NERVOUS SYSTEMS

BREAK DOWN (3 TYPES)

• Central nervous system (CNS) {brain/spinal cord}
• Peripheral nervous system (PNS) {nerves}
• Autonomic nervous system (ANS)

CENTRAL NERVOUS SYSTEM

CENTRAL NERVOUS SYSTEM

• Brain and spinal cord
• Occupies midline of body/central located
• Brain - protected by cranial cavity of skull
• Spinal cord - surrounded in spinal cavity by vetebral column
• Brain/spinal cord covered by: meninges (covered by protective membranes)

DIVISIONS OF BRAIN [PART 1]

• part 1: Brainstem
• 3 parts of brainstem: oblongata, pons, & midbrain
• Structure: white matter freckled with bits of gray matter
• Function: gray matter = reflex centers (respiration/heart beat)

PART 1...CONT'D

• Function: sensory tracts = conduct impulses to higher parts of brain
• Function: motor tracts = conduct impulses from high part of brain to spinal cord

DIVISIONS OF BRAIN [PART 2]

• part 2: Diencephalon
• Structure/function of the hypothalamus/thalamus
• Hypothalamus: control center for ANS
• Thalamus: relays sensory impulses to cerebral cortex

DIVISIONS OF BRAIN [PART 3]

• part 3: cerebellum
• 2nd largest part of (human) brain
• Helps produce muscle contractions/movement
• So we can maintain balance, move smoothly, and posture

DIVISIONS OF BRAIN [PART 4]

• part 4: CEREBRUM
• Largest part of (human) brain
• Outler layer of gray matter: cerebral cortex
• Made up of lobes
• Composed of: dendrites and cell body of neurons

DIVISIONS OF BRAIN [PART 4] ...CNT'D

• Interior of cerebrum: white matter
• White matter: Nerve fibers arranged in bundles aka tracts
• Function: mental processes (sensations, conciousness, memory and voluntary movement

PERIPHERAL NERVOUS SYSTEM

PERIPHERAL (PNS)

• Includes: All nerves
• Nerves extend to the peripheral parts of body
• (They extend to the outlaying parts of body)

CRANIAL NERVES [PART 1]

• 12 pairs - attatched to under surface of the brain
• Connect brain w/ neck and structures in thorax and abdomen

SPINAL NERVES [PART 2]

• Structure: contain dentrites of sensory neurons/axons of motor neurons
• Functions: conduct impulses necessary for sensations & voluntary movement

AUTONOMIC NERVOUS SYSTEM

AUTONOMIC (ANS)

• Subdivision of PNS
• Structures that regulate automatic/involuntary functions
• Ex: heart rate, contractions of stomach
• Motor neurons that conduct impulses from spinal cord/brainstem to tissues
• 3 types of tissues: cardiac muscle, smooth, and grandular tissues

2 DIVISIONS OF ANS

• Sympathetic Nervous System
• Parasympathetic Nervous System

SYMPATHETIC NERVOUS SYSTEM

• Dendrites/cell bodies located in thoracic gray matter and upper spinal cord
• Chain of sympathetic ganglia in front of each side of spinal column
• Axons leave spinal cord in anterior roots of spinal column
• Function: emergency/stress system (fight or flight response)

PARASYMPATHETIC NERVOUS SYSTEM

• Dendrites/cell bodies in gray matter or brain stem
• Function: dominates control of many visceral effectors
• Dominates in everyday conditions

AUTONOMIC NEUROTRANSMITTERS

• Cholinergic fibers: release acetlycholine
• Adreneric fibers: release noradrenaline

ANS AS A WHOLE

• Regulates body's automatic functions
• Quicky restores homeostasis
• Visceral effectors doubly innervated
• (They are effected by both div of ANS)

CELLS OF THE NERVOUS SYSTEM

GLIAL

• Astrocytes: star shaped; Anchor blood vessels to neurons
• Microgilia: small cells; move in inflammedd blood tissue
• Olgiodendrocytes: form myelin sheaths on axons
• Wraps around axon, forming myelin sheath

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NEURONS

• Dentrites: conduct impulses to cell body
• Cell body: main body of cell
• Axon: conducts impluses away from cell body
• Classified according to function
• 3 types: Sensory, motor, interneurons

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TYPES OF NEURONS

• Sensory: conduct impulses to spinal cord & brain
• Motor: conduct impulses to muscles (away from brain/spine)
• Interneurons: impulses from sensory to motor neurons

NERVES

NERVE: BUNDLE OF PERIPHERAL AXONS

• Tract: bundle of central axons
• White matter: tissue of myelinated axons (nerves or tracts)
• Gray matter: tissue of cell bodies & unmyekinated fibers

NERVE COVERINGS: FIBROUS CONNECTIVE TISSUE

• Endonerium: surrounds individual fibers within a nerve
• Perineurium: surrounds a group of nerve fibers
• Epineurium: surrounds the entire nerve

NERVE IMPULSES

• Self propagating wave of electrical disturbance
• Travels along the surface of a neuron membrane

SYNAPSE

• Chemical compounds released from axon terminals
• Released into synaptic cleft
• Neurotransmitters bind to specific receptor molecules in membrane
• Neurotransmitters: acetylcholines, catecholamines, and other compounds