Chapter 29: Bleeding and Shock
Topics
● The Circulatory System
● Shock
● Bleeding
The Circulatory System
Main Components
● Heart
● Blood vessels
● Blood
● Heart
○ Job is to pump blood
■ Supplies oxygen and nutrients to body’s cells
■ Must pump at an adequate rate and rhythm
● Arteries
○ Carry oxygenated blood away from the heart
○ Have thick, muscular walls that enable dilation and constriction
● Capillaries
○ Microscopic blood vessels
○ Vital exchange site
■ Oxygen, nutrients passed through capillary walls in exchange for carbon
dioxide from cells
● Veins
○ Carry oxygen-depleated blood rich in carbon dioxide back to the heart
○ Contain one-way valves to prevent back flow of blood
● Functions of blood
○ Transportation of gases
○ Nutrition
○ Excretion
○ Protection
○ Regulation
● Perfusion
○ Adequte circulation of blood throughout body
● Hypoperfusion
○ Inadequate perfusion of body’s tissues and organs
Shock
● Inadequate tissue perfusion
● If hypoperfusion persists, cells and organs will die
Pathophysiology of Shock
● Four causes
○ Volume problems
, ○ Pump problems
○ Blood vessel tone problems
○ Obstruction of blood flow
Volume Problems
● Hypovolemia
○ Blood is lost (absolute hypovolemia)
○ Plasma is removed from circulatory system (relative hypovolemia)
○ Not enough blood volume in blood vessels, so pressure falls
○ Both absolute and relative hypovolemia are called hypovolemic shock
○ Hemorrhage shock is loss of blood
Pump Problems
● Caused by failure of the heart to pump blood
● Usually related to a mechanical problem of the heart
● Blood cannot be moved vause of a drop in blood pressure
● Categorized as cardiogenic shock
Blood Vessel Tone Problems
● All blood vessels dilate at the same time
○ Blood cannot fill entire circulatory system
○ Referred to as distributive shock
● Types of distributive shock
○ Anaphylactic shock
○ Neurogenic shock
○ Septic shock
Obstruction of Blood Flow
● Blood flow is blocked
○ Called obstructive shock
● Caused by conditions such as:
○ Pulmonary embolism
○ Cardiac tamponade
○ Tension pneumothorax
Fight or Flight
● Baroreceptors stimulate release of epinephrine and norepinephrine
○ Blood vessels constrict
○ Skin becomes cool and pale
○ Skin becomes sweaty
○ Kidneys produce less urine
○ Nausea and vomiting
○ Increased heart rate and contractility
Topics
● The Circulatory System
● Shock
● Bleeding
The Circulatory System
Main Components
● Heart
● Blood vessels
● Blood
● Heart
○ Job is to pump blood
■ Supplies oxygen and nutrients to body’s cells
■ Must pump at an adequate rate and rhythm
● Arteries
○ Carry oxygenated blood away from the heart
○ Have thick, muscular walls that enable dilation and constriction
● Capillaries
○ Microscopic blood vessels
○ Vital exchange site
■ Oxygen, nutrients passed through capillary walls in exchange for carbon
dioxide from cells
● Veins
○ Carry oxygen-depleated blood rich in carbon dioxide back to the heart
○ Contain one-way valves to prevent back flow of blood
● Functions of blood
○ Transportation of gases
○ Nutrition
○ Excretion
○ Protection
○ Regulation
● Perfusion
○ Adequte circulation of blood throughout body
● Hypoperfusion
○ Inadequate perfusion of body’s tissues and organs
Shock
● Inadequate tissue perfusion
● If hypoperfusion persists, cells and organs will die
Pathophysiology of Shock
● Four causes
○ Volume problems
, ○ Pump problems
○ Blood vessel tone problems
○ Obstruction of blood flow
Volume Problems
● Hypovolemia
○ Blood is lost (absolute hypovolemia)
○ Plasma is removed from circulatory system (relative hypovolemia)
○ Not enough blood volume in blood vessels, so pressure falls
○ Both absolute and relative hypovolemia are called hypovolemic shock
○ Hemorrhage shock is loss of blood
Pump Problems
● Caused by failure of the heart to pump blood
● Usually related to a mechanical problem of the heart
● Blood cannot be moved vause of a drop in blood pressure
● Categorized as cardiogenic shock
Blood Vessel Tone Problems
● All blood vessels dilate at the same time
○ Blood cannot fill entire circulatory system
○ Referred to as distributive shock
● Types of distributive shock
○ Anaphylactic shock
○ Neurogenic shock
○ Septic shock
Obstruction of Blood Flow
● Blood flow is blocked
○ Called obstructive shock
● Caused by conditions such as:
○ Pulmonary embolism
○ Cardiac tamponade
○ Tension pneumothorax
Fight or Flight
● Baroreceptors stimulate release of epinephrine and norepinephrine
○ Blood vessels constrict
○ Skin becomes cool and pale
○ Skin becomes sweaty
○ Kidneys produce less urine
○ Nausea and vomiting
○ Increased heart rate and contractility
