Chapter 7 Nervous system reverse Flashcards
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Sensory input
integration
motor output
Nervous System
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monitor changes occuring inside and outside the body
gather information
Sensory input
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process and interpret sensory input
decide if action is needed
Integration
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respond to integrated stimuli
activate muscles or glands
voluntary and involuntary
motor output
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Central Nervous system
Peripheral Nervous System
Organization of Nervous System
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brain and spinal cord
Central Nervous System
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nerves outside the brain and spinal cord
cranial and spinal nerves
peripheral nervous system
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sensory (afferent) division
Motor (efferent) division
Nerve functional classification
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nerve fibers that carry information to the CNS
and the central canal
Sensory nerves
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nerve fibers taht carry impulses away from the CNS
1 Somatic nervous system: voluntary, skeletal muscle
2: Autonomic nervous system: involuntary, smooth and cardiac muscle and glands
motor nerves
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consists of neurons and neuroglia
Nervous tissue
structure
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structural and functional unit of the nervous system and conduct nerve impulses
neurons
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supports cells that provide physical support, insulation and nutrients to neurons
neuroglia
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astrocytes
microlia
ependymal cells
oligodendrocytes
satellite cells
schwann cells
Support cells
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abundant star chaped cells
form barrier between capillaries and neurons
control chemical environment of brain
Astrocytes
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phagocytose bacterial cells anc cellular debris in the CNS
Remove debris
microglia
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line cavities of the brain and spinal cord
circulate cerebrospinal fluid
ependymal cells
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wrap around nerve fibers (axons) in the CNS
poroduce myelin sheaths
oligodendrocytes
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protect neuron bodies in ganglia of the peripheral nervous system
satellite cells
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form myelin sheath around axons in the PNS
schwann cells
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Nerve cells
specialized to transimt nerve impulses
Neurons
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cell body
Dendrites
Axon
Neuron regions
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nucleus
large nucleolus
nissl substance
specialized rough ER
Neurofibrils maintain shape
Cell body
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short highly branched cytoplasmic extensions
conduct signals toward the cell body
Dendrites
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1 per neuron
arises from the axon hillock
may have many branches (collaterals)
trigger zone region that initiates action potential (impulse)
conduct impulse away from cell body to axon termials
terminals contain vessels with neurotransmitters
axon
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separated by gap from next neuron
1 synaptic cleft: fluid filled gap between adjacent neurons
2 synapse: junction between nerves
axon terminals
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schwan cells surrounds region of several axons but does not form myelin sheath
unmylenated axon
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in PNS schwann cells wrap around peripheral axons in jelly roll fashion
layers of cell membrane create myelin sheath, whitish fatty material
neurilmma: portion of schwann cell that contains most of the cytoplasm and nucleus (outer surface)
in CNS aligodendrocytes form the myelin sheath (no neurolemma)
Nodes of ranvier: gaps in myelin sheath
myelinated axon
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most are located in CNS
1 gray matter: cell bodies and unmyelinated fibers
2 Nucleus: cluster of cell bodies within the white matter of CNS
Locatoin of neuronal cell bodies
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collectoin of cell bodies outside the CNS or in the PNS
Ganglion
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Sensory (afferent)
Motor (efferent)
Interneurons
Functional classification of neurons
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most unipolar some bipolar
cell bodies in ganglia
carry impulses from sensory receptors to the CNS
receptor-specialized dendritic ending
cutaneous sensr organs
proprioceptors-dectect stretch or tension
sensoru neuron function
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multipolar neurons
cell body within the CNS
carry implulses from teh CNS to viscera, muscles and glands
motor neuron function
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found in pathways within the CNS
multipolar
some cell bodies in nuclei of CNS
connect neurons
interneurons function
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multipolar: many extensions from the cell body
bipolar: one axon and one dendrite
unipolar: short single process leaving the cell body
Structural classification of Neurons
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irritability: ability to respond to stimuli
conductivity: ability to transmit an impluse
functional properties of neurons
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potential difference across cell membrane
plasma membrane is polarized at rest
fewer + ions are inside the cell than outside
resting potential caries with cell type-40 to -90 mV
Cell membrane potential
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distributino of ions across plasma membrane
1 Na+ high outside cell, low inside
2 K+ low outside cell, high inside
negatively charged molecules: DNA, RNA, proteins
membrane permeable to Na+ and K+
Na+/K+ pump (2 Na+ out, 2 K+ in)
Membrane potential cause
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depolarization
repolarization
Membrane potential changes
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membrane potential bnecomes less negative
Na+ channels open
K+ channels close
Na+ enters cell
membrane depolarization
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membrane potential returns to resting membrane potential (RMP)
K+ channel opens
Na+ channel closes
K+ leaves cell
Membrane repolarization
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rapid sequence of depolarization and repolarization
Nerve impulses
Action potentials
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membrane potential at which an action potential is genterated
stimuli from other neurons sum to bring membrane to threshold
Nerve impulse threshhold potential
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if the action potential starts it is propagated over the entire axon
if not enough it begins ar trigger zone and ends at axon terminals
nerve impulse propagation
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action potentials occur only at nodes of ranvier
saltatory conduction: AP appears to jump from node to node
Fast 120m/sec
Nerve impulse
myelinated axons
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action potential travels along the entire plasma membrane
slow .5 m/sec
Nerve impulse
unmyelinated axon
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neurons not in direct contact
separated by small gap : synaptic cleft
Synapse
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axon terminal of presynaptic neuron
synaptic vesicles filled with neurotransmitter
synaptic cleft
receptors on postsynaptic membrane
synapse structure
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impulses not directly able to cross to another nerve
action potential causes vesicle to move to membrane
neurotransmitter is released from axon terminal
neurotransmitter diffuses across synaptic cleft
neurotransmitter binds to protein receptors on dendrite of next neuron, post synaptic neuron
to stop a signal the neurotransmitter is broken down
synapse signal transmission
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rapid predictable and involuntary response to stimuli
simplest neural pathway (reflex arc)
Relexes
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Sensory receptor-sensory neuron-interneuron-motor-neuron-effector
reflex pathway
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somatic reflexes: effectors are skeletal muscles
autonomic reflexes:
smooth muscle regulation
heart and BP regulation
regulation of glands
digestive system regulation
Reflex types and regulation
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3 lbs
contains about 100 billion multipolare neurons
4 major sections
cerebrum, diencephalon, brain stem, cerebellum
Brain anatomy
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2 cerebral hemispheres
paird left and right superior part of brain
connected internally by corpus callosum
includes more than half of brain mass
surface is made of ridges (gyri) and grooves (sulci)
Cerebrum
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fissures divide the cerebrum into lobes
frontal lobe
parietal lobe
occipital lobe
temporal lobe
Lobes of cerebrum
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primary motor area:
voluntary control of skeletal muscle
sends impulses to skeletal muscles
Borca’s area:
motor speech
involved in our ability to speak
problem solving and language comprehension
Frontal lobe
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somatic sensory area
receives and interprets impulses from the bodies sensory receptors
speech and language region
parietal lobe
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visoin center
Occipital lobe
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olifaction (smell
Hearing
Temporal lobe
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gray matter: outer layer in cerebral cortex composed mostly of neuron cell bodies
white matter: fiber tracts deep to the gray matter
tract: bundle of fibers (axons) within the CNS
Basal nuclei: regions of gray matter burried within the white matter
Cerebrum layers
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sits on top of the brain stem
enclosed by cerebral hemispheres
main parts: Thalamus and Hypothalamus
Diencephalon
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surrounds third ventricle
relay staton for sensory impulses
transfers impulses to the correct part of cortex for localization and interpretation
Thalamus
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located under the thalamus
important autonomic nervous system center
helps regulate body temp
controls water balance
regulates metablolism
important part of the limbic system (emotions)
pituitary gland attached
Hypothalamus
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attaches to spinal cord
3 parts
Midbrain
Pons
medulla oblongata
Brain stem
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mostly composed of tracts of nerve fibers
reflex center for vision and hearing
midbrain
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mostly composed of fiber tracts
modifies activity of respiratory centers in the medulla
pons
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lowest part of brain stem
merges into spinal cord
includes important fiber tracts
contains important control centers
heart rate control, BP regulatoin, respiratory centers sets rate and depth of breathing, swallowing and vomiting
medulla oblongata
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cooridinates skeletal muscle activity
helps maintain posture, balance and equilibrium
Cerebellum
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scalp and skin
skull and vertebral column
meninges
cerebrospinal fluid
blood brain barrier
CNS protection
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3 connective tissue membranes covering brain and spinal cord
dura mater
arachnoid mater
pis mater
meninges
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double layered external covering
periosteum: attached to inner surface of skull
Meningeal layer: out covering of brain
folds inward in several areas
dura mater
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middle layer
web like
arachnoid mater
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clings to surface of brain and spinal cord
contains superficial blood vessels
Pia mater
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space between acrachnoid and pia mater
filled with cerebrospinal fluid
subarachnoid space
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space bewtreen meninges surrounding spinal cord and bonds of vertebral canal
filled with adipose and loos connective tissue
Epidural space
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similar to blood plasma composition
formed by the choroid plexus, reabsorbed by arachnoid villi
watery cushion to protect brain
ciculated in subarachnoid space, ventricles and central canal of spinal cord
cerebrospinal fluid
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4 interconnected cavities with in the brain filled with CSF
CSF flows through
Ventricles
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CSF accumulates and exerts pressure on the brain if not allowed to drain
newborns
Hyrocephalus
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includes the least permeable capillaries of the body
excludes many potentially harmful substances
useless against:
fats and fat soluable molecules
respiratory gases (CO2 and O2)
alcohol
Nicotine
Anesthesia
Blood brain barrier
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slender column of nerve fibers (tracts) and neurons
center for spinal reflexes
Spinal Cord
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extends from the foramen magnum of skull to the first or second lumbar vertebra
31 pairs of spinal nerves arise from spinal cord
Cauda equina
anterior median fissure
posterior median sulcus
Spinal cord surface anatomy
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gray matter is mostly cell bodies
Dorsal (posterior) horns
Anterior (ventral) horns
Gray commissure surround the central canal
central canal is filled with CSF
Spinal cord internal anatomy
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White mater-fiber tracts
ascending tracts carry sensory information to brain
descending tracts conduct motor impulses from brain to motor neurons
pathways between brain and spinal cord
Spinal cord exterior
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leave at each level of vertebra
dorsal roots: sensory fibers
sensory neurons found in dorsal root ganglia
ventral roots: motor fibers
motor neurons are found in the anterior horn
spinal nerve forms where posterior and anterior roots merge
Spinal nerves
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Nerves and ganglia outside the CNS
cranial nerve arises from brain
spinal nerves arise from spinal cord
Peripheral Nervous System
PNS
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bundle of neuron fibers
nerve
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neuron fibers bundled by connective tissue
endoneurium surrounds each fiber
groups are bound into fascicles by perineurium
fascicles are bound together by epineurium
nerve structure
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portion of PNS that function automatically
2 neurons in series from CNS to effector
regulates activites of cardiac, smooth muscle and glands
Autonomic Nervous System
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Sympathetic nervous system
Parasympathetic nervous system
autonomic nervouse subdivisions
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extraordinary situations-fight or flight
exercise, excitement, emergency and embarrassment
Sympathetic Nervous System
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housekeeping activites (rest and repose)
digestoin, defacation and diereses
Parasympathetic Nervous System
