Nervous System Flashcards
Axon
Transmits electrical signal (action potential) from the soma to the synaptic knob.
The axon hillock
Integrates excitatory and inhibitory signals from the dendrites and fires an action potential if the excitatory signals are strong enough to reach threshold
Dendrites
Receive incoming signals and carry them to the soma
Myelin sheth
Acts as an insulation around the axon and speeds conduction
Soma
Cell body, contains nucleus, endoplasmic reticulum, ribosomes
Synaptic bouton
Lies at the end of the axon and releases neurotransmitters
Collection of cell bodies in the CNS
Nucleus
Collection of cell bodies in the PNS
ganglion
Astrocytes
Nourish neurons and form the blood-brain barrier which controls the transmission of solutes from the bloodstream into the Nervous system
Ependymal Cells
Lines the ventricles of the brain and produces cerebrospinal fluid, which physically support the brain and serves as a shock absorber
Microglia
Are phagocytic cells that ingest and break down waste products and pathogens in the central nervous system
Oligodendrocytes (CNS) and Schwann Cells (PNS)
Produce mylenin around the axons
What neural structure initiates the action potential?
Axon Hillock
What maintains the resting potential? what is the resting potential
The Na+/K+ ATPase at about -70mV
Temporal Summation
Integration of multiple signals close to each other in time
Spacial Summation
Integration of multiple signals that are close to each other in space/location
During action potential which ion channel open first? how is it regulate? What effect does it have on the polarization of the cell?
The sodium channel opens first at threshold -50mv.
Regulated by inactivation, which occurs at +35nV. Inactivation can only be reversed by repolarization of the cell. Opening of sodium channel causes depolarization.
During action potential what channel opens second, how is it regulated and what effect does it have on the polarization of cell?
Potassium (K) channel opens second at around +35mV. it is regulated by closing at low potential (below -70mV). Opening of potassium channel results in repolarization and eventually hyperpolarization.
Absolute refractory Period
The cell is unable to fire an action potential regardless of the intensity of a stimulus
Relative refractory period
Cell can fire an action potential only with a stimulus that is stronger than normal
What ion is responsible for the fusion of neurotransmitter containing vesicles with nerve terminal membrane?
Calcium
3 methods by which a neurotransmitter’s action can be stopped?
- Enzyme degradation
- Re uptake
- Diffusion
What parts of the nervous system is the PNS
Cranial and spinal nerves and sensors
Monosynaptic reflex
a sensory (afferent, presynaptic) neuron fires directly onto a motor (efferent, post synaptic) neuron.
polysynaptic reflex,
A sensory neuron may fire directly onto a motor neuron, but interneurons are used as well. Interneurons fire onto other motor neurons
Which is he neurotransmitter used in both ganglia of of both SNS and PNS?
acetylcholine released by preganglionic neuron in both SNS and PNS
postganglionic neuron in SNS: norepinephrine
postganglionic neuron in PNS: acetylcholine
Dorsal root ganglion
Contains all the cell bodies of sensory neuron
Primary different between somatic and automatic nervous systems in the PNS?
Somatic= one motor neuron Automatic= 2 neurons that work in series ( preganglionic and poatganglionic)
