Nervous System Flashcards
Cells type in the neural tissue and does many other functions
Neurological cells
A cell type in neural tissue that transmit impulses
Neurons
Brain and spinal cord
Central nervous system (CNS)
Cranial nerves and spinal nerves
Peripheral nervous system (PNS)
Sensory receptors gather information and informant ions carried to the CNS
Sensory function.
Sensory information used to create sensations, memory, thoughts, decisions
Integrative function.
Decisions are acted upon
Impulses are carried to effectors
Motor functions
A division of motor functions of PNS- transmits impulses to skeletal muscles
Somatic
Division of motor functions if PNS- transmits impulses to smooth muscles, cardiac muscle and glands
Autonomic
Part of a neuron in the nervous system- transmits impulses and releases neurotransmitter to another neuron or effector
Axon
Axons which are tightly wrapped by neuroglial cells which are termed what?
Myelinated
Contains myelinated axons
Considered fiver tracts
White matter
Contains I myelinated structures
-cell bodies, dentrites
Gray matter
Due to structural differences, neurons can be classified into 3 major groups
Bipolar neurons
Unipolar neurons
Multipolar neurons
Two processes
Eyes, ears, nose
Bipolar neurons
One process
Ganglia of PNS
sensory
Unipolar neurons
Classification of neurons: Afferent Carry impulse to CNS Most are unipolar Some are bipolar Ex: from senses to CNS
Sensory neurons
Classification of neurons; Links neurons Multipolar Located in the CNS Found inside brain and spinal cord
Interneurons
Classification of neurons:
Multipolar
Cary impulses away from CNS
Carry impulses to effectors
Motor neurons
Types of neuroglial cells in the CNS
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependyma or ependymal
- scar tissue
- aid metabolism if certain substances
- induce synapse formation
- connect neurons to blood vessels
- part of blood brain barrier
Astrocytes
Myelinating cell
Oligodendrocytes
Phagocytize cell
Microglia
Ciliated
Line central canal of spinal cord
Line ventricles of brain
Ependyma or ependymal
Types of neuroglial cells in the PNS
Schwann cells
Satellite cells
Produces myelin found on peripheral myelinated neurons and Soren up neurotransmission
Schwann cells (PNS)
Support clusters of neuron cell bodies (ganglia)
Satellite cells (PNS)
Neurons can not divide
If cell body is injured, the neuron usually if a peripheral axon is injured it may regenerate
Neuroglia and axonal regeneration
If it transmits neurons toward the post neuron
Pre-synaptic neuron
When transmitters are going away from the post
Post- synaptic neuron
Are released when impulse reaches synaptic knob
Neurotransmitters
A cell membrane is usually electrically charged, or polarized, so that the inside of the membrane is negatively charged with respect of the outside of the membrane ( which is then positively charged)
This is as a result of unequal distribution of ions on the inside and outside of the membrane
Cell membrane potential
Potassium K+ ions are the major intercellular positive ions (cations)
.
Sodium Na+ ions are the major extracellular positive ions
.
A polarized membrane and inside of the cell is negative relative to the outside of the cell
Resting membrane potential (RMP)
Caused by various stimuli: Temperature changes Light Pressure Chanel's are 1: chemically gated 2: voltage gated or 3; mechanically gated
Local potential changes
At rest the membrane is polarized
RMP= -70
Sodium channels open and membrane does what?2
Depolarize
Potassium leaves cytoplasm and membrane does what?
Re polarizes (+30)
Brief Period of what (-90)
Hyper polarization
As Na+ moves into the membrane depolarizes until it reaches +30 mV
Action potential
As membrane potential drops below -70mV the membrane is what?
Hyper polarized
K+ moves out of membrane and then does what?
Repolarizes
Is conducted whenever a stimulus of threshold intensity or above is applied to and axon
Nerve impulse
If a neuron axon responds at all, it responds completely- with an action potential
Nerve impulse
All impulses carried on an axon are what?
The same strength
Myelinated axons transmit impulses through what? Which is faster than impulses along unmyelinated axons.
Saltatory conduction
1st event leading to nerve impulse conduction
Nerve cell membrane maintains resting potential by diffusion of Na+ down their concentration gradients as the cell pumps
2nd event leading to nerve impulse conduction
Neurons receive stimulation, causing local potentials, which may sum to reach threshold
3rd event leading to nerve impulse conduction
Sodium channels in the trigger zone in the axon open
4th event leading to nerve impuls conduction
Sodium ions defused inward, depolarizing the membrane
5th event leading to nerve impulse conduction
Potassium channels in the membrane open
6th event leading to nerve impulse conduction
Potassium ions diffuse outward, repolarizing the membrane
7th event leading to nerve impulse conduction
The resulting action potential causes an electric current that stimulates adjacent portions of the membrane
8th event leading to impulse conduction
Action potentials occur sequentially along the length of the axon as nerve impulse
