Module 1 and 2 Learning Objectives Flashcards
What are the different divisions of the nervous system?
central and peripheral nervous systems
What is part of the CNS?
- brain
- spinal cord
What is part of the PNS?
- peripheral nerves
- cranial nerves
- spinal nerves
What is the role somatic nervous system?
- innervates body wall and voluntary muscle
What is the role of the autonomic nervous system?
- innervate smooth muscle, cardiac muscle, and glands
What are the two divisions of the autonomic nervous system?
- parasympathetic (rest and digest)
- sympathetic (fight or flight)
What are the 5 major subdivisions of the central nervous system?
- cerebral hemispheres (telencephalon)
- diencephalon
- cerebellum
- brainstem
- spinal cord
What are the meninges of the CNS?
- dura mater
- arachnoid mater
- pia mater
What is the name for the space between the arachnoid mater and its significance?
- subarachnoid space
- contains cerebral spinal fluid (CSF)
- arachnoid trabecular anchor arachnoid to pia
What are the four ventricles of the brain and what do they do?
- lateral ventricles (2)
- 3rd ventricle
- 4th ventricle
What is the pathway of CSF through the ventricles?
lateral ventricles > interventricular foramen > 3rd ventricle > cerebral aqueduct > 4th ventricle > central canal
What makes up gray matter?
- cell bodies and dendrites
What makes up white matter?
- axons and myelin sheath
What are two important white matter areas in the cerebrum?
- corpus callosum
- internal capsule
What is the corpus callosum?
- largest bundle of commissural fibers that connect the right and left hemispheres of the brain
What is the internal capsule of the brain?
- fiber projections that descend from brain to brainstem and spinal cord
- also ascend from lower centers to cerebral cortex
What is a tract?
- collection of axons with same origin, termination, and function
What is a commissure?
- axons that cross midline from one area of CNS equivalent area of the other on the opposite side
What is a decussation?
- similar to commissure
What does the acronym, SAME DAVE stand for?
- sensory, afferent
- motor, efferent
- dorsal, afferent
- ventral efferent
What is the difference between a sulcus and gyrus?
- sulcus = depression/valley
- gyrus = ridge/mountain
What is neuralation?
- when the neural tube closes the 4th week of embryo development
What is significant about the telencephalon?
- experiences tremendous growth
- swells, and rotates
- C shaped
- derives cerebral hemispheres
What is the role of convolutions on the brain?
- increase surface area
What is the clinical significance of Spina Bifida?
- defective closure of caudal neural tube
- spinal cord forms outside of vertebral column, causing sac to appear on infants back
- spinal cord is susceptible to injury
What are the segmental levels of the spinal cord?
- cervical = 8
- thoracic = 12
- lumbar = 5
- sacral = 5
- coccygeal = 1
Where does the spinal cord terminate and what is the structure at the termination?
- L1/2 vertebrae
- conus medullaris
What are the longitudinal furrows of the spinal cord?
- posterior/dorsal median sulcus
- anterior/ventral median fissure
- dorsolateral sulcus
- ventrolateral sulcus
What are the enlargements of the spinal cord?
- cervical enlargement = C4-T1
~ brachial plexus - lumbosacral enlargement = L2 = S3
~ lumbar and sacral plexus
What makes up paired spinal nerves?
- dorsal root and dorsal root ganglion
- ventral root
What is the internal organization of the spinal cord and its significance of size?
- butterfly or H shaped
- size of gray matter related to richness of peripheral nerves (larger if more peripheral nerves come from here)
What is a myotome and dermatome?
- myotome: single peripheral nerve segment innervating a group of muscles
- dermatome: single spinal level innervating section of skin
How does the brainstem act as a conduit?
- ascending tracts pass through to thalamus or cerebellum
- descending tracts pass through to spinal cord or cerebellum
What is the reticular formation of the brainstem?
- integrates functions for respiration, consciousness, complex motor patterns
What are the cranial nerves associated with the medulla, pons, and midbrain?
- medulla: IX, X, XI, XII
- pons: V, VI, VII, VIII
- midbrain: III, IV
How can you remember which cranial nerves are associated with the structures of the brain?
5, 6, 7 ,8 who do we appreciate?
Pons!
How does the cerebellum connect to the cerebrum and what are its 3 parts?
- connected by paired peduncles (superior, middle, inferior)
- parts: 2 cerebellar hemispheres and vermis
How are the two cerebral hemispheres separated?
- deep longitudinal fissure
What are the regions of the corpus callosum?
- rostrum
- genu
- body
- splenium
What is a commisurotomy?
- separation of cerebral hemispheres by cutting the corpus callosum
What are the lobes of the cerebral hemispheres?
- frontal
- parietal
- temporal
- occipital
- limbic (system) [parts of fontal parietal, and temporal lobes]
What are the major sulci that can be seen in the lateral view of the brain?
- lateral sulcus
- central sulcus
What are the major structures of the hemisected view of the brain?
- cingulate sulcus
- cingulate gyrus
- parahippocampal gyrus
- hippocampus
- parieto-occipitaq sulcus
- calarine sulcus
What is the section of the brain you can see if you separate the frontal, parietal, and temporal lobes?
insula
What are the white matter structures of the cerebral hemispheres?
- corona radiata
- internal capsule
What are neurons and can they be replaced?
- communication unit of the nervous system
- rely on electricity with chemical synapses
- 100 billion at birth, cannot be replaced
What are neuroglial cells?
- cells that rely on chemical interactions
- play role in support, injury, and disease in the nervous system
What are the cells of the nervous system?
- neurons
- neuroglial cells
What is the unique property of neuroglial cells?
- retain mitotic properties to allow for the growth of new glial cells
What are the neuroglial cells of the CNS?
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
What are the characteristics of astrocytes?
- largest, most elaborate
- star shaped
- involved in the blood brain barrier (supplying nutrients to neurons)
- supports synaptic function
What are the characteristics of oligodendrocytes?
- formation and maintenance of myelin sheath
- single oligodendrocyte can myelinate segments of 7-70 axons
- abundant in white matter
What are the characteristics of microglia?
- 10 to 20% of all glial cells
- resemble macrophages
- throughout CNS
- abundant in gray matter
- defense against infection
What are the characteristics of ependymal cells?
- from choroid plexus
- line central canal and ventricular system
What are the neuroglial cells of the PNS?
- Schwann cells
- satellite cells
What are the characteristics of Schwann cells?
- synonymous to oligodendrocytes
- abundant
- form myelin sheath of PNS
What are the characteristics of satellite cells?
- surround cells bodies in PNS
- play role in maintaining metabolism of ganglion cells
What are the morphology;ogical classifications of neurons?
- unipolar/pseudounipolar
- bipolar
- multipolar
What are the characteristics of pseudopolar neurons?
- single process extending from soma
- found in sensory spinal nerves and some cranial nerves
What are the characteristics of bipolar neurons?
- two processes extending from soma
- cells found in retina and CN I and CN VIII
What are the characteristics of multipolar neurons?
- 3 or more processes extending from soma
- throughout entire nervous system
What are the challenges surrounding neurons?
- high energy demand
- must travel great distance
What are the major anatomical structures of a neuron?
- soma (body)
- axon
- dendrites
What is the role of the soma?
- contains organelles
- metabolic center
- as long as soma is intact, neuron may have chance for axonal regeneration
What is the role of organelles?
- manufacture and transport cell components
- support high metabolic rate
travel along axon to/from cell body
What is the role of rough ER?
- principal protein synthesizing structure
What is the role of ribosomes?
- assemble amino acids into proteins
What is the role of the Golgi complex?
- hub of traffic
What is the role of mitochondria?
- powerhouse of cell, ATP synthesis
What are the names of axons in the CNS and PNS?
- tracts/pathways: CNS
- spinal/cranial nerves: PNS
What are the roles of the different types of afferent axons?
- 1A: location of body in space, high speed
- A-beta: touch, lower speed
- A-delta: fast tissue damage
- C: slow tissue damage
What is key to axonal regeneration?
- depends on extent of damage
- soma must be intact
- myelin and connective tissue protect
- favorable if no damage to connective tissue and axon
What are the classes of of peripheral nerve injury?
- neuropraxia (I)
- axonotemsis (II)
- neurotmesis (III)
What are the characteristics of neuropraxia?
- mildest, most common
- compression or local ischemia
- conduction proximal + distal of injury
- relieved if compression relieved
- days to weeks recovery
What are the characteristics of axonotmesis?
- axon damage, still connective tissue
- conduction lost distally
- myelin degeneration distally (Wallerian Degeneration)
- severe compression or crush
- may regenerate
- 1 mm/day if relieved
What are the characteristics of neurotmesis?
- transection of axon
- cut or gunshot wound
- axonal sprouting
- loss of connective tissue and axon
What is resting membrane potential?
- 65 mV
What is a graded potential?
- small flux in potential energy that does not result in a action potential
What is a spatial summation?
multiple neurons adding to graded potential, may result in action potential if threshold met
What is temporal summation?
- single neuron repeatedly firing
What are the stages of action potential?
- threshold reached
- rising phase (depolarizing)
- overshoot phase (membrane potential reverses)
- falling phase (repolarization)
- undershoot phase (membrane hyper polarizes)
- repolarization
What is an absolute refractory period?
- time directly after repolarization
- determined by voltage gated Na channel
What is a relative refractory period?
towards state of potential returning to normal potential (-65 mV)
- determined by electrochemical state of neuron
What is a synapse and what happens at this junction?
- connection between two neurons
- action potential reaches presynaptic terminal
- voltage gated calcium channels open
- calcium activates motor proteins to fuse to vesicles to membrane and release neurotransmitters
- neurotransmitter binds to receptor and sodium can enter post synaptic neuron
What is postsynaptic potential?
- changes in postsynaptic neuron membrane potential caused by ion channels interacting with neurotransmitter from the presynaptic neuron (graded potential)
What is the difference between excitatory and inhibitory postsynaptic potentials?
- excitatory = depolarizing
- inhibitory = hyper polarizing
What is receptor potential?
- graded response in that the number of channels that open is proportional to magnitude of the stimulus
- decays in short distance, non-propagated
What are the three kinds of neurotransmitters?
- amino acids
- amines
- peptides
What are amino acids?
- small, synthesized, and packaged in synaptic vesicles
What are amines?
- small, synthesized, and packaged in synaptic vesicles
What are peptides?
- large, synthesized and packed in dense - core vesicles
What are the amino acid neurotransmitters?
- glycine: inhibitory
- glutamate: excitatory
- aspartate: excitatory
- gamma: amino butyric acid (GABA): inhibitory
What are the amine neurotransmitters?
- acetylcholine
- dopamine
- norepinephrine
- epinephrine
- serotonin
- histamine
What are some peptide neurotransmitters?
- dynorphin
- enkephalin
- substance P
Where are neurotransmitters produced?
- small: produced locally in axon terminal
- large: must be synthesized and packaged in cell body
What is the difference between convergence and divergence?
- convergence: according to postsynaptic neuron
- divergence: according to presynaptic neuron
What is multiple sclerosis?
- attack on oligodendrocytes of myelin sheath of CNS
What is glioblastoma?
- cancer attacks astrocytes
- mitotic property becomes a problem
What is acute inflammatory demyelinating polyneuropathy?
- motor and somatosensory nerves
- decrease amplitude of action potential
What is diabetic neuropathy?
- high blood pressure causing capillaries to be damaged, nerves do not get nutrition, axonal degeneration
What happens when humeral fracture results in axonotmesis of radial nerve?
- results in shoulder, wrist, and elbow extension weakness
What does botox do to a nerve?
- stops Ash release to initiate muscle contraction
