Neural Tissue for Final EXAM Flashcards
what are the subdivisons of the nervous system
central nervous system
peripheral nervous system
what organs make up the central nervous system (CNS)
brain
spinal cord
what are the subdivisions of the peripheral nervous system
sensory divison
motor divison
what does the sensory division do?
carries signals from receptors to CNS
what are the subdivisions of the sensory division
Visceral sensory division
Somatic sensory division
Special senses
what does the Visceral sensory division do?
carries signals from the viscera (heart, lungs, stomach, and urinary bladder)
what does somatic sensory division do?
carries signals from receptors in the skin, muscles, bones, and joints
what are the subdivisions of the motor division
Visceral motor division
Somatic motor division
what does motor division do
carries signals from CNS to effectors (glands and muscles that carry out the body’s response).
what does Somatic motor division do?
carries signals to skeletal muscles leading to muscular contraction and somatic reflexes (involuntary muscle contractions).
what does visceral motor division do?
carries signals to glands, cardiac and smooth muscle. Its involuntary responses are visceral reflexes.
what is another name for visceral motor division
autonomic nervous system
what are the subdivisions of the visceral motor division
Sympathetic division
Parasympathetic division
what is the responsibility of the Sympathetic division
is responsible for the fight or flight response. It tends to arouse the body for action. It increases the heart rate, heart contractility, respiratory rate, but inhibits digestive and urinary systems.
what is the responsibility of the Parasympathetic division
is responsible for the rest and digest response. It slows heart rate, breathing but stimulates digestive and urinary systems.
What makes up the Peripheral nervous system (PNS)
the entire nervous system except the brain and spinal cord
(nerves and ganglia)
carries signals from receptors to CNS
Sensory (afferent) division
what are the two components of the autonomic nervous system
Sympathetic nervous system
Parasympathetic nervous system
what are the cells of the nervous tissue
neurons
neuroglia
cells used for communication by the nervous tissue
Neurons
Supporting cells of the nervous tissue
Neuroglia
what are the three classes of neurons
Sensory neurons
Interneurons
Motor neurons
Detect stimuli and transmit information about them toward the CNS
Sensory neurons
Receive signals from many neurons, integrates, processes and determines the appropriate response. Lie entirely within CNS connecting motor and sensory pathways (about 90% of all neurons).
Interneurons
Send signals out to muscles and gland cells (the effectors).
Motor (efferent) neurons
contains the nucleus and other structures common to living cells
soma
Multiple branches that come off the soma responsible for receiving signals from other neurons
Dendrites
the elongated portion of the neuron located in the center of the cell between the soma and terminals
axon
the region of a neuron that controls the initiation of an electrical impulse based on the inputs from other neurons or the environment
axon hillock
swellings that form contact points (synapses) with other cell, contains synaptic vesicles full of neurotransmitter
Axon terminals
what are the neuroglia of the central nervous system (CNS)
Ependymal cells
Astrocytes
Microglia
Oligodendrocyte
Cuboidal epithelium with cilia on apical surface that line internal cavities of the brain. They secrete and circulate cerebrospinal fluid (CSF).
Ependymal cells
Most abundant glia in CNS. Star shaped cells that cover brain surface and most non synaptic regions of neurons.
Astrocytes
Macrophages that develop from white blood cells (monocytes) and become concentrated in areas of damage.
Microglia
Octopus like cells with arm-like processes that wrap around nerve fibers forming myelin sheaths in CNS that speed signal conduction.
Oligodendrocytes
what are the neuroglia of the peripheral nervous system
Schwann cells
Satellite cells
Wind around the axon and form myelin sheaths. Assist in regeneration of damaged fibers.
Schwann cells
Surround the somas of PNS neurons inside ganglia. They provide electrical insulation and regulate the chemical environment.
Satellite cells
Consists of the plasma membrane of glial cells, made up of 20% protein and 80% lipid.
myelin
what are the function of myelin
Provides insulation around the axon and increases action potential conduction velocity.
what is the myelin formed by in the CNS
Oligodendrocytes
what is the myelin formed by in the PNS
Schwann cells
what are the factors that can affect the speed of conduction
Diameter of the fiber
Presence of myelin
how does the diameter affect conduction
Larger axons have more surface area and conduct signals more
rapidly.
how does the Presence or absence of myelin Presence or absence of myelin
Myelin speeds signal conduction. Many neurons have unmyelinated axons and they have slower signal conduction compared to myelinated axons.
what is the resting membrane potential of neurons
-70 mV
how is the resting membrane potential of neurons made
Caused by separation of charge (ions) across the cell membrane with the inside of membrane negative relative to outside
- Moves 3 Na+ out of the cell and brings 2 K+ into
the cell using 1 ATP - Helps create and maintain the sodium and
potassium ion concentration gradients across the
membrane.
Na+/K+ pump
At normal resting membrane potential, an electrical gradient opposes the chemical gradient for potassium ions (K+). The net electrochemical gradient tends to force potassium ions out of the cell.
Potassium Ion Gradients
At the normal resting membrane potential, chemical and electrical gradients combine to drive sodium ions (Na+) into the cell.
Sodium Ion Gradients
Change in membrane potential at and nearby point of stimulation may be a depolarization or a hyperpolarization.
Local potential
Rapid up-and-down shift in membrane potential that can travel a long distance down an axon. Always a rapid depolarization followed by repolarization and hyperpolarization.
Action potential
Two types of change in membrane potential:
Local potential
Action potential
shift in the voltage across the membrane to a less negative value
Depolarization
shift in the voltage across the membrane to a more negative value.
Hyperpolarization
label this
Period of resistance to stimulation during an action potential and for a few milliseconds after when it is difficult or impossible to initiate another action potential.
Refractory period
what are the Refractory period two phases
relative refractory period
absolute refractory period.
A stronger stimulus than usual is needed to trigger a new AP. During hyperpolarization, a larger depolarization (local potential) is required to reach threshold for another action potential to be triggered
relative refractory period
No stimulus of any strength will trigger another action potential due to inactivation of voltage-gated Na+ channels.
absolute refractory period.
occurs in unmyelinated axons that have voltage-gated channels along their entire length.
continuous propagation
in myelinated axons where electrical signal seems to jump from node to node. Moves faster through “insulated” segments covered with myelin and slows down when it reaches the bare axon of the nodes.
saltatory propagation
a small gap at the end of a neuron that allows a signal to pass from one neuron to the next.
Synapses
which releases neurotransmitter and transmits the signal toward a synapse
Presynaptic neuron
responds to neurotransmitter
postsynaptic neuron
- Axon terminal of presynaptic neuron contains
synaptic vesicles containing neurotransmitter. - Postsynaptic neuron membrane contains
neurotransmitter receptors. The neurotransmitter
receptors are ligand-gated ion gates that open
when neurotransmitters bind to them.
chemical synapse
what are the events that lead to the cessation of the signal
Degradation
Reuptake
Diffusion
how does the cessation of the signal occur
Presynaptic cell stops releasing neurotransmitter
Enzyme in synaptic cleft breaks down neurotransmitter
Degradation
Neurotransmitter (or its breakdown products) reabsorbed into axon terminal
Reuptake
Neurotransmitter (or its breakdown products) simply diffuse away from synapse into nearby ECF
Diffusion
are chemicals secreted by neurons that have long term modulatory effects on groups of neurons
Neuromodulators
- is a simple neuromodulator
- Gas that enters postsynaptic cells and
activates second messenger pathways
Nitric oxide (NO)
is a voltage change from Resting membrane potential towards threshold and usually results from Na+ flowing into the cell
Excitatory Postsynaptic Potential (EPSP)
occurs when the cell’s voltage becomes more negative than it is at rest
Inhibitory Postsynaptic Potential (IPSP)
is the process of adding up postsynaptic potentials and responding to their net effect which occurs in the trigger zone.
Summation
what are the two types of Summation
Temporal summation
Spatial summation
Occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades. Allows EPSPs to add up over time to a threshold voltage that triggers an action potential.
Temporal summation
Occurs when EPSPs from several different synapses add up to threshold at an axon hillock. Simultaneous input from multiple presynaptic neurons are required for the postsynaptic neuron to fire.
Spatial summation
occurs when one presynaptic neuron enhances another one
Presynaptic facilitation
occurs when one presynaptic neuron suppresses another one
Presynaptic inhibition
ability of synapses to change
Synaptic plasticity
process of making transmission easier
Synaptic potentiation
may last a lifetime and can hold more information than short term memory.
Long term memory (LTM)
memories you can put into words
Explicit
