Chapter 8: Nervous System Flashcards
major regulatory system that detects sensations and control movements, physiological processess and intellectual functions
Nervous System
Functions of the Nervous System
- Receiving Sensory Input
- Integrating Information
- Controlling muscles and glands
- Establishing and maintaining mental activity
receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs
Neurons
Neurons are also known as
nerve cells
Parts of a Neuron
- Cell Body
- Dendrites
- Axons
source of information for gene expression
Cell Body
usually receive information from other neurons or from sensory receptors and transmit information toward the cell body
Dendrites
conduct action potentials from one part of the brain/spinal cord to another part
Axons
Types of Neurons
- Sensory Neuron
- Motor Neuron
carries information to the CNS from the body
Sensory Neuron
send information to the body from the CNS
Motor Neuron
Categories of Neurons
- Multipolar Neurons
- Bipolar Neurons
- Pseudo-unipolar Neurons
a category of neurons that has two processes; one dendrite and one axon
Bipolar neurons
a category of neurons that has many dendrites and a single axon
Multipolar Neuron
a category of neurons that appears to have an axon and no dendrites
Pseudo-unipolar neurons
carry out different functions that enhance neuron function and maintain normal conditions within nervous tissue
Glial Cells
Types of Glial Cells in the CNS
- Astrocytes
- Ependymal Cells
- Microglia
- Oligodendrocytes
major supporting cells in the CNS
Astrocytes
line the fluid-filled cavities within the CNS
Ependymal Cells
immune cells of the CNS that helps protect the brain by removing bacteria and cell debris
Microglia
provide an insulating material that surrounds axons
Oligodendrocytes
Type of Glian Cells in the PNS
Schwann Cell
specialized layers that wrap around the axons of some neurons formed by the oligodendrocytes in the CNS and Schwann cells in the PNS
Myelin Sheaths
consists of neurons and microglia and one of the four major tissue types
Nervous Tissue
consists of bundles of parallel axons with their myelin sheath
White Matter
white matter of the PNS forms
nerves
white matter of the CNS forms
nerve tracts
consists of groups of neuron cell bodies and their dendrites where there is very little myelin
Gray Matter
gray matter on the surface of the brain
cortex
clusters of gray matter on the surface of the brain
nuclei
cluster of neuron cell bodies in the PNS
ganglion
uneven charge distribution in an unstimulated or resting cell
Resting Membrane Potential
inside = ___ charged
outside = ___ charged
negatively, positively
Higher concentration of K+ immediately ___ the cell
inside
Higher concentration of Na+ immediately___ of the cell membrane
outside
required to maintain the greater concentration of Na+ (outside) and K+ (inside) the cell membrane
Sodium-Potassium Pump
Sodium-Potassium pump actively transports _____ and ____ of the cell
K+ into the cell and Na+ out of the cell
voltage across the cell membrane changes from -70 mV to +20mV
Depolarization
the voltage across the cell membrane returns to -70mV
Repolarization
the charge on the cell membrane briefly becomes more negative than the resting membrane potential
Hyperpolarization
all-or-none change in membrane potential in an excitable tissue that is propagated as an electrical signal
Action Potential
2 Basic Types of Ion Channels
- Leak Channels
- Gated Channels
Types of Gated Channels
- Chemically gated channels
- Voltage-gated channels
opened by neurotransmitters or other chemicals
Chemically gated channels
Voltage-gated channels
opened by a change in membrane potential
Types of Action Potential
- Continuous Conduction
- Saltatory Conduction
Conducted along the entire axon cell membrane
Continuous Conduction
“jump” from one node of ranvier to the next along the length of the axon
Saltatory Conductuon
intiated and opened by chemically-gated channels and activates voltage-gated channels to initiate an action potential
Local Potential
junction where the axon of one neuron interacts with one another neuron or with cells of an effector organ
Synapse
an involuntary reaction in response to a stimulus applied to the periphery and transmitted to the CNS
Reflexes
neuronal pathway by which a reflex occurs and the basic functional unit of the NS
Reflex Arc
5 Basic Components of Reflex Arc
- Sensory Receptor
- Sensory Neuron
- Interneuron
- Motor Neuron
- Effector Organ
Neuronal Pathways: Two Simple Pathways
- Converging Pathways
- Diverging Pathway
two or more neurons synapse with the same postsynaptic neuron
Conversing Pathways
axon from one neuron divides and synapses with more than one other postsynaptic neuron
Diverging Pathway
allows integration of multiple subthreshold local potentials
Summation of signals in neuronal pathways
can bring the membrane potential to threshold and trigger an action potential
Summation of the local potentials
occurs when the local potential originate from different locations on the postsynaptic neuron
Temporal Summation
occurs when local potentials overlap in time and can occur from a single input that fires rapidly
Spatial Summation
Divisions of the Nervous System
Central Nervous System & Peripheral Nervous System
Communication link between the CNS and the various parts of the body
PNS
Information from PNS to CNS is either: ___, ___ or ___
ignored, triggers a reflex or evaluated
Central Nervous System consists of?
Brain and Spinal Cord
Peripheral Nervous System consists of?
Nerves and Ganglia
3 Parts of Spinal Cord
- Superficial White Matter Portion
- Deep Gray Matter Portion
- Spinal Nerves
Two Spinal Reflexes
- Knee-jerk Reflex
- Withdrawal Reflex
used by clinicians to determine if the higher CNS that normally influence this reflex are functional.
Knee-jerk reflex
Knee-jerk reflex is also known as
Patellar reflex
function is to remove a limb or a body part from a painful stimulus
Withdrawal Reflex
Withdrawal Reflex is also known as
Flexor reflex
