Nervous System Flashcards
Rhombencephalon
Most primitive parts of brain
Myelencephalon:
-medulla > basic autonomic function (❤️, breathing)
-switching point for white & gray matter
Metencephalon:
-cerebellum
•coordination & equilibrium(balance) >motor functions
•body & vermis (worm), very folded
•large in fish, birds, mammals
•arbor vitae: white matter on inside of cerebellum
Embryology of brain
Prosencephalon = forebrain -telencephalon and diencephalon Mesencephalon = midbrain -no formal subdivision Rhombencephalon -metencephalon and mesencephalon
Mesencephalon
Mesen = middle Pons = floor of midbrain -autonomic relay point Optic lines transmit to superior colliculus -fish & amphibs start to enlarge Auditory info transmits to inferior colliculus (below) -amniotes start to enlarge *tectum = roof of midbrain
Prosencephalon : diencephalon
1) epithalamus
-pineal gland
•median (parietal) eye
-choroid plexus = secretes CSF in any ventricle
2) thalamus
-relay center to cerebrum
-interpret pain, temp.
-sleep, wakefulness
3) hypothalamus
-homeostasis center > regulation
-optic chiasma ventral
-pituitary ventral (landmark)
Prosencephalon : telencephalon
Cerebral hemispheres -increase in size (amniotes ~20x larger) -duplication of centers that process stimuli •cerebral cortex (sensory/motor) •hippocampus (recent memory) •basal ganglia (motor/decision making) -olfactory bulbs and lobes -corpus callosum or commissure •decussating (crossing) nerve tracts
All brain regions
Internal hollow ventricles
Cerebrospinal fluid (nutrients, salt + H2O balance) secreted by choroid plexus
Hydrocephalus ("water on the brain") occurs when intraventricular foramina are blocked -> CSF can't drainNeuron
- cell body
- dendrites
- axon
Synapse
Gap between neurons
Nerve
Axons bundled together in connective tissue sheath (epineurium)
Neuroglia
Half of the mass of brain and spinal cord are neurons
Other half are Neuroglia (supporting cells)
Functions of Neuroglia cells
- secrete myelin
- remove debris
In CNS: oligodendroglial
In PNS: Schwann cells
*nodes of ranvier = spaces between myelin
Sensory nerves
Cell bodies in PNS (usually in ganglia)
Receives messages from PNS (external or internal stimuli)
Motor nerve
Cell bodies in CNS
Sends out messages to muscles and glands (Effectors)
Mixed nerve
Contain both sensory and motor nerves
Most vertebrate nerves are mixed
Spinal cord
Shorter than the vertebral column (gap used for spinal taps, epidural)
Swellings in cervical & lumbar regions
Gray matter -inside of spinal cord -cytoplasm of cell bodies White matter -outside of spinal cord -axons (myelin sheath)
Spinal cord nerves
Spinal nerves are split into branches near spinal cord
Dorsal root of spinal nerve
Enters spinal cord does ally
Carries sensory fibers
Sensory ganglion just outside the spinal cord
Ventral root of spinal nerve
Leaves the spinal cord ventrally (inside)
Carries motor fibers
Interneurons IN spinal cord
Help coordinate between sensory and motor fibers
Relay point
Reflex arc
- Sensory receptor
- Sensory neuron
- Into dorsal root of spinal cord
- Interneuron in spinal cord
- Out ventral root of spinal cord
- Motor neuron
- To muscle
Autonomic nervous system
Subdivision of PNS
Involuntary nervous system
Enervates viscera
Thoracic and lumbar regions -> sympathetic system
-fight or flight (rev up ❤️, decrease digestion)
Craniosacral system -> parasympathetic
-rest and repose
Cranial nerves
- Amniotes (reptiles, birds, mammals) and sarcopterygii (lung fish, lobe-finned fish) have 12 cranial nerves
- Amphibs and fish have 10 cranial nerves
- Other 2 nerves were originally spinal nerves that became incorporated into the brain case
OOOTTAFAGVAH (names I-XII)
SSMMBMBSBBMM (sensory-motor-both)
Nerve I
Olfactory
Sensory
-smell
-some tetrapods have separate vomeronasal nerves
Nerve II
Opic
Sensory
-vision
-nerves cross in optic chiasma
Nerve III
Oculomotor
Motor
-moves eyes
Nerve IV
Trochlear
Motor
-moves eyes
Nerve V
Trigeminal
Both
-face and jaw innervation
Nerve VI
Abducens
Motor
-moves eyes
Nerve VII
Facial
Both
-taste, facial expression, saliva, tears
Nerve VIII
Auditory
Sensory
-also called vestibulocochlear
-hearing, equilibrium
Nerve IX
Glossopharyngeal
Both
-back of tongue, taste, senses carotid blood pressure, swallowing
Nerve X
Vagus
Both
-senses aortic blood pressure, senses taste, slows heart, stimulates digestion
Nerve XI
Accessory
Motor
-swallowing muscles
-also called “spinal accessory”
Nerve XII
Hypoglossal
Motor
-hyoid, tongue, speaking
