Nervous System

• Homeostasis is maintained through control systems, including the sensors, control center, and communicating system.
• Negative feedback loops work to reduce deviations from the set point, whereas positive feedback mechanisms are used for rapid changes.
• The__________ serves as the main processing center for the entire nervous system

  Central Nervous system
• an organ located within the skull that functions as organizer and distributor of information for the body

  Brain
• large, upper part of the brain that controls activity and thought.

  Cerebrum
• the part under the cerebrum that controls posture, balance, and coordination

  Cerebellum
• part that connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate, and blood pressure.

  brain stem
• serves as a channel for signals between the brain and the rest of the body, and controls simple musculoskeletal reflexes without input from the brain.

  spinal cord
• connects the central nervous system to the organs and limbs

  Peripheral nervous system
• What are the two divisions of Peripheral Nervous system ?

  Somatic Nervous system

  Autonomic nervous System
• system is associated with the voluntary control of body

  Somatic Nervous system
• nerves that carry motor and sensory signals between the spinal cord and the body.

  Spinal Nerves
• nerve fibers that carry information into and out of the brain stem

  Cranial Nerves
• system is associated with the involuntary control of body

  Autonomic nervous system
• is activated when the body is in a dynamic role or stress. (e.g., increased heart rate and breathing, dilation of pupil, sweating, etc.)

  Sympathetic
• it maintains body functions and restores the body to normal or relaxed mode.

  Parasympathetic
• Two main parts of somatic nervous system

  • Spinal
  • Cranial
• Two divisions of Autonomic Nervous system ?

  • sympathetic
  • parasympathetic
• The basic unit of the nervous system is the nerve cell.
• Nerve cells are also called neurons.
• Neuron has three major structural features : Dendrites, Cell Body, Axon
• There are twelve to fourteen billions of neurons in one part of the brain alone. A neuron has a cell body containing the nucleus
• Dendrites carry impulses towards the cell body
• A cell may have as many as 200 dendrites carrying impulses toward the cell body. A single dendrite can be over one meter long.
• Axons carry impulses away from the cell body
• Axons carry impulses away from the cell body. Axons pass impulses to the dendrites of other neurons or cell body of muscle cells. Axons can be grouped together into cable-like bundles called nerved
• are cells with the special ability to carry signals or impulses. Thoughts, emotions, learning, and many body functions are carried by nerve impulses in the neurons

  Neurons
• Neurons are cells with the special ability to carry signals or impulses. Thoughts, emotions, learning, and many body functions are carried by nerve impulses in the neurons. A nerve impulse is a combination of an electrical charge and a chemical reaction. A nerve impulse is not a flow of electricity, but an electrochemical signal moving along a neuron.
• nerve impulse cannot jump from one neuron to another. When a nerve impulse comes to the end of an axon, it produces the chemical, called neurotransmitter, to be released. The chemical crosses the space between neurons called synapse and stimulates the nerve impulse to start in the next dendrite.
• The nervous system is assisted by five sense organs: the eyes, ears, nose, tongue, and skin.
• These sense organs are constantly receiving information from the environment and sending messages to the brain.
• These senses aid in the survival of human beings.
• A stimulus is any factor in the environment that may trigger a nerve impulse.
• A response is a reaction to a stimulus.
• A stimulus is received by the body and a response is made.
• Only the axon of the neuron releases neurotransmitters that cross the space between neurons. Reaction time is the length of time between application of a stimulus and detection of a response.