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Published byClifford Haynes Modified over 9 years ago
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Introduction to Physiology
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The Six Levels of Organization Chemical level –Atoms Cell Level Tissue Level –A tissue is a group of similar cells and the materials surrounding them
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Organ Level –An organ is composed of 2+ tissue types that perform the same functions Organ System Level –Organ system is a group of organs that have a common function (11 major organ systems) Organism Level
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Homeostasis Existence and maintenance of a constant internal environment Mechanisms keep body temperature near an ideal normal range called set points. –The points need to remain in a normal range.
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Negative Feedback Negative means that any deviation from the set point is made smaller or resisted Regulates most body systems There are three components –Receptor –Control center –Effector
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Receptor Monitors the value of some variables Detects changes and sends message to the brain Example: Blood pressure
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Control Center Establishes the set points around which the variable is maintained Receives messages and tells body how to react
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Effector Can change the value of the variable Example: Sweat, raise/lower blood pressure
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Positive Feedback Rare Creates a deviation further from the normal set point Example: Natural birth
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Body Positions Anatomical position –Face directed forward –Upper limbs hanging to the side, palms facing forward Supine –A person lying face upwards Prone –A person lying face downwards
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Directional terms of the trunk Superior = Cephalic –Up, towards the head Inferior = Caudal –Down, towards the “tail” Posterior =Dorsal –Back side Anterior = Ventral –Front, belly side
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Directional terms of the trunk Medial –Towards the midline Lateral –Away from the midline
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Directional terms of the limbs Proximal –Nearest the point of attachment Distal –Furthest from the point of attachment
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Planes Sagittal –Separates a body into a left and right –Midsagittal/Median Separates body into equal left and right halves –Parasagittal Unequally divides left and right sides
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Transverse = Horizontal –Horizontally divides body into superior and inferior portions (top and bottom) Frontal = Coronal –Vertically divides body into anterior and posterior portions (front and back) –Face remains intact
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Body Cavities The trunk contains 3 large cavities: –Thoracic Surrounded by rib cage Partition called the mediastinum separates left and right parts Mediastinum contains the heart, thymus, trachea, esophagus
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Abdominal cavity –Contains most of the digestive tract Pelvic cavity –Located within the pelvic bones
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The pelvic and abdominal cavities are not physically separated and are sometimes called the abdominopelvic cavity
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Serous Membranes Membrane that lines trunk cavities and organs Serous membranes are made of 2 layers: –Visceral serous is in contact with internal organs –Parietal serous lines the walls of the cavity
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The thoracic cavity contains 3 serous membrane – lined cavities: –1 Pericardial cavity –2 Pleural cavities
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The Pericardial Cavity Surrounds the heart The visceral pericardium touches and covers the surface of the heart, which is contained within the parietal pericardium.
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The Pleural Cavities Surrounds each lung Each lung is covered by visceral pleura, which is contained within a parietal pleura.
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The Peritoneal Cavity Covers the abdominopelvic cavity Each organ is covered by a visceral peritoneum, which is located within the parietal peritoneum.
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