-nervous+system-

=**__ THE NERVOUS SYSTEM (Mina) __**=
 * Nervous system is a physical connected network of cells, tissues, and organs that controls thoughts, movements. **

**__Homeostasis__** • Homeostasis involves keeping the internal environment balanced • sensors gather data • control center receives data, sends messages • communication system delivers messages to target organs, tissues • targets respond to change • Feedback compares current conditions to set ranges. – Torn vessel stimulates release of clotting factor – growth hormones stimulate cell division
 * Homeostasis is the regulation and maintenance of the internal environment.**[[image:http://www.jedword.com/wp-content/uploads/2011/01/kid-child-running-thumb.jpg width="268" height="268" align="right"]]
 * Negative feedback are necessary for homeostasis.**
 * Positive feedback increases change.**

**__Neurons__** • A neuron has three parts. – cell body has nucleus and organelles – dendrites receive impulses – axon carries impulses • Neurons have other structures to transmit signals. – Schwann cell – synapse – terminal • Resting potential means no signal is being transmitted. – more Na+ outside of cell – more K+ inside of cell • An action potential is a moving electrical impulse. – It is generated by a stimulus. – Na+ enters, and cell becomes positively charged. – K+ leaves, and area of positive charge moves. • A chemical signal passes between neurons. – Impulse reaches terminal. – Neurotransmitters released into synapse. – Neurotransmitters stimulate next cell. • There are three kinds of neurons. – **Sensory neurons** are part of the peripheral nervous system (PNS). These neurons detect stimuli and bring signals to the central nervous system (CNS). – **Interneurons** are found in the CNS. They transmit and process signals in the brain and spinal cord. – **Motor neurons** are those in the PNS that produce responses by taking messages from the CNS and bringing them to a muscle or organ.
 * The nervous system is composed of highly specialized cells**
 * Neurons receive and transmit signals.**

**__The Central nervous system and the Peripheral nervous system__** • The CNS includes the brain, brain stem, and spinal cord. • The PNS includes four systems of nerves. • The CNS and PNS pass signals between one another. • Sensory receptor generates impulse. • PNS passes impulse to CNS. • CNS interprets impulse. • CNS passes impulse to PNS. • PNS stimulates a response. • The brain has three parts. – cerebrum controls thought, movement, emotion – cerebellum allows for balance – brain stem controls basic life functions • The brain stem has three parts. – midbrain controls some reflexes – pons regulates breathing – medulla oblongata controls heart function, swallowing, coughing • The spinal cord controls reflexes. – sensory neuron sends impulse to spinal cord – spinal cord directs impulse to motor neuron – does not involve the brain **The PNS links the CNS to muscles and other organs.** • The somatic nervous system regulates voluntary movements. • The autonomic nervous system controls involuntary, functions • sympathetic nervous system: “fight vs. flight” • parasympathetic nervous system: calms the body, conserves energy
 * The central nervous system interprets information, and the peripheral nervous system gathers and transmits information.**
 * The nervous system’s two parts work together**
 * The CNS processes information.**

OTHER LINKS: [|what neurons looks like] [|what make neuron different] [|in depth of how nervous system works] [|the CNS and PNS]

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Abishek. "Difference Between CNS and PNS | Difference Between | CNS vs PNS." //Difference Between Similar Terms and Objects//. Web. 15 May 2011. . =====