Fundamentals of the Nervous System Flashcards
Nervous system:
- Master control and communication system
- Has three overlapping functions:
- Sensory ______ monitor _______ inside and outside the body
- – Change = a _______
- – Gathered information = _______ input
- -_______ and _______ sensory input
- – makes decisions - _______
- Dictates a _______ by activating _______ organs (muscle or glands)
- – Response = _______ output
receptors, changes
- stimulus
- sensory input
Gathers and processes
- decision - integration
Response
effector
motor
What are the most basic divisions of the nervous system?
CNS
PNS
The CNS consists of the ______ and ______ _____.
It is the ________ and _______ centre
The PNS is _______ the CNS
- Consists of ______ extending from the brain and spinal cord
- _______ nerves link all regions of the body to the _____
- _______ are clusters of neuronal _____ _____ outside the CNS
brain and spinal cord
integrating and command
outside
nerves
peripheral, CNS
ganglia, cell bodies in PNS
What are ganglia?
Clusters of neuronal cell bodies outside the CNS
Sensory ______ and motor ______:
Sensory (______) signals picked up by sensory ________.
- Carried by _____ fibres of the PNS to the CNS
Motor (_______) signals are carried away from the _____
- innervate _____ or ______
- — tell them to _______ or ______
Input, output
afferent, receptors
nerve
efferent, CNS
muscles, glands
contract, secrete
Whether sensory input or motor output, efferent and afferent always refer to what?
the CNS
The PNS is divided according to the region they serve:
- _______ body region
- consists of structures _____ to the _____ body cavity
- ________ body region
- consists of viscera ______ the _____ body cavity
Results in 4 main subdivisions of the PNS, which are?
Indicate which are outgoing motor commands, which are incoming sensory and from where they are coming from/where are they going to.
Somatic
- external to ventral body cavity
Visceral
- within the ventral body cavity
Somatic motor - outgoing motor command skeletal muscle - voluntary
visceral motor - outgoing motor commands to smooth muscle and cardiac and glands - involuntary
Somatic sensory - incoming sensory information from the outside
Visceral sensory - incoming sensory info from organs of the ventral body cavity
What are the viscera?
Organs of the ventral body cavity - abdominopelvic and thoracic
– heart, lungs, digestive organs
Draw out the complete nervous system organization.
Include a brief description of each and which organs are involved.
Refer to notes
What does somatic sensory detect?
What are the special somatic senses?
General somatic senses
- touch, pain, vibration, pressure, temperature, proprioceptive senses
Special somatic senses
- hearing
- balance/eqb
- vision
How are propioceptive senses detected?
What is it?
Detect stretch in tendons and muscle. (joints)
body sense - position and movement of body in space
What does visceral sensory detect?
General visceral senses:
- stretch, pain, temperature, nausea and hunger
Special visceral senses:
- taste, smell
Describe both somatic motor and visceral motor.
In your answer provide which is the effector organ, if it is under voluntary control or not and indicate any further subdivisions.
Somatic motor
- effectors are skeletal muscle
- voluntary control
Visceral motor
- effectors are smooth muscle, cardiac muscle, glands and visceral organs
- involuntary
- makes up the ANS
What are the two main cell types of nervous tissue?
Briefly describe them
Neurons - conduct electrical signals
- excitable cells
Neuroglia - support cells
- nonexcitable
- surround and wrap neurons
What is the basic unit of the nervous system?
What are its special characteristics?
Neuron
Special characteristics:
- longevity
- do not divide (exception are neural stem cells)
- high metabolic rate (require lots of oxygen and glucose)
What are the different parts of a typical neurons?
Briefly describe.
For the first, decscribe how it changes between CNS and PNS.
For the second, describe the function and the direction of impulse conduction.
For the third, describe how many a typical neuron has, and the direction of impulse conduction.
Cell body - soma
- contains a single nucleus surrounded by the cytoplasm
- most cell bodies are in the CNS, ganglia are cell body clusters in the PNS
Dendrites
- extensively branching from the cell body, receive signals from other neurons
- increases SA for receiving synaptic communication
- transmit signals toward the cell body
Axons
- neuron has only one
- impulse generator and conductor
- transmit impulses away from the cell body
Describe how the diameter of an axon is important.
Larger diameter axons will conduct impulses faster.
Resistance in an axon decreases as _______ increases.
diameter
What do myelin sheaths effectively do?
Increase speed of conduction
What are the two major classifications of neurons?
Structural - based on the number of processes extending from the cell body.
Functional - based on the direction the nerve impulse travels relative to CNS
What are the subdivisions of the structural neuron classification? Describe.
Structural
- Multipolar: more than two processes; numerous dendrites, one axon, most abundant
- bipolar: two processes; rare, found in special sensory organs
- unipolar - pseudounipolar: one short, single process
- starts off bipolar during development
- majority of sensory neurons
What is the functional neuronal classification subdivided into. Describe each.
Functional: Sensory (afferent) neurons: - impulses toward CNS - virtually all unipolar - cell bodies in ganglia outside PNS - Short single process divides into: -- central process - runs centrally to CNS -- peripheral process - extends peripherally to the receptors
Motor (efferent) neurons:
- carry impulses away from CNS to effector organs
- most are multipolar
- cell bodies within CNS
Interneurons:
- most are multipolar
- lie between motor and sensory neurons
confined to CNS
Neuroglia:
Six types of _______ cells.
- _ in the CNS
- _ in the PNS
Provide ______ for neurons by:
- ______ the neurons
- Keeping the electrical activities of ______ neurons from ________ with each other
supporting
4
2
support
insulating
adjacent
interfering