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HAN 200 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

nervous system divisions

A
  • two main divisions of the nervous system
    1. central nervous system (CNS)- brain and spinal cord
    2. peripheral nervous system (PNS)- spinal nerves and cranial nerves
  • two functional subdivisions of PNS:
    1. sensory (afferent) division- brings to the CNS
    2. motor (efferent division- brings commands from the CNS out
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2
Q

overview

A
  1. Receptors detect changes in internal and external environment (somatic, special, visceral sensory receptors)
  2. sensory division of the PNS brings info to the CNS from receptors
  3. information processing in the CNS (integration)
  4. motor division of the PNS carries motor commands from the CNS to peripheral tissues -> somatic nervous system/ autonomic nervous system
  5. SNS -> skeletal muscle or ANS -> smooth muscle, cardiac muscle, glands, adipose tissue
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3
Q

somatic sensory receptors

A

-position, touch, pressure, pain and temperature sensations

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4
Q

special sensory receptors

A

provide sensations of smell, taste, vision, balance, and hearing

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5
Q

visceral sensory receptors

A

-monitor internal organs

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6
Q

sensory division of PNS

A
  • impulses from sensory receptors to the CNS
  • somatic sensory receptor
  • visceral sensory receptor
  • special sensory receptor
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7
Q

sensory division of PNS

A
  • impulses from sensory receptors to the CNS
  • somatic sensory receptor
  • visceral sensory receptor
  • special sensory receptor
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8
Q

cells of the nervous system

A
  • there are two main types of cells in the nervous system:
    1. neurons: the wiring of the nervous systems circuits, conduct information (impulses)
    2. glia: support the function of the neurons, do not usually conduct information
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9
Q

features of the neuron

A
  • cell body (soma)
  • lack centrioles bc they typically cant divide
  • dendrites- recieve the information
  • axon- conducts the action potential away from cell body
  • terminal braches (telodenria)- synaptic terminals
  • schwann cells- wrap axon with myelin
  • node of ranvier- unmyelanated gaps
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10
Q

cell body

A
  • nucleus, cytoplasm and organelles
  • neurotransmitters- proteins needed for transmission of signals from neuron to neuron
  • many CNS neurons lack centrioles and cannot divide and repair
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11
Q

dendrites

A

branch from cell body

  • receive stimuli and conduct signal to cell body
  • sometimes stimuli is not great enough to warrant a response
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12
Q

axon

A
  • conducts impulses away from cell body
  • telodendria- distal branches of axon
  • synaptic knobs- neurotransmitters in vesicles
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13
Q

schwann cells

A

-

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14
Q

synaptic knob

A
  • have vesicles that contain a neurotransmitter
  • sends the signal to target cell or effector
  • presynaptic cell
  • the postsynaptic cell would be the target cell (could be another neuron, skeletal muscle, gland)
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15
Q

different types of synapses

A
  • with anther neuron
  • neuromuscular- postsynaptic cell is a muscle fiber
  • neuroglandular- postsynaptic cell is a gland cell
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16
Q

classifications of neurons

A
  • neurons are classified by structure or function
  • three anatomical classes of neurons
    1. multipolar nuerons
    2. bipolar neurons
    3. unipolar neurons
  • functional classes of neurons
    1. motor neurons (away CNS)
    2. sensory neurons (to CNS)
    3. interneurons (connection between sensory and motor)
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17
Q

polarity of neuron

A
  • poles- number of processes extending from the cell body
  • multipolar neuron- has more than 2 extensions (dendrites) (most are interneurons rest are motor neurons)
  • bipolar neuron- two process extend -> one is a fused dendrite, the other is an axon (sensory neurons)
  • unipolar neuron- one process extends and then it splits, one side acts as dendrites, the other is acting as the axon (sensory neurons)
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18
Q

nerves

A

bundles of peripheral nerve fibers held together by several layers of connective tissue

  • made of many neurons
  • neuron (aka, nerve fiber)- single nervous system cell
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19
Q

endoneurium

A

-surrounds each nerve fiber or neuron

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20
Q

perineurium

A

surrounds a fiber bundle (fassicle)

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21
Q

epineurium

A

surrounds several fascicles and their blood supply to form a complete nerve
-surrounds a nerve

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22
Q

tract

A

bundles of nerve fibers within the CNS

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23
Q

mixed nerves

A

most peripheral nerves often carry fibers that are bringing sensory information in one direction and motor information in the other direction

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24
Q

glia cells in CNS

A
  • astrocytes
  • ependymal-
  • microglial-
  • oligodendrocytes-
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25
Q

astrocytes

A
  • star shaped, largest, most common
  • attach neurons and capillaries in the brain
  • pick up glucose from blood to feed neurons
  • help form blood-brain barrier (BBB)
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26
Q

microglia

A
  • small, usually stationary

- engulf, destroy microorganisms and cell debris

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27
Q

ependymal cell

A
  • resemble epithelial cells
  • form thin sheets lining fluid filled cavities
  • produce cavity fluid or keep it circulating
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28
Q

oligodendrocytes

A
  • small with few processes
  • help hold nerve fibers together
  • produce fatty myelin sheath around neurons
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29
Q

glia cells in PNS

A
  • shwann cells- form the myelin around the axons

- satelitte cells- may from myelin around cell body

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30
Q

schwann cells

A
  • support nerve fibers in PNS
  • form myelin sheath around nerve fibers
  • nodes of ranvier- gap in sheath between shwann cells
  • wrap around
  • white fibers- myelinated
  • gray fibers- unmyelinated
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31
Q

satellite cells

A

may form myelin around cell bodies

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32
Q

membrane potentials

A
  • membrane potential- the difference in electrical charge across a plasma membrane
  • due to excess of (+) ions outside plasma membrane and (-) ions inside it
  • they have the potential to move towards each other
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33
Q

membrane potentials measured

A
  • polarized membrae- has a negative pole and a positive pole
  • size of potential difference in both sides is measured in volts or millivolts (mV)
  • the charge on the inside of a polarized membrane determines - or +
  • ex. -70mV -> 70mV is the size of the potential (difference) and - is the charge inside the membrane
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34
Q

resting membrane potentials

A
  • transmembrane potential of a resting (not conducting an impulse) cell
  • neuron resting membrane potential (RMP) is roughly -70mV
  • ionic transport mechanisms cause imbalance
  • gated channels- allow specific molecules to diffuse when their gate is open
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35
Q

adding sodium

A
  • increases the mV
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36
Q

types of potentials and their actions

A
  • a stimulus produces a temporary localized change in resting potential- graded potential (decreases with distance from the stimulus)
  • if graded potential is sufficiently large enough (-60,-55mV), an action potential is triggered and travels along he axon to synaptic terminals
  • synaptic activity produces graded potentials in postsynaptic cells plasma membrane
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37
Q

chemically gated ion channel

A
  • same as in muscles

- neurotransmitter released -> binds to receptors -> sodium flows in

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38
Q

voltage gated channel

A
  • open in response to changes in membrane potential (threshold)
  • sodium can rush in when its open -> trigger an action potential
  • once the voltage is high enough the gates close
  • ex. voltage gated sodium, potassium or calcium channels
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39
Q

resting membrane potentials (cont.)

A
  • neuron plasma membrane channels for large anions (- particles) are closed or non existent
  • chloride ions (Cl-) stay on the outside of plasma membrane, repelled by protein anions on the interior
  • only the (+) charged ions sodium (Na+) and potassium (K+) can cross neurons membrane
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40
Q

passive leak channels

A
  • responsible for the transmembrane potential
  • remain open
  • K+ out, Na+ in
  • there are more channels fro K than Na -> this is why the membrane is - at rest
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41
Q

gated channels and the permeability of the plasma membrane

A
  • gated channels in plasma membrane open or close in response to stimuli
  • there are three different types of gated channels
    1. chemically gated channels
    2. voltage gated channels
    3. mechanically gated channels
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42
Q

mechanically gated channels

A
  • open in response to physical distortion of the membrane surface
  • important in sensory receptors- touch, pressure, vibration
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43
Q

graded (local) potentials

A
  • slight shift away from RMP in a specific region of the plasma membrane
  • sitmulus gated channels- open in response to stimulus causing excitation of a nerve
  • permits more Na+ to enter cell
  • size of membrane potential is reduced
  • depolarization- movement of the membrane potential towards zero mV
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44
Q

depolarization

A

movement of the membrane potential towards zero mV

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45
Q

inhibition

A
  • graded potential
  • stimulus triggers opening of stimulus gated K+ channels
  • K+ diffuses out of cell causing excess (+) ions outside and increase in membrane potential
  • becomes more negative
  • hyperpolarization-movement of the membrane potential away from 0 mV (below the usual RMP)
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46
Q

graded

A

varies with stimulus strength, declines with distance from site of initial depolarization

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47
Q

propagation of the action/graded potential

A
  1. chemically gated sodium channel
  2. exposure to chemical opens channel and sodium ions enter the cell. Depolarization occurs
  3. sodium ions spread out inside the cell and a local current is produced
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48
Q

action potential

A
  • a brief reversal of membrane potential with total voltage change of about 100mV (-70mV to +30mV)
  • action potential begins with opening of voltage gated sodium ion channels -> channels open like domino effect
  • neurons receive info from graded potentials on dendrites and cell body
  • action potentials, once initiated, affect an entire excitable membrane over entire axon
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49
Q

steps in the mechanism that produces an action potential

A
  1. stimulus triggers stimulus gated Na+ channels to open, Na+ diffuses in, depolarization occurs
  2. threshold potentials is reached, voltage gated Na+ channels open
  3. more Na+ enters the cell through voltage gated Na+ channels, further depolarization occurs
  4. magnitude of action potential peaks at +30mV when voltage gated Na+ channels close
  5. repolarization begins when voltage gated K+ channels open to allow diffusion of K+ out
  6. brief period of hyperpolarization then RMP is restored by sodium potatssium pump and ion channels return to resting state
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50
Q

action potential: refractory period

A
  • brief period where an area of the axons membrane resists re-stimulation
  • absolute refractory period- approximately .5ms after membrane surpasses the threshold potential it will not respond to any stimulus
  • relative refractory period- a few ms after the ARP when the membrane is repolarizing -> can respond if the stimulus is larger enough
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51
Q

conduction of the action potential

A
  • polarity changes during the action potential causes electrical current to flow to adjacent areas of the membrane
  • voltage gated Na+ channels in the next segment of the membrane open
  • Na+ rushed in causing action potential in this next segment
  • the cycle continuously repeats
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52
Q

two ways an action potential may be conducted

A
  • action potentials may affect adjacent portions of the plasma membrane one of two ways
    1. continuous propagation- occurs along unmyelinated axon, slower, gates open like a domino effect
    2. saltatory propagation- occurs along myelinated axons, faster,
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53
Q

continuous propagation

A
  • action potential appears to move in a series of tiny steps
  • slower
  • unmyelinated
  • action potential generated in an initial segment affects more distal portions of axon
  • each step take only a millisecond, but steps must be repeated alone entire axon
  • propagation along an unmyelinated axon only travels at a speed of 1 meter per second
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54
Q

saltatory propagation

A
  • areas of myelin sheaths resist ion movement and therefore inhibit local flow of current
  • electrical changes in the membrane can only occur at gaps in myelin (nodes of ranvier)
  • action potential occurs at one node then current flows under myelin sheath to next node
  • action potential seems to leap from node to node, faster
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55
Q

diameter

A

-larger the diameter the fast the action potential travels

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56
Q

synapses

A
  • nervous system messages transmitted along axons: action potentials (nerve impulses)
  • transfer of nerve impulses, to another neuron or effector cell, occurs at a synapse
  • synapse has two neurons: presynaptic and postsynaptic
  • chemical synapses (muscle) and electrical synapses (cardiac)
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57
Q

chemical synapses

A
  • more common, allow the release and reception of chemical neurotransmitters
  • three structures make up a chemical synapse
    1. synaptic knob- bulge at end of terminal branch (has vesicles with neurotransmitters)
    2. synaptic cleft- space between synaptic knob and postsynaptic neuron plasma membrane
    3. plasma membrane of postsynaptic neuron
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58
Q

electrical synapses

A
  • less common, allow flow of ions between neurons
  • pre and postsynaptic membranes locked together by gap junctions
  • change in transmembrane potential of one cell produces local currents affecting other cell
  • simple way to synchronize activity of all interconnected neurons
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59
Q

postsynaptic potentials

A
  • graded potentials that develop in a postsynaptic membrane in response to a neurotransmitter
  • EPSP- (excited postsynaptic potentials) depolarization of postsynaptic membrane that shifts potential closer to threshold (membrane is facilitated)
  • IPSP- (inhibitory postsynaptic potential) hyperpolarization of the postsynaptic membrane (inhibited) requiring very large depolarizing stimulus to achieve threshold
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60
Q

summation

A
  • the adding together of numerous impulses from multiple neurons at an axon hillock
  • spatial summation- the sum of local potentials from different location of the postsynaptic membrane producing an action potential
  • temporal summation- the sum of rapid stimulation to a postsynaptic neuron over a brief period of time producing action potentials (same spot -> rapid fire)
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61
Q

summation of excitatory and inhibitory signals

A
  • both excitatory and inhibitory transmitters are released at the same postsynaptic membrane
  • excitatory neurotransmitters produce EPSP
  • inhibitory neurotransmitters produce IPSP
  • if EPSPs predominate enough to depolarize the membrane, an action potential results
  • if IPSP predominate so that threshold potential is not produced, no action potential
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62
Q

the brain: general facts

A
  • the largest organ in adults: weights 3 ibs.
  • full size by age 18 (rapid growth until 9)
  • six major divisions:
    1. medulla oblongata
    2. pons
    3. midbrain
    4. cerebellum
    5. diencephalon
    6. cerebrum
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63
Q

brain stem

A
  • medulla oblongata
  • pons
  • midbrain
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64
Q

functions of major brain regions

A
  • cerebrum- conscious thought, memory storage and processing, sensory processing, regulation of skeletal muscle contraction
  • cerebellum- coordination, modulation of motor commands from cerebral cortex
  • diencephalon- link between cerebrum and CNS
  • brain stem- processes visual and auditory info, maintains consciousness, somatic and visceral motor control, regulates autonomic function
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65
Q

gyri

A

elevted ridges

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66
Q

fissures

A
  • deep
  • separate the lobes
  • divide cerebrum into 5 lobes
  • longitudinal fissure separates hemispheres
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67
Q

cerebrum

A

-2 cerebral hemispheres form superior part of brain
-83% of total brain mass
-gyri
-sulci
-fissures
lobes:
-central sulcus
-lateral sulcus
-transverse fissure
-parieto-occiptial sulcus

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68
Q

sulci

A

shallow grooves between gyri

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69
Q

central sulcus

A
  • runs down the lateral aspect of cerebrum
  • separates the frontal lobe from parietal lobe
  • anterior to the central sulcus is the precentral gyrus
  • posterior to the central sulcus is the postcentral gyrus
70
Q

lateral sulcus

A

-separates temperal lobe from frontal and parietal

71
Q

transverse fissure

A

-separates cerebrum from cerebellum

72
Q

parieto-occipital sulcus

A

-separates the parietal lobe from the occipital lobe

73
Q

cerebral cortex

A
  • superficial layer of grey matter: unmyelinated neurons and cell bodies
  • the executive suite of the nervous system
  • our conscious mind- awareness of sensations, communication, memory, understanding and initiate voluntary movements
  • billions of neurons (all are interneurons)
  • 40% of brain mass
  • functional areas
74
Q

functions and the regions in the cerebral cortex

A
  • the lobes of the cerebral cortex contains regions with specific functions
  • three kinds of functional areas
    1. motor areas issues voluntary commands to skeletal muscles
    2. sensory areas are concerned with conscious awareness of sensation
    3. association areas interpret incoming data and coordinate a motor response
75
Q

motor areas

A
  1. primary motor cortex- in precentral gyrus
    - precise, conscious of skeeltal muscles
    - pyramidal (corticospinal) tracts
  2. Premotor cortex- anterior to precentral gyrus
    - plans movements (coordinates with sensory info)
  3. Brocas area- anterior, inferior to premotor area
    - speech production
  4. frontal eye field- voluntary eye movements
76
Q

speech

A
  • brocas area

- wernickes area- sensory for speech

77
Q

sensory and association areas

A
  1. primary somatosensory cortex- in postcentral gyrus
    - receives info from somatic sensory receptors in skin and proprioceptors
    - spatial discrimination
  2. somatosensory association cortex- integrates sensory input (temp., pressure, etc) from somatosensory cortex
  3. visual areas: primary visual cortex receives info from the retina and the visual association area uses past visual experience for recognition
  4. auditory areas- primary auditory cortex interprets pitch, loudness and location and the auditory association area stores memories of sounds and perceives sound stimulus
78
Q

sensory and association areas (cont.)

A
  1. vestibular (equilibrium) cortex- conscious awareness of head position and balance
  2. primary olfactory cortex- responsible for conscious awareness of odors
  3. Gustatory cortex- perceives taste
  4. visceral sensory area- perception of visceral sensations (upset or full stomach, full bladder)
  5. Wernickes area- interpretation of speech/language
79
Q

cerebral white matter

A
  • deep to gray matter of cerebral cortex
  • mostly myelinated fibers bundled into tracts
  • fibers and tracts classified by direction they run:
  • association fibers- connect different parts of same hemisphere
  • commissural fibers- connect gray areas of two hemispheres, cross over, ex. corpus callosum
  • projection fibers- project to and from cortex to and from lower areas (sensory to cortex, motor from cortex)
80
Q

diencephalon

A
  • interbrain
  • consists of several structure around the 3rd ventricle
  • the man structures of the diencephalon are:
  • hypothalamus
  • thalamus
  • epithalamus
  • pineal gland
81
Q

epithalamus

A
  • superior to the third ventricle, forming the roof of the diencephalon
  • contains the choroid plexus of the third ventricle
  • connects limbic system (emotions, learning, and memory) to rest of the brain
  • regulates hormones secreted by pineal gland
82
Q

pineal gland

A
  • found above corpora quadrigemina (midbrain) in posterior, inferior part of epithalamus
  • tiny gland plays a role in biological clock
  • an endocrine structure
  • secretes hormone melatonin
  • melatonin- timekeeping hormone or sleep hormone
83
Q

thalamus

A
  • dumbbell shaped mass of gray matter
  • major relay station fro sensory impulses (pain, temp, pressure, proprioception, touch) on their way to the cerebral cortex
  • geniculate bodies- groups of nuclei that assist in processing auditory and visual input -> *medial (auditory) and lateral (visual) geniculate nuclei
  • almost all inputs ascending to cerebral cortex funnel through thalamic nuclei
84
Q

hypothalamus

A
  • links nervous system to endocrine system
  • indirectly helps control function of every cell in body (controls secretion of pituitary gland)
  • controls the autonomic nervous system
  • link between the cerebral cortex and lower centers between psyche and soma
  • regulates water and thirst- synthesizes hormones released by posterior pituitary (ADH maintains water balance)
  • regulates appetite food intake, body temperature
85
Q

brain stem

A
  1. midbrain
  2. pons
  3. medulla oblongata
    - between cerebrum spinal cord
    - produces rapidly programmed, automatic behaviors necessary for survival
    - 10 of 12 cranial nerves originate here
86
Q

brainstem: structure

A
  • three of brains divisions make up brainstem:
    1. medulla oblongata- (most inferior part) blends into spinal cord at foramen magnum skull
    2. pons (middle)- bridge that links higher brain centers with spinal cord and motor cortex with cerebellum
    3. midbrain (uppermost part)- regulates auditory and visual reflexes and controls alertness
87
Q

medulla oblongata

A
  • 1” in length, links brain with spinal cord at foramen magnum
  • center for coordination of autonomic reflexes
  • autonomic reflex centers:
  • respiration
  • cardiac center
  • vasomotor
  • vomiting, coughing, sneezing, swallowing
88
Q

the pons

A
  • bridge, located between medulla and midbrain, links cerebellum with rest of brain and spinal cord
  • white matter- ascending (sensory) and descending (motor) tracts
  • gray matter- nuclei of cranial nerves V, VI, VII, part of VIII
  • respiratory centers (pneumotaxic and apneustic) adjust rate set by medulla
89
Q

midbrain

A
  • mid-section of brain between pons and cerebrum
  • white matter tracts and reticular formation
  • cerebral peduncles- little feet of cerebrum, conducts impulses between midbrain and cerebrum
  • substantia nigra- neurotransmitters dopamine produced
  • red nucleus- relay motor info affecting limb flexion
  • **corpora quadrigemina:
  • inferior colliculi (2)- auditory reflex centers
  • superior colliculi (2)- visual reflex centers
90
Q

cerebellum

A
  • little brain: cauliflower shaped, 11% of brain mass, dorsal to the pons and medulla
  • balance, equilibrium, coordination
  • processes inputs from cerebral motor cortex, monitors proprioceptive, visual, tactile, balance, auditory sensations
  • provides precise timing and appropriate patterns of skeletal muscle contraction
  • two primary function of the cerebellum:
    1. adjusts the bodys postural muscles
  • coordinates balance and equilibrium
    2. conscious and subconscious fine turning movements
  • motor commands with proprioceptive info
91
Q

language and memory

A
  • bracas area- formation of speech
  • wernicks area- understanding language
  • short term memory- 7 or 8 chunks of info
  • long term memory- transferred from STM, limitless capacity, but can be forgotten -> influenced by emotions, rehearsal, association
  • hippocampus of temporal lobe- major role in memory consolidation and access (Ach)
92
Q

protection of the brain

A
  • bone (skull), membranes (meninges), watery cushion (cerebrospinal fluid)
  • meninges: 3 connective tissue layers:
  • cover and protect CNS
  • protect blood vessels
  • contain CSF
  • form partitions in the skull
93
Q

Dura mater

A
  • outermost meninges
  • toughest
  • thickest
94
Q

arachnoid mater

A
  • middle meninges

- spider like appearance

95
Q

pia mater

A
  • third meninges
  • inner
  • sits rights on the brain and spinal cord
  • thin
  • blood vessels
  • meningitis
96
Q

subdural space

A

-space between the dura mater and arachnoid mater

97
Q

subarachnoid space

A
  • space between the arachnoid mater and pia mater

- where the cerebrospinal fluid travels

98
Q

falx cerebri

A

-infolding of the dura mater that separates the cerebral hemispheres down the longitudinal fissure

99
Q

superior sagittal sinus

A
  • blood flow from the brain travels back towards the heart

- site were cerebrospinal fluid joins back with the blood

100
Q

coverings of the brain and spinal cord

A
  • outer covers:
  • bone- cranial bones and vertebrae
  • inner coverings:
  • meninges- three layers of membranes
    1. dura meter: outermost, strong
    2. arachnoid mater- middle, spiderweb
    3. pia mater: inner, delicate, blood vessels
101
Q

falx cerebelli

A

-separates cerebellar hemispheres

102
Q

tentorium cerebelli

A

-separates cerebrum from cerebellum

103
Q

epidural space

A

-between dura mater and vertebrae

104
Q

cerebrospinal fluid (CSF)

A
  • provides a protective cushion around brain and spinal cord
  • acts as a diffusion medium for dissolved gases, nutrients, chemical messengers, and waste
  • utilized by brain to monitor changes in the internal environment
  • found in subarachnoid space in brain and spinal cord and within their cavities and canals
  • *flows from the lateral ventricles through the interventricular foramen to the third ventricle and travels through the cerebral aquaduct of the midbrain to the fourth ventricle to the central canal
105
Q

formation and circulation of CSF

A
  1. separation of fluid from blood in choroid plexus
  2. ependymal cells release CSF into fluid spaces
  3. from lateral ventricles through interventricular foramen into 3rd ventricle
  4. through cerebral aquaduct into 4th ventricle
  5. into central canal of spinal cord or through median and lateral foramen into cisterna magna
  6. circulates in subarachnoid space
    - continuously recycled
106
Q

arachnoid granulation

A

the site at which cerebrospinal fluid is absorbed into the venous circulation

107
Q

brain dysfunctions

A
  • concussion- temporary alteration in brain function after blow to head
  • subdural or subarachnoid hemorrhage- from head trauma, may become fatal
  • cerebrovascular accidents (CVA’s)- “strokes”, blood flow to brain area is blocked (ischemia)
  • alzheimers disease- progressive degenerative disease resulting in dementia
  • parkinsons disease- degeneration of dopamine releasing hormones of substania nigra
  • huntingtons disease- fatal hereditary disorder
108
Q

brain stem

A

ends with the medulla oblangata

109
Q

cervical spinal nerves

A

8

  • named by the one below it: first cervical nerve exits between the atlas and occipital bones of the skull
  • second cervical nerve exists between C1 and C2
110
Q

thoracic spinal nerves

A

12

-named by the one above it: first one exits between T1 and T2

111
Q

lumbar spinal nerves

A

5

112
Q

sacral spinal nerves

A

5

113
Q

coccygeal nerve

A

1

-Co1

114
Q

conus medullaris

A

distal end of the spinal cord at about the L1 L2 vertebrae

115
Q

conus medullaris

A
  • spinal cord ends in a structure called the conus medullaris at about the L1 L2 spinal level
  • distal end of the spinal cord at about the L1 L2 vertebrae
116
Q

cauda equina

A
  • continuation of spinal nerves below the conus medullaris

- down and out of spinal cords

117
Q

filum terminale

A
  • continuation of the dura mata

- anchors the spinal cord to the cocxyx

118
Q

ventral root

A

motor neurons leave the spinal cord through here

-strictly motor

119
Q

dorsal root

A
  • bring sensory information back to the spinal cord

- strictly sensory

120
Q

gray matter: the region of integration

A
  • the outward projections of gray matter, on spinal cord cross section, are called horns
    1. posterior gray horn- somatic and visceral sensory nuclei
    2. *lateral gray horn: visceral motor nuclei (only in thoracic and lumbar spine)
    3. anterior gray horn: somatic motor nuclei
  • gray commissures- axons that cross from one side of cord to other
121
Q

white matter: carries information

A
  • myelinated and unmyelinated fibers organized according to body region innervated
  • white matter on each side of spinal cord is divided into 3 regions called columns (funiculi)
  • the columns contain tracts- bundles of axons that relay same type of info in same direction
    1. ascending- carry sensory info to brain
    2. descending- motor output to the spinal cord
    3. transverse- one side of cord to another
122
Q

spinal cord trauma and disorders

A
  • paralysis- (loss of motor function)- falccid paralysis vs. spastic paralysis or paraplegia vs. quadriplegia (all extremedies)
  • poliomyeltitis- polio virus
  • ALS- genetic and environmental factors:
  • lou gehrigs disease
  • progressive neuromuscular condition
  • death within 5 years
123
Q

spinal nerves

A

-exit in pairs from the lateral spinal cord
-connective tissue layers: endoneurium, perineurium and epineurium
-each spinal nerve branches to form rami:
-dorsal ramus- innervates muscles, joints, skin of the back
ventral ramus- innervates lateral and anterior trunk and the limbs
-ramus carry both sensory and motor

124
Q

dermatomes

A
  • specific region of the skin monitored by a single spinal nerve
  • ex. C4- shoulder
125
Q

shingles

A
  • sits on the dorsal root of the spinal nerve
  • lays dormit and wakes up later
  • specific dermatome regions
  • viral latency
126
Q

spinal nerves provide sensory and motor innervation

A
  • each branch of a spinal nerve carries motor and sensory innervation to specific regions
  • the ventral root of each spinal nerve contains somatic and visceral motor neurons
  • the dorsal root of each spinal nerve carries sensory information to the spinal cord
  • the dorsal and ventral roots unite just lateral to the IVE to form a spinal nerve
127
Q

dorsal ramus

A
  • contains motor fibers to skin, skeletal muscles of back

- sensory fibers back from the same regions

128
Q

ventral ramus

A
  • contains motor fibers to ventrolateral body surface, body wall and limbs
  • sensory fibers back from the same regions
129
Q

sympathetic nerve

A
  • contains motor fibers to smooth muscle, glands, visceral organs of thoracic, abdominal cavities
  • sensory info back from visceral organs
130
Q

pathway

A

-spinal cord -> dorsal root (sensory) and ventral root (motor) join together to form a -> spinal nerve (mixed sensory and motor) splits and branches to -> dorsal ramus (mixed) and ventral ramus (mixed) and sympathetic nerve (mixed) -> ventral rami join to form nerve plexuses

131
Q

nerve plexuses

A
  • ventral rami of adjacent spinal nerves blend their fibers to form a series of nerve trunks
  • the interwoven network of nerves (plexuses) allows compound muscles to be innervated by fibers from more than one spinal nerve
  • there are four major plexuses
    1. cervical plexus
    2. brachial plexus
    3. lumbar plexus
    4. sacral plexus
132
Q

cervical plexus

A
  • ventral rami of spinal nerves
  • C1-C5
  • *phrenic nerve- made up of fibers from spinal levels C3, C4, C5, descends down from the cervical plexus and innervates the diaphragm
  • damage to C2 can kill you because of damage to phrenic nerve
133
Q

brachial plexus

A
  • innervation of the upper extremities
  • made up of the ventral rami of spinal nerves C4-T1
  • axillary nerve
  • musculocutaneous nerve
  • radial nerve
  • ulna nerve- funny bone
  • median nerve- carpal tunnel
134
Q

lumbar plexus and sacral plexus

A
  • Lumbar: spinal segments T12-L4 ventral rami spinal nerves
  • Sacral: spinal segments L4-S4 ventral rami spinal nerves
  • sciatic nerve- L4- S3, splits to tibial and fibial nerve, 5 different spinal levels
135
Q

spinal reflexes

A
  • reflexes are pre-programmed, rapid automatic responses to specific stimuli
  • the simple circuits of the PNS control reflexes
  • reflexes preserve homeostasis by making quick adjustments in organ/system function
  • when a reflex is activated, there is little variability in the motor response produced
  • neural reflex- sensory fibers-> integration center in CNS -> motor response to effectors
136
Q

steps in a reflex arc

A

withdrawl reflex

  1. the arrival of a stimulus and activation of a receptor
  2. the activation of a sensory neuron
  3. information processing
  4. the activation of a motor neuron
  5. the response of a peripheral effector
137
Q

classification of relfexes

A
  1. development- innate (born with) or acquired reflexes (learned)
  2. nature of the resulting motor response- somatic (skeletal) or visceral reflex (involuntary)
  3. complexity of neural circuit involved- polysynaptic or monosynaptic reflex
  4. the site of information processing- spinal (segmental, intersegmental) or cranial
138
Q

monosynaptic reflex: stretch reflex

A
  • the most common monosynaptic reflex type
  • provides automatic regulation of skeletal muscle length
  • the sensory receptors are muscle spindles which consist of intrafusal muscle fibers
  • stimulus (increased muscle length) -> activates sensory neuron -> triggers a motor response (contraction of stretched muscle
  • ex. stretch reflex
139
Q

polysynaptic reflex: withdrawal and crossed extensor reflexes

A
  • withdrawal reflexes- move affected body part away from the stimulus
  • ipsilateral reflex arc (response is on the same side of the body)
  • strongest ones are triggered by painful stimuli
  • cross extensor reflexes- involve a contralateral reflex arc
  • additional motor response occurs on opposite side of the stimulus (happens on both sides of the body)
  • ex. stepping on something you pick up one foot (flexes) and brace yourself with the other (extense)
140
Q

reflexes in neurological testing

A
  • reinforcement- the facilitation of motor neurons involved in reflexes
  • reflexes involved in testing for neurological impairment:
    1. stretch reflexes- biceps, triceps, achilles
    2. babinski sign (newborns flex toes -> superficial)
    3. superficial reflexes- abdominal, plantar, cremasteric (stroke skin -> tighten)
141
Q

cranial nerves

A
  • peripheral nerves that branch of the brain or brain stem
    1. olfactory- smell (S)
    2. optic- sight (S)
    3. oculomotor- eye movement (M)
    4. trochlear- eye movement (M)
    5. trigeminal- motor and sensory for the face, trigeminal neurolga-> condition of face pain (B)
    6. abduncens- eyeball movement (M)
    7. facial- facial expression, bells polsy-> face freezes, stroke (B)
    8. vestibulocochlear- hearing, equilibrium (S)
    9. glossopharyngeal- tongue, taste (B)
    10. vagus- visceral muscle movement (B)
    11. spinal accessory- trapezius and sternocledomastoid movement, shoulder shrug (M)
    12. hypoglossal- movement of the tongue, damage to this nerve causes tongue to lean towards one size (M)
  • M- motor
  • S- sensory
  • B- both
142
Q

autonomic nervous system

A
  • control and feedback to and from visceral organs
  • involuntary
  • sympathetic
  • parasympathetic
  • sensory fibers -> sensory receptors -> send info to CNS regarding visceral organs -> carried out by either parasymp or symp - target involuntary
143
Q

Autonomic nervous system

A
  • sensory (afferent) pathways provide feedback
  • motor (efferent) pathways bring signals to visceral organs through either sympathetic and parasympathetic divisions
  • regulates involuntary effectors such as:
  • cardiac muscle
  • smooth muscle
  • glandular epithelium
  • adipose tissue
  • kidneys
144
Q

major functions of ANS

A
  • major functions of ANS maintaining homeostasis:
  • regulate heart rate
  • smooth muscle contraction
  • glandular secretion
  • metabolism
  • Dual innervation of effectors:
  • many autonomic effectors receive input from parasympathetic and sympathetic pathways
  • antagonistic effects- one inhibits, other stimulates
145
Q

structure of the ANS: basic plan of autonomic pathways

A
  • each pathway: autonomic nerves, ganglia and plexuses made of efferent autonomic neurons
  • efferent autonomic regulation depends on feedback from the sensory pathway
  • preganglionic neuron- conducts impulses from brainstem or cord to autonomic ganglion
  • postganglionic neuron- conducts impulses away from ganglion to the effector
146
Q

2 synapses

A
  • 2 sets of neurons
  • one that leaves the CNS- preganglionic
  • one that goes to the visceral organs- postganglionic
  • synapse at the autonomic ganglia
  • 2 synapses- one between pregnaglionic and postganglionic, and one between postganglionic and the effectors
147
Q

autonomic conduction path

A
  • cell body is in the lateral horn of the gray mater
  • leaves by the ventral root makes a loop and meets the autonomic ganglia synapse
  • signal goes off to effectors
148
Q

sympathetic neurons

A
  • sympathetic preganglionic neurons are very short -> autonomic ganglia are close to the spinal cord
  • because they are so short it forms the sympathetic chain ganglia
  • sympathic postganglionic neurons are very long
149
Q

splanchric nerve

A

pass through autonomic ganglia without synapsing and synapse some place else

150
Q

preganglionic

A

myelinated

151
Q

postganglionic

A

unmyelinated

  • in symapthetic the postganglionic neuron releases norepinephrine neurotransmitters
  • in parasympathetic the postganglionic neuron releases ACh neurotransmitters
152
Q

autonomic neurotransmitters

A
  • ACh
  • norepinephrine
  • both parasympathetic and sympathetic use ACh are the preganglionic and postganglionic synapse
  • only the sympathetic uses norepinephrine at the second synapse between postganglionic and effectors
153
Q

sympathetic division

A
  • thoracolumbar division

- nerve fibers originate in the thoracic and upper lumbar spine (T1-L2)

154
Q

parasympathetic division

A
  • craniosacral division

- origin is in cranial nerves 3, 7, 9, 10, S2, S3, S4

155
Q

structure of sympathetic pathways- fight or flight

A
  • sympathetic preganglionic neurons:
  • short
  • dendrites, cell bodies in lateral gray horns T1-L2
  • sympathetic chain ganglia or sympathetic trunk
  • *can synapse with postganglionic neuron or pass through ganglia without synapsing -> more wide ranging effects
  • can ascend or descend sympathetic trunk and synapse with other chains postganglionic neurons
  • Sympathetic postganglionic neurons:
  • long
  • dendrites and cell bodies in chain ganglia or collateral ganglia
  • some return to spinal nerves by gray ramus
  • distributed to sympathetic effectors by spinal nerves or separate autonomic nerves
156
Q

strucure of the parasympathetic pathways

A
  • parasympathetic preganglionic neurons:
  • long
  • neurons and cellbodies in brainstem nuclei or lateral gray columns of sacral cord
  • axons in cranial nerves 3, 7, 9, 10 and some pelvic nerves
  • travel long distance before synapsing with postganglionic neurons -> close to visceral organs

parasympathetic postganglionic neurons:

  • short
  • dendrites and cell bodies in parasympathetic ganglia
  • lie near, or in, autonomic effectors
  • parasympathetic preganglionic neurons synapse with postgnalgionic neurons to one effector- response by *one organ
157
Q

cholinergic

A
  • receptive to ACh

- both sympathetic and parasympathetic postganglionic neurons are cholinergic

158
Q

sympathetic

A
  • heightened levels of somatic activity

- fight or flight response

159
Q

parasympathetic

A
  • visceral function
  • energy conservation
  • rest and digest
160
Q

ANS neurotransmitters and target organ membrane receptors

A
  • the effects of ANS stimulation are mediated by the membrane receptors of target organs
  • sympathetic effects are the result of epinephrine and norepinephrine interaction with adrenergic receptors in plasma membrane
  • parasympathetic control relies on the neurotransmitter ACh and ACh receptors
  • number of type of receptor will affect if it is more sympathetic or parasympathetic
161
Q

sympathetic stimulation and effects

A
  • norepinephrine (NE) and epinephrine (E)- released by adrenergic fibers (postganglionic sympathetic)
  • two classes of sympathetic adrenergic receptors- alpha and beta receptors
  • NE mostly stimulates alpha and E affects both
  • localized effects of NE last a few seconds
  • NE and E released by adrenal medulla has generalized effects lasting up to a few minutes
  • bind on plasma membrane
162
Q

parasympathetic stimulation and effects

A
  • acetylcholine (ACh)- released by cholinergic fibers (axons of preganglionic sympathetic and pre and postganglionic parasympathetic fibers)
  • two types of ACh receptors in postsynaptic and target cell membranes: nicotinic and muscarinic receptors
  • nicotinic receptor exposure to ACh opens chemically gated channels in postsynaptic cell -> always excitatory
  • muscarinic receptor stimulation produces longer lasting excitatory or inhibitory effects
163
Q

general function of the ANS

A
  • ANS function to regulate autonomic effectors to maintain or quickly restore homeostasis
  • both divisions are tonically active (parasympathetic more)
  • principle of autonomic antagonism- both divisions exert opposite influences on effectors
  • autonomic centers exert influence on the ANS
  • CNS hierarchy- control of autonomic function
164
Q

visceral reflexes control most visceral functions

A
  • short reflex- travel to the autonomic ganglia -> peripheral effector
  • do not synapse in CNS
165
Q

interoceptors

A
  • monitor tissues and organs
  • ex. nociceptors (pain), tactile receptors (touch), thermoreceptors (temp), baroreceptors (pressure), chemoreceptors (chemicals)
166
Q

baroreceptors

A
  • sense pressure
  • signal to intestines when they detect the stomach is being stretched, also in bladder
  • aortic arch, carotid -> blood pressure
167
Q

chemoreceptors

A
  • sense chemicals
  • respiratory centers in the medulla oblongata- respond to pH and carbon dioxide in cerebrospinal fluid
  • carotid bodies- pH in arterial blood
  • aortic bodies- pH in arterial blood
  • monitor CO2 levels
168
Q

motor control of the ANS

A
  • ANS level of activity is controlled by brainstem centers that regulate specific visceral functions
  • rapid and automatic responses to stimuli
  • brainstem centers are regulated by the hypothalamus
  • hypothalamus also interacts with all other portions of the brain and acts as the headquarters of the ANS
169
Q

summary: function of the sympathetic division

A
  • emergency system during times of stress
  • fight or flight
  • opposes effects of parasympathetic impulses during rest
  • ex. normal rate and strength of heartbeat
  • maintains normal tone of smooth muscle in blood vessel walls
  • ex. maintaining blood pressure during abnormal circumstances
170
Q

summary: functions of the parasympathetic division

A
  • the dominant controller of most autonomic effectors most of the time
  • dominates during non fight or flight responses
  • rest and repair

HAN 200 (3 decks)

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