AMA Anatomy & Physiology/Medical Terminology/Pathology 6 Nervous System

Nervous System Function: One of the most complex systems in the body. Contains more than 100 billion nerve cells. Coordinates all the activities of the human body both voluntarily or consciously and involuntarily or unconsciously. (Sight, taste, hearing, touch, speaking, moving muscles, thinking, breathing and the heart pumping blood and more). Function: One of the most complex systems in the body. Contains more than 100 billion nerve cells. Coordinates all the activities of the human body both voluntarily or consciously and involuntarily or unconsciously. (Sight, taste, hearing, touch, speaking, moving muscles, thinking, breathing and the heart pumping blood and more). Nervous impulses (the release of electrical energy), travel all over the body from external receptors (sense organs) to the brain, where they are interpreted, and are then sent back to the appropriate parts of the body. Nervous impulses (the release of electrical energy), travel all over the body from external receptors (sense organs) to the brain, where they are interpreted, and are then sent back to the appropriate parts of the body.

Structure of the Nervous System 2 major divisions: Central and Peripheral Central Nervous System: Brain: controls body activities; cerebrum controls thought; medulla oblongata in the brain stem controls involuntary such as respiratory, cardiac and vasomotor Brain: controls body activities; cerebrum controls thought; medulla oblongata in the brain stem controls involuntary such as respiratory, cardiac and vasomotor Spinal Cord: column of nervous tissue extending from the medulla oblongata to the lumbar area of the spinal cord (nerves go from here to all parts of the body) Spinal Cord: column of nervous tissue extending from the medulla oblongata to the lumbar area of the spinal cord (nerves go from here to all parts of the body)

Structure of the Nervous System continued: 2 major divisions: Central and Peripheral Peripheral Nervous System: Cranial Nerves: carry impulses between the brain and the head and neck (exception is the vagus nerve which carries messages to and from the neck, chest and abdomen); mainly voluntary Cranial Nerves: carry impulses between the brain and the head and neck (exception is the vagus nerve which carries messages to and from the neck, chest and abdomen); mainly voluntary Spinal Nerves: carry messages between the spinal cord and the chest, abdomen and extremities; mainly voluntary Spinal Nerves: carry messages between the spinal cord and the chest, abdomen and extremities; mainly voluntary Plexus: large networks of nerves in the peripheral nervous system Plexus: large networks of nerves in the peripheral nervous system

Structure of the Nervous System continued: Autonomous Nervous System: included in the peripheral nervous system, function involuntarily to control breathing, cardiovascular, digestion etc… Autonomous Nervous System: included in the peripheral nervous system, function involuntarily to control breathing, cardiovascular, digestion etc… Sensory (afferent) nerves carry messages toward the spinal cord and brain Sensory (afferent) nerves carry messages toward the spinal cord and brain Motor (efferent) nerves carry messages from the spinal cord and brain to muscles telling them how to respond Motor (efferent) nerves carry messages from the spinal cord and brain to muscles telling them how to respond Sympathetic Nerves: stimulate the body in times of stress and crisis by increasing heart rate, relax airways for more oxygen, stimulates adrenal gland to secrete adrenaline, inhibits digestion Sympathetic Nerves: stimulate the body in times of stress and crisis by increasing heart rate, relax airways for more oxygen, stimulates adrenal gland to secrete adrenaline, inhibits digestion Parasympathetic Nerves: act as a balance to sympathetic and restore homeostasis after crisis is over Parasympathetic Nerves: act as a balance to sympathetic and restore homeostasis after crisis is over