CH. 1A The Human Body: An Orientation Lecture Notes PDF

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CH. 1A The Human Body: An Orientation Lecture Notes...

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Chapter 1 – Part A The Human Body: An Orientation Why This Matters • Learning and understanding anatomical terminology allows you to communicate accurately with your colleagues in the health sciences. 1.1 Form and Function of Anatomy & Physiology • Anatomy • Study of the structure of body parts and their relationship to one another • Physiology • Study of the function of body parts; how they work to carry out lifesustaining activities

Topics of Anatomy • Subdivisions of anatomy: • Gross or macroscopic anatomy is the study of large, visible structures • Regional anatomy looks at all structures in a particular area of the body • System anatomy looks at just one system (cardiovascular, nervous, muscular, etc.) • Surface anatomy looks at internal structures as they relate to overlying skin (visible muscle masses or veins seen on surface) Topics of Anatomy (cont.) • Subdivisions (cont.) • Microscopic anatomy deals with structures too small to be seen by naked eye • Cytology: microscopic study of cells • Histology: microscopic study of tissues • Developmental anatomy studies anatomical and physiological development throughout life • Embryology: study of developments before birth • To study anatomy, one must know anatomical terminology and be able to observe, manipulate, palpate, and auscultate

Topics of Physiology • Subdivisions of physiology • Based on organ systems (e.g., renal or cardiovascular physiology) © 2016 Pearson Education, Inc.

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Often focuses on cellular and molecular levels of the body Looks at how the body’s abilities are dependent on chemical reactions in individual cells To study physiology, one must understand basic physical principles (e.g., electrical currents, pressure, and movement) as well as basic chemical principles

Complementarity of Structure and Function • Anatomy and physiology are inseparable • Function always reflects structure • What a structure can do depends on its specific form • Known as the principle of complementarity of structure and function 1.2 Structural Organization • Human body is very organized, from the smallest chemical level to whole organism level: • Chemical level: atoms, molecules, and organelles • Cellular level: single cell • Tissue level: groups of similar cells • Organ level: contains two or more types of tissues • Organ system level: organs that work closely together • Organismal level: all organ systems combined to make the whole organism 1.3 Requirements for Life Necessary Life Functions • Maintenance of life involves: • Maintaining boundaries • Movement • Responsiveness • Digestion • Metabolism • Excretion • Reproduction • Growth Necessary Life Functions • Maintaining boundaries • Separation between internal and external environments must exist • Plasma membranes separate cells • Skin separates organism from environment • Movement © 2016 Pearson Education, Inc.

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Muscular system allows movement Of body parts via skeletal muscles Of substances via cardiac muscle (blood) and smooth muscle (digestion, urination) Contractility refers to movement at the cellular level

Necessary Life Functions (cont.) • Responsiveness • Ability to sense and respond to stimuli • Withdrawal reflex prevents injury • Control of breathing rate, which must change in response to different activities • Digestion • Breakdown of ingested foodstuffs, followed by absorption of simple molecules into blood

Necessary Life Functions (cont.) • Metabolism • All chemical reactions that occur in body cells • Sum of all catabolism (breakdown of molecules) and anabolism (synthesis of molecules) • Excretion • Removal of wastes from metabolism and digestion • Urea (from breakdown of proteins), carbon dioxide (from metabolism), feces (unabsorbed foods)

Necessary Life Functions (cont.) • Reproduction • At the cellular level, reproduction involves division of cells for growth or repair • At the organismal level, reproduction is the production of offspring • Growth • Increase in size of a body part or of organism

Necessary Life Functions (cont.) • Humans are multicellular, so to function, individual cells must be kept alive • Organ systems are designed to service the cells • All cells depend on organ systems to meet their survival needs • There are 11 organ systems that work together to maintain life Survival Needs © 2016 Pearson Education, Inc.

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Humans need several factors for survival that must be in the appropriate amounts; too much or too little can be harmful: • Nutrients • Oxygen • Water • Normal body temperature • Appropriate atmospheric pressure

Survival Needs (cont.) • Nutrients • Chemicals for energy and cell building • Carbohydrates: major source of energy • Proteins: needed for cell building and cell chemistry • Fats: long-term energy storage • Minerals and vitamins: involved in chemical reactions as well as for structural purposes • Oxygen • Essential for release of energy from foods • The body can survive only a few minutes without oxygen Survival Needs (cont.) • Water • Most abundant chemical in body; provides the watery environment needed for chemical reactions • Also is fluid base for secretions and excretions • Normal body temperature • If body temp falls below or goes above 37°C, rates of chemical reactions are affected • Appropriate atmospheric pressure • Specific pressure of air is needed for adequate breathing and gas exchange in lungs 1.4 Homeostasis • Homeostasis is the maintenance of relatively stable internal conditions despite continuous changes in environment • A dynamic state of equilibrium, always readjusting as needed • Maintained by contributions of all organ systems Homeostatic Controls • Body must constantly be monitored and regulated to maintain homeostasis • Nervous and endocrine systems, as well as other systems, play a major role in maintaining homeostasis • Variables are factors that can change (blood sugar, body temperature, © 2016 Pearson Education, Inc.

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blood volume, etc.) Homeostatic control of variables involves three components: receptor, control center, and effector

Homeostatic Controls (cont.) • Receptor (sensor) • Monitors environment • Responds to stimuli (things that cause changes in controlled variables) • Control center • Determines set point at which variable is maintained • Receives input from receptor • Determines appropriate response

Homeostatic Controls (cont.) • Effector • Receives output from control center • Provides the means to respond • Response either reduces stimulus (negative feedback) or enhances stimulus (positive feedback) Homeostatic Controls (cont.) • Negative feedback • Most-used feedback mechanism in body • Response reduces or shuts off original stimulus • Variable changes in opposite direction of initial change • Examples • Regulation of body temperature (a nervous system mechanism) • Regulation of blood glucose by insulin (an endocrine system mechanism) Homeostatic Controls (cont.) • Example of negative feedback: • Receptors sense increased blood glucose (blood sugar) • Pancreas (control center) secretes insulin into the blood • Insulin causes body cells (effectors) to absorb more glucose, which decreases blood glucose levels Homeostatic Controls (cont.) • Positive feedback • Response enhances or exaggerates the original stimulus • May exhibit a cascade or amplifying effect as feedback causes variable © 2016 Pearson Education, Inc.

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to continue in same direction as initial change Usually controls infrequent events that do not require continuous adjustment, for example: Enhancement of labor contractions by oxytocin Platelet plug formation and blood clotting

Homeostatic Imbalance • Disturbance of homeostasis • Increases risk of disease • Contributes to changes associated with aging • Control systems become less efficient • If negative feedback mechanisms become overwhelmed, destructive positive feedback mechanisms may take over • Heart failure

© 2016 Pearson Education, Inc.

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