Science 3rd quarter reviewer for quizes and exam

• The nervous system connects all body parts and transmits signals from one part to another.
• The nervous system is a system of cells, tissues, and organs that regulates the body's responses to internal and external stimuli.
• Each part of the nervous system has a specific role as it functions as an important part of a system.
• The Central Nervous System (CNS) serves as the main processing center for the entire nervous system.
• The CNS consists of two main components, namely the Brain and the Spinal Cord.
• The Brain is an organ located within the skull that functions as an organizer and distributor of information for the body.
• The Brain has three main parts: Cerebrum, Cerebellum, and Brain Stem.
• The Cerebrum is the large, upper part of the brain that controls activity and thought.
• The Cerebellum is the part under the cerebrum that controls posture, balance, and coordination.
• The Brain Stem is the part that connects the brain to the spinal cord and controls automatic functions such as breathing, digestion, heart rate, and blood pressure.
• The Spinal Cord 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.
• The Peripheral Nervous System (PNS) connects the central nervous system to the organs and limbs.
• The PNS has two main divisions: the Somatic Nervous System and the Autonomic Nervous System.
• The Somatic Nervous System is associated with the voluntary control of body movements and has two main parts: Spinal Nerves and Cranial Nerves.
• The Autonomic Nervous System is associated with the involuntary control of body movements and has two subdivisions: Sympathetic and Parasympathetic.
• The Sympathetic Nervous System is activated when the body is in a dynamic role or stress, such as increased heart rate and breathing, dilation of pupil, sweating, etc.
• The Parasympathetic Nervous System maintains body functions and restores the body to normal or relaxed mode.
• Systems are made of cells that turns into tissues and became an organs
• 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.
• Imagine that you have a board with a row of switches.
• Quickly clicking each switch in the row on and off will give you an idea of how a nerve impulse travels along a neuron.
• Ampulse cannot jump from one neuron to another.
• When a nerve impulse comes to the end of an axon, it produces the chemical, eliineurotransmitter, to be released.
• The chemical crosses the space between neurons called synapse and stimulates the nerve impulse to start in the next neuron.
• 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.
• An organism must be able to respond to a stimulus in order to survive.
• Messages do not travel in both directions along the same neuron.
• 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.
• The next activity that you will perform will enable you to understand these concepts better.
• Use your body's senses to detect the stimuli in your environment and execute the corresponding response.
• There are twelve to fourteen billions of neurons in one part of the brain

  alone.

  A neuron has a cell body containing the nucleus. Projecting out from the

  cell body are root-like structures. These are the dendrites and axons. 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. AxXons 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 arouped

  together into cable-like bundles called nerves.