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Summary - The Human Body An Orientation (Ch1)
Introduction to Anatomy and Physiology I (University of Wollongong)
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CH 1: THE HUMAN BODY: AN ORIENTATION Anatomy and physiology Anatomy: the science of the morphology or structure of organisms (What and Where) How is anatomy studied? Gross anatomy: • Systemic anatomy • Regional anatomy • Surface anatomy • Functional anatomy Microscopic anatomy: • Histology • Developmental Physiology: concerns the function of the body and its quest to sustain life. Explainable only in terms of its underlying anatomy (How and Why) How is physiology studied? Cell: • Molecular physiology Systems physiology: • The ‘working’ system • Regulation and control • Integration between systems PRINCIPLE OF COMPLEMENTARILY OF STRUCTURE AND FUNCTION Maintaining life Necessary life functions: • Maintaining boundaries – keeping internal environment separate from external environment • Movement • Responsiveness – ability to sense changes • Digestion • Metabolism – all chemical reactions that occur within the body cells • Excretion – removing waste • Reproduction – cellular (body growth and repair) and organismal (having a baby) • Growth Survival needs (must be in appropriate amounts): • Nutrients – chemical substances used for energy and cell building • Oxygen • Water – accounts for 60-­‐80% of our body weight • Normal body temperature -­‐ 37°C • Appropriate atmospheric pressure – the force that air exerts on the surface of the body SHS111 Anatomy & Physiology I -­‐ 1 Distributing prohibited | Downloaded by Humaira Patel (homaira.patel7786@gmail.com)
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Homeostasis – maintaining stable internal conditions th
Walter Cannon (20 century) ‘a dynamic state of equilibrium, or balance, in which internal conditions vary, but always kept within a relatively narrow limit’ Three components: 1. Receptor – monitors the environment & responds to changes by sending info to control centre 2. Control centre – determines the appropriate response 3. Effector – results of the response then fee back to influence the effect of the stimulus, either reducing it (in negative feedback) or enhancing it (in positive feedback) so that the whole process continues at an even faster rate Negative feedback mechanisms: • Most homeostatic control mechanisms are negative feedback mechanisms – the output shuts off the original effect of the stimulus or reduces its intensity • Cause the variable to change in a direction opposite to that of the initial change, returning it to its ideal value • GOAL: prevent sudden severe changes within the body (eg. Regulating blood volume and body temperature)\ • Eg. When blood volume decreases, receptors in the body sense this change and the hypothalamus of the brain (the control centre) stimulates the release of ADH (hormone that controls blood volume) to the blood. This change prompts the kidneys to reabsorb more water and return it to the bloodstream SHS111 Anatomy & Physiology I -­‐ 2 Distributing prohibited | Downloaded by Humaira Patel (homaira.patel7786@gmail.com)
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Positive feedback mechanisms: • The result or response enhances the original stimulus so that the response is accelerated • The change that results proceeds in the same direction as the initial change • Normally control infrequent events that do not require continuous adjustments • E.g. Enhancement of labor contractions during birth à oxytocin (a hypothalamic hormone) intensifies labor contractions during the birth of a baby, oxytocins causes the contractions to become more frequent and more powerful. The increased contractions causes more oxytocins to be released until the baby is finally born • Eg. Blood clotting Homeostatic imbalance: • Most disease can be regarded as a result of disturbance to homeostasis • As we age our body’s control systems become less efficient and our internal environment becomes less and less stable SHS111 Anatomy & Physiology I -­‐ 3 Distributing prohibited | Downloaded by Humaira Patel (homaira.patel7786@gmail.com)
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The Language of Anatomy Anatomical position: • standard body position that provides a reference point to accurately describe body parts and position • body erect, feet slightly apart, palms facing forward, thumbs pointing away from the body Directional terms: Supine: lying on the back, face upward Prone: lying face downward SHS111 Anatomy & Physiology I -­‐ 4 Distributing prohibited | Downloaded by Humaira Patel (homaira.patel7786@gmail.com)
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Regional terms Axial: main axis of our body – includes the skull, vertebral column, sternum, ribs Appendicular: includes all limbs and pelvis Body Planes Sagittal plane: vertical plane that divides body into left and right parts (a sagittal plane that lies exactly in the midline is the median plane, or midsagittal plane. All other planes, offset from the midline, are parasagittal planes) Transverse plane: runs horizontally from left to right, dividing the body into superior and inferior parts Coronal plane: (or frontal plane) divides the body into anterior and posterior parts Body Cavities Dorsal body cavity: à Cranial cavity à Vertebral cavity Ventral body cavity: (houses the visceral organs. Body cavities are separated by the diaphragm) à Thoracic cavity à Abdominopelvic cavity SHS111 Anatomy & Physiology I -­‐ 5 Distributing prohibited | Downloaded by Humaira Patel (homaira.patel7786@gmail.com)