Nervous System

$How the Nervous System Works$

• The nervous system coordinates all activities
• Your nervous system is a complex network that allows communication between the brain and body
• The brain, spine, and nerves work together, transmitting messages between organs, tissues, and cells.

$Central Nervous System v. Peripheral Nervous System$

1. The central nervous system (CNS) consists of the brain and spinal cord

1. The CNS receives messages from the nerves and in the PNS, interprets them, and sends out a response
   2. The peripheral nervous system (PNS) gathers information from inside and outside your body

1. The PNS includes nerves that extend from the brain, spinal cord, and sensory receptors, such as those in the skin

$Understanding Neurons$

• Neurons: nerve cells

1. Sensory Neurons: Carry messages from receptors in the body to the CNS
2. Motor Neurons: Carry messages from the CNS back to muscles or glands in response to an impulse
3. Internuerons: Communicate with connect other neurons

$Central Nervous System$

• The central nervous system is made up of the brain and spinal cord
• The brain and spinal cord send and receive impulses to and from nerves in the body

1. Sections of the brain

      1. the brain coordinates and controls the activities of the nervous system 2. your brain helps you to receive and process message; to think, remember, reason, and feel emotions; and to coordinate muscle movements

• Cerebrum
  • The largest and most complex part of the brain
  • Billions of neurons in the cerebrum are the center of conscious thought, learning, and memory
• Cerebellum
  • The second largest part of the brain
  • The cerebellum coordinates the movement of skeletal muscles and maintains the body’s posture and balance
• Brain Stem
  • A 3-inch long stalk of nerve cells and fibers that connects the spinal cord to the rest of the brain
  • Incoming sensory impulses and outgoing motor impulses pass through the brain stem

$Peripheral Nervous System (PNS)$

• The peripheral nervous system is made up of the nerves that are not in the brain and spinal cord
• The PNS carries messages between the CNS and parts of the body

1. Autonomic Nervous System

1. The autonomic nervous system control such involuntary functions as digestion and heart rate
2. A reflex is the body’s spontaneous response to stimulus
   2. Somatic Nervous System

1. The somatic nervous system involves voluntary responses that are under your control
2. Sensory neurons relay messages from the eyes, ears, nose, tongue, and skin to the CNS, and motor neurons carry impulses from the CNS to skeletal muscles

$Caring For your Nervous System$

1. Eat a well-balanced diet
2. Exercise regularly
3. Get enough sleep
4. Wear a safety belt when in a motor vehicle
5. Never die into shallow water
6. Wear a helmet and other protective gear while riding a bicycle, motorcycle, or other open vehicle, or when playing a contact sport
7. Avoid using drugs an alcohol

$Problems of the Nervous System$

1. Headaches: can be caused by muscle tension, eyestrain, exposure to fumes, a sinus infection, dehydration, or food allergies
2. Head Injuries

1. Concussion: Cause by a bump, blow, or jolt to the head or by a hit to the body that causes the head and brain to move rapidly back and forth
2. Contusion: A bruising of the brain tissues that causes swelling
3. Coma: A state of unconsciousness caused by major trauma
   3. Spinal Injury: Swelling of the spinal cord or tissue around it can result in temporary loss of nerve function. If the spinal cord is severed, paralysis results
   4. Meningitis: An inflammation of spinal and cranial meninges caused by bacterial or viral infection
   5. Degenerative Diseases: occur over time as cells break down