Nervous System** Flashcards
What are the 3 functions of the nervous system?
Major controlling, regulatory, and communication, keeps us in touch with the internal and external environment, responsible for maintaining and regulating homeostasis
What are the 2 parts of the nervous system?
CNS and PNS
All nerves of the body residing outside of the brain and spinal cord
PNS
Consists of brain and spinal cord
CNS
Skeletal system
Somatic
Smooth muscle, cardiac muscles, glands
Autonomic
Contains the nucleus and most of the cytoplasm
Cell body
Projections that bring impulses into the neuron
Dendrite
Long projection that carries impulses away form the neuron
Axon
Insulating layer produced by Schwann cells
Myelin Sheath
Sheath formed form Schwann cells on the exterior of some axon
Neurlilemma
Gaps between Schwann cells
Nodes of Ranvier
Junction between 2 communicating neurons
Synapse
Has many processes and part of brain or spinal cord
Multipolar neuron
2 processes; eyes nose, ears
Bipolar neuron
1 process; outside the brain and spinal cord
Unipolar neuron
Carry impulses from the body part into the brain or spinal cord
Sensory neuron
Most common type of neuron that communicates from one neuron to the other; relays information
Interneurons
Carry nerve impulses out of brain or spinal cord to effectors (glands or muscles)
Motor neuron
Support neurons and phagocytize bacterial cells and cellular debris, part of the immune system
Microglial cells
Where are microglial cells found?
CNS
Provide insulating layers of myelin around axons within brain and spinal co
Oligodendrocytes
Structural support, join parts by their abundant cellular processes, help regulate concentrations of nutrients and ions within tissue
Astrocytes
Where are oligodendrocytes found?
Align along nerve fibers
Where are astrocytes found?
between neurons and blood vessels
Specialized epithelial cells in the CNS that produce CSF
Ependymal cell
Where are ependymal cells found?
brain and spinal cord
Forms a myelin sheath around axons
Schwann cells
Where are Schwann cells found?
PNS
Brings impulse to synapse
Presynaptic neuron
Receiving neuron at synapse
Postynaptic neuron
Chemical in a synaptic cleft which relays information across the gap
Neurotransmitter
Houses neurotransmitters
Synaptic vesicle
The action of the neurotransmitter on a postynaptic cell is either _______ or _____.
Excitatory or inhibatory
Turning a process on
Excitatory
Turning a process off
inhibitory
Areas of high concentration or low concentration
Gradient
There is an uneven arrangement of ions inside and outside the membrane of the neuron
Cell membrane potential
Why does a cell membrane potential occur?
There are ion pumps that for K+ into the cell and Na+ outside of the cell. There are also ion gates
In a resting neuron, all Na+ gates are ____(open or closed)
Closed
What is the result when the Na+ gates are closed?
There are more positive ions on the outside of the cell
What happens when there is a stimulus applied to a dendrite?
Na+ channels open
As the generator potential builds in the dendrite, what do the ions begin to do?
spread to the cell body and then to the initial segment of the axon
Chemicals that cross the synapse
Neurotransmitters
What do the neurotransmitters do?
Bond to receptor sites on the dendrite of the next neuron
How does the myelin sheath help?
Speeds up the process
Bring sensory information towards CNS
Afferent/sensory fibers
Carry impulses form CNS to effectors
Efferent/motor neurons
The routes that nerve impulses follow as they travel through the nervous system
Nerve pathways
Simplest of the nerve pathways
Reflex arc
Automatic Responses to a change in the environment
Reflex
What do reflexes help with?
Maintain homeostasis by controlling involuntary processes like heart rate, breathing rate, etc.
What do monosynaptic reflexes include?
2 neurons and 1 synapse
Reflex contraction of a muscle when an attached tendon is pulled
Stretch reflex
Reflexes associating with maintaining normal body posture
Postural reflex
Involves one or more integrated neurons in the reflex arc pathway
Polysynaptic
Nerve cells
Neuron
How long do neurons last?
Lifetime
Cluster of cell bodies in the CNS/PNS
nuclei
Bundle of nerve fibers running through the CNS
tracts (nerves)
Bundle of nerve fibers running through the PNS
Ganglia
What’s the difference between white and gray matter?
Gray is unmyelinated while white is
Gradient of electrochemical potential for an ion that can move across a membrane
Electrochemical gradient
The difference in electrical charge between the inside and outside of an undisturbed nerve cell membrane
Resting membrane potential
Loss of an electric charge
Depolarization
Change in cell membrane making it more negative
Hyperpolarization
Second phase of the action potential
Repolarization
What is the state of sodium channels during the resting state, depolarization, repolarization, and after hyperpolarization?
Close, close, open, close
What is the state of channels during the resting state, depolarization, repolarization, and after hyperpolarization?
Close, open, close, close
How is an action potential propagated?
Na+ ions travel down the axon; resting potential, depolarization, repolarization, hyperpolarization
The neurons responds completely not partway through
All or nothing response
What variables influence the conduction velocity of a neuron?
If it is myelinated or not, thickness of axon
Is there an accumulation of positive or negative charges in a resting neuron?
negative
A drug that blocks the opening of sodium channels
Novocaine
What are 2 important factors that drive the movement of Na+ and K+ across the membranes?
Electrochemical and concentration gradient
How many Na+ ions get out of the cell?
3
How many K+ ions get into the cell?
2
