Biology: Chapter 3: The Nervous System Flashcards
What are neurons
Highly specialized cells responsible for the conduction of impulses
What are the two ways which neurons communicate
Electrical and Chemical
What are the parts of a neuron
Dendrites
Axon
Axon Hillock
Soma
Nerve Terminal
What are the Nodes of Ranvier
Exposed areas in the myelin sheath that permit saltatory conduction
What creates myelin in the CNS
Oligodendrocytes
What creates myelin in the PNS
Schwann Cells
Nerves vs Tracts
Nerves carry multiple types of information (sensory, motor, both) while tracts only carry one
What are clusters of neurons called in the CNS
Nuclei
What are clusters of neurons called in the PNS
Ganglia
What are Astrocytes
Glial cells that nourish neurons and form the Blood Brain Barrier which controls transmission of solutes from the blood stream into nervous tissue
What are Ependymal Cells
Glial cells that line the ventricles of the brain and produce cerebrospinal fluid which supports the brain and serves as a shock absorber
What are Microglia
Glial cells that are phagocytic meaning they ingest and break down waste products and pathogens in the CNS
What is the resting membrane potential
-70 mV
How is resting membrane potential maintained
selective permeability of ions and Na/K ATPase
What is the ratio of ions transported by Na/K ATPase
3 Na ions out for every 2 K ions in
What do Excitatory signals do to neurons
depolarize
What do Inhibitory signals do to neurons
Hyperpolarize
What is temporal summation
Integration of multiple signals near each other in time
What is spatial summation
Integration of multiple signals near each other in space
What is the first step of an action potential
Threshold is reached, voltage gated Na ion channels open causing Na influx which depolarized the cell
What is the second step of an action potential
Once the cell is depolarized to 35 mV Na channels are inactivated and K channels open causing the cell to repolarize
What is the third step of an action potential
K channels cause the cell to become hyperpolarized which then closes K channels and the refractory period begins while Na/K ATPase restores the membrane potential
what are the phases of the refractory period
Absolute and Relative
How is neurotransmitter released
Once the AP reaches the nerve terminal voltage gated Ca channels open causing an influx of Ca which causes NT vesicles to fuse with the presynaptic membrane which are then released into the synaptic cleft
How are neurotransmitters removed from the synaptic cleft
Degradation
Re-uptake
Diffusion
What are the three types of neurons
afferent (sensory), efferent (motor), interneurons
What is white matter in the CNS
consists of myelinated axons
What is gray matter in the CNS
consists of unmyelinated cell bodies and dendrites
What is the organization of white matter/gray matter in the spinal cord vs the brain
brain –> white matter deeper than gray matter
spinal cord –> gray matter is deeper than white matter
What are the divisions of the PNS
somatic and autonomic
What is the somatic division
control voluntary function (muscles and skeleton)
What is the autonomic division
controls involuntary function
What are the divisions of the autonomic division
parasympathetic and sympathetic
What does the parasympathetic system control
rest and digest
What does the sympathetic system control
fight or flight
What is a monosynaptic reflex arc
sensory neuron fires onto the motor neuron directlyw
What is a polysynaptic reflex arc
sensory neuron may fire onto a motor neuron as well as interneurons that fire onto other motor neurons
