NERVOUS SYSTEM Flashcards
Function of Nervous System that is responsible for gathering information
it’ sensory receptors monitor changes, called stimuli,
occurring inside and outside the body
Sensory Input
Function of Nervous System
that processes and interprets sensory input and decides whether action is needed
Integration
Function of Nervous System that is responsible for a response, or effect, activates muscles or glands
Motor output
Nervous system classifications are based on:
▪ Structures (structural classification)
▪ Activities (functional classification)
It consists of
▪ Brain
▪ Spinal cord
Function is
▪ Integration; command center
▪ Interprets incoming sensory information
▪ Issues outgoing instructions
Central nervous system (CNS)
It’s function is:
▪ Nerves extending from the brain and spinal cord
▪ Spinal nerves—carry impulses to and from the spinal cord
▪ Cranial nerves—carry impulses to and from the brain
Functions
▪ Serve as communication lines among sensory organs, the brain and spinal cord, and glands or muscles
Peripheral nervous system (PNS)
FUNCTIONAL CLASSIFICATION
▪ Nerve fibers that carry information to the central
nervous system
▪ Somatic sensory (afferent) fibers carry information from the skin, skeletal muscles, and joints
▪ Visceral sensory (afferent) fibers carry information from visceral organs
Sensory (afferent) division
FUNCTIONAL CLASSIFICATION
▪ Nerve fibers that carry impulses away from the central nervous system organs to effector organs (muscles and glands)
Motor (efferent) division
Two subdivisions of efferent division
•Somatic Nervous System
•Autonomic Nervous System
Support cells in the CNS are grouped together as?
neuroglia
▪General functions of neuroglia
▪ Support
▪ Insulate
▪ Protect neurons
▪Nervous tissue is made up of two principal cell types
▪ Supporting cells (called neuroglia, or glial cells, or glia)
•Resemble neurons
•Unable to conduct nerve impulses
•Never lose the ability to divide
▪ Neurons
Type of Supporting Cells that is
▪ Abundant, star-shaped cells
▪ Brace and anchor neurons to blood capillaries
▪ Determine permeability and exchanges between blood
capillaries and neurons
▪ Protect neurons from harmful substances in blood
▪ Control the chemical environment of the brain
CNS glial cells: astrocytes
Type of Supporting Cell that is :
▪ Spiderlike phagocytes
▪ Monitor health of nearby neurons
▪ Dispose of debris
CNS glial cells: microglia
Type of Supporting Cell that is :
▪ Line cavities of the brain and spinal cord
▪ Cilia assist with circulation of cerebrospinal fluid
CNS glial cells: ependymal cells
Type of supporting cell that
▪ Wrap around nerve fibers in the central nervous
system
▪Produce myelin sheaths
CNS glial cells: oligodendrocytes
Type of Supporting Cell in PNS
That form myelin sheath around nerve fibers in the PNS
Schwann cells
Type of Supporting Cell in PNS that
▪ Protect and cushion neuron cell bodies
Satellite cells
What is the function of Neurons and nerve cells?
Cells specialized to transmit messages (nerve
impulses)
What are the Major regions of all neurons?
▪ Cell body—nucleus and metabolic center of the cell
▪ Processes—fibers that extend from the cell body
What is the major region neuron that has —nucleus and is metabolic center of the cell
Cell body
What is the fibers that extend from the cell body
Processes
What is the Intermediate filaments that maintain cell shape
Neurofibrils
UNDER Processes (fibers)
What —conduct impulses toward the cell body- Neurons may have hundreds of this
Dendrites
UNDER PROCESSES conduct impulses away from the cell body
▪ Neurons have only one of this arising from the cell body
at the axon hillock
▪ End in terminals, which contain vesicles with neurotransmitters
▪ terminals are separated from the next neuron by a gap
Axon
What is the gap between axon terminals and the
next neuron
Synaptic cleft
What is the functional junction between nerves where a nerve impulse is transmitted
Synapse
NEURON THAT IS
▪ White, fatty material covering axons
▪ Protects and insulates fibers
▪ Speeds nerve impulse transmission
Myelin
▪Myelin sheaths
▪ Schwann cells—wrap axons in a jelly roll–like fashion
(PNS) to form the myelin sheath
▪ Neurilemma—part of the Schwann cell external to the myelin sheath
▪ Nodes of Ranvier—gaps in myelin sheath along the axon
▪ Oligodendrocytes—produce myelin sheaths around axons of the CNS
▪ Lack a neurilemma
▪Myelin sheaths
▪ Schwann cells—wrap axons in a jelly roll–like fashion
(PNS) to form the myelin sheath
▪ Neurilemma—part of the Schwann cell external to the myelin sheath
▪ Nodes of Ranvier—gaps in myelin sheath along the axon
▪ Oligodendrocytes—produce myelin sheaths around axons of the CNS
▪ Lack a neurilemma
Types of sensory receptors.
(a) Free nerve endings (pain and temperature receptors)
(b) Meissner’s corpuscle
(touch receptor)
(c) Lamellar corpuscle (deep
pressure receptor)
(d) Golgi tendon organ (proprioceptor)
(e) Muscle spindle (proprioceptor)
FUNCTIONAL CLASSIFICATIONS OF NEURONS ARE
▪ Motor (efferent) neurons
—-Carry impulses from the central nervous system to viscera and/or muscles and glands
▪ Interneurons (association neurons)
—Cell bodies located in the CNS
Connect sensory and motor neurons
Structural classification of neurons
•MULTIPOLAR NEURONS — many extensions from the cell body
All motor and interneurons are multipolar
Most common structural type
•BIPOLAR NEURONS — one axon and one dendrite
Located in special sense organs, such as nose and eye
Rare in adults
•UNIPOLAR NEURONS —
—have a short single process leaving
the cell body
Sensory neurons found in PNS ganglia
Conduct impulses both toward and away from the cell body
▪Functional properties of neurons the
Ability to respond to a stimulus and convert it to a nerve impulse
Irritability
Functional properties of neurons that has the ability to transmit the impulse to other neurons,
muscles, or glands
Conductivity
Electrical conditions of a resting neuron’s membrane
▪ The plasma membrane at rest is inactive (polarized) ▪ Fewer positive ions are inside the neuron’s plasma
membrane than outside
▪ K+ is the major positive ion inside the cell
▪ Na+ is the major positive ion outside the cell
▪ As long as the inside of the membrane is more negative (fewer positive ions) than the outside, the cell remains inactive
Electrical conditions of a resting neuron’s membrane
▪ The plasma membrane at rest is inactive (polarized) ▪ Fewer positive ions are inside the neuron’s plasma
membrane than outside
▪ K+ is the major positive ion inside the cell
▪ Na+ is the major positive ion outside the cell
▪ As long as the inside of the membrane is more negative (fewer positive ions) than the outside, the cell remains inactive
▪ A stimulus changes the permeability of the neuron’s
membrane to sodium ions
▪ Sodium channels now open, and sodium (Na+) diffuses into the neuron
▪ The inward rush of sodium ions changes the polarity at that site and is called depolarization
Action potential initiation and generation
In the resting state, the external face of the membrane is slightly positive; its internal face is slightly negative. The chief extracellular ion is sodium (Na+), whereas the chief intracellular ion is potassium (K+). The membrane is relatively impermeable to both ions.
Resting membrane is polarized