Term
| Autonomic Nervous System (ANS) |
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Definition
• A system of motor neurons that innervate smooth muscle, cardiac muscle, and glands
• Maintains homeostasis
• No conscious control necessary |
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Term
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Definition
• Autonomic (Involuntary)
– Smooth muscle (visceral)
– Cardiac muscle
– Glands |
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Term
Somatic vs Autonomic Nervous
Systems |
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Definition
• Somatic
– Single axon
– Cell bodies in CNS
• Autonomic
– Pre and post ganglionic neurons
– Cell bodies in and outside CNS |
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Term
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Definition
• Parasympathetic
– Most active in nonstressful situation
– Concerned with keeping body energy use as low
as possible
• Sympathetic
– “Fight or flight” system
– Stimulated by vigorous physical activity |
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Term
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Definition
– Slows heart rate
– Constricts peripheral blood vessels
– Constricts bronchi
– Constricts pupils
– Aids or speeds up digestion and absorption of
nutrients |
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Term
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Definition
– Accelerates heart rate
– Causes a release of epinephrine (adrenaline)
– Constricts visceral blood vessels
– Dilate bronchi
– Dilate pupils
– Slows down digestion |
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Term
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Definition
• Structures that are specialized to respond to changes
in their environment (stimuli)
• Their activation trigger nerve impulses along afferent
fibers that transmit the impulse toward the CNS
• Classified by type |
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Term
| Types of Sensory Receptors |
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Definition
• Mechanoreceptors
– Touch, pressure (including blood pressure),
vibration, stretch, and itch
• Thermoreceptors
– Temperature
• Photoreceptors
– Respond to light (eye)
• Chemoreceptors
– Smell, taste, blood chemistry
• Nociceptors
– Respond to potentially damaging stimuli (pain) |
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Term
|
Definition
• A nerve consists of multiple nerve fibers or
neurons
• Nerves may be
– Sensory (afferent) nerves
– Motor (efferent) nerves
– Mixed nerves (most nerves are this type) |
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Term
|
Definition
– Often carry both somatic and autonomic (visceral)
neurons
– Neurons may be classified according to the region
they innervate
• Somatic afferent; somatic efferent
• Visceral afferent; visceral efferent |
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Term
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Definition
• Associated with the brain
• Twelve pairs
• Each have a name and Roman numeral for
identification
• The first two pairs attach to the forebrain and
the rest originate from the brain stem
• Serve only the head and brain structures with
the exception of the Vagus nerve (X) |
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Term
Cranial Nerve
Olfactory (I) |
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Definition
- Originate in the cerebrum
– Sensory
– Carry afferent impulses for sense of smell |
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Term
Cranial Nerve
Oculomotor (III) |
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Definition
– Originate in the midbrain
– Motor
– Movement of the eye
– Part of the parasympathetic nervous system |
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Term
Cranial Nerve
Trigeminal (V) |
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Definition
– Originate from the pons
– Sensory and motor (mixed)
– Sensory – Conveys afferent impulses from the teeth, gums, & mucous membranes of the nose and mouth
– Motor – Efferent impulses to the muscles of mastication (chewing)
– Largest of the cranial nerves |
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Term
Cranial Nerve
Abducens (VI) |
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Definition
– Originate in the pons
– Motor
– Efferent impulses to the lateral rectus muscle of
the eye |
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Term
Cranial Nerve
Vestibulocochlear (VIII) |
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Definition
– Originate from the pons
– Sensory
– Afferent impulses for sense of equilibrium
(vestibular) and sense of hearing (cochlear) |
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Term
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Definition
– Originate from the medulla oblongata
– Sensory and motor (mixed)
– Afferent and efferent impulses from and to neck,
thorax, and abdomen
– A part and major contributor to the
parasympathetic nervous system
– Longest of the cranial nerves; has most extensive
distribution |
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Term
Cranial Nerve
Accessory (XI) |
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Definition
– Originate in the medulla oblongata
– Motor
– Efferent impulses to muscles of the larynx,
esophagus, and trapezius |
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Term
|
Definition
• 31 pairs
• Arise from the spinal cord
• Supply all parts of the body except the head
and some areas of the neck
• All are mixed nerves
• Enlargements of the cervical and lumbar regions |
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Term
| The Central Nervous System |
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Definition
| The Brain and The Spinal Cord |
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Term
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Definition
• Average adult man’s brain weighs about 1600
grams (3.5 lbs)
• Average adult woman’s brain weighs about
1450 grams
• Contains approximately 100 billion neurons |
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Term
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Definition
• Cerebral Hemispheres
• Diencephalon
– Thalamus, Hypothalamus, Epithalamus
• Brain Stem
– Midbrain, pons, medulla oblongata
• Cerebellum |
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Term
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Definition
• Form the superior part of the brain
• Account for about 83% of total brain mass
• Marked by elevated ridges of tissue called gyri
• The gyri are separated by shallow grooves
(sulci) or deeper grooves (fissures) |
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Term
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Definition
• Hemispheres
• Longitudinal Fissure
• Central Sulcus
• Lateral Sulcus |
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Term
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Definition
• Frontal – Anterior to the central sulcus and superior
to the lateral sulcus
• Parietal – Posterior to the central sulcus
• Temporal – Inferior to the lateral sulcus
• Occipital – Posterior to the parietal and temporal
lobes
• Insula – Deep within the brain covered by parts of
the frontal, parietal, and temporal lobes |
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Term
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Definition
• Forms the central core of the forebrain
• Consists of
– Thalamus
– Hypothalamus
– Epithalamus |
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Term
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Definition
• Consists of the
– Midbrain
– Pons
– Medulla Oblongata |
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Term
|
Definition
• Midbrain
– Conduction pathway between higher and lower
brain centers
– Visual and auditory reflex centers
– Contains nuclei for cranial nerves III and IV (eye
movement) |
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Term
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Definition
• Pons
– Between the midbrain and medulla oblongata
– Conduction pathway between higher and lower
brain centers
– Relay information from the motor cortex of the
cerebrum to the cerebellum
– Contain nuclei that assist in respiration
– Contain nuclei for cranial nerves V, VI and VII |
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Term
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Definition
• Medulla Oblongata
– Conduction pathway between higher brain
centers and spinal cord
– Contains nuclei for cranial nerves VIII – XII
– These nuclei receive impulses from skin, control
heart rate & blood vessel diameter, and control
respiratory rate & depth of breathing |
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Term
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Definition
• Located dorsal to the pons and medulla
• Receives and processes information from the cerebral cortex and proprioreceptors throughout the body.
• Sends information to the cerebral cortex that helps maintain posture & balance and ensures smooth, coordinated movements |
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Term
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Definition
• The brain is protected by:
– Bone (skull)
– Membranes (meninges)
– Watery cushion (cerebrospinal fluid)
• Also protected from harmful substances in the blood by the blood-brain barrier |
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Term
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Definition
• Three connective tissue membranes that
surround the brain and spinal cord
• The three meninges are the
– Dura mater
– Arachnoid
– Pia mater |
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Term
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Definition
• Dura mater
– Two-layered sheet of fibrous connective tissue
– Subdural space
• Filled with cerebrospinal fluid |
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Term
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Definition
• Arachnoid mater
– Thin layer of connective tissue
– Beneath the arachnoid membrane is the
subarachnoid space – weblike extensions span this space
– Cerebrospinal fluid fills this space
– The subarachnoid space contains the largest blood vessels serving the brain |
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Term
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Definition
• Pia mater
– Very thin layer
– Clings to the brain
– Contains many tiny blood vessels |
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Term
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Definition
• Found in and around the brain and spinal cord
• Provides buoyancy to the brain
• Provides protection from blows and other
trauma
• Also helps to nourish the brain |
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Term
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Definition
• A selective protective mechanism that inhibits the passage of materials from the blood into brain tissue
• Helps maintain a stable environment for the brain
• Brain capillaries are the least permeable capillaries in the body |
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Term
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Definition
• Enclosed within the vertebral column
• About 17 inches long
• Provides a two-way conduction pathway to and from the brain
• A major reflex center
• Protected by bone, meninges, and
cerebrospinal fluid |
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Term
| Anatomy of the Spinal Cord |
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Definition
• Gray matter
– Neuron cell bodies and their unmyelinated processes
– Posterior (dorsal) horns
• Dorsal roots (sensory)
– Anterior (ventral) horns
• Ventral roots (motor)
• White matter (Funiculi)
– Myelinated nerve fibers that make up nerve tracts |
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Term
Fundamentals of the Nervous
System and Nervous Tissue |
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Definition
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Term
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Definition
The master controlling and communicating
system of the body
-Three functions
Sensory input
Integration
Motor output |
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Term
Organization of the Nervous
System |
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Definition
Central Nervous System (CNS)
-Brain and Spinal Cord
Peripheral Nervous System (PNS)
-Outside the CNS
-Consists of the cranial and spinal nerves |
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Term
| Peripheral Nervous System |
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Definition
Sensory (Afferent) Division
-Keeps CNS informed
Towards CNS
-Motor (Efferent) Division
Transmits impulses from the CNS to the
muscles and glands
-sends messages away from CNS |
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Term
Organization of the Nervous
System (continued) |
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Definition
Motor Division of the PNS
-Somatic Nervous System
Voluntary
-Autonomic Nervous System
Involuntary
Subdivisions
• Sympathetic nervous system
• Parasympathetic nervous system |
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Term
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Definition
-Nervous tissue is highly cellular
Densely packed (< 20% of CNS is
extracellular space)
Two principal types of cells
Neurons
Supporting cells |
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Term
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Definition
t Referred to as neuroglia or glial cells
CNS (4)
Astrocytes
Microglia
Ependymal cells
Oligodendrocytes
PNS (2)
Satellite cells
Schwann cells |
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Term
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Definition
Neurons = Nerve cells
Structural units of the nervous system
React to physical and chemical changes occurring the body, conducting nerve impulses
Long lifespan
Have a nucleus but do not divide or reproduce (amitotic)
High metabolic rate – require continuous and abundant supply of oxygen and glucose |
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Term
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Definition
Cell body
Contains a nucleus and other cellular organelles
Dendrites
Receptor surfaces of the neuron; transmit nerve impulse toward the cell body
Axon
Generate nerve impulses and transmit them away from the cell body |
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Term
| Classifications of Neurons |
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Definition
Structure
Multipolar Neurons
Bipolar Neurons
Unipolar Neurons
Function
Sensory (Afferent) Neurons
Motor (Efferent) Neurons
Interneurons |
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Term
| Types of Neurons – General Structures |
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Definition
General Somatic Efferent
Signal runs from brain or spinal cord to
muscles
General Visceral Efferent
Signal runs from brain or spinal cord to smooth muscles and glands
General Somatic Afferent
Signal runs from muscles to brain and spinal
cord
General Visceral Afferent
Signal runs from organs to brain or spinal cord |
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Term
| Types of Neurons – Cranial Structures |
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Definition
Special Visceral Afferent
Signal runs from senses of taste and smell to the brain
Special Somatic Afferent
Signal runs from senses of sight, hearing, and equilibrium to the brain |
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Term
Somatic Motor Systems
- Effectors |
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Definition
• Somatic (Voluntary)
– Skeletal Muscles |
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Term
| Types of Neurons – Cranial Structures (a |
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Definition
Special Visceral Efferent
Signal runs from the brain to control chewing, swallowing, expression, and speaking |
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Term
| Types of Neurons – General Structures (a |
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Definition
General Visceral Efferent
Signal runs from brain or spinal cord to smooth muscles and glands |
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Term
|
Definition
– Originate in the cerebrum
– Sensory
– Carry afferent impulses for vision |
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Term
CRANIAL NERVE
Trochlear (IV) |
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Definition
– Originate in the midbrain
– Motor
– Eye movement
– Smallest of the cranial nerves |
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Term
CRANIAL NERVE
Facial (VII) |
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Definition
– Originate in the pons
– Sensory and motor (mixed)
– Sensory – Afferent impulses from the tongue
(taste)
– Motor – Efferent impulses to the muscles of facial
expression
– Part of the parasympathetic nervous system |
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Term
CRANIAL NERVE
Glossopharyngeal (IX) |
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Definition
– Originate in the medulla oblongata
– Sensory and motor (mixed)
– Sensory – Afferent impulses for taste, touch,
pressure, & pain from back of tongue and pharynx
– Motor – Efferent impulses to small muscles &
glands on back of tongue
– Part of the parasympathetic nervous system |
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Term
CRANIAL NERVE
Hypoglossal (XII) |
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Definition
– Originate in the medulla oblongata
– Motor
– Efferent impulses to muscles of the tongue |
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Term
|
Definition
Originates in Cerebrum
Sensory
Carr Afferent Impulses for Vision |
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