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Chapter 7
Pathophysiology
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7-1
Objectives
7-2
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
• 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
• Difficulty breathing,
shortness of breath
• Changes in blood
pressure
• Abnormal heart
rhythms
• Skin color changes
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
• 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