Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 7-1 Chapter 7 Pathophysiology

7-2 Objectives

Terminology Disease Pathology Pathophysiology 7-3

Cell Metabolism Anabolism Catabolism 7-4

Cellular Respiration Cellular respiration –The process whereby energy is released from molecules such as glucose and made available for use by the cells and tissues of the body. 7-5

Glycolysis 7-6

Anaerobic Metabolism 7-7

Aerobic Metabolism 7-8

Glucose Some of the glucose absorbed from the digestive system is used immediately Most is stored –As glycogen in muscle and the liver –As fat –Converted to fuel for energy later Insulin helps transport glucose from the blood into cells 7-9

Cell Reproduction Necessary for body growth, wound healing, and cell replacement Most cells reproduce as quickly as they die Some cells do not reproduce 7-10

Cell Reproduction Tumor (neoplasm) –Benign –Malignant Metastasis 7-11

Cellular Injury and Death Most diseases start with an injury to the cell. Cellular injury can occur if a cell is changed or damaged to the point that normal function is negatively affected or permanently impaired. 7-12

Cellular Injury and Death Free radicals –Highly reactive molecules –Byproduct of many normal cellular reactions within the body –Excessive number can damage cells and impair the body’s ability to fight illness –Antioxidants 7-13

Cellular Injury and Death Hypoxia –Lack of oxygen available to the tissues –Most common cause of cellular injury –Deprives the cell of oxygen and interferes with energy (ATP) production 7-14

Cellular Injury and Death Ischemia –Reduced blood supply –Most common cause of hypoxia –Prolonged ischemia results in cellular injury Infarct –Death of tissue due to ischemia 7-15

Factors Affecting Cell Function 7-16

Oxygenation and Ventilation Delivery of oxygen and removal of carbon dioxide Requires open airway Requires sufficient oxygen in surrounding air Requires adequate rate and depth of movement of thoracic cage 7-17

Perfusion –Circulation of blood through an organ or a part of the body 7-18

Factors Affecting Cell Function A blocked airway, or an injury or disease that affects oxygenation or ventilation, can lead to –Hypoxia (lack of oxygen) and/or –Hypercarbia (increase in carbon dioxide). 7-19

Factors Affecting Cell Function Cell metabolism can be disrupted if there is inadequate oxygen in the air that is breathed in Possible causes –Low oxygen environment –Toxic gases –Lung infection –Infection or disease that narrows the airway and causes wheezing –Excess fluid in the lungs –Excess fluid between the lungs and blood –Poor circulation 7-20

Factors Affecting Cell Function If rate or depth of breathing is not adequate, an insufficient volume of air will be moved into and out of the lungs Tidal volume Minute volume Possible causes of an inadequate rate or depth of breathing 7-21

Cardiac Output Cardiac output –The amount of blood the heart pumps each minute –Determined by multiplying stroke volume by heart rate Stroke volume –The amount of blood ejected by the ventricles of the heart with each contraction. 7-22

Venous Return Venous return –Amount of blood returning to the ventricles Frank-Starling law of the heart 7-23

Heart Rate Heart rate affects cardiac output. If heart rate is too fast, less time for ventricles to refill before the next contraction Heart rate too slow –Decreased cardiac output and reduced organ perfusion 7-24

Signs and Symptoms of Decreased Cardiac Output Restlessness Changes in mental status Fatigue Cold, clammy skin Skin color changes Difficulty breathing, shortness of breath Changes in blood pressure Abnormal heart rhythms 7-25

Blood Vessel Walls 7-26

Blood Vessel Function Large arteries –Conductance vessels –Examples Aorta Carotid arteries Pulmonary arteries –Walls are thick and elastic, allowing them to expand and recoil 7-27

Blood Vessel Function Medium-sized arteries –Distributing vessels –Examples: Brachial and femoral arteries –Made up primarily of smooth muscle –Have less elasticity than larger arteries –Diameter remains relatively constant 7-28

Blood Vessel Function Arterioles –Resistance vessels –Smallest arteries –Made up of smooth muscle –Provide the greatest resistance to blood flow through the arterial circulation –Arteriovenous shunts 7-29

Blood Vessel Function Capillaries –Exchange vessels –Functional units of the circulatory system –Most numerous of the blood vessels –One cell layer –Precapillary sphincters 7-30

Blood Vessel Function Venules and veins –Capacitance vessels –Function as reservoirs –Venules Smallest branches of veins –Examples of large veins Superior and inferior vena cavae 7-31

Peripheral Vascular Resistance (PVR) PVR is the opposition that blood encounters in the blood vessels as it travels away from the heart. Vasodilation Vasoconstriction 7-32

Blood Pressure Blood pressure –The force exerted by the blood on the inner walls of the heart and arteries 7-33

Shock Shock is the inadequate circulation of blood through an organ or a part of the body. –Also called hypoperfusion 7-34

Hypovolemic Shock A condition in which there is a loss of blood, plasma, or water from the body Results in an inadequate volume of fluid in the circulatory system to maintain adequate perfusion 7-35

Cardiogenic Shock A condition in which the heart fails to function effectively as a pump 7-36

Obstructive Shock Occurs when blood flow is slowed or stopped by a mechanical or physical obstruction 7-37

Distributive Shock Refers to conditions that cause massive dilation of the blood vessels, redistributing fluid volume –Massive infection Septic shock –Severe allergic reaction Anaphylaxis –Loss of nervous system control Neurogenic shock –Psychological causes Psychogenic shock 7-38

Disease Risk Factors 7-39

Disease Risk Factors Age Gender Lifestyle Environment Heredity 7-40

Causes of Disease 7-41

Causes of Disease Pathogenesis –Mechanism by which a disease develops Etiology –The study of cause “Unknown etiology” or “idiopathic” –Cause of a disease is unknown 7-42

Signs, Symptoms, Syndromes Some diseases develop in stages –Incubation period –Signs and symptoms evident –Convalescent (recovery) period Sign –Objective finding Symptom –Subjective finding Syndrome 7-43

Physical Agents Mechanical forces Extremes of temperature Electrical forces Radiation exposure 7-44

Chemical Agents Chemical agents or irritants can injure the cell membrane and other cell structures or produce free radicals that continue to damage cell components. 7-45

Inflammation –A tissue reaction to disease, injury, irritation, or infection –Characterized by: Pain Heat Redness Swelling Possible loss of function 7-46

Infection An infection results when the body is invaded by pathogens 7-47

Immune Disorders Antigen Antibody Allergen Anaphylaxis 7-48

Immune Disorders Autoimmune disorders –Example: Rheumatoid arthritis Immunodeficiency disorders –Causes Genetic disease Medications Chemotherapy Radiation Infection 7-49

Hereditary Factors Congenital disease or condition –Present at birth Some congenital conditions, although present at birth, are not inherited. 7-50

Nutritional Imbalances Proper nutrition is essential to good health. A diet lacking essential nutrients can affect the body’s ability to break down, absorb, or use food. Being overweight or obese increases the risk of many diseases and health conditions. 7-51

Questions? 7-52