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Functions of the Nervous System
- Gather Info
- Process Info (internal/external)
- Coordinating all body systems
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Structural & Functional divisions of the Nervous System
- Central Nervous System: Brain & Spinal Cord
- Peripheral Nervous System: Nerves outside of brain
- ~Sensory (afferent) nerves: messages going to CNS
- ~Motor (efferent) nerves: messages going away from CNS
- **Somatic Nervous System: Skeletal Muscle
- **Autonomic Nervous System: Smooth Muscle, Cardiac Muscle, glands
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Types of cells that make up the nervous system
- Neurons: Functional unit of nervous system specialized to recieve and send information
- Neuroglia: Cells that support and protect neurons (outnumber neurons 9:1)
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Components of a Neuron
- Cell Body: Have components of all other cells
- Axon: Impulse goes away from cell body
- Dendrites: Receive info from other neurons and send to cell body
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Structure of a Neuron
- Unipolar Neuron: Most of Sensory Neurons
- Bipolar Neuron: Very specialized Neurons
- Multipolar Neuron: Most cells are
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Function of a Neuron
- Sensory Neurons (afferent): Sends impulse to CNS, mostly unipolar
- Motor Neurons (efferent): Sends impulse away from CNS to muscles and glands, mostly unipolar
- Interneurons: Recieve and send messages between neurons ~found in CNS, 99% of neurons are interneurons
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Function of Neuroglia
- PNS:
- Neuoglia that form the mylan sheeths
- 80% lipids & 20% proteins
- (Schwann Cell) Neurolemmocyte, creates the husk
- CNS:
- Makes mylan sheeths
- provides/monitors cerebral spinal fluid
- line interior & exterior of spinal cord
- help form the blood brain barrier
- hold neurons to capalaries
- recycle neurotransmitters
- type of macrophage
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Nerve message transmitted from neurons dendrites to its axon terminal
- Resting membrane potential: Outside is positive inside is negative
- Action potential: causes the release of a neurotransmitter from a presynaptic neuron (difuses across the synaptic cleft)
- neurotransmitter binds to a receptor on a post synaptic membrane
- a threshold potential is reac hed
- Ion channels open in post synaptic neuron
- action potential (nerve impulse, depolarization)
- neurotransmitters are removed from synaptic cleft
- repolarization is going back to the resting membrane potential
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Synapses
- Where neurons meet and communicate
- Presynaptic Neuron: Sends the message
- Postsynaptic Neuron: receives the message
- Synaptic Cleft: space between
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Neurotransmitters
- Chemical messengers released by a presynaptic neuron
- ~dopamine
- ~adreneline
- ~seratonin
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Salatory Conduction
when action potential jumps between gaps in the mylan sheeth
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Ganglion vs neucleus & Nerve vs tract/column & Cranial Nerves vs Spinal Nerves
- Ganglion is a group of cell bodies in the PNS
- Nucleus is a group of cell bodies in the CNS
- Nerve is a bundle of nerve fibers in PNS
- Tract/Column is a bundle of nerve fibers in CNS
- Cranial Nerves go to and from brain
- Spinal nerves go to and from spinal cord
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Nerve Cell Injury
- Pressure: Reduce the blood supply and conduction is impaired
- Cut Injury: Regeneration is more likely in the periferal nervous system
- Ischemic Injury: Lack of blood-No blood supply
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Neuron Regeneration
- CNS - Unlikely
- PNS - as long as the body is aligned
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Anatomy of the Spinal Cord
- 31 segments:
- ~8 cervical spinal nerves
- ~12 Throacic spinal nerves
- ~5 Lumbar spinal nerves
- ~5 Sacral spinal nerves
- ~1 Coccygeal spinal nerves
- Spinal cord made of cell bodies
- Costesequina at L1
- Cervicle & Lumbar enlargements that go out to the limbs
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Difference between Gray Matter & White Matter & the distribution of each in the spinal cord
- Gray Matter:
- found on interior of spinal cord and surrounds the central canal
- Unmylenated
- Mostly cell bodies
- posterior side is sensory info
- anterior are somatic and motor neurons
- lateral gray horns are autonomic
- Function of gray matter is passing information
- White Matter:
- Mylanated
- Function to carry infro from one place to another
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3 Layers of Meninges & their structures
- Pia Mater: binds to spinal cord
- Arachnoid: Sub Arachnoid Space, Cerebral spinal fluid, blood vessels
- Dura Mater: Thick protective outer layer
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Describe Spinal Nerves
- Carry Information to and from spial cord and the rest of the body
- 3 pairs of nerves for each spinal segment each pair of nerve will have a dorsal root
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Define Sensory Receptor
a cell or nerve ending of a sensory neuron that responds to a specific stimulous
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Classification of Sensory receptors - TOUCH
- Touch (Parietal Lobe):
- Pressure Receptors-Mechanoreceptors notice pressure & touch
- temperature receptors-thermoreceptors notice cold & warmth
- Pain receptors (nociceptors)-chemoreceptors notice when tissues are damaged and will send out pain receptors
- Proprioceptors-type of mechanoreceptors, tension and stretch of tendons and muscles (spoon to mouth)
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Classification of sensory receptors - SIGHT & TASTE
- Sight: (Occipital lobe) Photo receptors
- rods (see gray) - see shape and movement
- cones (see colors) cones don't work in the dark
- Taste (Parietal lobe)
- Taste goes with smell
- Taste salt, sweet, bitter, sour, umami (savory)
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Classification of sensory receptors SMELL & HEARING
- Smell (temporal lobe)
- Olfactory receptors
- smell is 10,000 times more powerful than taste (emotion & memories)
- Hearing (temporal lobe)
- Sound waves hit the tempanic membrane
- stimulate the ossicle, hit the cochlea
- Typanic membrane (eardrum)
- Ossicles (3 ear bones-malleous, incus, stape)
- Cochlea
- Organ or corti (go the the auditory receptors (hairs)
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Receptor Stimulation
- If the stimulous is strong enough, an action potential occurs
- action potential either happens or it doesn't
- the stronger the stimulous the greater the frequency of the action potential
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Define Dermatone
Dermatones are regions of skin served by the sensory neurons of a single segment (1pair of nerves)
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Define Nerve Plexuses. Name the plexuses and the nerves that arrise from each
- Nerve Plexuses: Complex networks of intertwining spinal nerves
- Cervical Plexus: c1-c5, burried under SCM goes to head & neck
- Brachial Plexus: C5-T1 under armpit, goes to upper extremity
- Lumbosacral Plexus: T12-S4 sciatic nerve comes here (largest nerve in the body)
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Define Reflex. List the components of a reflex arc and explain reciprocal innervation
- Automatic motor response to a specific sensory signal specific set of neuropathways
- Sense organ or recepor-stretch, pain, or pressure receptors
- Sensory Neuron- Sends message to the CNS
- Central Nervous System-either brain or spinal cord send info to motor neuron
- Motor Neuron-sends message to the effector
- Effector-Muscle or gland tha receives the message
- Reciprocal innervation (reciprocal inhibition):
- Neuron to antagonist is inhibited
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Describe the stretch reflex. Explain how muscle spindles are involved
- Prevents over stretching of skeletal muslces.
- stimulous is stretching muslce or tendon
- receptor is a muslce spindle
- response is contracting the stretched muslce
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Describe the inverse stretch (tendon) reflex. Explain how golgi tendon organs are involved
- Prevents excess tension (lifting something too heavy & drop it)
- stimulous is muslce tension
- receptor is golgi tendon organ
- response is to relax the contracted muscle
Wihdrawl reflex - pain, hot, automatic reflex too hot too painful
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Explain the concept of final common pathway
A somatic motor neuron that goes to a skeletal muslce that is the final common pathway
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Explain the pathways of sensory information in the spinal cord
- Sensory pathways (how it gets from here to there)
- Sensory messages coming through the dorsal route getting carried to the brain on different tracts on the spinal cord, messages first go to the thalamus then the sensory cortex
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List the four major divisions of the brain
- cerebellum
- cerebrum
- diencephalon
- brain stem
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Identify the major landmarks and divisions of the cerebrum
- Lobes: temporal lobe, frontal lobe, occipital lobe, parrietal lobe
- Sulcus: (Groove) central sulcus divides the frontal & parrieal lobes
- Gyrus: (ridge) pre central gyrus, post central gyrus
- Fissure: (deep sulcus) divides left and right hemispheres
- Hemispheres:
- Left-Speech, Language, Analytical skills, holds world view
- Right-Spacial, intuition, insight, subtle aspects of language (metaphors) reads facial expressions
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Describe the distribution of gray matter and white matter in the cerebrum
- Gray Matter:Cerebral corex-this exterior layer of the cerebrum -a concious thought
- basal nuclei (basal ganglia)-Planning, starting, stopping and monitoring the intensity of movement (soccer w/3yr old vs. adults)
- White Matter:
- Corpus Calosum-fibers that communicate between the hemispheres
- association fibers-within the same hemisphere
- projection fibers-outside of hemispheres
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Describe he location and function of the primary motor cortex
in the pre-central gyrus of the frontal lobe, voluntary muscles that are working
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distinuish between primary sensory areas and sensory association areas.
- Primary areas-taking raw data, make it concious (i see this (drink))
- association areas-I've seen something like this before based on experience, understanding the sensations
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name the lobes of the cerebral cortex involved with different sensations
- touch and proprioception - in the post central gyrus
- taste (Gustatory) - in the parrietal lobe
- hearing (auditory) - in the temporal lobe
- smell (olfactory) - in the temporal lobe
- vision ( ) - in the occipital lobe
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describe the location and function of the major integrative areas of the cerebral cortex
- Integrative areas of cerebral cortex-how we integrate infor, processing info from many sources
- prefrontal cortex: highly developed in humans, intelect, mood, personality, abstract thought, concience, predict a response to something
- general interpretive area: making sense of info, left hemisphere
- language area: left hemisphere, understanding written and spoken langualge. Broca's area involved in speech
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Describe the location and function of the limbic system
- (basic survival)
- Emotion, memory, sexual behavior, fear, rage, motivation (rewards vs. punishment...enough not to make behavior to happen again)
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describe the locaion and function of the cerebellum
coordinates skeletal muscle movements, makes them smooth (piano)
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name two main divisions of the diencephalon and give the functions of eaach
- Thalamus: relay point for sensor information
- Hypothalamus: (housekeeping, make sure everything works) homeostatic control center: blood bressure, heart rate, digestion, temp, sleeping, hormones
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Name the three divisions of the brainstem from superior to inferior. Describe the functions of the brainstem
- Brainstem: connects the brain to the spinal cord
- Divisions: mid-brain, Pons, Medula Oblongotta (gets instruction from hyposthalamus to cough, sneeze, hiccup)
- functions: skeletal motor control, reticular activationg system (helps keep cortex alert)
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Define "cranial nerve". Give the distribution, major functions, and comon names of cranial nerves I, II, V, VII, VIII, X
- Cranial Nerves: Cell body in brainstem
- I (olfactory nerves) - sensory fibers for smell
- II (optical nerves) - sensory fibers for sight
- V (trigeminal nerves) - mostly sensory fibers to the face, some motor nerves for he face
- VII (faacial nerves) - mostl motor fibers for facial expression a few sensory taste fibers
- VIII (vestibulocochlear nerves) - sensory from the ears & equilibrium
- X (Vagus nerves) Parasympathetic & motor info (to heart lungs & kidney
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Describe the structures and pathways involved in skeletal muscle control
- Skeletal motor neurons (lower motor neurons) - final common pathway, cranial nerves: cell bodies in brainstem, Spinal nerves, cell bodies in spinal cord
- Primary motor cortex (upper motor neurons) - sending messages to motor neurons of the brainstem and the spinal cord
- Cerebellum - coordinates and makes skeletal muscle ativity smooth(drunk) info from proprioceptors eyes & inner ear
- Basal Nuclei (basal ganglia) - receiving info from all different parts of brain (starting, stopping, monitoring intensity of movements, maintaining muslce tone)
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Describe the formation, circulation and function of cerebrospinal fluid in the brain
- cerebrospinal fluid - watery fluid bathes and protects brain, makes about 700ccs
- Formation: choroid plexuses - specialized capalaries that filter plasma and takes the proteins out
- Circulation: goes from ventricals down central canal of spinal cord back up through the subarachnoid space (craniosacral work)
- Functions: to give brain boyancy to keep brain from squishing its self, protects against trauma nutrients, chemicals are carried in cerebral spinal fluid
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Describe how the autonomic nervous system differs from the somatic nervous system
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Name the two divisions of the autonomic nervous system, compare them in terms of structure and function. name the neurotransmitters used by each
- Sympathetic Division (thoracolumbar division):
- Function: fight or flight, deal w/threat, heart rate increase & force of contraction goes up, blood pressure increase, inhibit digestion and move blood to skeletal muscles, open up bronchioles, dialated pupils
- location of cell bodies in CNS: preganglionic cell body is inside T1-T12, most of the post ganglionic cell bodies are right next to the spine
- Neurotransmitters: preganglionic is acedocoline, postganglionic is epinephrin
- receptors: for acedocoline (ach) are cholinergic, adrenergil go with epinephrin
- Parasympathetic Division (craniosacral division):
- Function: rest & digest/repair, digestion, repair, blod pressure decrease, heart rate decrease, breathing slows
- Location of cell bodies in CNS: pregangliotic cell bodies- brain stem and sacral segments, postgangliotic cell bodies- ganglia in walls of organs
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Describe how autonomic function is controlled
- the hypothalimus is boss
- autonomic areas of brainstem can have an influence
- defication, urination, controlled at spinal cord level
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describe age-related changes in the nervous system
- loss of sensory-hearing, vision, taste, smell
- declines of some autonomic functions-constipation, dry eyes, incontenance
- problems with balance
- reflexes slow
- memory loss
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describe the possible effects of massage on the nervous system
- reduces stress to increase the brains abilities/life
- increase nerve function by increase blood flow
- Parasymathetic - stimulate to get relaxation and better digestion stimulates which then...
- interrupts pain/spasm cycle
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