘jump’ of the imulse around the myelin.
Saltatory Conduction
What are 3 structures that make up a synapse?
Synaptic knob
Synaptic cleft
Plasma membrane of post-synaptic neuron or effector
_____________: These cells wrap themselves around axons of some
nerve fibres found in the PNS.
Schwann cells
The outer cell membrane of the
Schwann cell is called the _________ and can play an important role in the regeneration of cut and injured axons.
neurilemma
Schwann cells along
with the axon do not touch and leave gaps called ______.
Nodes of Ranvier
____________: These cells coil around many different axons in the CNS. They lack Neurilemma. Nodes of Ranvier are present but further apart.
Oligodendrocytes
A _____________ is an electrical signal or disturbance that carries a message
that travels along the surface of neurons in a tract (CNS) or a nerve (PNS).
nerve impulse
An impulse has to
be started or initiated by a stimulus such as _________ ___________ ____________.
pressure, temperature or chemical changes.
A
nerve impulse travels in _______ direction, either toward the CNS over ________ or away
from the CNS over __________, toward effector organs; muscles or glands.
one
sensory nerves
motor nerves
A nerve impulse (___________ or _________) is a self-
propagating wave of electrical disturbances that travel along
the surface of a neuron’s plasma membrane.
graded potential or action potential
A ___________ occurs on the dendrite or cell body of aneuron. An _______ only occurs on the axon of a neuron.
graded potential
action potential
________ allow nerves to communicate with each other by generating and propagating graded and action potentials.
Nerve impulses
________________ must be initiated by a stimulus; pressure, temperature, chemical changes, etc. If the stimulus initiates a
______“________, the potential has to reach the neuron’s axon in order to generate an action potential.
Graded potentials
The inside of the cell is also positively charged, but there is ____
sodium inside the cell than outside the cell therefore we can say that the inside of the
cell has a __“__ than positive charge as compared to the outside of the neuron; or we
can say the inside of the neuron is _____ charged.
less
less
negatively
Resting neuron membrane
potential range is _______ (average______)
- 40 to -90
- 70 millivolts
