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