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”)
ENS
• neurons in the GI tract
neurons are located in the enteric plexuses (GI
tract)
• Submucosal plexus
• Myenteric plexus
• the sensory neurons - monitor changes in the GI
tract
• the motor neurons - help regulate digestive
system activities
What are 4 protective structures
- Vertebral column
- Meninges
- Blood vessels
- Cerebrospinal fluid
What is the length of the adult spinal cord
42–45cm
How many grooves does the spinal cord has
2 the anterior and posterior sulcus
How many pair of spinal nerves emerge from spinal
segments
31 pairs
how many pairs of cervical nerves we have? And what are the numbers
8 pairs and the first pair emerges between the
atlas and the occipital bone, represented as C1–C8
How many pairs of thoracic nerves do we have and what are the numbers
12 pairs, T1–T12
How many pairs of lumbar nerves do we have and what are the numbers
5 pairs, L1–L5
How many pairs of sacral nerves do we have and what are the numbers
5, S1–S5
How many pairs of coccygeal nerves do we have and what is the number?
1, Co1
What are the 2 roots that the spinal nerve is formed by
The anterior (ventral) root - motor neuron axons
• The posterior (dorsal) root - sensory nerve fibers
- the posterior root ganglion: the cell bodies of
sensory neurons.
What is a mixed nerve
The merger of a posterior root and an
anterior root
What are the 2 major functions of the spinal cord
- The white matter tracts in the white matter of the spinal cord • transmit nerve impulses between the brain and the periphery.
- The gray matter of the spinal cord • receives and integrates the incoming and outgoing information
* these 2 help maintaining homeostasis
What is the integrating center for spinal
reflexes
The grey matter
What does Somatic reflexes involve
contraction of skeletal muscles
What are the 4 major parts of an adult brain
Cerebrum
Diencephalon
Brain stem
Cerebellum
What are the 3 cranial meninges
Outer dura mater
Middle arachnoid mater
Inner pia mater
What part of the brain produces most of the cerebrospinal fluid
(CSF)
The choroid plexus
What type of cells does the blood-brain barrier has
endothelial cells
What does the blood brain barrier separates
the circulating blood from the brain extracellular fluid
(Cerebrospinal Fluid - CSF) in the central
nervous system (CNS).
