1. Nervous system

2. Nervous system Directs the functions of all the human bodys systems.
More than 100 billion nerve cells (neurons) in the body link together to receive stimuli and respond to stimuli.
Stimuli- anything that cases a reaction or response. Elements from the external or internal environment that are strong enough to set up a nervous impulse.
Every activity, voluntary or involuntary is controlled by the nervous system.

3. Neurons Neurons = masses of nerve cells that transmit information
1. Cell Body – Branches or fibers that reach out to send or receive impulses. contains the nucleus and two extensions Dendrites – Thin branching extensions of the cell body. Conduct nerve impulses toward the cell body. Shorter, more numerous, receive information Axons – Single, long “fiber” which conducts impulse away from the cell body, sends information
Neurons- basic element of the nervous system. Specialized cells that vary greatly in function, shape and size. All neurons have 3 parts..
Cell Body - contains the nucleus and two extensions
Dendrites – shorter, more numerous, receive information
Axons – single, long “fiber” which conducts impulse away from the cell body, sends information. Covered by tissue called myelin sheath. At the end of the axon are fibers which the impulses leaving the neurons pass.
The impulse jumps between neurons over a space called a synapse. After being told to do so by a neurotransmitter, a tiny sac at the end of nerve fibers.

4. Nervous system Central Nervous System (CNS): brain and spinal cord.
Peripheral Nervous System (PNS): nerves of the body

5. Central nervous system
Consist of the brain and spinal cord. This is the center of control.
Receives and interprets all stimuli and sends nerve impulses to instruct muscles and glands to act or to respond to certain actions.

6. Central nervous system
Brainstem- Include the midbrain, pons, and medulla oblongata.
Cerebellum- Area that coordinates musculoskeletal movement to maintain posture, balance, and muscle tone.
Cerebrum- Right and left hemispheres and outer portion called the cerebral cortex.
Each lobe has 4 parts: Frontal, parietal, temporal, and occipital.
Diencephalon- Contain the thalamus and hypothalamus. Serves as a relay center for sensations.
Cerebrospinal fluid (CSF)- watery fluid throughout the brain and spinal cord to help cradle and cushion the brain.
BRAINSTEM-
Midbrain concerned with visual reflexes. Pons control certain respiratory functions. Medulla oblongata contains centers that regulated heart and lung functions, swallowing, vomiting, coughing, and sneezing.
CEREBELLUM-Area that coordinates musculoskeletal movement to maintain posture, balance, and muscle tone.
CEREBRUM-
Cerebral cortex is the area of conscious decision making. The right and left lobe are divided into 4 parts. FRONT lobe controls voluntary motor movements, expressions, and moral behavior. PARIETAL lobe controls and interprets the senses and taste. TEMPORAL lobe controls memory, equilibrium, emotions, and hearing. OCCIPITAL lobe controls vision and various forms of expression.
DIENCEPHALON- Integrates with the autonomic nervous system to control heart rate, blood pressure, temperature regulation water, and electrolyte balance, digestive functions, behavioral responses, and glandular activities.

7. Peripheral nervous system
Includes 12 pairs of cranial nerves that carry impulses to and from the brain
And 31 pairs of spinal nerves that carry messages to and from the spinal cord.
Subsystems:
Somatic Nervous System- Voluntary system. Receives and process sensory input from the skin, muscles, tendons, joints, eyes, tongue, nose, and ears. Also excites voluntary contraction of skeletal muscle.
Autonomic Nervous System- Involuntary system. Carries impulses form the central nervous system to the glands, involuntary muscle, and various membranes. Stimulates organs, glands, and senses by secretion of substances.
Somatic Nervous System- Voluntary system. Receives and process sensory input from the skin, muscles, tendons, joints, eyes, tongue, nose, and ears. Also excites voluntary contraction of skeletal muscle.
Autonomic Nervous System- Carry impulses form the central nervous system to the glands, involuntary muscle, and various membranes. Stimulates organs, glands, and senses by secretion of substances.

8. Diseases and disorders
Concussions- An injury to the brain caused by an impact with an object.
Alzheimers Disease- Progressive degeneration of neurons in the brain. Mental capacity worsens over time.
Parkinsons Disease- Degeneration of nerves in the brain, which cause tremors, muscle weakness, and difficulty in walking.
Epilepsy- Chronic, recurrent seizure activity. Caused by abnormal conditions in the brain that trigger sudden, excessive electrical activity.

9. Jobs and professions
Neurologist- Physician who specializes in nervous system disorders. Diseases of the brain, spinal cord, muscles, and blood vessels that relate to these structures.
Otorhinolaryngologist- physician/surgeon who specializes in head and neck surgery.