The Nervous System Flashcards
What are the 3 germ layers?
Ectoderm
Mesoderm
Endoderm
- From day 15 to end of eighth week
- Organs are formed.
Embryonic stage
- End of eight week until birth
- Nervous system develops more fully; myelination begins.
Fetal stage
this germ layer develops into sensory organs , epidermis, and nervous system
Ectoderm
this germ layer develops into dermis, muscles, skeleton, and excretory and circulatory systems
Mesoderm
this germ layer gives rise to epithelia and glands (GI tract, respiratory tract, and genitourinary tract
Endoderm
formation of the neural tube and happen between day 18-26
Neurulation
What are the two layers called that the neural tube differentiates into during day 26?
Mantle layer
Marginal layer
inner layer contains cell bodies; will become gray matter
Mantle layer
outer layer contains processes of cells whose bodies are located in inner layer; will become white matter
Marginal layer
What do the cranial part of the neural tube form?
brain
What do the caudal part of the neural tube form?
spinal cord
What do the central cavity of the neural tube form?
- ventricles of the brain
- central canal of the spinal cord
What are the groups of cells?
ventral and dorsal
dorsal cell group that has sensory neurons
Alar plate
ventral cell group that has motor neurons
Basal plate
What is formed when the motor and sensory nerves merge?
Spinal nerve
What kind of nerves are formed by the spinal nerve?
Mixed nerves
What are the two neurons that the brain is divided into?
Afferent neurons
Efferent neurons
neurons that carry information from sensory receptors of the skin and other organs to the central nervous system
Afferent neurons
neurons that carry motor information away from the central nervous system to the muscles and glands of the body
Efferent neurons
What are the 5 developmental regions of the brain (secondary brain vesicles)?
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
flexure between the forebrain and midbrain
Cephalic flexure
flexure between the hindbrain and spinal cord
Cervical flexure
flexure between the metencephalon and mylencephalon
Pontine Flexure
What are the 3 primary brain vesicles?
Forebrain
Midbrain
Hindbrain
Name the two regions that the brain is divided into
Neurocranium
Viscerocranium
What are the 4 arches that the ventral part of the forming head expand into?
Arch 1
Arch 2
Arch 3
Arch 4 and 6
What cranial nerve is arch 1 innervated by?
cranial verve 5 “ trigeminal” - muscles of mastication
What cranial nerve is arch 2 innervated by?
cranial nerve 7 “Facial” - muscles of facial expression
What cranial nerve is arch 3 innervated by?
cranial nerve 9 “glossopharyngeal” - gives rise to the stylopharyngeus muscle
What cranial nerve is arch 4 & 6 innervated by?
cranial nerve 10 “vagus” - gives rise to the internal muscles of the soft palate
What type of nerves innervate the arches?
cranial nerves
the skeletal muscle of the head and deep neck that form within the arches is classified as what?
pharyngeal (branchial) arch muscles
What does the neurocranium region of the brain form?
- form around the neural tube (future brain)
- form protective case for the brain
What does the viscerocranium region of the brain form?
- forms around the endoderm tube
- forms the visceral components of the head (mouth, nasal cavity, and pharynx)
- forms the skeleton of the face and skull
What are the functions of the adult nervous system?
- functions to detect changes in the internal/external environment
- brings about the appropriate responses in muscles, organs, and glands
What are the components of the adult nervous system?
- neurons
- neuroglia
Sequence of events following stimulation of a sensory receptor:
Do neuroglial cells transport or process information?
No
What are the 3 main types of glia?
- oligodendrocytes
- astrocytes
- microglia
a type of glia that form the myelin sheath within the CNS
oligodendrocytes
a type of glia that form the selectively permeable barrier between the circulatory system and the neurons of the brain and spinal cord, generating the blood-brain barrier
astrocytes
a type of glia cell that has a phagocytic role in response to nervous system damage
microglia
What are the 2 type of glial cells in the PNS?
- Schwann cells
- Satellite cells
a type of glial cell in the PNS that forms the myelin sheath of nerve fibers
Schwann cells
a type of glial cell in the PNS that regulate the environment around neurons
Satellite cells
What does the central nervous system (CNS) include?
Brain
Spinal cord
What does the peripheral nervous system (CNS) include?
- Cranial nerves- and branches
- Spinal nerves- and branches
- Ganglia
a type of neuron that carry information from the peripheral receptors in the CNS
Afferent neurons
a type of neuron that carry impulses away from the CNS
Efferent neurons
a type of neuron (relay) located entirely within the CNS that project to other CNS neurons
Interneuron
regions of the nervous system that are enriched with large numbers of nerve cell bodies.
* nuclei
* ganglia
* cortex
Grey matter
regions of the nervous system that contain mostly nerve processes (nerve fibers, axons). Myelin makes them appear white.
* tracts
* nerves
White matter
part of the brain that’s consciously aware
cerebral cortex
the grey matter that helps to coordinate movement
basal ganglia
the main motor pathways
brain stem
ascending pathways that convey sensory information to a conscious level
sensory pathways
descending pathways from the cerebral hemisphere that control movement
motor pathways
means to cross from one side of the body to the other side (contralateral)
decussate
sensory information from the skin and musculoskeletal systems
Somatosensation
information from the skin is superficial or cutaneous and includes:
touch, pain, temperature, and pressure
Information from the musculoskeletal system includes:
proprioception and pain
what neuron crosses the the other side (decussate)
2nd order neuron
What are the 4 neurons?
1st order neuron
2nd order neuron
3rd order neuron
target neuron
What neuron is in the thalamus?
3rd order neuron
a type of matter that synapses and processes information
grey matter
a type of matter that transmits information
white matter
a neuron that starts in the precentral gyrus
upper motor neuron
a neuron that ends in the skeletal muscle
lower motor neuron
what are the neurons in the motor pathway?
upper and lower motor neurons
swirly neurons identify what type of sensation?
proprioception
specialized receptor that responds only to a specific type of stimulus, adequate stimulus, and under normal conditions.
sensory receptor
receptors that pay attention to chemicals
chemoreceptors
receptors that respond to pressure, touch, and vibration
mechanoreceptors
receptors that respond to changes in temperature
thermoreceptors
are regions of skin that are innervated by sensory axons from a single spinal nerve
dermatomes
for the limbs the two distinct distributions of sensory innervation are
peripheral nerve and dermatome
made up of subsets of sensory axons that are derived from several different spinal nerves.
peripheral nerves
nerve impulses generated from the original stimuli
sensory information
awareness of stimuli from the senses
sensation
What are the names of the first-order neuron axons?
Distal and Proximal
an axon that conducts messages from the receptor to the cell body
distal axon
an axon that project from the cell body into the spinal cord or brainstem
proximal axon
Touch is categorized as
fine or crude
Regarding dermatomes, the somas of the neuron are the ______ stacked and all the strings (axons) are gathered together to make a _______.
balloons, spinal nerve
is made up of subsets of sensory axons that are derived from several different spinal nerves
peripheral nerve
proprioceptors found in skeletal muscle that respond to quick and prolonged stretches of the muscle
muscle spindles
Tendon organs signal the force generated by the muscle contraction or by a passive stretch of the tendon
Golgi tendon organs
complete severance of peripheral nerve results in a lack of sensation
hypoesthesia/paresthesia
impaired balance or coordination can be due to damage to the brain, nerves, or muscles.
Ataxia
the lower motor neuron to the skeletal muscle is called
the final common pathway
Are the only neurons that convey signals to extrafusal and intrafusal skeletal muscle fibers
motor neuron
group of muscles innervated by a single spinal nerve
myotomes
What happens if you damage a motor neuron?
Decrease or loss of reflexes
Paresis or paralysis
Atrophy
Decrease or loss of muscle tone
Fibrillations
receptors that fire only to indicate pain
nociceptors
receptors that respond to the mechanical deformation of joint capsules and ligaments
joint receptor
the neural tube defect that results when the inferior neuropore does not close
spina bifida
the meninges and some cases the spinal cord protrude through the posterior opening in the vertebrae
spina bifida cystica
What are the three types of spina bifida cystica?
- Meningocele
- Meningomyelocele
- Myeloschisis
protrusion of the meninges through the bony defect
Meningocele
neural tissue with the meninges protrudes outside the body
Meningomyelocele
most severe defect, consisting of a malformed spinal cord open to the surface of the body, which occurs when the neural folds fail to close
Myeloschisis
