Organization of the Nervous System Flashcards
Describe dendrites
-collect electric signals
-have ion channels
What is a cell body
-integrates incoming signals and generates outgoing signal to an axon
What is the purpose of the axon
-passes electrical signals to dendrites of another cell
What is the CNS
-brain and spinal cord
-integrates, processess and coordinates sensory data and motor commands
-where higher functions lie
->intelligence
->memory
->learning
->emotions
What is the PNS
-carries sensory information from receptors to the CNS
->afferent
-carries motor commands from the CNS to the periphary
Describe the brain in terms of the CNS? What are the three major parts
-cerebrum, brainstem, cerebullum(little brain)
How is the PNS divided into nerves
-31 pairs of spinal nerves
-12 pairs of cranial nerves
What is the term for a collection of axons for CNS vs PNS
-CNS is a tract
-PNS are nerves
How is the CNS protected
-it is protected by:
-bone encases the brain
-meninges
->dura(thickest meninges) and wraps the brain
->arachnoid matter is in the middle(you can see blood vessels through it)
->pia matter is closest to the cerebral cortex
-cerebral spinal fluid in between arachnoid and pia matter
->CSF runs all around the brain
Is there space between dura, skull and arachonoid matter
-no
Describe the arachnoid matter
-sealed in epithelial tissue
-if you are touching blood vessels, you know you are touching the arachnoid matter
What are gyri or gyrus
-the lumps on the brain
What are valleys in between gyri
-sulcus or sulci
What happens as you grow up from being a new born to an adult
-increased folds
->increased surface area as a result
->more cortical tissue added as a result
What is a major sulci in the brain
-the central sulcus
->divides the brain into its lobes
->a border
-divides the precentral gyrus(primary motor cortex) and the post central gyrus(primary somatosensory cortex)
What is a fissure
-a bigger sulcus
->an example is the lateral(sylviian) fissure
->also helps you find the lobes of the brain
Where is the precentral gyrus
-it is in the frontal lobe
Where is the postcentral gyrus
-it is in the parietal lobe
What are features of the frontal lobe
-thinking, planning, personality
-motor planning
->frontal lobe is the motor coordinating part of the brain
What are the features of the parietal lobe
-it deals with sensation, association, perception
->parietal lobe interprets sensations
What are the features of the occipital lobe
-it is for vision
What are the features of the temporal lobe
-auditory cortex, learning and memory
What does more innervation for a tissue mean for cortical space
-more innervation-increased cortical space
What is the grey matter
-cortex
What is the white matter
-medulla
Where do cortical neuronal cell bodies reside in
-they reside in the cortex(gray matter)
->they are not mylienated
Where do axons of cell bodies extend into?
-they extend into the medulla
->they are mylienated in most cases
What is a short association fiber
-it goes from one gyrus to another
What are long association fibers
-staying in the same side of the hemisphere
->they can go from one lobe of the brain to another
-an example would be limbic system
What is a commissural fibers
-axons that crosses into another side of the brain hemisphere
-communication between the different sides of the brain
What are projection fibers
-go down from brain to spinal cord or brain stem
Is spinal cord encased in bone
-yes
Describe the grey matter of the spinal cord
-central canal for the CSF
-Dorsal horn
->receives sensory information from the periphary nervous system
-ventral horn
->motor commands to motor neurons
What surrounds the grey matter of the spinal cord
-mylienated axons
Where in the brain do cranial nerves come off
-brain stem
Where do spinal nerves come off
-they come off the vertebrae
How many cervical vertebrae and neurons
-7 cervical vertebrae and 8 cervical neurons
How many thoracic vertebrae and nerves
-12
How many lumbar, sacral and coccygeal vertebrae and nerves
-Lumbar(5)
-Sacral(5)
-Coccygeal(1)
What is the plexus
-bunch of spinal nerves that intermix with each other
Where do bunch of spinal nerves that don’t intermix
-segmental
->T2-T12
Where are the cell bodies of sensory neurons found
-in the dorsal root ganglion of the PNS
Does the spinal cord have dorsal sensory and ventral motor
-yes
Are the motor roots in the CNS or PNS
-CNS
-the sensory roots are in the opposite, or the PNS
What is the dorsal ramus and the ventral ramus
-the dorsal innervates the back of the body, while the ventral innervates the front of the body
-they both have motor, sensory and autonomic nerves
What is the dermatome
-band of skin with its own sensory innervation
Describe the 5 landmark dermatomes
-T2=sternal angle
-T4=nipple
-T7=xiphoid
-T10=umbilicus
-L1=suprapubic
-the dermatomes in between those landmarks can be filled in
What does the somatic nerves innervate
-skin, muscle, bone of body wall
-parietal membranes(pleura, pericardium, peritoneum)
Why is the T7 spinal nerve important
-because that is where the dorsal primary and ventral primary ramus seperates
-dorsal primary goes to pravertebral muscles
-the ventral primary ramus goes to skeletal muscle such as intercostal muscles or abdominal muscles
Where does the sensory afferent travels
-it travels via visceral afferent fibres
-there are other ones specific for pain sensation
Where in the spinal cord is the sympathetic nervous system housed
-thoracolumbar outflow
Where is the parasympathetic nervous system housed
-craniosacral outflow
Does the sympathetic nervous system go to the skin at all levels?
-yes
-sweat glands, skin, shivers
Does skin have pharasympathetic
-no
Are the sympathetic and parasympathetic nervous system two cell body systems
-yes
->both have preganglionic and postganglionic cell bodies
-para has a longer preganglionic axon, while it is the opposite for the sympathetic
Is visceral afferents associated with sympathetic
-yes
->primarily for pain
->ischemia or inflammation
Why is there sympathetic innervation at every level of skin
-because sympathetic is just at thoracolumbar
->to reach everything else, all part of the skin ned to be innervated
What are the sympethatic nerves that go to the heart directly
-cardiac nerves
What are the 3 different paths for sympathetic
-skin
-heart
-digestion
Is direct pain always somatic
-yes
-it is sharp, well focused and easily localized
-carried by spinal nerves
What is referred pain
-pain that arises from an injured or inflamed structure in the body
-you get injury in one place but feel the pain elsewhere
-feeling of tingling in your fingers after hitting your funny bone
How is referred pain classified
-somatic or visceral
-visceral is always referred to dermatome
->no visceral map in the brain
Describe visceral referred pain
-the pain arises from the visceral organ but goes to the dermatome
->so that’s because it is carried by visceral afferent fibres, which respond to stretch, ischemia and chemoreception
How does the pain of visceral referred pain feel
-it is vague, dull and ill focused
