Neurology
Study of the Nervous System
Functions of the Nervous System
Senses environmental and internal changesIntegration of the informationResponds to the information
Central Nervous System
Brain & Spinal Cord(Basically 1 organ)
Peripheral Nervous System
Nerves that come off of the CNS into the periphery of our body
Afferent System
*Sensory* System - Takes information from receptors TO the control center
Efferent System
*Motor System* - Takes information AWAY from the control center TO an effector
Somatic Nervous System
Deals with efferent pathways that are ALWAYS going to voluntary skeletal muscle
Autonomic Nervous System
Primarily an efferent pathway, deals with anything that works on an involuntary basisHeart, smooth muscle, glandsCan be divided up into the *Sympathetic division and Parasympathetic* division
Sympathetic Nervous System
Fight or Flight"When there are some stressors, deviation from the set points, not maintaining homeostasis, need to be more active. Faster heartbeat, etc.Deals with the viscera
Parasympathetic Nervous System
Rest and Digest" " Idle mode"When at rest/asleep/in homeostasis there is a lot of parasympathetic activity. Slower heart rate, etc.A lot of parasympathetic activity during sleepDeals with the viscera
Neuroglia
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Neuron
Functional unit of the nervous systemNeurons don't divide "The neuron that does the work, the circuitry, that evaluates the set points and stress, the neuron that conducts info from a control center to an effector or a receptor to a control center
Neuroglia
The "Support Tissue"Neuroglia DOES divide If someone has a brain tumor, it's not a neuron but the Neuroglia that's the problem - they have a "Glioma
How much Neuroglia is there per Neuron?
50-80 Neuroglia cells per 1 neuron
Astrocyte
FUNCTION: Conduct nutrients to the Neuron from a source(Can also conduct appropriate nutrients to an Axon)Has Cytoplasmic extensions coming off of it, and forming plate-like structures that envelop capillaries Makes contact with Neurons, and other cells
Blood-Brain Barrier
Blood-Brain Barrier = Endothelia + AstrocyteHighly selective fluid barrier that separates the blood from the nervous tissue; Astrocytes conduct appropriate nutrients to Neurons, while keeping the wrong ones out
Microglia
White blood cells - LeukocytesEliminates dead tissue, plays a role in the immune response to infection
Axon
Long appendage coming off of a Neuron
Schwann Cells
Special cells in the peripheral nervous system that wraps around the Axon nerve fibers. Forms a Myelin sheath of pure phospholipid bilayer around the axonSchwann cells are not in intimate contact with each other - part of the Axon is exposed, we call this a "Node"Not all Axons have Schwann cells
Function of Schwann Cells
1. Insulates & protects the Axon, keeps it from coming into contact with another Axon2. In conjunction with nodes, greatly increase the rate of impulse propagations (130 meters/second vs 3 meters/second)3. Healing response: if an Axon has been damaged, it will help guide the Axon where it needs to growSimilar to the rubber sheath surrounding a copper wire
Unmyelinated Axon can conduct an impulse how fast?
About 3 meters/second
Myelinated Axon can conduct an impulse how fast?
About 130 meters/second
Is impulse conduction faster in myelinated or unmyelinated neurons?
Myelinated
How to Schwann cells help neurons regrow?
Br creating a tube for where the axon needs to grow, which the axon will grow through
Neuron body has all organelles for a Eukaryotic except for which ones?
Except for the ones involved in cell division
Dendrite
Conducts an impulse to the cell body(the word "Dendrite" means "branch")
Axon
Conducts an impulse away from the cell body
A neuron has many _________, but only one ____
many dendrites; only one axon
Axon Hillock
Tapered, cone-shaped region of an axon where it joins the cell body.The "trigger" that determines whether the neuron is going to conduct an impulse down the axon or not. Neurons can only have 1 trigger, never 2
Axoplasm
Cytoplasm inside the Axon
Axolemma
Axon cell membrane
Axon collaterals
Branches coming off of the axon
Synaptic End Bulbs
The terminal end of an axon, has a "bulb" shape. same physiology (function) as Synaptic End Bulbs from Myology lecture
Synaptic Vesicles
Vesicles that contain neurotransmitters
Myelinated Neuron
Nerve fiber with Schwann Cells covering parts of the Axon leaving Nodes in between.
Unmyelinated Neuron
A nerve cell no Schwann Cells/Myelin
Neuralfibral Nodes
Narrow gaps between the ends of the segments of myelin that insulate single nerve axons.
Multipolar Neurons
A neuron that has many poles/extensions from the bodyOne is an axon, the others are all dendritesFound in control centers, creating complex circuitry evaluating information and comparing it to the set point. You want a lot of appendages for this.Also found in Efferent motor neurons
Bipolar Neurons
A neuron with two poles coming off of itThey act like "little wires" conducting specific information from one location to anotherLocation: Organs of special sense;> Retina (special cells picking up specific frequencies of light)> Hearing (Special cells picking up specific frequencies of sound)
Unipolar Neurons
Neurons with only 1 pole coming off of the cell body. Found in Afferent Sensory NeuronsAxons & dendrites are determined by presence and absence of Myelin sheath (everything covered in Myelin is Axon). If there's a synaptic end bulb, it's an Axon.Developmentally starts out as bipolar, then the two poles migrate towards each other.A
Afferent Neuron
Goes from Receptor to Control CenterALWAYS Unipolar
What type of neurons are in the control center?
Multipolar
Association Neurons
Interneurons make associations with the genetically predetermined Set PointsAlso neurons that store & access memories
Interneurons
Multipolar neurons within the "control centers" with complex circuitry that communicate internally and intervene between the sensory inputs and motor outputsCan be either Excitatory or Inhibitory
Which Neurons store & access memories?
Association Neurons
Efferent motor neurons are _______polar?
Multipolar
Nerve Processes
Bundles of Axons in cable-like structures
Fiber Tracks
Nerve process (axon bundle) in the Central Nervous System
Ascending (Sensory) Tracts
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Descending (Motor) tracts
...
Nerve
Nerve process (axon bundle) in the Peripheral Nervous System
Nerves are in the _____ nervous system
Peripheral
Fiber Tracks are in the _____ nervous system
Central
Nerve cell arrangement is similar to the structure of a _____
muscle
Perineurium
Connective Tissue surrounding fascicles (bundles) of Axons
Endoneurium
Connective Tissue surrounding individual nerve fibers/axons
Epineurium
Connective tissue surrounding the entire nerve
The Spinal Cord is located in the _____ _____
Vertebral Canal
Which part of the brain enters the Vertebral Canal
Medulla Oblongata (part of the brain stem)
In adults, the spinal cord stops between ___ and ___.
T12 and L1(Conus Terminalis)
Spinal nerves form the ____ ____ ____
Peripheral Nervous System
Conus Terminalis
Region where the spinal cord stops, between T12 & L1
Spinal Nerves go through the
Intervertebral foramen
How many cervical spinal nerves are there?
8 (C1-C8)
Where is the "freebie"/extra cervical spinal nerve located?
Between the Brain and the Atlas
Why is there a Cervical Enlargement in the spinal cord?
Cell bodies of motor neurons for Upper Appendages are housed there
Why is there a Lumbar Enlargement in the spinal cord?
Cell bodies of motor neurons for Lower Appendages are housed there
Which spinal nerves "droop" through the vertebral canal until they reach their respective intervertebral foramen?
Lumbar nerves
Meninges
A set of 3 membranes covering the brain and spinal cord, that protect it:Dura MatterArachnoidPia Matter
Dura Matter
The outermost layer of the meninges surrounding the brain and spinal cordVery tough connective tissue sheath, adjacent to periosteum
Arachnoid
Middle layer of the meninges, attached to Dura Mater
Pia Matter
Very thin, highly vascular membrane in intimate contact with the brain itself
The Central Nervous System has a sort of ____ consistency
Gelatinous
The entire Central Nervous System (brain and spinal cord) is suspended in
Cerebrospinal Fluid
Cerebrospinal Fluid functions
Acts as a "shock absorber" the protect the CNS from physical traumaSupplies nutrients and removes waste from nervous tissue
Subarachnoid Space
A space in the Meninges beneath the Arachnoid Membrane and above the Pia Mater that contains the Cerebrospinal Fluid, as well as little ligament-like structures holding the brain in place
Subdural Space
...
Epidural Space
Space between Periosteum and Dura MaterA lot of adipose connective tissue for protection, and vasculature as well.
Innermost Meningeal Layer
pia mater
Outermost Meningeal Layer
Dura Mater
Middle Meningeal Later
Arachnoid
Two Lateral Ventricles of brain
Left & Right, CSF flows from this one into the third ventricle
How many ventricles are in the brain?
4
Cerebral Aquaduct
Little "tube" that connects the third and fourth ventricles
How much Cerebrospinal Fluid is produced per day?
500 mL
Choroid Plexus
Collection of blood vessels and Neuroglia that creates a highly selective fluid barrier that allows a very precise fluid to flow out of it from the blood into the lateral ventriclesThere are 4 of these, 3 laterally; one in the 3rd and 4th ventricle tooThey each produce a portion of the total 500ml of CSF produced every day
Median Aperture
An opening in the roof of the fourth ventricle that connects to the subarachnoid space, CSF can flow through here
Arachnoid villi
Allows CSF to flow into blood sinus and return to general blood circulation
Lateral Apertures
pair of openings from the fourth ventricle to the subarachnoid space on either side and between the medulla and cerebellum that CSF flows through
Superior Sagittal Sinus
Blood sinus where CSF is reabsorbed into general blood circulation
Myelin sheath is multiple layers of _____ _____
Phospholipid Bilayer
Are dendrites ever myelinated?
No
Central Canal
Spans length of spinal cord. Contains flowing CSF. Supplied nutrients and removes waste from surrounding neural tissue.
Anterior Median Fissure
Divides the spinal cord into left and right halves
Posterior Median Sulcus
Divides the spinal cord into left and right halves
Gray Matter (Spinal cord)
Has control centers("CPU")Consists of cell bodies, dendrites, axons
White Matter (Spinal cord)
Consists of Myelinated fiber tracts that communicate info.("Cables")No control centersGets it's white color from Phospholipid Bilayer of the Myelin
Dorsal Root Ganglion
Contains cell bodies of sensory neurons; thus increased size
The Dorsal root is ALWAYS _____
Sensory
The Ventral root is ALWAYS _____
Motor
EPSP
Excitatory Postsynaptic Potential; produced by excitatory interneurons
IPSP
Inhibitory Postsynaptic Potential; produced by inhibitory interneurons
Excitatory Interneurons
Produces Excitatory Postsynaptic Potentials
Inhibitory Interneurons
Produces Inhibitory Postsynaptic Potentials
Posterior (Dorsal) Horns
Has synapses with different sensory neurons.Comes in contact with interneurons, either excitatory or inhibitory
Anterior (Ventral) Horns
Somatic/VoluntaryVoluntary skeletal muscle motor neurons are always housed here
Lateral Horns
Automatic/InvoluntaryAny involuntary neurons are housed here
Ascending Tracts
ALWAYS carries sensory information from receptors to the brain
Descending Tracts
ALWAYS motor tracts, going from brain to motor neurons
Naming of tracks
Binomial nomenclature: two wordsFirst word is Origin, second is destination'Example: Corticospinal. Originates in the Cerebral Cortex, going to spinal ford. Therefore is descending, therefore a motor neuron.
Order of nerve impulses
1. Receptor picks up information2. Picked up by a unipolar afferent neuron3. Goes through the Dorsal route4. Enters Posterior Gray Horn5. Synapses with Interneurons ( the "circuitry", either excitatory or inhibitory)6. Goes through Efferent motor neuron to effector
Involuntary/Autonomic Motor neurons are housed in the
Lateral Gray Horn
Voluntary/Somatic Motor neurons are housed in the
Anterior Gray Horn
Efferent Motor neurons go through the
Ventral Route
Ventral Route is always _____
efferent/motor
Afferent Sensory Neurons are always _____
Excitatory
excitatory interneurons
Cause EPSPs in the motor neuron going to the flexor muscle (ex: the biceps - flexes to pull the hand away from the hot stove). (withdrawal reflex)
Stretch Reflex
Protects muscle from overstretching & being damaged when thing & thick filaments don't disengaged
Tendon Relfex
Protects from too much stress
Muscle Spindle
Special Receptor Muscle cell that has been modified to monitor the stretching that occurs in the muscle
Tendon Organ
Monitors the tension and stress on this
Dermatome
Area of skin supplied by a single spinal nerve
The Peripheral Nervous System can be divided up into the _____ System and the _____ System
Afferent & Efferent
The Efferent System can be divided up into the _____ Nervous System and the _____ Nervous System
Somatic & Autonomic
The Autonomic Nervous System can be divided up into the _____ Division and the _____ Division
Sympathetic & Parasympathetic
When we're at rest, the ____ system is dominant
Parasympathetic
Ganglion
A "knot" of nervous tissue that connects 2 motor neurons
In the Autonomic Nervous System, how many motor neurons are there?
2
Preganglionic Neuron
The neuron that's between the CNS and the Ganglion in the autonomic nervous system
Postganglionic Neuron
The neuron that's between the Ganglion and the Viscera in the autonomic nervous system
Anterior Gray Horn synapses with _____ _____ _____
Voluntary motor neurons
Unipolar afferent (sensory) neurons bring information into the _____ _____ _____
Posterior gray horn
Efferent (Motor) Neuron cell body is housed in the _____ _____ _____ only
Anterior Gray Horn
Preganglionic Neuron cell body is in the _____ _____ _____
Lateral Gray Horn
Autonomic Neurons service only the _____, _____, and _____ _____.
Heart, glands, and smooth muscle
In the Parasympathetic System, Preganglionic neurons are very _____, postganglionic neurons are very ___
Long, Short
In the Sympathetic System, Preganglionic neurons are very _____, postganglionic neurons are very ___
Short, Long
Neurotransmitter for Voluntary Skeletal muscle is always _____
Acetylcholine (Ach)
When there is a Ganglion - between pre and post ganglionic neurons, the Neurotransmitter is always _____
Acetylcholine (Ach)
Parasympathetic Neurotransmitter in Effectors is _______
Acetylcholine (Ach)
Sympathetic Neurotransmitter in Effectors is _______
Norepinephrine
In the heart, if Norepinephrine goes up, and Ach goes down, the heart rate will go _____
Up (sympathetic response)
In the heart, if Ach goes up, and Norepinephrine goes down, the heart rate will go _____
Slower (parasympathetic response)
Our body "Idling
Basal Metabolic Rate
Preganglionic Sympathetic Neurons come from
Thoracic and the first 2 Lumbar vertebrae only
Preganglionic Parasympathetic Neurons come from
Certain Cranial nerves, and 3 sacral nerve only
Synaptic Chain Ganglions
Facilitates an integrated Sympathetic nervous response
Blood vessels only have _____ stimulation
Sympathetic
Sweat glands and the Erector Pili muscle only have only have _____ stimulation
Sympathetic
Adrenal gland secretes
Adrenaline (Epinephrine)
Kidneys only have _____ stimulation
Sympathetic
Digestive System, Heart, and Lungs can be both _____ and _____
Sympathetic and Parasympathetic
Skeletal muscle is integrated by:SympatheticParasympatheticBothNeither
Neither (somatic/voluntary NOT autonomic)
The Heart is integrated by:SympatheticParasympatheticBothNeither
Both
Involves Thoracic and Lumbar Spinal segmentsSympatheticParasympatheticBothNeither
Sympathetic
Has long preganglionic Neurons:SympatheticParasympatheticBothNeither
Parasympathetic(Sympathetic has short)
Has short post ganglionic Neurons:SympatheticParasympatheticBothNeither
Parasympathetic
Digestive Tract innervated bySympatheticParasympatheticBothNeither
Both
Dominant when sleepingSympatheticParasympatheticBothNeither
Parasympathetic
Involves ONLY AcetylcholineSympatheticParasympatheticBothNeither
Parasympathetic
Break out into a cold sweatSympatheticParasympatheticBothNeither
Sympathetic (peripheral vasculature vasoconstricts); hot blood gets away from integument
Fight or flight response:SympatheticParasympatheticBothNeither
Sympathetic
Lateral Gray HornSympatheticParasympatheticBothNeither
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Anterior Gray HornSympatheticParasympatheticBothNeither
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Involuntary neurons are housed in the _____ _____ _____ of the spinal cord
Lateral Gray horn
Voluntary (Motor) neurons are housed in the _____ _____ _____ of the spinal cord
Anterior Gray Horn
Efferent Motor neurons always go through the _____ _____
Ventral Root