Nuerophysiology part II Flashcards
photo of the autonomic nervous system
autonomic nervous system
-AKA visceral nervous system
-hypothalamus contains integrative centers
-higher order functions including consciousness, learning, intelligence
integrative centers of the hypothalamus
-coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions
visceral motor nuerons
-preganglionic nuerons in brainstem and spinal cord
-pre ganglionic fibers - axons of preganglionic nuerons
-after pre ganglionic fibers leave the CNS, they synapse on ganglionic nuerons
-autonomic ganglia - contain many ganglionic nuerons that innvervate visceral effectors
sympathetic and parasympathetic division working together
-usually have opposing effects
-may also work independently - only one division innervates some structures
-may work together, with each controlling one stage of a complex process
responses to increased sympathetic activity
-heightened mental alertness
-increased metabolic rate
-reduced digestive and urinary function
-activation of energy reserves
-increased respiratory rate and dilation of respiratory passageways
-increased heart rate and blood pressure
-activation of sweat glands
responses to increased parasympathetic activity
-decreased metabolic rate
-decreased heart rate
-increased secretion by salivary and digestive glands
-increased motility and blood flow in digestive tract
-stimulation of urination
sympathetic division anatomy
-thoracolumbar division
-short preganglionic fibers in thoracic and lumbar segments of spinal cord
-preganglionic nuerons located between T1 and L2
-cell bodies in lateral horns
-axons enter anterior roots
-ganglionic nuerons in ganglia near spinal cord
-long post ganglionic fibers to target organs
thorocolumbar division
sympathetic ganglionic nuerons synapse
-adrenal medullae
-collateral ganglia
-sympathetic chain
sympathetic chain ganglia photo
collateral ganglia photo
adrenal medullae
-center of adrenal gland
-modified sympathetic ganglion at center of each adrenal gland
-innervated by preganglionic fibers that synapse on cells that secrete epinephrine and norepinephrine
-bloodstream carries nuerotransmitters throughout the body
-causes change in metabolicc activities of different cells
-effects last much longer than those producerd by direct sympathetic innervation
arenal medullae photo
stimulation of sympathetic preganglionic nuerons
-release ACh at synapses with ganglionic nuerons
-effect is always excitatory
sympathetic ganglionic nuerons
-release nuerotransmitters at target organs
-telodendria form branching networks with varicosities
varicosity
-packed with nuerotransmitter vesicles
-membrane receptors scattered across target cells
parasympathetic division anatomy
-long preganglionic fibers brainstem and sacral segments of spinal cords
-S2-S4
-ganglionic nuerons in peripheral ganglia adjacent to target organs
-short ganglionic fibers in or near target organs
parasympathetic division photo
ganglionic nuerons in peripheral ganglia
-terminal ganglion are near target organ, usually paired
-intramural ganglion are embedded in tissues of target organ and consists of interconnected masses and clusters of ganglion cells
parasympathetic preganglionic fibers leave brain inc ranial nerves
-III (oculomotor)
-VII (facial)
-IX (glossopharyngeal)
-X (vagus)
where do parasympathetic division synapse
-ciliary, ptergopalatine, submandibular and otic ganglia
sympathetic vs parasympathetic photo
dual innervation
-most vital organs are innervated by both divisions of ANS
-two divisions often have opposing effects
-parasympathetic postganglionic fibers travel by cranial nerves to peripheral destinations
-sympathetic innervation reaches same strcutures
autonomic plesuses and ganglia photo
somatic nervous systen
-controls contractions of skeletal muscles
-sensory or motor pathways
two motor nuerons of somatic motor pathways
-upper and lower motor nuerons
lower motor nueron
-cell body lies in a nucelus of brainstm or spinal cord
-innervates single motor unit in skeletal muscle
-activation triggers a contraction in innervated muscle
-damage eliminates volunatry and reflex control over innervated motor unit
upper motor nueron
-cell body lies in a CNS processing center
-synapses on lower motor nueron
-activity may facilitate or inhibit lower motor nueron
motor homunculus
-functional map of primary motor cortex
-corresponds with specific regions of the body
-indicated degree of fine motor control avaliable
-proportions are similar to those of sensory motor homunculus
medial pathway
-control muscle tone and gross movements of neck trunk and proximal limb muscles
-upper motor nuerons in vestibular nuclei, superior and inferior colliculi and reticular formation
lateral pathway
-controls muscle tone and precise movements of distal parts of the limbs
-axons of upper motor nuerosn in red nuceli deccusate in brain and descent into spinal cord of rubrospinal tract
sensory pathways
-series of nuerons that relay sensory info from receptors to CNS
sensory receptors
-sepcialized cells or cell processes that monitor specific conditions in the body or external environment
-when stimulated, a receptor generated action potentials that are sent along sensory pathways
afferent division of the nervous system
-somatic and visceral sensory pathways
efferent division of the nervous system
-somatic motor portion
-carries out somatic motor commands that control peripheral effectos
-commands travel from motor centers in brain along somatic motor pathways
sensation
-arriving info
perception
-conscious awareness of a sensation
general senses
-temperature
-pain
-touch
-presure
-vibration
-proprioception
special senses
-olfaction
-gustation
-vision
-equilibirum
-hearing
special sensory receptors
-provide sensations of special senses
-located in sense organs such as eye or ear
-protected by surrounding tissues
interpretation of sensory info
-stimulus reaches cortical nuerons via labeled line
-each labeled line carries info about one modality or type of stimulus
-frequency and pattern of action potentials contain info about strength duration and variation ofs timulus
-your perception of the nature of stimulus depends on path it takes to CNS
detection of stimuli
-receptor specificity - each receptor has a characteristic sensitivity
-receptive field - area monitored, larger is more difficult to localize stimulus
transduction
-converstion of an arriving stimulus into an action potential by a sensory receptor
general sensory receptors
-nociceptors
-thermoreceptors
-mechanoreceptors
-chemoreceptors
Nociceptors
-free nerve endings with large receptive fields
-in superficial portions of skin
-in joint capsules and within periostea of bones
-around walls of blood vessels
-sensitive to: temperature extremes, mechanical damage, dissolved chemicals
thermoreceptors
-free nerve endings in demis, skeletal muscles, liver, hypothalamus,
-sensations are conducted along same pathways that carry pain sensations (reticular formation, thalamus and primary somatosensory cortex)
mechanoreceptors
-sensitive to physical stimuli that distort plasma membranes
-membranes contain mechanically gated ion channels that ipen or close in response to stretching, compression, twisting and other distortions of the membrane
cchemoreceptors
-respond to water and lipid solible substances that are dissolved in body fluids
-seconds for a response
-pH, CO2, O2
-carotid bodies and aortic bodies
carotid bodies
near origin of internal cartodi arteries
-sends info through cranial nerve IX
aortic bodies
between major branches of aortic arch
-sends info through cranial nerve X
major somatic sensory pathways
-spinothalamic pathway
-posterior column pathway
-spinocerebellar pathway
somatic sensory pathway
-carry sensory info from skin and muscles of body wall head neck and lumbs to CNS
spinothalamic pathway
-crude touch, pressure, pain and temperature
-first order nuerons enter spinal cord and synapse within posterior horns
-second order nuerons cross to opposite side of spinal cord before ascending
-third order nuerons in ventral nuclei of thalamus
-sent to primary somatosensorty cortex
spinothalamic pathway anterior vs lateral
abterior - crude touch and pressure
-lateral - pain and temp
lateral spinothalamic photo
posterior column pathway
-fine touch, vibration, pressure, proprioception
-left and rught gracile fasiculus
-left and right cuneate fasiculus
-after second order nuweons of grcaile and cuneate nuclei descussate
-third order nueron in thalamus
-processing in thalamus
-nuclei sort info based on nature and region of body involved
posterior column pathway photo
spinocerebellar pathway
-convey information about positions of muscles, tendons and joints from spinal cord
-this info doesnt reach awareness
spinocerebellar tracts
-posterior and anterior
posterior spinocerebellar tract
-axons do not cross to opposite side of cord
-travel through inferior cerebellar peduncle
anterior spinocerebellar tract
-sesnations reach cerebellar cortex through superior cerebllar peduncle
-many axons cross over twice, once in spinal cord, once in cerebellum
posterior tract of spinocerebllar photo
visceral sensory pathways
-info collected by interorecptors
-primarily within thoracic and abdominopelvic cavities
-interreceptors include nociceptors, baroreceptors, thermoreceptors, tactile receptors and chemoreceptors
-not as numerous as in somatic tissues
