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I ntroduction to the Endocrine System The endocrine system refers to the hormone system of the body.  H ormones are chemicals produced by living cells in very very small amounts. They are transported around the body in the blood. Hormones regulate and co-ordinate different organs in the body. Click on the picture for a large detailed image of the endocrine system. ........  Hormones are classified into two groups Peptides Made of proteins Fast acting Short – lived E.g. Insulin and ADH Steroids Slow acting Long lasting Usually end in “one” E.g. Testosterone and Progesterone. Hormones control themselves by a means of feedback control. Feedback control basically means that when the hormone is in large supply, the gland stops making it. When the level of hormone is low, the gland secretes the hormone until the level rises again. . ...

What is the cardiac cycle. The cardiac cycle is the sequence of events that occur when the heart beats. There are two phases of this cycle: Diastole - Ventricles are relaxed. Systole - Ventricles contrac t   . .......... Exercise increases blood flow through the heart so that the cardiac cycle accelerates to accommodate the increased demand for oxygen. The normal cycle is around 0.8 seconds. This accelerates with faster and more powerful atrial and ventricular contraction, which is stimulated by the cardiac centre in the brain. Heart rate:- is defined as the number of heart contractions in each minute. #  There are two distinct periods in the cardiac cycle- one of the heart muscle relaxation (cardiac diastole), the other of contraction (cardiac systole) During cardiac diastole • The bicuspid and tricuspid valves are closed and the atrium is full. • Once full with blood, the atria forces the bicuspid and tricuspid valves to open and fill the ven...

The endocrine system  is comprised of glands. Glands are -  Group of specialized cells that produce secretions Exocrine glands:  Secrete through a duct Endocrine glands:  Ductless, secrete hormones directly into blood stream   Hormones:   Regulate activities of cells and other organs     Target tissue:  Specific tissue acted upon by a hormone   Some endocrine glands: 1.  Pituitary 2.  Thyroid 3.  Parathyroid 4.  Adrenal 5.  Pancreas 6.  Gonads Source:  http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endocrines.gif Pituitary gland:  Master Gland; it releases hormones that effect the function of other glands; controlled by hypothalamus         Anterior pituitary:  also called adenohypophysis         produces:             1. (HGH) -  Human...

A. The Heart     1. Has 4 chambers         a.  Right Atrium         b.  Left Atrium         c.  Right Ventricle         d.  Left Ventricle     2. Made up of   cardiac   muscle             Heart walls have 3 layers:             a.  epicardium             b.  myocardium             c.  endocardium     3. Myocardium: mass of cells connected by  gap junctions         a. this means that an  action potential   originating anywhere in a myocardium will always be transmitted to all cel...

The Study of Body Function Download Chemical Composition of the Body Download Cell Structure and Genetic Control Download Enzymes and Energy Download Cell Respiration and Metabolism Download Interactions Between Cells and the Extracellular Environment Download The Nervous System: Neurons and Synapses Download The Central Nervous System Download The Autonomic Nervous System Download Sensory Physiology Download Endocrine Glands: Secretion and Action of Hormones Download Muscle: Mechanisms of Contraction and Neural Control Download Heart and Circulation Download Cardiac Output, Bloodflow, and Blood Pressure Download The Immune System Download Respiratory Physiology Download Physiology of the Kidneys Download The Digestive System Download Regulation of Metabolism Download Reproduction Download