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Internal Organs Structure & Function Heart & Respiratory System Heart: -Located in the left center of the chest, below the ribcage & sternum, between lungs. -Size of a clenched fist Heart: A muscular organ Consists of 4 chambers: right & left atria and right & left ventricle Each chamber is separated by a valve to prevent blood from flowing the wrong way Primary Function: Circulates oxygenated blood throughout the body to the working tissues A single heartbeat consists of contraction of both atria followed by contraction of both ventricles Path of blood flow: Right side pumps blood to lungs to become oxygenated blood Left side pumps blood to the rest of the body Back from body -- into Right Atrium- into Right Ventricle - To the Lungs-- Back to the Left Atrium- To the rest of the body! Conduction System Specialized electrical conduction system controls the contraction of the heart Called the Purkinje Fibers Electrocardiogram P wave : atrial depolarization (contraction) QRS Complex : ventricle depolarization / contraction T wave : ventricle repolarization Key Terms Bradycardia : fewer than 60 beats per minute Tachycardia : greater than 100 beats per minute Stroke Volume (SV): amount of blood ejected with each beat Cardiac Output : the volume of blood ejected per minute from the heart Cardiac output = SV x HR Artherosclerosis : excessive build up of cholesterol in the heart arteries, which blocks blood flow Maximal Heart Rate : 220 – (a person’s age in years)= max. heart rate Lungs: -Located within the ribcage; 2 sides (or lobes), made of elastic tissue Lungs: Deliver oxygenated blood to the tissues of the body through gas exchange! Oxygen to Carbon Dioxide Oxygenation of blood 2 lungs sitting in thoracic cavity Under rib cage, anterior to the heart Weigh approximately 1 kg Volume : 4-6 Liters of air Huge surface area If spread out, lung tissues would cover half of a tennis court Highly vascularized area Respiratory Pathway Mouth or Nose Bronchioles Alveoli Trachea Bronchi Lungs Alveoli Lungs contain more than 300 million alveoli. Thin-walled, membranous sacs Receive largest blood supply of all organs! Alveoli Alveoli Millions of thin-walled capillaries (blood) and alveoli (air) lie side by side Gas diffuses across the thin barrier Exercise Exercise increases the total lung capacity Better shape = more efficient gas exchange Max VO2 = maximal oxygen consumption The region where oxygen consumption plateaus during exercise Measures a person’s aerobic fitness The Lymphatic / Immune System How the Body Fights Against Disease The Network of Channels The System Network of channels with specialized tissues and organs Lymph organs : spleen, tonsils, & thymus Lymph nodes The Channels The vessels are very low in pressure Connect lymph nodes and the organs About 3 Liters of lymph enter the blood stream every 24 hours The Warriors Lymphocytes are created in red blood cells Protect the body against foreign substances Macrophages help the immune system by gobbling up foreign substances and activate the lymphocytes Lymph Nodes Clusters of the lymphatic channels Filters lymph as it heads to the bloodstream Activates the Immune system if needed! Lymphoid Organs Thymus : early years, secretes hormones to fight against certain diseases Tonsils : “invite” infections in to trap the bacteria The Spleen: -Largest Lymph organ in the body -Located under the diaphragm on the left side The Spleen: Resevoir for Red Blood Cells Regulates number of Red Blood Cells in Circulation Destroys ineffective Red Blood Cells Produces antibodies & Lymphocytes Cleans blood and is on immune system surveillance Digestive Organs Digestive Organs: Stomach Small Intestines Large Intestines Pancreas Liver Gallbladder Stomach: -Found in left quadrant, between esophagus and small intestines Stomach: Storage and mixing chamber for ingested food Some digestion & absorption occur here Gastric secretions assist in the partial digestion of proteins and alcohol & caffeine Food is mixed with secretions from stomach glands to form Chyme, which then passes into the small intestines Small Intestines: -Found between the stomach and large intestines -3 Portions: Duodenum, Jejunum, & Ileum -20 feet in length Small Intestines: Chyme mixes with secretions from the liver & pancreas Chyme moves through the small intestines over a period of 3-5 hours, propelled by peristaltic contractions Most digestion and absorption occurs in the small intestines Large Intestines: -Connected to the small intestines -3 divisions: Cecum, Colon, & Rectum -6 ½ feet long Large Intestines: Chyme is converted into feces through the absorption of water, secretion of mucus, & activity of microorganisms Pancreas: -Located between small intestines & the Spleen Pancreas: Secretes Pancreatic juice, critical in digestion of protiens, fats, & carbohydrates Produces insulin and glucagon, controls the amount of sugar & amino acids in the blood Liver: -Largest internal organ in the body -Found in upper right quadrant, underneath the diaphragm -Weighs about 3 pounds Liver: Consists of 2 lobes Performs digestive & excretory functions Absorbs & stores excessive glucose Processes nutrients Detoxifies harmful chemicals Secretes bile, essential in neutralizing & diluting stomach acid and digesting fat Gallbladder: -Pear-shaped, saclike structure found underneath the liver Gallbladder: Storage reservoir for bile secreted by the liver Secretes stored bile into the small intestines after a meal The Urinary System Kidneys: -Situated on either side of the spine, in center of the back Kidneys: Primary function is to filter metabolic wastes, ions, or drugs from blood and expel them from the body via urination Bladder: -Hollow organ, lies posteriorly to the Pubic Symphysis Bladder: Stores Urine