Lecture 1 : CNS Flashcards
central nervous system
brain and spinal cord
integration and command center
Peripheral Nervous system
paired spinal and cranial nerves
carries messages to and from the spinal cord and brain
- has sensory division and motor division
Sensory( afferent) Division
Sensory afferent fibers- carry impulses from skin, skeletal muscle and joints to the brain
Visceral afferent fibers- transmit impulses from visceral organs to the brain
( arrives)
Motor (efferent) division
transmits impulses from the CNS to the effector organs.
(pathways exit to muscle or glands.
2 types of Motor Divsion
Somatic Nervous system- Voluntary system
Autonomic Nervous system- involuntary
- regulates smooth muscle, cardiac muscle and gland
ANS
sympathetic - increase in energy (fight or flight)
parasympathetic- decrease in energy ( rest and digest)
Two principal cell types of the nervous system
Neurons
supporting cells
Neurons
send action potential, electrical signals out to other cells
Supporting cells
as a group- glial cells and neuroglia.
CNS support Cells
- Astrocytes
- microglia
- ependymal cells
- oligodrendrocytes
PNS support cells
Schwann cells and satellite cells
Gangelion
group of neuron cell bodies in the pns ( outside the brain and the spinal cord
Astrocytes
- support and brace neurons
- anchor neurons to their nutrient supplies
- wrap around capillaries in the brain- glia limitans
guide migration of young neurons
control the chemical environment
Microglia
small glial cells
Ependymal Cells
line the cavities of the brain and spinal column
Oligodendrocytes
branched cells that wrap CNS nerve fibers (myelin
Schwann cells
surround fibers of the PNS
satellite cells
surround neuron cell bodies within ganglia of the PNS
Neurons (nerve cells)
- has a body, axon and dendrites
- long lived, amitotic, and have high metabolic rate.
Processes
-arm like extensions from the soma
2 types- dendrites and axons
Bundle of Axon
called tract in the CNS
called nerve in the PNS
Myelin Sheath
- protects the axon
- electrically insulate fibers from one another
- increase the speed of nerve impulse transmission
Axons of the PNS
myelinated by schwann cells
Nodes of Ranvier
gaps in the myelin sheath between adjacent schwann cells
Axons of the CNS
- myelin sheaths are formed by oligodendrocytes
- no neurilemma
Multipolar Neuron
1 axon and many dendrites
- motor neuron, leaves CNS
Bipolar Neuron
1 axon and 1 dendrite
-olfaction, vision, hearing ,taste
unipolar
1 axon with a receptive end
-general sensations ( skin, skeletal muscles and joints)
Toward the CNS
Types of plasma membrane ion channels
- Passive, leakage or channels- does not need stimulus
- chemically gated channels- chemicals cause gates to open
- voltage gated channels
- mechanically gated channels
Resting membrane potential
(-70mv) across the membrane of a resting neuron
Sodium/ potassium Pump
pumps 3 Na out of the cells and 2K into the cell. trying to maintain a (-) charge inside the cell
Depolarization
plasma membrane becomes more positive
Repolarization
cell returns to polarized state
hyperpolarization
cell becomes extra negative on the inside
