Human Anatomy and Physiology Eleventh Edition PDF

Human Anatomy and Physiology Eleventh Edition Chapter 01 Part A The Human Body: An Orientation PowerPoint® Lectures...

Human Anatomy and Physiology Eleventh Edition Chapter 01 Part A The Human Body: An Orientation PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community College Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Why This Matters Learning and understanding anatomical terminology allows you to communicate accurately with your colleagues in the health sciences. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Video: Why This Matters (Career Connection) Click here to view ADA compliant video: Why This Matters (Career Connection) https://mediaplayer.pearsoncmg.com/assets/mAfsrO_a_405TaZ2RUqVuzYBT67WACS6 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 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 life-sustaining activities Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Topics of Anatomy (1 of 2) 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) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Topics of Anatomy (2 of 2) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Topics of Physiology Subdivisions of physiology – Based on organ systems (e.g., renal or cardiovascular physiology) – 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Complementarity of Structure and Function (1 of 2) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Complementarity of Structure and Function (2 of 2) The sharp edges of incisors The flat surfaces of molars (structure) (structure) make them ideal for make them ideal for grinding, like a cutting like scissors (function). mortar and pestle (function). Figure 1.1 Complementarity of structure and function. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (1 of 7) Atoms Molecules Organelle Smooth muscle cell Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Smooth muscle tissue Cardiovascular system Tissue level Tissues consist of similar types of cells. Heart Blood vessels Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelial tissue Organ level Organs are made up of different types of tissues. Organismal level Organ system level The human organism is made up of many organ Organ systems consist of different systems. organs that work together closely. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (2 of 7) Atoms Molecules Chemical level Atoms combine to form molecules. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (3 of 7) Atoms Molecules Organelle Smooth muscle cell Chemical level Cellular level Atoms combine to form molecules. Cells are made up of molecules. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (4 of 7) Atoms Molecules Organelle Smooth muscle cell Chemical level Cellular level Atoms combine to form molecules. Cells are made up of molecules. Smooth muscle tissue Tissue level Tissues consist of similar types of cells. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (5 of 7) Atoms Molecules Organelle Smooth muscle cell Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Smooth muscle tissue Tissue level Tissues consist of similar types of cells. Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelial tissue Organ level Organs are made up of different types of tissues. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (6 of 7) Atoms Molecules Organelle Smooth muscle cell Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Smooth muscle tissue Cardiovascular system Tissue level Tissues consist of similar types of cells. Heart Blood vessels Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelial tissue Organ level Organs are made up of different types of tissues. Organ system level Organ systems consist of different organs that work together closely. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Levels of Structural Organization (7 of 7) Atoms Molecules Organelle Smooth muscle cell Chemical level Atoms combine to form molecules. Cellular level Cells are made up of molecules. Smooth muscle tissue Cardiovascular system Tissue level Tissues consist of similar types of cells. Heart Blood vessels Blood vessel (organ) Smooth muscle tissue Connective tissue Epithelial tissue Organ level Organs are made up of different types of tissues. Organismal level Organ system level The human organism is made up of many organ Organ systems consist of different systems. organs that work together closely. Figure 1.2 Levels of structural organization. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 1.3 Requirements for Life Necessary Life Functions Maintenance of life involves: – Maintaining boundaries – Movement – Responsiveness – Digestion – Metabolism – Excretion – Reproduction – Growth Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Necessary Life Functions (1 of 5) Maintaining boundaries – Separation between internal and external environments must exist  Plasma membranes separate cells  Skin separates organism from environment Movement – 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Necessary Life Functions (2 of 5) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Necessary Life Functions (3 of 5) 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) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Necessary Life Functions (4 of 5) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Necessary Life Functions (5 of 5) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Examples of Interrelationships Among Body Organ Systems Digestive system Takes in nutrients, breaks them Respiratory system down, and eliminates unabsorbed Takes in oxygen and matter (feces) eliminates carbon dioxide Food O2 CO2 Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Blood CO2 O2 Urinary system Heart Eliminates Nutrients nitrogenous wastes and Interstitial fluid excess ions Figure 1.3 Examples of interrelationships Nutrients and wastes pass among body organ between blood plasma and systems. cells via the interstitial fluid Integumentary system Feces Protects the body as a whole Urine from the external environment Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (1 of 12) Hair Skin Nails (a) Integumentary System Forms the external body covering, and protects deeper tissues from injury. Synthesizes vitamin D, and houses cutaneous (pain, pressure, etc.) receptors, and sweat and oil glands. Figure 1.4a The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (2 of 12) Bones Joint (b) Skeletal System Protects and supports body organs, and provides a framework the muscles use to cause movement. Blood cells are formed within bones. Bones store minerals. Figure 1.4b The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (3 of 12) Skeletal muscles (c) Muscular System Allows manipulation of the environment, locomotion, and facial expression. Maintains posture, and produces heat. Figure 1.4c The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (4 of 12) Brain Nerves Spinal cord (d) Nervous System As the fast-acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands. Figure 1.4d The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (5 of 12) Pineal gland Thyroid Pituitary gland gland Thymus Adrenal gland Pancreas Testis Ovary (e) Endocrine System Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells. Figure 1.4e The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (6 of 12) Heart Blood vessels (f) Cardiovascular System Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood. Figure 1.4f The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (7 of 12) Red bone marrow Thymus Lymphatic vessels Thoracic duct Spleen Lymph nodes (g) Lymphatic System/Immunity Picks up fluid leaked from blood vessels and returns it to blood. Disposes of debris in the lymphatic stream. Houses white blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against foreign substances within the body. Figure 1.4g The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (8 of 12) Nasal cavity Pharynx Bronchus Larynx Trachea Lung (h) Respiratory System Keeps blood constantly supplied with oxygen and removes carbon dioxide. These exchanges occur through the walls of the air sacs of the lungs. Figure 1.4h The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (9 of 12) Oral cavity Esophagus Liver Stomach Small intestine Large intestine Rectum Anus (i) Digestive System Breaks down food into absorbable units that enter the blood for distribution to body cells. Indigestible foodstuffs are eliminated as feces. Figure 1.4i The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (10 of 12) Kidney Ureter Urinary bladder Urethra (j) Urinary System Eliminates nitrogenous wastes from the body. Regulates water, electrolyte, and acid-base balance of the blood. Figure 1.4j The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (11 of 12) Prostate Penis Ductus Testis deferens Scrotum (k) Male Reproductive System Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. Figure 1.4k The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved The Body’s Organ Systems and Their Major Functions (12 of 12) Mammary glands (in breasts) Ovary Uterine Uterus tube Vagina (l) Female Reproductive System Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. Figure 1.4l The body’s organ systems and their major functions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Survival Needs (1 of 3) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Survival Needs (2 of 3) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Survival Needs (3 of 3) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Homeostatic Controls (1 of 6) 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, blood volume, etc.) Homeostatic control of variables involves three components: receptor, control center, and effector Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Homeostatic Controls (2 of 6) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Homeostatic Controls (3 of 6) Effector – Receives output from control center – Provides the means to respond – Response either reduces stimulus (negative feedback) or enhances stimulus (positive feedback) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Homeostatic Controls (4 of 6) 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) Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Homeostatic Controls (5 of 6) 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Figure Animation: Homeostasisi and Negative Feedback Mechanisms Click here to view ADA compliant Animation: Homeostasisi and Negative Feedback Mechanisms https://mediaplayer.pearsoncmg.com/assets/sci-ap-homeostasis-and-negative-feedback-mechanisms Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Interactions Among the Elements of a Homeostatic Control System Maintain Stable Internal Conditions (1 of 6) 3 Input: Information 4 Output: Information sent along afferent Control sent along efferent pathway to control Center pathway to effector. center. Afferent Efferent pathway pathway Receptor Effector 2 Receptor detects change. 5 Response of effector feeds back to reduce IMB A LA the effect of 1 Stimulus NC E stimulus and produces returns variable change in BALANCE to homeostatic variable. level. IMB AL AN CE Figure 1.5 Interactions among the elements of a homeostatic control system maintain stable internal conditions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Interactions Among the Elements of a Homeostatic Control System Maintain Stable Internal Conditions (2 of 6) IM BA 11 Stimulus LA NC produces E change in variable. BALANCE IM BA LA NC E Figure 1.5 Interactions among the elements of a homeostatic control system maintain stable internal conditions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Interactions Among the Elements of a Homeostatic Control System Maintain Stable Internal Conditions (3 of 6) Receptor 2 Receptor detects change. IM BA 11 Stimulus L AN produces CE change in variable. BALANCE IM BA LA NC E Figure 1.5 Interactions among the elements of a homeostatic control system maintain stable internal conditions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Interactions Among the Elements of a Homeostatic Control System Maintain Stable Internal Conditions (4 of 6) 3 Input: Information sent along afferent Control pathway to control Center center. Afferent pathway Receptor 2 Receptor detects change. IM BA 11 Stimulus L AN CE produces change in variable. BALANCE IM BA LA NC E Figure 1.5 Interactions among the elements of a homeostatic control system maintain stable internal conditions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Interactions Among the Elements of a Homeostatic Control System Maintain Stable Internal Conditions (5 of 6) 3 Input: Information 4 Output: Information sent along afferent Control sent along efferent pathway to control Center pathway to effector. center. Efferent Afferent pathway pathway Receptor Effector 2 Receptor detects change. IM BA L AN 11 Stimulus CE produces change in BALANCE variable. IM BA LA NC E Figure 1.5 Interactions among the elements of a homeostatic control system maintain stable internal conditions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Interactions Among the Elements of a Homeostatic Control System Maintain Stable Internal Conditions (6 of 6) 3 Input: Information 4 Output: Information sent along afferent Control sent along efferent pathway to control Center pathway to effector. center. Efferent Afferent pathway pathway Receptor Effector 2 Receptor 5 Response detects change. of effector feeds IM back to reduce BA the effect of L AN 11 Stimulus CE stimulus and produces returns variable change in to homeostatic BALANCE level. variable. IM BA LA NC E Figure 1.5 Interactions among the elements of a homeostatic control system maintain stable internal conditions. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Body Temperature is Regulated by a Negative Feedback Mechanism Control Center (thermoregulatory center in brain) Afferent Efferent pathway pathway Receptors Temperature-sensitive Effectors cells in skin and brain Sweat glands Sweat glands activated Body temperature IMB Response rises ALA NC Evaporation of sweat E Body temperature falls; Stimulus: Heat BALANCE stimulus ends Stimulus: Cold IMB Response ALA Body temperature rises; NC Body temperature E falls stimulus ends Effectors Receptors Skeletal muscles Temperature-sensitive cells in skin and brain Efferent Afferent pathway pathway Shivering begins Control Center (thermoregulatory center in brain) Figure 1.6 Body temperature is regulated by a negative feedback mechanism. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Homeostatic Controls (6 of 6) Positive feedback – Response enhances or exaggerates the original stimulus – May exhibit a cascade or amplifying effect as feedback causes variable 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved A Positive Feedback Mechanism Regulates Formation of a Platelet Plug (1 of 5) 1 Break or tear occurs in blood vessel wall. Positive feedback cycle is initiated. 3 Released 2 Platelets chemicals Positive adhere to site attract more feedback and release platelets. loop chemicals. Feedback cycle ends when plug is formed. 44 Platelet plug is fully formed. Figure 1.7 A positive feedback mechanism regulates formation of a platelet plug. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved A Positive Feedback Mechanism Regulates Formation of a Platelet Plug (2 of 5) 1 Break or tear occurs in blood vessel wall. Positive feedback cycle is initiated. Figure 1.7 A positive feedback mechanism regulates formation of a platelet plug. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved A Positive Feedback Mechanism Regulates Formation of a Platelet Plug (3 of 5) 1 Break or tear occurs in blood vessel wall. Positive feedback cycle is initiated. 2 Platelets adhere to site and release chemicals. Figure 1.7 A positive feedback mechanism regulates formation of a platelet plug. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved A Positive Feedback Mechanism Regulates Formation of a Platelet Plug (4 of 5) 1 Break or tear occurs in blood vessel wall. Positive feedback cycle is initiated. 3 Released 2 Platelets chemicals adhere to site Positive attract more and release feedback platelets. chemicals. loop Figure 1.7 A positive feedback mechanism regulates formation of a platelet plug. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved A Positive Feedback Mechanism Regulates Formation of a Platelet Plug (5 of 5) 1 Break or tear occurs in blood vessel wall. Positive feedback cycle is initiated. 3 Released 2 Platelets chemicals adhere to site Positive attract more and release feedback platelets. chemicals. loop Feedback cycle ends when plug is formed. 44 Platelet plug is fully formed. Figure 1.7 A positive feedback mechanism regulates formation of a platelet plug. Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved 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 Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved Copyright Copyright © 2019, 2016, 2013 Pearson Education, Inc. All Rights Reserved