Flashcards in Chapter 11- Cardiovascular Deck (71)
What does the Cardiovascular system consist of?
Heart (a pump)
Vascular system (a collection of pipes making up a plumbing system)
What is its main function?
Supply oxygen and nutrients to the tissues
Remove carbon dioxide and waste products
Where is the heart located?
Behind the sternum just slightly to the left of midline of the body
Occupies a space called the thoracic mediastinum between the lungs
(Also in the mediastinum - esophagus, trachea, thymus)
Extends from the level of the second rib to about the level of the sixth rib
Inferiorly, rests on the diaphragm
What are the four borders of the heart?
Superior, inferior, medial, and lateral
Superior border is called the base and is wider than the inferior surface which is called the apex
What are the three surfaces of the heart?
Sternocostal, diaphragmatic, and pulmonary
What is the base of the heart?
The superior border (the top portion)
formed by the left atrium
What is the apex of the heart?
The inferior portion (the bottom portion where it kinda makes a point)
formed by the left ventricle
Describe the chambers of the heart
right and left atrium
right and left ventricle (pumping chambers)
Atria are separated by a septum or wall called the interatrial septum
Ventricles are separated by a wall called the interventricular septum.
Septum that separates the atria from the ventricles, the atrioventricular septum
The walls of the ventricles are thicker than the walls of the aorta
How does the right atrium receive blood?
Receives blood that is returning from the body to the heart and blood from the coronary sinus
Right atrium forms the right border
Blood being returned to the heart is deoxygenated so there is a depression in the inter atrial septum called fossa ovalis - this depression was a valve in the fetus which allowed the fetus to get blood
How does the right ventricle receive blood?
Receives deoxygenated blood from the right atrium and pumps into the lungs to be oxygenated
This chamber forms the anterior surface of the heart
It has three muscles that are attached to the tricuspid valve that prevent the valve from falling into the right atrium when pressure in the right ventricle builds
How does the Left atrium receive blood?
Forms most of the base of the heart
Four pulmonary veins carrying oxygenated blood enter the left atrium. They do not have valves
How does the left ventricle receive blood?
Receives blood from the left atrium
Works harder than any other chamber because it pumps oxygenated blood out of the heart via the aorta into the systemic circulation . Its myocardium is twice as think as that of the right ventricle.
What are the four valves of the heart
Pulmonary semilunar valve
Aortic semilunar valve
Describe the Tricuspid valve
Right AV or atrioventricular valve
Between the right atrium and right ventricle
Consists of three cusps or leaflets which prevent blood from flowing back into the right atrium when the right ventricle contracts
Cusps are anchored by cordlike structures called chordae tendinae to specialized cardiac muscle called papillary muscles . These muscles contract when the ventricles contract . Prevent the valve from falling into the right atrium and keeps blood from flowing back into the upper chamber
Describe the Pulmonary semilunar valve
Between the right ventricle and the trunk of the pulmonary arteries, prevent blood from flowing back into the right ventricle .
Its cusps are shaped like half moons which is why its called semi lunar valve
Describe the Bicuspid valve
Mitral valve (because its shaped like a hat) or the left AV valve
Between the left atrium and the left ventricle
Has Two cusps
Also has chordae tendinae attached to papillary muscles like the tricuspid valve
Prevents blood from flowing back into left atrium when the left ventricle contracts
Describe the Aortic semilunar valve
Between the left ventricle and the aorta
Prevents blood from flowing back into the left ventricle and also has halfmoon shaped cusps hence "semi lunar"
Describe the Innermost layer of the heart
Innermost layer is called the endocardium.
Very thin and lined with endothelium
Protects by lining the chambers, heart valves and large blood vessels
Describe the Middle layer of the heart
Middle layer is the muscular myocardium.
Cardiac muscle makes up 90% of the heart
responsible for pumping action of the heart
Thickest in the left ventricle
Describe the Outermost layer of the heart?
Outermost layer is the epicardium.
Also known as the visceral pericardium, contains fat
Cushions the heart if the chest experiences blunt trauma
What is the membrane that surrounds the heart?
Entire membrane around the heart is called the pericardium
Outer fibrous layer called the parietal pericardium
Innermost layer called the visceral pericardium
secretes a watery fluid that acts to reduce friction between the two membranes
Inflammation of the innermost lining of the heart and the valves
Bacterial infections are the most common cause
Weakness, fever, excessive sweating, general body aches, difficulty breathing, and blood in the urine
Treatment addresses the underlying cause
Inflammation of the muscular layer of the heart
Most common cause is a viral infection
Especially with Coxsackie B
Unexplained fever, chest pain that is, dyspnea, decreased urine output, fatigue, and fainting
Treatment normally includes steroids, bed rest, and a low-sodium diet
Inflammation of the pericardium
Most commonly caused by complications of viral or bacterial infections
Sharp, stabbing chest pains, fever, fatigue, and orthopnea
“Friction rub” may be heard.
Treatment includes analgesics for pain and diuretics are used to remove excess fluids around the heart.
Describe the cardiac cycle
Events from one heart beat to the next. There is more pressure on the left side of the heart than the right
Two atria of the heart contract and then relax simultaneously
Two ventricles also contract and relax simultaneously
Contraction - Atrial systole and ventricular systole
Relaxation - Atrial diastole and ventricular diastole
When atria contract the ventricles relax and vice versa
When the atria contract- Tricuspid and bicuspid valves open, and blood enters the ventricles
Right ventricle contracts, tricuspid valve closes- Pulmonary semilunar valve opens and blood enters the pulmonary trunk
Left ventricle contracts, the bicuspid valve closes- Aortic semilunar valve opens and blood enters the aorta
Number of cardiac cycles per minute - Same as the heart rate (pulse rate)
How does Strenuous exercise impact heart rate
Increases the heart rate because there is a greater demand for oxygen
How does Parasympathetic system impact heart rate
“Slows” things down
Vagus nerve, cranial nerve X, is the parasympathetic innervation to the heart
How does Sympathetic innervation impact heart rate
Increases heart rate, part of the “flight or fight” response
How does Cardiac control center impact heart rate
Medulla oblongata of the brain
Blood pressure rises, this control center ends impulses to decrease the heart rate
How does An increase in body temperature impact heart rate
Increases the heart rate
How does Low concentration of potassium ions
impact heart rate
Decreases the heart rate, but a high concentration causes an arrhythmia
How are heart sounds heard and caused by
Heard through auscultation with a stethoscope
Caused by turbulence created by the closing of the valves
Describe the 1st heart sound
First heart sound (S1)
Described as lubb
Closing of the tricuspid and bicuspid valves when the ventricles contract
louder and longer than heart sound 2 (s2)
Describe the 2nd heart sound
Second heart sound (S2)
Described as dubb
Pulmonary and aortic semilunar valves close as the atria contract
What are murmurs?
Abnormal heart sounds
Graded from 1 to 6, with 1 being barely audible and 6 being quite loud
Cause of all heart murmurs is not known
Signs and symptoms vary considerably depending on the cause and severity
Mild heart murmur, there may be no symptoms at all
Many times, no treatment is required
What factors influence Stroke Volume
Amount of blood returning to the heart which is called preload
Contractility or strength of contraction of the heart
Force that resists ejection of blood from the ventricles which is called afterload
The amount of blood pumped out of the ventricle during systole is called stroke volume
What factors influence Heart Rate (HR)
Nervous system regulation
Hormones such as epinephrine
What is the Conduction System
Electrical activity of the heart that is responsible for the contraction of the atria and ventricles
Inherent rhythmic activity
“Self-excitability” is called autorhythmicity.
Describe the Sinoatrial (SA) Node
Collection of specialized cardiac muscle fibers that have a certain rate of activity
SA node is located in the posterior wall of the right atrium
Primary or “natural pacemaker”
Responsible for setting the heart rate
Heart rate is approximately 70 bpm
Controlled by Autonomic nervous system and innervated by both PNS (speeds it up) and SNS (slows down heart)
Heart rate > 100 bpm is called tachycardia
Heart rate < 60 bpm is called bradycardia
Electrical impulse or action potential travels from the SA node to the muscle fibers of both the right and left atria
Causing them to contract. The action potential reaches the atrioventricular node
Describe the Atrioventricular (AV) Node
Located in the interatrial septum
Electrical impulses that leave the SA node travel to the AV node.
Restrained for a very brief period of time before it is allowed to go forward
Called the secondary pacemaker
Something happens to the SA node, the AV node takes over and is innervated by both PNS (speeds it up) and SNS (slows down heart)
After the impulse reaches the AV node- Atria contracts and impulses are sent to the bundle of His
What is the bundle of His
Also known as the atrioventricular or AV bundle
Located in the interventricular septum
Bundle splits into left and right bundle branches near the apex of the heart
Transmits electrical impluses to Purkinje Fibers
What are Purkinje Fibers
Fibers are located in the lateral walls of the ventricles.
Impulses flow through the Purkinje fibers, stimulating the heart muscle
Causing the ventricles to contract
What is ECG
Physicians use the ECG to look at the electrical activity of the heart.
Correlates to the contraction and relaxation of the heart
A basic ECG recording is made while the patient is at rest.
Six electrodes with lead wires attached to the chest and four more—one to each extremity
What is an ECG tracing
Tracing contains several straight segments and several waves that represent atrial and ventricular activity.
Caused by a narrowing or spasm of coronary arteries
Not immediately life threatening
Pain is usually described as a tight feeling in the chest and is often brought about by stress or physical activity, called stable angina
Acid from the stomach enters the esophagus, the individual may experience a burning sensation in the chest.
Gastroesophageal reflux disease, or GERD
Intense stress or fear
Often accompanied by increased heart and breathing rates
Membranes surrounding the lungs become inflamed.
Sharp chest pain that usually feels worse when a patient coughs or inhales
Inflammation at the junction of the rib bone and sternum
Blood clot in an artery in the lungs
Pain is severe, sharp, and increases with deep breaths or coughing
Strained or injured muscles
Fractured ribs tend to produce sharp and localized chest pain.
Inflammation of the gallbladder (cholecystitis) or pancreas
Pain associated with these conditions usually begins in the abdomen and spreads to the chest.
Diagnostic tests- ECG
Determine if someone is experiencing or has experienced a heart attack in the past
ECGs performed while a patient is exercising or has been given drugs to increase the heart rate
Diagnostic tests- Blood tests
When heart tissue is damaged, cardiac muscle releases certain enzymes into the blood.
Creatine phosphokinase and lactate dehydrogenase
Diagnostic tests-Chest x-ray
X-rays show the size and shape of the lungs and heart
Diagnostic tests-Nuclear scan
Follows radioactive substances through the blood vessels of the heart and lungs
Reveal narrow or obstructed arteries
Diagnostic tests- Electron beam computerized tomography
Much like a CT scan of the arteries and is useful for finding narrowed arteries
Diagnostic tests-Coronary catheterization
Uses a contrast medium that is followed through coronary arteries
Diagnostic tests- Echocardiogram
Uses sound waves to visualize the shape or defects of the heart
Diagnostic tests- Endoscopy
Insertion of a tube with a tiny camera down the throat and into the stomach
Congestive Heart Failure (CHF)
Failure of the heart to pump effectively
Risk factors include smoking, being overweight, a diet high in fats and cholesterol, a lack of exercise,
Left-sided heart failure
Lightheadedness, kidney failure, shortness of breath, pulmonary hypertension, and cough
Right-sided heart failure
Fluid accumulation and edema of the feet, ankles, liver, and abdomen
Nausea and loss of appetite which can lead to cachexia
Treatment options include medications to slow a rapid heart beat, diuretics to decrease edema and fluid accumulation in the lungs, and medications to reduce blood pressure.
Myocardial Infarction (MI)
Cardiac muscle sustains damage because of the resulting ischemia
Heart tissue that dies in an MI does not regenerate
Caused by obstruction of the coronary arteries as a result of atherosclerosis, a thrombus, or an embolus
Recurring, squeezing chest pain
Chewing an aspirin at the onset of symptoms
In an unconscious patient, CPR should be administered
Use of an AED and thrombolytic drugs to destroy the blood clots that block a coronary artery
Angioplasty or coronary artery bypass graft to open up the coronary arteries
• AST (SGOT)
• CK isoenzyme
• LD isoenzyme
• HDL cholesterol
• LDL/HDL cholesterol
• Lipoprotein phenotype
• ECG/Holter Monitor
• Stress test
Volume of blood that is pumped out of the left or right ventricle each minute
Cardiac Output (CO) = Stroke Volume (SV) x Heart Rate (HR)
Resting stroke volume of 74 mL
Resting heart rate of 72 bpm
74 mL x 72 bpm = 5,328 mL/min
First wave, or upward deflection, represents depolarization (contraction) of the atria
Second element consists of three waves (Q, R, and S) that represent ventricular depolarization (contraction)
Third element is the T wave and it represents the repolarization (relaxation) of the ventricles
Represents conduction time from atrial excitation to ventricular excitation
Begins at the end of the S wave and ends at the beginning of the T wave