Chap 3 - Nervous System.txt

Body's principal control system, regulates all bodily functions via electrical impulses transmitted thru nerves

• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)

Consists of the brain and the spinal cord

Composed of the cranial nerves from the brain and peripheral nerves from the spinal cord

Subdivision are: somatic nervous system (aka. voluntary) & automatic nervous system (aka involuntary)

• Somatic sensory
• Somatic motor
• Visceral (automatic) sensory
• Visceral (automatic) motor

Afferent nerves that transmit sensations such as touch, pressure, pain, temperature, & position

Efferent fibers that carry impulses to the skeletal (voluntary) muscles

Afferent tracts that transmit sensations from the visceral organs.

Sensation such as need to pee & take a crap

Efferent fibers that exit the CNS & branch to supply nerves to the cardic muscle & smooth muscle of the viscera (organs) & glands

Governs voluntary functions (those we consciously control)

ie. control of movement & skeletal muscles

Subdivision of the peripheral nervous system

Controls involuntary bodily functions (ie. smooth muscle, cardiac muscle, glands)



Subdivision of the peripheral nervous system

Divided into: sympathetic nervous system & parasympathetic nervous system

Groups of autonomic nerve cells located outside the CNS

Nerve fibers that extend from the CNS to tht autonomic ganglia

Nerve fibers that extend from the autonomic ganglia to the target tissues

Division of the automatic nervous system

Prepares the body for 'fight or flight'

• Body reacts by:
• * ^ HR
• * Bronchioles dilate
• * Pupils dilate
• * Decrease organ & digestion activity
• * Vasocontriction

Nerves: thoracic & lumbar regions

Adrenal medulla gland is responsible for the release of the hormones

• Neurotransmitters: epinephrine (80%)
• norepinephrine (20%)

• Sympathetic chain ganglia
• Collateral ganglia

• ^ BP
• Stimulation of secretion by sweat glands
• Constriction of blood vessels in the skin
• ^ in blood flow to skeletal muscles
• ^ HR
• ^ force of cardiac contraction
• Bronchodilation
• Stimulation of energy production

• Reduction in blood flow to abdominal organs
• Decreased digestive activity
• Relaxation of smooth muscle in the wall of the urinary bladder
• Release of glucose stores from the liver

• Adrenergic receptors
• Dompaminergic receptors

• * Alpha₁
• * Apha₂

• * Beta₁
• * Beta₂

• Peripheral vasoconstriction
• Mild bronchoconstriction
• Stimulation of metabolism

Prevent overrelease of norepinephrine

• ^ HR
• ^ cardiac contractile force
• Cardiac automaticity & conduction

• Vasodilation
• Bronchodilation

Dilation of renal, coronary & cerebral arteries

Division of the automatic nervous system

Controls the 'feed or breed' or rest & regenerative

Arises from the brainstem & sacral segments of the spinal cord

• Body actions:
• * decreased HR & cardiac contractile force
• * bronchioles constrict
• * Pupils constrict
• * sexual stimulation
• * ^ digestive activity

Nerves: sacral region & cranial nerves (vagus nerve)

Neurotransmitters: Acetylcholine

• III: oculomotor nerve
• VII: facial nerve
• IX: glossopharyngeal nerve
• X: vagus nerve

• Nicotinic
• Muscarinie

Nicotinic_N (neuron): found in autonomic ganglia; parasympathetic & sympathetic systems

Nicotinic_M (muscle): found at the neuromuscular junction, initiate muscular contraction; somatic nervous system

promoting the parasympathetic response

• * nerve cell
• * fundamental component of nervous system

• * Soma: cell body, contains the nucleus, mitochondria & ribosomes
• * Dendrites: transmit electrical impulses to cell body
• * Axons: transmit electrical impulses away from the cell body
• * Synaptic terminals: affect another neuron or effector

• '+' charged on outside
• '-' charged on the inside

• NA rapidly surges into the cell
• K rapidly leaves the cell
• thus depolarization of the neuron

substance released from axon terminal of neuron on excitation travels across the synpatic cleft to either excite or inhibit the target cell

examples: acetylcholine, norepinephrine, dopamine

Within the cranium vault protected by the skull

• frontal bone
• occipital bone
• parietal bones
• temporal bones
• sphenoid bones
• ethmoid bones

protective membranes that cover the entire CNS

• Dura Mater: durable outermost layer
• Arachnoid Membrane: weblike structure middle layer
• Pia Mater: innermost layer

space b/t the pia mater & anachnoid membrane

space b/t the dura mater & arachnoid membrane

Epidural space

• Its a watery clear fluid
• brain & spinal cord are bathed in it

• Cerebrum
• Diencephalon (thalmus & hypothalmus)
• Mesencephalon (midbrain)
• Pons
• Medulla Oblongata
• Cerebellum

• Cerebrum
• Diencephalon

• Located in the anterior & middle are of the cranium
• Contains '2' hemispheres which are joined together by the corpus callosum
• Responsible for: sensory & motor actions, intelligence, learning, analysis, memory, language

• personality
• motor

Speech

Vision

Sensory

• covered by the cerebrum
• aka. interbrain
• thalamus, hypothalamus & limbic system
• Responsible for: involuntary actions, temperature regulation, sleep, water balance, stress response & emotions
• Major role: regulating autonomatic nervous system

• Mesencephalon (midbrain)
• Pons
• Medulla Oblongata

• Brainstem
• Cerebellum

• aka. midbrain
• Located b/t the diencephalon & the pons
• Responsible for: motor coordination & eye movement

• Located b/t midbrain & medulla oblongata
• Contains connections b/t the brain & spinal cord

• Located b/t the pons & the spinal cord
• Marks the division b/t the spinal cord & brain
• Responsible for: controlling respirations, cardiac activity, vasomotor activity

• Located in the posterior fossa
• Consists of '2' hemispheres
• Responsible for: fine motor movement, posture, equilibrium, muscle tone, balance & coordination

• Operates in the lateral portion of the medulla, pons & midbrain
• Sends impulses to & receives impulses from cerebral cortex
• Responsible for: maintaining consciousness & ability to respond to stimuli

• Carotid system is anterior
• Vertebrobasilar system is posterior

Venous drainage thru venous sinuses & internal jugular veins

Central nervous system pathway responsible for transmitting sensory input from the body to the brain & for conducting motor impulses from the brain to the body muscles & organs.

Acts as a reflex center

Deep crease along the ventral surface of the spinal cord that divides the cord into right & left halves

Shallow longitudinal groove along the dorsal surface of the spinal cord

Areas in the CNS dominated by nerve cell bodies; the central portion of the spinal cord

Material that surrounds gray matter in the spinal cord

Made up largely of axons

Bundles of axons along the spinal cord that transmit signals from the body to the brain

• Fasciculus Gracilis
• Fasciculus Cutaneous
• Spinothalamic Tracts

• * Carry sensory impulses of light touch
• * Vibration
• * Positional sense from the skin, muscles, tendons & joints

**Injury results in deficits on same side of body

• * Conducts pain & temperature (anterior)
• * Conducts touch & pressure (lateral)

** Injury results in opposite side deficits

Bundles of axons along the spinal cord that transmit signals from the brain to the body

• Corticospinal Tract
• Reticulospinal Tract
• Rubrospinal Tract

Responsible for voluntary & fine muscle movement

Consists of '3' subtracts: one lateral, one medial, one anterior

Responsible for: sweating & muscular activity associated w/ posturing

Control the fine motor functions of the hands & feet

• Peripheral nerve roots that branch in pairs from the spinal cord
• Have both sensory & motor components
• Provide largest part of innervation to skin, muscles & internal organs
• There are '31' pairs of spinal nerve roots

Topographical region of the body surface innervated by one nerve root

• C₃: collar region
• C₇: little finger
• T₄: nipple line
• T₁₀: umbilicus
• S₁: small toe

muscle & tissue of the body innervate by a spinal nerve root

• C₅: arm extension
• C₇: elbow extension
• T₁: knee extension
• S₁: ankle flexion

• C₁-C₈: Cervical
• T₁-T₁₂: Thoracic
• L₁-L₅: Lumbar
• S₁-S₅: Sacral
• Co: Coccygeal

• Ventral Roots: carry motor impulses from the cord to the body
• Dorsal Roots: carry sensory impulses from the body to the cord

Nerve roots converging in a cluster of nerves to form as a group

• Those primary processing functions that the spinal cord performs
• Maintaining balance & muscle tone

Special neurons in the cord that intercept sensory signals from our 'reflex response'

12 pairs of nerves that originate in the brain & supply nervous control to the head, neck & certain thoracic & abdominal organs

• I: Olfactory nerve - smell
• II: Optic nerve - vision
• III: Oculomotor nerve - eye movement, pupil constriction
• IV: Trochlear nerve: ocular movement
• V: Trigeminal nerve: sensitivity of face
• VI: Abducens nerve: Ocular movement
• VII: Facial nerve: facial expression
• VIII: Acoustic nerve: hearing
• IX: Glossopharyngeal nerve: viseral sensibility
• X: Vagus nerve: involuntary muscle control
• XI: Spinal accessory muscle: speech
• XII: Hypoglossal nerve: movement of tongue