Nervous system Flashcards
2 main components of the nervous system
1) Central NS (brain and spinal cord)
2) Peripheral NS ( nerves)
Major functions
1) Sensory function= stimuli, detection and transmission to the CNS (sensory neurons)
2) Integrative function= analysis, storage and decisions regarding
responses (interneurons)
3) motor function transmission of response directions (motor
neurons)
3 types of neurons
- Multipolar – single axon and multiple dendrites; over 99% of all neurons
- Bipolar – one axon and one dendrite and cell body between them; eye and olfactory. epithelium (nasal cavity)
- Pseudounipolar – only one fused axon, divides into two processes; general sensory neurons
Classification of neurons
*Sensory (afferent) neurons – carry information toward CNS; usually pseudounipolar
or bipolar
*Interneurons (association) neurons – relay information within CNS between
sensory and motor neurons; multipolar
*Motor (efferent) neurons – carry information away from the cell body in CNS to
effectors; mostly multipolar
What are the 4 types of neuroglia found in the CNS
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
What type of neurons (2) is found in the PNS
- Schwann cells surround PNS axons
* Satellite cells surround the cell bodies of neurons in the PNS ganglia
What is white matter
Is aggregations of unmyelinated and myelinated axons
• myelin gives this tissue a white colour
What does grey matter contain
neuronal cell bodies, dendrites, unmyelinated axons,axon terminals, and neuroglia, all of which are unmyelinated
What are the 3 types of neural circuits
*Simple series circuit= a presynaptic neuron - a single postsynaptic
neuron - another postsynaptic neuron ….
*Diverging circuit= a presynaptic neuron forms synapses with several
postsynaptic neurons (i.e., divergence)
*Converging circuit= several presynaptic neurons form synapses with a
single postsynaptic neuron (i.e., convergence)
What does the PNS contains
a) sensory or afferent neurons - from sensory
receptors to the CNS
b) motor or efferent neurons - from the CNS to
muscles and glands
How do you divide the sensory (afferent) division
Somatic sensory= Carries general sensory stimuli from muscle, bones, joints, skin. (Skeletal and muscles)- voluntary
Visceral sensory= Carries stimuli from organs. (urinary bladder and stomach)- involuntary
What are effectors
Organs that carry out the effects of the nervous system
What does the voluntary somatic nervous system (SNS),
which consists of
1) Somatic sensory neurons - input from somatic and special sensory receptors to the CNS
2) Somatic motor neurons - output from the
CNS to skeletal muscles
What are 2 types of neurons that can be found in the Involuntary autonomic nervous system
(ANS)
- autonomic (visceral) sensory neurons -
visceral receptors to the CNS - autonomic motor neurons - the CNS to smooth
muscle, cardiac muscle, and glands
What are the 3 divisions of the involuntary autonomic nervous system
(ANS)
- sympathetic division - supports exercise
and emergency actions, i.e., “fight-or-flight”
responses - Parasympathetic division - promotes “restand-digest” activities
- Involuntary enteric nervous system
(ENS; the “brain of the gut”)
