Download nervous system

NERVOUS
SYSTEM
FUNCTIONS
• TO DETECT CHANGES AND FEEL
SENSATIONS
• TO INITIATE APPROPRIATE
RESPONSES TO CHANGE
• TO ORGANIZE INFORMATION FOR
IMMEDIATE USE AND TO STORE IT
FOR FUTURE USE
DIVISIONS OF THE NS
• CNS
INCLUDES BRAIN AND SPINAL
CORD
• PNS
INCLUDES CRANIAL NERVES,
SPINAL NERVES, AND THE
AUTONOMIC NERVOUS SYSTEM
(ANS)
PARTS OF A NERVE CELL
• DENDRITES – TRANSMIT
IMPULSES TOWARDS THE CELL
BODY
• CELL BODY – CONTAINS
NUCLEUS
• AXON – TRANSMIT IMPULSES
AWAY FROM THE CELL BODY
• BETWEEN NERVE CELLS ARE
SYNAPSES
• NEUROTRANSMITTERS SUCH AS
ACETYLCHOLINE CARRY THE
IMPULSE ACROSS THE SYNAPSE
• THESE ARE DESCRIBED AS A
CHEMICAL TRANSMISSION
WHAT’S SIMILAR IN THE CNS
AND THE PNS?
• BOTH CONTAIN THE MYELIN
SHEATH (A SHEATH THAT
ELECTRICALLY INSULATES
NEURONS FROM ONE ANOTHER)
• THE MYELIN SHEATH ALLOWS
SMOOTH NERVE IMPULSE
TRANSMISSION FROM ONE
NEURON TO ANOTHER
WHAT’S DIFFERENT IN THE
CNS AND THE PNS?
• CNS
• THE MYELIN SHEATH IS FORMED
BY OLIGODENDROCYTES, A
SPECIALIZED CELL THAT
CANNOT REGENERATE
FOR EXAMPLE
• THE PHRENIC NERVE – C3-C5
WHAT’S DIFFERENT IN THE
CNS AND PNS?
• PNS
• THE MYELIN SHEATH IS MADE OF
SCHWANN CELLS
• THE NUCLEI ARE OUTSIDE OF
THE MYELIN SHEATH AND
CALLED A NEUROLEMMA
• THESE CAN REGENERATE
THE REFLEX ARC
• THE PATHWAY NERVE IMPUSLES
TRAVEL WHEN A REFLEX IS
ELICITED
5 ESSENTIAL PARTS TO REFLEX
1. RECEPTORS – DETECT STIMULUS
AND GENERATE IMPULSE
2. SENSORY NEURON – CARRY
IMPULSES TO THE CNS
3. CNS – CONTAINS 1 OR MORE
SYNAPSES
4. MOTOR NEURON – CARRY
IMPULSES FROM THE CNS TO THE
EFFECTOR
5. EFFECTOR – PERFORMS ACTION
STRETCH REFLEX
• KEEPS OUR BODY UPRIGHT
WITHOUT THINKING
FLEXOR REFLEX
• AKA WITHDRAWAL REFLEX
• PREVENTS INJURY BY PULLING
AWAY FROM A
PAINFUL
STIMULUS
SPINAL CORD
• TRANSMITS MESSAGES TO AND
FROM THE BRAIN
• EXTENDS FROM THE
FORAMEN MAGNUM
TO L2
• CALLED THE CAUDA
EQUINA AFTER
L2
SPINAL CORD
• THE CENTER OF THE CORD
CONTAINS GRAY MATTER THAT
CARRIES MOTOR IMPULSES
• THE EXTERNAL PORTION OF THE
CORD CONTAINS WHITE MATTER
THAT CARRIES SENSORY
IMPULSES
SPINAL CORD
• ASCENDING TRACTS CARRY
SENSORY IMPULSES TO THE
BRAIN (WHITE MATTER)
• DESCENDING TRACTS CARRY
MOTOR IMPULSES AWAY FROM
THE BRAIN (GRAY MATTER)
• THE CENTRAL CANAL CONTAINS
CSF
SPINAL NERVES
• 31 PAIRS OF SPINAL
NERVES
8 CERVICAL
12 THORACIC
5 LUMBAR
5 SACRAL
1 COCCYGEAL
SPINAL NERVES
• EACH SPINAL NERVE HAS 2
ROOTS
• THE DORSAL ROOT CARRIES
IMPULSES IN TO THE CORD
• THE VENTRAL ROOT CARRIES
IMPULSES OUT OF THE CORD
BRAIN
• CEREBRUM – LARGEST PART OF
THE BRAIN
• THE TWO HEMISPHERES ARE
CONNECTED BY THE CORPUS
CALLOSUM THAT CONNECTS THE
RIGHT AND LEFT HEMISPHERES
• THERE IS A LATERAL VENTRICLE
IN EACH HEMISPHERE
CEREBRUM
• THE CEREBRAL CORTEX
(SURFACE) IS FOLDED
EXTENSIVELY WITH GYRI THAT
ALLOWS MILLIONS MORE
NEURONS
CEREBRUM
•
•
•
•
4 LOBES
FRONTAL – MOTOR AREAS
PARIETAL – SENSORY AREAS
TEMPORAL – AUDITORY AND
OLFACTORY AREAS
• OCCIPITAL – VISUAL AREA
• PITUITARY – CONTROLS GROWTH
• THALAMUS – INTEGRATES
SENSATIONS
• HYPOTHALAMUS – MANY
FUNCTIONS
• CEREBELLUM – COORDINATION,
POSTURE, EQUILIBRIUM
• VENTRICLES (4) – CONTAINS THE
CHOROID PLEXUS THAT MAKES
CSF
BRAINSTEM
• MIDBRAIN – VISUAL AND
AUDITORY REFLEXES
• PONS – 2 RESPIRATORY CENTERS
FOR NORMAL BREATHING
• MEDULLA OBLONGATA –
REGULATES HEART RATE, BLOOD
PRESSURE, AND RESPIRATION.
ALSO A REFLEX CENTER FOR
COUGHING, SNEEZING,
SWALLOWING, VOMITING
CONNECTIVE TISSUE MEMBRANES
• COVER BRAIN AND SPINAL CORD
• CALLED MENINGES
• 3 LAYERS
• DURA MATER – THICK OUTER
LAYER
• ARACHNOID MEMBRANE –
MIDDLE LAYER
• PIA MATER – INNERMOST LAYER
• SUBARACHNOID SPACE –
CONTAINS CSF
CSF
• CEREBROSPINAL FLUID
• BRINGS NUTRIENTS TO CNS
NEURONS AND REMOVES
WASTES TO THE BLOOD
• ACTS AS A CUSHION FOR CNS
CRANIAL NERVES
• 12 PAIRS
• EMERGE FROM THE BRAIN STEM
OR OTHER PARTS OF THE BRAIN
CN I – OLFACTORY
CN II – OPTIC
CN III – OCULOMOTOR
CN IV – TROCHLEAR
CN V – TRIGEMINAL
CN VI – ABDUCENS
CN VII – FACIAL
CN VIII – ACOUSTIC
CN IX – GLOSSOPHARYNGEAL
CN X – VAGUS
CN XI – ACCESSORY
CN XII - HYPOGLOSSAL
AUTONOMIC NERVOUS SYSTEM
•
•
1.
2.
PART OF THE PNS
2 DIVISIONS
SYMPATHETIC
PARASYMPATHETIC
THESE ARE INTEGRATED BY THE
HYPOTHALAMUS
• SYMPATHETIC – “FIGHT OR
FLIGHT”, DOMINATES DURING
STRESSFUL SITUATIONS
• PARASYMPATHETIC – DOMINATES
DURING NONSTRESSFUL
SITUATIONS AND INCREASES
PERISTALSIS DURING DIGESTION