The Nervous System The nervous system is the major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory. Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis. Through its receptors, the nervous system keeps us in touch with our environment, both external and internal. Like other systems in the body, the nervous system is composed of organs, principally the brain, spinal cord, nerves, and ganglia. These, in turn, consist of various tissues, including nerve, blood, and connective tissue. Together these carry out the complex activities of the nervous system. The various activities of the nervous system can be grouped together as three general, overlapping functions: 1. Sensory 2. Integrative 3. Motor Millions of sensory receptors detect changes, called stimuli, which occur inside and outside the body. They monitor such things as temperature,...

The following headings are discussed. 1. Cardiac cycle  2. Cardiac output 3. Stroke volume  4. Heart rate  5. Blood pressure  6. Blood and it's components  7. Classification of blood (ABO and Rhesus) 8. Diseases of circulatory system  1. Cardiac Cycle The cardiac cycle refers to the sequence of events that occur during one complete heartbeat. It involves the coordinated contraction (systole) and relaxation (diastole) of the atria and ventricles, resulting in the pumping of blood throughout the body. Phases are:    Diastole (Relaxation and Filling): The heart chambers are relaxed, and blood flows from the atria into the ventricles. This is the longer phase, allowing the ventricles to fill adequately.    Systole (Contraction and Ejection): The ventricles contract, forcing blood into the pulmonary artery (from the right ventricle) and the aorta (from the left ventricle). 2. Cardiac Output (CO) Cardiac output is how many liters of blood your...

When the respiratory system is mentioned, people generally think of breathing, but breathing is only one of the activities of the respiratory system. The body cells need a continuous supply of oxygen for the metabolic processes that are necessary to maintain life. The respiratory system works with the circulatory system to provide this oxygen and to remove the waste products of metabolism. It also helps to regulate pH of the blood. Respiration is the sequence of events that results in the exchange of oxygen and carbon dioxide between the atmosphere and the body cells. Every 3 to 5 seconds, nerve impulses stimulate the breathing process, or ventilation, which moves air through a series of passages into and out of the lungs. After this, there is an exchange of gases between the lungs and the blood. This is called external respiration. The blood transports the gases to and from the tissue cells. The exchange of gases between the blood and tissue cells is internal respiration. Finally, the...

INTRODUCTION TO THE DIGESTIVE SYSTEM The digestive system includes the digestive tract and its accessory organs, which process food into molecules that can be absorbed and utilized by the cells of the body. Food is broken down, bit by bit, until the molecules are small enough to be absorbed and the waste products are eliminated. The digestive tract, also called the alimentary canal or gastrointestinal (GI) tract, consists of a long continuous tube that extends from the mouth to the anus. It includes the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. The tongue and teeth are accessory structures located in the mouth. The salivary glands, liver, gallbladder, and pancreas are major accessory organs that have a role in digestion. These organs secrete fluids into the digestive tract. Food undergoes three types of processes in the body: Digestion Absorption Elimination Digestion and absorption occur in the digestive tract. After the nutrients are absorbed,...