Fundamentals of the Nervous System
List The General Functions of The Nervous System:
What does motor input activate?
-Muscles and Glands
What are the 2 structural classifications of the Nervous system?
-Central Nervous System
-Peripheral Nervous System
What does the CNS consist of?
What does the PNS consist of?
- Nerves outside the brain and spinal cord
Sensory (afferent) division
-Nerve fibers carry info to the CNS
Motor (efferent) division
-Nerve fibers carry info away from CNS
What are the 2 subdivisions of the motor division?
-Somatic Nervous System(voluntary)
-Autonomic Nervous System(involuntary)
What does the Somatic Nervous System control?
(Hint: Voluntary; you control it)
What does the Autonomic Nervous System Control?
(Hint: Involuntary; out of your control)
What are the 2 type of cells in the Nervous System?
-support cells(glial cells)
-Nuerons (Nerve Cells)
CENTRAL NERVOUS SYSTEM
What type of Nueroglia does the CNS consist of?
-for blood-brain barrier between capillaries and nuerons
-Spider-like phagocytic macrophages
-Dispose of debris and dead nuerons
-On autopsy, areas of brain damage may be found by looking for increase microglia
Describe Ependymal Cells:
-line cavities of the brain and spinal cord
-contain cilia that circulate cerebrospinal fluid
-forms myelin sheath in the CNS
PERIPHERAL NERVOUS SYSTEM
What type or Nueroglia does the PNS consist of?
What is the function of Satellite Cells?
-Protects nueron cell body
What are the functions of Schwann cells?
-Forms myelin sheath around axons in the PNS
What are the functions of Myelin Sheath?
-insulates and protects the axon
-High lipid concentration
What is multiple sclerosis?
An autoimmune disease that affects the brain and spinal cord(CNS); damages and scars nuerons and myelinated axons.
Who is at high risk for multiple sclerosis?
-Females are 2x more at risk than males
What are the main differences between Nueroglia and Nuerons?
Nueroglia- support, insulate, cushion, and protects nuerons, cannot transmit impulses, can divide
Nuerons-Irritability(responds to stimuli) and Conductivity( transmits impulses to effectors)
What are the 2 major regions of nuerons?
What are the sub units of the Cell Body(nucleus and metabolic center of the cell)?
-Nissl bodies, nuerofibrils, nucleus, large nucleolus, mitochondria
What are the sub units of the Processes(fibers that extend from the cell body)?
What are the functions of dendrites?
-receives signals and conducts impulses toward the cell body
What are the functions of an axon?
-conducts impulses away from the cell body
What are the sub units of an axon?
-axon hillock sheath, myelin sheath, nodes of ranvier, axon terminals, synaptic vesicles w/ nuerotransmitters, synaptic cleft, and synapse.
What sub unit of the axon determines if threshold is reached?
What are some examples of nuerotransmitters?
-dopamine, seratonin, GABA, ACh
What is white matter?
-dense collection of myelinated fibers.
What is gray matter?
-collections of unmyelinated fibers and cell bodies.
What are the 3 FUNCTIONAL classification of neurons?
-Motor (efferent) neurons
-Internuerons (association neurons)
Describe a Sensory Neuron:
-Bring impulses toward the CNS from receptors
-Unipolar w/ cell body in ganglia
Describe a Motor Neuron:
-Carry impulses away from the CNS to effector muscles and glands.
-Cell body in CNS.
What is a internueron?
-cell confined to the CNS; short extensions
What are the 2 STRUCTURAL classifications of Neurons?
What resting membrane potential?
-inside of cell has fewer positive ions than outside
What is action potential?
-temporary reversal of membrane potential across membrane
Stimulus Received-->Deporazation-->Action Potential-->Repolarization-->Refractory Period
What is Ecitatory Postsynaptic Potential(EPSP)?
-increases membrane permeability to NA+ and depolarizes postsynaptic membrane
-increases likelihood to fire an AP
What is Inhibitory Postsynaptic Potential(IPSP)?
-increases permeability to K+ and hyperpolarizes postsynaptic membrane
-decreases likelihood to fire an AP
How do anesthetics work?
-Act at the site of application to prevent pain sensations by blocking VG Na+ channels; therfore, no Action Potentials are generated in the sensory neurons and no Nuerotransmitters are released from sensory neurons to CNS neurons and if there are no ESPS in CNS than there is no perception of pain.
What is norepinephrine(NE)?
-a major neurotransmitter used between certain CNS nerve cells to communicate with one another.
What happens if too much NE is released?
-can cause over excitation & euphoria
-cocaine and amphetamines cause excess release of NE while also blocking breakdown via MAO->Cells exhuast themselves and are NE depleted->depression occurs until homestatic NE balance occurs->hospitalization can occur.
What happens if not enough nuerotransmitters like NE or Serotonin is released?
-Depression occurs and antidepressants called MAOI may need to be prescribed.