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Anatomy & Physiology
Nervous System
Nervous System
• 2 main sections– Central Nervous System (CNS)– Peripheral Nervous System (PNS)
Central Nervous System
• Brain = mass of nerve tissue• Weigh about 3 lbs.• Reaches full size @ about 6yrs. Old
• 3 – 5 min. supply of oxygen for nerve cells
• Blood brain barrier = blood flowing is filtered; harmful chemicals cannot enter the brain
Spinal Cord
• Connected from medulla oblongata to lower back (lumbar)
• Vertebrae surround & protect spinal cord
• Responsible for carrying info to the brain & to body cells
Meninges
• 3 layer covering of the brain & spinal cord (protects)• Dura matter
– Tough outer membrane
• Arachnoid membrane– Web like middle layer
• Pia mater– Inner layer; attached to brain
• Cerebrospinal fluid (CSF) = clear, watery liquid surrounding brain & spinal cord (cushions)
Sections of the Brain
• Cerebrum– Largest section– Separated into lobes
– Responsible for reasoning, thoughts, emotions, memory, speech, senses, movement
• Cerebellum– Located below the back of the cerebrum– Responsible for muscle coordination, balance,
posture, muscle tone
• Diencephalon– Hypothalamus• Regulates temp. appetite, water balance, sleep, &
blood vessels
– Thalamus• Directs sensory impulses
Brainstem
• Midbrain– Responsible for conducting eye & auditory reflexes
• Pons– Responsible for certain reflexes (chewing, saliva)– Assist with respirations
• Medulla oblongata– Connects with spinal cord– Responsible for regulating heartbeat, respirations,
swallowing, coughing, & blood pressure
Peripheral Nervous System
• 2 types of systems– Somatic– Autonomic
• Somatic– 12 pairs of cranial nerves (along with spinal
nerves)– Responsible for special senses
• Autonomic– Maintains a balance of involuntary functions
– Sympathetic / Parasympathetic maintains balance (homeostasis)• Sympathetic – prepares the body for an emergency
(increases heart rate, blood pressure)
• Parasympathetic – after an emergency (slows the body actions)
Structures of the Brain
• Corpus Callosum– Large bundle of nerve fibers – Connects L & R hemispheres
• Cerebellum– Regulates balance, posture, movement, muscle
coordination
Structures
• Spinal Cord– Connects to the medulla oblongata
• Medulla Oblongata– Top portion of the spinal cord– Controls automatic functions (heartbeat,
breathing)
Structures
• Pons– Connects cerebrum with cerebellum
• Pituitary gland– Attach to the base of brain; secretes hormones
• Hypothalmus– Regulates temp., appetite, sleep, blood vessels