Chapter 12 Flashcards
Nerve
A bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels that lies outside the brain and spinal cord
How many pairs of cranial nerves emerge from the brain?
Twelve
How many pairs of spinal nerves emerge from the spinal cord?
31
Sensory receptor
Structure of the nervous system that monitors changes in the external or internal environment
What divisions is the PNS system divided into
Sensory division and motor division
Sensory or afferent division
Conveys input into the CNS from sensory receptors in the body provides the CNS with sensory information about the somatic senses and special senses
Motor or Efferent division
Conveys output from the CNS two effectors further subdivided into somatic nervous system and autonomic nervous system
Somatic nervous system
Conveys output from the CNS to skeletal muscles only because it can be consciously controlled the action of this part of the PNS is voluntary
Autonomic nervous system
Conveys output from the CNS to smooth muscle cardiac muscle and glands not normally under conscious control the action of the ANS is involuntary
What are the two main branches of the autonomic nervous system?
Sympathetic nervous system and parasympathetic nervous system And enteric nervous system
Parasympathetic nervous system
Rest and digest activities
Sympathetic nervous system
Supports exercise or emergency action “fight or flight” response is
Enteric nervous system
Confined to the wall of the G.I. tract helps regulate the activity of the smooth muscles and glands of the G.I. tract
What are the three basic functions of the nervous system?
- Sensory
- integrative
- motor
Sensory function
Sensory receptors detect internal stimuli examples blood pressure or external stimuli the information is not carried into the brain and spinal cord
Integrative function
The nervous system processes sensory information by analyzing it and making decisions for appropriate responses an activity known as integration
Motor function
After sensory information is integrated if the nervous system may all it an appropriate motor response by activating effectors (muscle and glands) through cranial and spinal nerves
Electrical excitability
The ability to respond to a stimulus and convert it into an action potential
Action potential
An electrical signal that propagates along the surface of the membrane of a neuron
What’s the cell body of the neuron known as
Perikaryon or soma
What’s the term for free ribosomes in clusters of rough endoplasmic reticulum of the neuron?
Nissl bodies
Neurofibrils
Composed of bundles of intermediate filaments that provide the cell shape and support
Microtubules
System moving materials between the cell body and axon
Lipofuscin
A pigment that occurs as clumps of yellowish brown granules in the cytoplasm a product of neuronal lysosome is that accumulates as a neuron ages
Ganglion
Collection of neuron cell bodies outside the CNS
Nerve fiber
General term for any neuronal process that emerges from the cell body of a neuron most have two kinds of processes dendrites and axons
Dendrites
Receiving or input portions of a neuron contain numerous receptor sites for binding chemical messengers from other cells usually short tapering in highly branched
Axon
Propagates nerve impulses towards another neuron, a muscle fibre, or a gland cell. an axon is a long, thin, cylindrical projection that often joins to the cell body at a cone shaped elevation called the axon hillock
Axon hillock
Cone shaped elevation on the axon
Initial segment
Part of the axon closest to the axon hillock
Trigger zone
Junction of the axon hillock and initial segment where nerve impulses arise
Axoplasm
Cytoplasm of axon
Axolemma
Plasma membrane of the neuron
Axon collaterals
Side branches on length of an axon
Axon terminal
Branch off the axon end
Synapse
Site of communication between two Neurons or between a neuron and an effectorcell
Synaptic bulbs and varicosities
The swelling at the tips of the axon terminal which contain many tiny sacs called synaptic vesicles that store neurotransmitters
What stores neurotransmitters?
Synaptic vesicles
Slow axinal transport
Convey’s axoplasm in One Direction only from the cell body toward the axon terminals supplies new exoplasm to developing or regenerating axons and replenishes exoplasm and growing and mature axons
Fast axonal transport
Capable of moving materials a distance of 200 to 400 mm per day uses proteins that function as motors to move materials along the surfaces of microtubules of the neuron cytoskeleton can move material in both directions away from and towards the cell body
Fast axonal transport - Anterograde
Occurs in a forward direction moves organelles in synaptic vesicles from the cell body to the axon terminals
Fast axonal transport - retrograde
Occurs backward direction moves membrane vessicles and other cellular material from the axon terminals to the cell body to be degraded or recycled as well as substances that enter the neuron at the axon terminals
Multipolar neurons
Have several dendrites in one axon
Bipolar neurons
One main dendrite and one axon