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The Human Nervous System

The Human Nervous System. The Nervous System has TWO Major Divisions. The Central Nervous System The Peripheral Nervous System. The Central Nervous System (CNS). The Central Nervous System (CNS) consist of the Brain and the Spinal Cord .

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The Human Nervous System

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  1. The Human Nervous System

  2. The Nervous System has TWO Major Divisions. • The Central Nervous System • The Peripheral Nervous System

  3. The Central Nervous System (CNS) • The Central Nervous System (CNS) consist of the Brain and the Spinal Cord. • The spinal cord carries messages from the body to the brain, where they are analyzed and interpreted.  • Response messages are then passed from the brain through the spinal cord and to the rest of the body. • Both the brain and the spinal cord are encased in bone.

  4. Brain • One of the most active organs of the human body • The brain receives 20% of the blood that is pumped from the heart • Brain and spinal cord float in a fluid known as cerebrospinal fluid. • This fluid cushions against shock. • Major parts of the Brain: • Cerebrum (Cerebral Cortex) • Cerebellum • Medulla Oblongata

  5. Thalamus – relay center between Brain and spinal cord • Hypothalamus – controls body temperature, blood pressure, and emotions

  6. Cerebral cortex • 3 major Functions • Sensory areas that receive impulses from sense receptors (Eyes, ears, taste, nose, pain, pressure, heat/cold, touch) • Motor areas that start impulses that are responsible for all voluntary movement • Associative areas of the brain are responsible for memory, learning and thought • The cerebral cortex has many folds called convolutions • Convolutions – are folds on the brain that increase surface area

  7. The Cerebellum • Controls all voluntary movements and some involuntary • The cerebellum helps with balance, rate of muscle contraction, and the muscles position in relation to gravity • Allows for smooth orderly movement • Also plays a role in sensory perception to maintain balance (inner ear)

  8. Medulla Oblongata • Connect the spinal cord to all other parts of the brain • Control involuntary activities • Breathing • Heartbeat • Blood flow • coughing

  9. Memory • Scientist do not know exactly how memories are created • 3 types of memory • Momentary – lasts a few min • Short-term – Several hours • Long-term – Weeks to years and longer • How memories change from short-term to long-term is unknown

  10. THE SPINAL CORD • 2 Important Functions • Connects the nerves of the peripheral nervous system with the brain • Controls certain reflexes which are automatic responses • The spinal cord is continuous with the brain and emerges from an opening at the base of the skull.

  11. The Peripheral Nervous System (PNS) • The Peripheral Nervous System (PNS) consists of the neurons NOT Included in the brain and spinal cord.  • AFFERENT NEURONS - Peripheral Neurons collect information from the body and transmit it TOWARD the CNS (sensory) • EFFERENT NEURONS. - Peripheral Neurons transmit information AWAY from the CNS (motor)

  12. Divisions of the Peripheral Nervous System • Somatic Nervous System – This system is responsible for body movements over which the individual has some conscious awareness or voluntary control • Autonomic Nervous System – This system is responsible for involuntary activities. • 2 divisions • Sympathetic • Parasympathetic

  13. THE SOMATIC NERVOUS SYSTEM • Regulates activities that ARE UNDER CONSCIOUS CONTROL, movement of skeletal muscles. • Every time you lift your finger or wiggle your toes, you are using the motor neurons of the Somatic Nervous System. nerve cell animation • Many nerves within this system are part of reflexes and can act automatically.

  14. THE AUTONOMIC NERVOUS SYSTEM • Regulates ACTIVITIES THAT ARE AUTOMATIC, OR INVOLUNTARY. • The nerves of the Autonomic Nervous System control functions of the body that are NOT UNDER CONSCIOUS CONTROL. • MAINTAINING HOMEOSTASIS IN THE FUNCTIONING OF MANY ORGANS OF THE BODY. • Examples:  heart rate, breathing rate, digestion salivation ect. . . .

  15. THE AUTONOMIC NERVOUS SYSTEM IS SUBDIVIDED INTO TWO PARTS:

  16. Sympathetic “Fight or Flight” Nervous System • The sympathetic nervous system prepares the body for sudden stress • For example if you see a robbery taking place. • When something frightening happens, the sympathetic nervous system takes over • makes the heart beat faster • diverts blood to your muscles and chest • makes the pupils dilate • causes the adrenal glands at the top of the kidneys to release adrenaline, to give extra power to the muscles for a quick getaway. • This process is known as the body's "fight or flight" response. • http://www.youtube.com/watch?v=LjX88mkzU4g&safety_mode=true&persist_safety_mode=1

  17. Parasympathetic “Sit and Digest” nervous system • It prepares the body for rest. • Slows heart rate • It also helps the digestive tract move along so our bodies can efficiently take in nutrients from the food we eat. • Opposite of the sympathetic

  18. REFLEXES • A reflex is an involuntary response to a STIMULUS. • Reflexes are very fast, and Most Reflexes Never Reach the Brain. • The reflex arc is an automatic, involuntary reaction to a stimulus. When the doctor taps your knee with the rubber hammer, she/he is testing your reflex (or knee-jerk). Reflex Arc

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