Unit 8 Flashcards
Neuron job
-Collect information, monitor and change stimuli
-Process and evaluate info: determine response
-initiate response through effectors
What is involved in the nervous system
Brain, spinal cord, nerves, ganglia
Cell body
the core of the cell that surrounds and protects
Axon
where electrical impulses from the neuron travel away to be received by other neurons. This where propagation happens.
Dendrites
receive information. Transmit graded potential along the plasma membrane
Synaptic Knob
Contains neurotransmitters
Axon Hillock
the region of a neuron that controls the initiation of an electrical impulse based on the inputs from other neurons or the environment. The electrical part of the electrochemical signal is called an action potential.
Synapse
transmission of nervous impulses from one neuron to another. Neurons are specialized to pass signals to individual target cells, and synapses are the means by which they do so.
Synaptic cleft
The space between two neurons across which the impulse is transmitted by a neurotransmitter is known as synaptic cleft
Myelin
an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord
Nodes of Ranvier (nerurofibrial node)
specialized regions in the axonal membrane that are not insulated by myelin.
Multipolar neurons
has multiple processes extending from the cell
Bipolar neurons
has 2 processes extending directly from the cell
unicellular neuron
dingle process extends directly from the cell and looks like a T
Sensory (afferent) neurons
Conduct sensory input from both somatic sensory and visceral sensory, Most are unipolar
Motor neurons
neurons of the motor nervous system. Conducts motor output away from the CNS to both somatic effectors and autonomic effectors. All are multipolar
Interneurons
Lie entirely within the CNS, they receive stimulation from neurons recieve, process, and store infant decide how the body responds to stimuli. Facilitated communication between sensory and motor neurons
Resting Membrane Potential
A resting (non-signaling) neuron has a voltage across its membrane called the resting membrane potential, or simply the resting potential. The resting potential is determined by concentration gradients of ions across the membrane and by membrane permeability to each type of ion.although the inactivation gate is open, the activation is closed and entry of Na+ is prevented
Electrochemical gradient
The electrochemical gradient determines the direction that ions will flow through an open ion channel and is a combination of two types of gradients: a concentration gradient and an electrical field gradient
Ligand-gated ion channels
channels respond to a neurotransmitter and are concentrated in the synapse
Voltage-gated ion channels
Respond to changes in the transmembrane electrical potential and are mainly located along the neuronal axal
Mechano-gated ion channels
respond to mechanical deformation
Graded potentials
primarily generated by sensory input, causing a change in the conductance of the membrane of the sensory receptor cell. Causes voltage gated Na+ channels to open.
Depolarizing graded potential
Depolarizing graded potentials are often the result of Na+ or Ca2+ entering the cell. Both of these ions have higher concentrations outside the cell than inside; because they have a positive charge, they will move into the cell causing it to become less negative relative to the outside.
Hyperpolarization graded potential
Hyperpolarizing graded potentials can be caused by K+ leaving the cell or Cl– entering the cell. If a positive charge moves out of a cell, the cell becomes more negative; if a negative charge enters the cell, the same thing happens.
Action potential
-minus 55 is threshold for the action potential
-An action potential is a signal which travels the length of a neuron
-if a neuron receives a threshold stimulus an AP is a produced and spread down the axon of the neuron to axom terminals
-If the stimulus is not strong enough, no AP will result
Repolarization phase
K+ channels open and K+ rushes outward.
The cell returns to a progressively more negative state until the RMP of -70mV is once again restored
Depolarization phase
Graded potentials depolarize the neuron from -70mV to threshold (-55mV) to cause an action potential
After-hyperpolarization phase
While the voltage-gated K+ channels are open, outflow of K+ can cause an after-hyperpolarizing phase of the action potential.
Membrane potential becomes even more negative (~ -90mV)
as the voltage-gated K+ channels close, the membrane potential returns to the resting level of -70mV
Absolute Refractory Period
the brief interval after a successful stimulus when no second shock, however maximal, can elicit another response.
Relative Refractory Period
the interval of time during which a second action potential can be initiated,
NeurotransmitterAction potential lead to the release of
Neurotransmitter
Neurotramission release can cause
Excitatory postsynaptic potential (EPSP) Inhibitory postsynaptic potential (IPSP)
EPSP generation
- Neurotransmitter is released
- Chemically gated cation channel opens
- EPSP is established
- EPSP moved toward the initial segment
IPSP generation
- Neurotransmitter is released
- Chemically gated K+ or Cl- channels open
- IPSP is established
- IPSP moves toward the initial segement
IPSP
An electrical charge (Hyperpolarisation) in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more difficult for a postsynaptic neuron to generate an action potential.
EPSP
An electrical change (Depolarisation) in the membrane of a postsynaptic neurone caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more likely for a postsynaptic neurone to generate an action potential.
Neuroglia
cells that help neurons do their job
Astrocytes
maintain the chemical environment
Oligodendrocytes
produce myelin in the CNS
Microglia
Participate in phagocytosis
Ependemal cells
Form and circulate CSF
Satellite cells
support cells in the PNS
Neurilemmocytes (Schwann cells)
produce myelin
CNS contain
Astrocytes
Oligodendrocytes
Microglia
Ependemal cells
PNS contain
Satellite cells
Neurilemmocytes (Schwann cells)
Central Nervous system
made up of the brain and spinal cord
Peripheral Nervous System
Nerves which are bundles in axons and ganglia (somatic sensory)
Somatic NS
detects stimuli and transmits information from receptors to the CNS
Motor NS
Initiates and transmits inform from the CNS to effectors
