The nervous system Flashcards
The nervous sytem is all about ….?
information and control
What does the nervous system do?
receives, processes, an distributes information by way of nerve impulses, and it directly or indirectly controls nearly all body functions.
What is the basic functional unit of the nervous system?
the neuron (nerve cell)
What two main divisions does the nervous system have?
Central nervous system and Peripheral nervous system
The Central nervous system is composed of ?
brain and spinal cord
The peripheral nervous system consists of _____ nerves that link the CNS with the ____________?
cordlike nerves rest of the body
The nervous system’s activities fall into 3 main categories ,what are they?
1) sensory functions 2)integrating functions 3) motor functions
In the brain and spinal cord the sensory information is received, analyzed stored, and integrated to produce a response.
A motor response instructs the body to do something such as contract a muscle
The neuron can be divided roughly into what?
a cell body
extensions - dendrites and axons
dendrites receive stimuli, or impulses from other neurons
axons - conduct nerve impulses away from the cell body toward another neuron or an effector cell (a cell that does something when stimulated, such as a muscle or gland cell)
What are the nodes of Ranvier?
located between adjacent glial cells are small gaps in the myelin sheath
- enhances the speed of conduction of nerve impulses along the axon
What are afferent nerves?
conduct nerve impulses toward the CNS (ad means toward) - ferre means carry
What are efferent nerves?
conduct nerve impulses away from the CNS (ex - away)
What is the direction of impulses?
Afferent vs efferent A comes before E
What are afferent nerves also called when they conduct sensations from the sensory receptors in the skin?
sensory nerves
What are efferent nerves called when they are the ones that cause skeletal muscles contraction and movement?
motor nerves
What is the Somatic nervous system’s function?
a conscious, or voluntary control of skeletal muscles
What is a autonomic nervous system?
part of the nervous system that controls and coordinates these automatic functions also called self-regulating system
What are examples of autonomic nervous system?
Blood pressure receptors inform the body that the pressure is too low
When a neuron is in a resting state, what does this mean?
it means a neuron is not being stimulated - even resting it is still working - it has to work at staying at the resting state
- active rest - has the potential to work
- electronically polarized at rest (like tiny charge batteries
What is the sodium potassium pump?
- specialized molecules located in the neuron’s cell membrane pump Na ions from the outside of the neuron to the inside and pump K ions from the inside to the outside
How much of the Na and K can the sodium potassium pump, pump at one time?
2 Na in and then the gate closes and 3 K go out
The cellular membrane separating Na and K is said to be polarized, why?
because it has 2 distinct poles of ions on either side of the membrane - this is accomplished by keeping Na (outside) on one side and K (inside) on the other side
What causes the negative charge in the cell and across the membrane?
the distribution of positive and negative charges from sodium, potassium, proteins, and other charged ions being more negative in the inside than the outside
What is the resting membrane potential?
the electrical difference in charges across the membrane
What is the net negative charge within the cell?
-70mV
What keeps this negative charge within the cell (the resting membrane potential?
the sodium potassium pump
What is depolarization?
when neuron receives enough stimulation (finger burning) eventually will fire. The Na channel will open and Na will flood in (not as strong)
- because the Na influx results in the loss of 2 distinct poles of Na and K on either side of the membrane
What makes the Na channel only allow sodium ions to pass?
because a higher concentration of Na is on the outside than on the inside. Na readily flow through open Na channels from outside to inside by passive diffusion
Sodium is also driven into the cell by?
by the concentration gradient (the difference between the concentration of the outside and the inside) and the positive Na ions are attracted to the net negative charge inside the cell
When does the cell go from a negatively charged resting membrane potential to a net positive charge?
During depolarization
What is action potential?
the significant change in electrical charge from negative to positive
What is repolarization?
the change of the cell’s charge back toward the net negative resting membrane potential
the only difference is that the Na and K are not in their original spots, they are in the opposite spots
What restores the Na/ K back to original locations?
needs ATP and the Na/K pump
What causes the cell to depolarize or fire?
it has reached the threshold - stimulus is strong enough
What is a threshold stimulus?
a stimulus of sufficient intensity to generate a nerve impulse
What is wave depolarization?
the wave of sodium channels opening to allow sodium influx (also called conduction of the action potential)
What is a nerve impulse?
this wave of depolarization or conduction of the action potential along the cell membrane
What is the all-or-nothing principle?
If the initial stimulus was strong enough to reach threshold, the action potential would be generated and conducted along the entire neuron with a uniform strength
- either the complete neuron depolarizes to maximum strength or it doesn’t depolarize
What is the refractory period?
means that the neuron is insensitive to new stimuli until it recovers from the previous nerve impulse
What is absolute refractory period?
the cell absolutely cannot respond
What is relative refractory period?
if a very large stimulus comes during the tail end of repolarization, it may be possible to stimulate anther depolarization.
What is salatory conduction?
a nerve impulse jumps from one node of Ranvier to the next, producing rapid conduction of the nerve impulse
