7-8 Study Guide Flashcards
General functions of nervous system
- Sensory input
- Integration
- Motor output
Sensory input
Get info/receive stimuli
Integration
Process and decide whether to react
Motor output
Activate response
Reaction of muscles or glands
CNS
Central nervous system
Brain and spinal cord
PNS
Peripheral nervous system
Cranial and spinal nerves
Subdivisions of PNS
Sensory (nerves)
motor (nerves)
Afferent system
Sense organs
Efferent system
Motor system
Somatic
Voluntary nerve
Skeletal muscles
Autonomic
Involuntary
Cardiac muscle
Smooth muscle
Glands
Autonomic system divided into
Parasympathetic
Sympathetic
Parasympathetic
Rest and digest
Conserves energy
Regulates body functions
Sympathetic
Fight or flight
Thoracolumbar
Endoneurium
Connective tissue sheath that surrounds each nerve fiber
Perineurium
Wraps groups of nerve fibers into a fascicle
Epineurium
Binds groups of fasicles
Neuroglia
Supporting cells
Resemble neurons
Unable to conduct nerve impulses
Never lose dividing ability
Nuclei
Clusters of cell bodies in CNS
Ganglia
Clusters of cell bodies in PNS (outside of CNS)
Tracts
Bundles of nerve fibers in CNS
Nerves
Bundles of nerve fibers in PNS
White matter
Collections of myelinated fibers (tracts)
Gray matter
unmyelinated fibers and cell bodies
Functional classification of neurons
Afferent
Efferent
Interneurons
Efferent/motor
Impulses from CNS to Muscles or glands
Interneurons
Association neurons
Cell bodies in CNS
Connect sensory and motor neurons
Afferent neurons
Impulses from sensory receptors to CNS
Receptors include:
Cutaneous sense organs in skin
Proprioceptors in muscles and tendons
Nissl bodies
Rough ER
Functional classification of neurons
Afferent (sensory)
Efferent (motor)
Interneurons (association neurons)
Structural classification of neurons
of processes
Multipolar
Bipolar
Unipolar
Unipolar neurons
Short, single process leaving cell body
Sensory found in PNS
Impulses toward and away from body
Bipolar neurons
One axon + one dendrite
Special sense organs, like nose and eyes
Rare in adults
Multipolar
Many extensions from cell body
Motor and interneurons
Most common structural type
Neurofibrils
Intermediate filaments that maintain cell shape
PNS glial cells
Schwann cells
Satellite cells
Schwann cells
Form myelin sheath around nerve fibers in PNS
Satellite cells
Protect and cushion neuron cell bodies
Astrocytes found in
CNS
Astrocytes
Abundant, start shaped,
- Brace and anchor neurons to blood capillaries
- Control chemical environment:
- Permeability, exchanges between blood capillaries and neurons.
- Protect from harmful substances in blood
Most abundant and versatile neuroglia
Astrocytes
Microglia found in
CNS
Microglia
1.Spider-like phagocytes
2. Monitor health of nearby neurons
3. Dispose of debris
Phagocytes that defend CNS cells
Microglia
Ependymal cells found in
CNS
Ependymal cells
Line cavities of brain and spinal cord
Cilia help circulate cerebrospinal fluid
Oligodendrocytes found in
CNS
Oligodendrocytes
Wrap around nerve fibers in CNS
Make myelin sheath
Line cerebrospinal fluid filled cavities
Ependymal cells
Have processes that form myelin sheaths around CNS nerve fibers
Oligodendrocytes
Satellite cells
Protect and cushion neuron cell bodies
Main regions of cerebral hemisphere
Cortex
White matter
Basal nuclei
Cortex
1.Superficial grey matter
2.Localizes and interprets sensory inputs
- Controls voluntary and skilled skeletal muscle activity
- Intellectual and emotional processing
Basal nuclei
Deep pockets of grey matter
Control skeletal muscle movements
Modify instructions of primary motor cortex
Regions of brain stem
Midbrain
Pons
Medulla oblongata
Reticular formation- a functional system
Midbrain
1.VA (visual, auditory)
2. Subcortical motor
3. 3-4
Pons
1.Info from cerebrum to cerebellum
2. Breathing
3. 5-7
Medulla oblongata
1.Crossover pyramids
2. 8-12
3. Senses from skin & proprioceptors
4. Vessel diameter, vomiting, heart rate
Reticular formation-a functional system
1.Alertness/ repetitive stimuli
2.skeletal/visceral muscle
3.Diffuse mass of Gray matter along brain stem
Cerebellum
- Motor cortex
- Balance, coordination, speech, timing
- Has outer cortex (grey)
White matter
Visual area
Occipital lobe
Auditory area
Temporal lobe
Olfactory area
Temporal lobe
Primary somatic sensory area location
Parietal lobe post central sulcus
Primary somatic sensory area
Impulses from body’s sensory receptors, pain temp, light touch (not special senses)
Left side of primary somatic sensory area receives impulses from
Right side and vice versa
Primary motor area location
Anterior to central sulcus
Primary motor area
consciously move skeletal muscles
Motor neurons form pyramidal (corticospinal) tract which descends to spinal cord
Broca’s area
Ability to speak
Left hemisphere
Anterior association area
Frontal lobe
Thinking reasoning
Process sensory inf
Posterior association area
Posterior Cortex
Thinking reasoning
Process sensory info
Speech area
For sounding out words
In temp. & parietal lobe
Cerebral white matter
Fiber tracts deep to grey matter
Corpus callosum connects
Hemispheres
Tracts like corpus are known as
Commisures
Association fiber tracts
Connect areas within a hemisphere
Projection fiber tracts connect the cerebrum with
Lower CNS centers
Cerebrum
Big part of brain
Diencephalon
Thalamus,
Hypothalamus,
Epithalamus
Most inferior part of brain stem that merges into spinal cord
Medulla oblongata
RAS
Reticular Activating System
Role in awake/sleep cycles and consciousness
Filter incoming sensory information
Extends from mammillary bodies to pons inferiorly
Midbrain
Cerebral aqueduct (tiny canal) connects third and fourth ventricles
Midbrain
Two, bulging fiber tracts cerebral peduncles convey ascending and descending impulses
Midbrain
Rounded protrusions, corpora quadrigemina are visual and auditory reflex centers
Midbrain
Meninges
Protection
Dura mater (periosteal and meningeal)
Arachnoid layer
Pia mater
Dura mater
Outermost
Leathery
Double layered external covering
Periosteal Dura mater
Connects to skull
Via inner surface
Meningeal dura mater
Outer covering of brain
Dura mater Folds inward in several areas
Falx cerebri
Tentorium cerebelli
Arachnoid layer
1.attach to pia mater
2.Web-like extensions in subarachnoid space. Subarachnoid filled with CSF
Pia mater
Internal layer, clings to brain and spinal cord
Arachnoid granulations protrude through dura mater and
absorb CSF into venous blood
CSF
Similar to blood plasma in composition
Watery cushion that protects brain and spinal cord
Made in Choroid plexuses
Choroid plexus
Capillaries in ventricles of brain
In epithalamus
CSF circulates in
Arachnoid space, ventricles, central canal of spinal cord
Lateral, 3rd, 4th ventricles
Explain CSF circulation
- CSF made by Choroid plexus of each ventricle
- CSF flows through ventricles and subarachnoid space. Some CSF flows through central canal of spinal cord
- CSF flows through subarachnoid space
- CSF absorbed into dural sinuses via arachnoid villi
Spinal cord structure extends from
Foramen magnum of the skull,
1st or second lumbar vertabra
Cauda equina is a
Collection of spinal nerves at the inferior ends of spinal cord
Function of spinal cord
2 way conduction pathway to and from brain
How many pairs of spinal nerves arise from the spinal cord?
31
Internal grey matter of spinal cord is mostly
Cell bodies
Dorsal horns house
Interneurons
Interneurons
Receive information from sensory neurons in dorsal root
Cell bodies are housed in
Dorsal root ganglion
Anterior (ventral) horns house motor neurons of
Somatic (voluntary) nervous system
Send information out ventral root
Motor neurons of somatic nervous system
Grey Matter surrounds the
Central canal filled with CSF
White matter of spinal cord made of
Myelinated fiber tracts
White matter of spinal cord has 3 regions
dorsal, lateral, ventral columns
Only pair of _____ ______ extends to thoracic and abdominopelvic cavities
Vagus nerves
Most cranial nerves are
Mixed nerves
Which nerves are sensory only?
Optic
Olfactory
Vestibulocochlear
CN1
Olfactory:
CN2
Optic
CN3
Oculomotor
CN4
Trochlear
CN5
Trigeminal
CN6
Abducens
CN7
Facial
CN8
Vestibulocochlear
CN9
Glossopharyngeal
CN10
Vagus
Pharynx, larynx, swallowing and phonation
CN 11
Accessory
Activate SCM& trapezius
CN12
Hypoglossal
Tongue movements
Impulses from tongue
Sympathetic
Fight or flight
Parasympathetic
Rest and digest
Parasympathetic aka as
Craniosacral division
Preganlionic neurons
Brain and spinal cord
Post ganglionic
Extend to organs that are served
Preganlionic neurons synapse with
Terminal ganglia
Synapse
Functional junction between nerves where nerve impulse is transmitted
Transmission down neuron is
Electrical
Transmission to next neuron is
Chemical
Propagation of action potential
- If enough Na enters cell, action potential starts and is propagated over the entire axon
- All or none impulse is propagated or not
- Fibers w/ myelin sheaths conduct impulses more quickly
Initiation and generation of action potential
- Stimulus changes permeability of membrane to Na+
- Na+ diffuses into the neuron
- Inward rush of Na+ depolarizes cell (inside becomes more positive)
- If stim and Na+ is strong enough, local depolarization lets neuron conduct action potential
Synapse transmission
Synapse transmission
1.AP reaches axon terminal, Ca2+ channels open
- Ca2+ gets NT to release from axon terminal through vesicles
- NT goes into synaptic cleft and attaches to receptors of next neuron
- If enough NT released, graded potential is generated. Nerve impulse happens beyond synapse. Kick starts Na+ entry into receiving cell
- Enzyme removes NT
Special senses include
Smell, taste, sight, hearing, equilibrium
Special sense receptors
Large sensory organs, eye and ear
Localized clusters of receptors (taste buds and olfactory epithelium)
____% of sensory receptors are in the eyes
70%
How many nerve fibers in each eye?
Over 1 million
Accessory structures of eye
-Extrinsic eye muscles
-Eyelids
-Conjuctiva
-Lacrimal apparatus
Canthus or commisures
Ends of eyes
Conjunctiva
-Covers sclera
-Lines lids and eyeball
-Connects w/ transparent cornea
-secretes mucus to lubricate eye and keep it moist
Lacrimal canaliculus
Tube where tears go. Goes into nose
Palpebral fissure
Opening between eyelids
Lacrimal caruncle
Fleshy inner part of inner corner
Eyelids
Meet at medial and lateral commisures (canthus)
Eyelashes
Tarsal glands produce oily secretion that lubricates the eye
Location of ciliary glands
Between eyelashes
Lacrimal apparatus made of
Lacrimal gland+ ducts
Lacrimal gland
Produces Lacrimal fluid (tears)
On lateral end of each eye
Ducts
1.Tears drain across eye into Lacrimal canaliculi,
- Then Lacrimal sac
- Nasolacrimal duct, empties into nasal cavity
Tears contain
Dilute salt solution
Mucus
Antibodies
Lysosome (destroys bacteria)
Function of tears
Cleanse, protect, lubricate the eye
Iris
Regulates amount of light entering eye
Fibrous layer
Sclera+ cornea
Cornea
Transparent,
Central anterior portion
Lets light pass through
Palpebra
Eyelid
Pupil
Dark part of eye
Photons of light pass
Mebum
Oily secretion that lubricates eye
Myopia
Nearsightedness
Long eyeball,
Light doesn’t reach retina
Hyperopia
Far sighted short eyeball