Intro to Nervous System and Spinal Cord Flashcards
Central Nervous System
Brain
Spinal Cord
Peripheral Nervous System
Autonomic Ganglia
Sensory Ganglia
Nerves and plexuses
Nervous tissues is defined as:
those cells and portions of the body characterized by voltage dependent changes in the permeability to the sodium ions
Hallmark of nervous system:
its excitability and the conduction of signals
The Neuron Theory
Functions of the nervous system reflect the functions of individual neurons, groups of neurons, and their connections
Gray matter
where there is a concentration of neuronal cell bodies with dendrites
White matter
concentration of axons from one place to another in the CNS
Somatic efferents
move skeletal muscle
Visceral efferents
move smooth muscle (autonomic)
Somatic afferents
give precise localized information
Visceral afferents
lots of information but poorly localized
Glia Cells of the CNS
Fibrous (white matter) and protoplasmic (grey matter) astrocytes
Oligodendrocytes (myelin forming)
Microglia (scavengers; monocyte derived)
Ependyma (line ventricles and central canal - contribute to choroid plexus)
Compared to unmyelintated cells, myelinated cells:
have huge fibers
transmit signals faster
What kind of cells make myelin
Oligodendrocytes in CNS
Sheath cells in PNS
Peripheral nerves can be described in terms of functional components of the fibers they carry:
Sensory fibers bring information to the CNS (Afferent)
Motor fibers carry information toward muscles in the PNS (Efferent)
Sensory Fiber Neurons
Pseudounipolar
Spinal Dorsal Root Ganglia
Cranial Nerve Ganglia
Motor Fiber Neurons
Multipolar Neurons
Spinal cord - spinal nerves
Brainstem - cranial nerves
Organization of the PNS: Somatic Afferents
Sensory fibers bring information to the CNS (Afferent)
Come from the body (soma) and carry precise information about place Pain Temperature Light Touch Vibration
Organization of the PNS: Visceral Afferents
Sensory Fibers bring information to the CNS (Afferent)
Come from internal organs (viscus) of the body and carry a lot of information that we cannot perceive
Osmolarity of the portal blood
CO2 in the blood and pressure in the carotid
Na+ in Blood
Pain (contractions/cramping, anoxia, distension)
Organization of the PNS: Somatic Efferents
Motor Fibers carry information toward muscles in the PNS (Efferent)
Multipolar neurons of the brainstem and ventral horn of the spinal cord
Connect directly from CNS neurons to cells of striated/skeletal muscles
Produce movement
Under direct voluntary control
May have automatic control but are able to be consciously activated or suppressed
Loss of cells in the CNS or their axons in peripheral nerves results in loss of movement
Weakness in a muscle is an innervation problem
