Chapter 20 - The Cardiovascular System: The Heart Flashcards
This is the pump that circulates blood throughout the human body.
The heart
What must each body cell receive a constant supply of at all times?
Blood
How many times does the heart beat per day? How man allows of blood does it pump each day?
100,000 / 3600 gallons
The heart is about the same size as?
A closed fist
The heart sits where?
In the thoracic cavity near the midline
The heart rests where?
On the diaphragm within the mediastinum
This is a mass of tissue that extends from the sternum to the vertebral column between the lungs.
Mediastinum
This is the inferior pointed portion of the heart that is directed to the left.
Apex
This is the road posterior surface of the heart
Base
Since the heart lies between the vertebral column and the sternum, what can be sued to force blood out of the heart and into circulation?
External chest compressions
What can be used to keep oxygenated blood circulating in the body when the heart suddenly stops beating?
Cardiopulmonary resuscitation (CPR)
This is the membrane that surrounds and protects the heart.
Pericardium
Name the 2 parts of the pericardium.
Fibrous and serous pericardium
This is the superficial portion of the pericardium
Fibrous pericardium
The serious pericardium consists of what two layers?
Outer parietal and inner visceral
This is the part of the serous pericardium that is fused to the fibrous pericardium.
Parietal layer
Between the parietal and visceral layers of the serous pericardium is a space called?
Pericardial cavity
What is the fluid inside the pericardial cavity?
Pericardial fluid
This fluid reduces friction between the fibrous pericardium and serous pericardium as the heart moves while pumping blood
Pericardial fluid
This is the thin transparent outer layer of the heart wall and is also known as the serous pericardium.
Epicardium
This tissue is the middle muscular layer composed of cardiac muscle (a striated, involuntary type of muscle tissue) which is responsible for the pumping action of the heart.
Myocardium
This is a thin layer that lines the chambers of the heart and covers the valves. It is continuous with the lining of the large blood vessels attached to the heart.
Endocardium
What aw the 4 chambers of the heart?
Right & left atrium and the right & left ventricle
These are the superior chambers of the heart. These are the inferior chambers.
Atria / ventricles
On the anterior surface of each atrium is a pouch-like structure called?
Auricle
What is the purpose of the auricle?
It allows the atria to hold more blood.
On the surface of the heart are sulci which are grooves that contain?
Coronary blood vessels and fat
This marks the boundary between the atria and ventricles
Coronary sulcus
This marks the boundary between the right and left ventricles
Interventricular sulcus (an anterior and posterior)
The right atrium receives blood from 3 main veins which are?
Superior vena cava, inferior vena cava, coronary sinus
This is a thin partition that separates the right atrium from the left.
Interatrial septum
The interatrial septum contains an oval depression called?
Fossa ovalis
The fossa ovalis is a remnant of the?
Foramen ovale
This is an opening in the interatrial septum of the fetal heart that normally closes soon after birth.
Foramen ovale
Blood passes from the right atrium into the right ventricle though?
The tricuspid valve
The tricuspid valve is what kind of valve?
Atrioventricular
This forms most of the anterior surface of the heart.
Right ventricle
These are the ridges and folds of the myocardium inside the ventricles of the heart. It is raises bundles of cardiac fibers.
Trabeculae carneae
These are cone-shaped trabeculae carneae which are connected to the tricuspid valve by way of tendon-like cords called?
Papillary muscles
This separates the right ventricle from the left.
Interventricular septum
Blood exits the right ventricle through? It then empties into what large artery?
The pulmonary semilunar valve / pulmonary trunk
The pulmonary trunk divides into?
A right and left pulmonary artery
The left atrium receives blood from the lungs through?
4 pulmonary veins
Blood passes from the left atrium into the left ventricle through?
The bicuspid (mitral) valve
The bicuspid is what kind of valve?
Atrioventricular
Blood passes from the left ventricle through? Then it passes into what large artery?
Aortic semilunar valve / aorta
During fetal life this temporary blood vessel shunts blood from the pulmonary trunk into the aorta.
Ductus arteriosus
How much blood enters the fetal lungs?
Only a small amount as they are on functioning
Shortly after birth, the ductus arteriosus normally closes and leaves a remnant called?
Ligamentum arteriosus
The Iigament arteriosum connects?
The aorta and the pulmonary trunk
What is the largest artery in the body?
The aorta
As the aorta exits the left ventricle of the heart it is specifically called?
Ascending aorta
The aorta becomes this as it curves and begins to run inferiorly down the body towards the legs.
Arch of aorta
The arch of aorta becomes?
The descending aorta
The descending aorta is subdivided into?
The thoracic and abdominal aorta
Which ventricle as the thickest walls? This results in?
Left ventricle so this chamber has the greatest pumping ability
The left ventricle is responsible for pumping blood to?
All areas of the body
What is the function of the heart valves?
To prevent the backward flow of blood
Valves open and close in response to?
Pressure changes as the heart contracts and relaxes
What are the 4 valves of the heart?
Tricuspid, bicuspid, pulmonary semilunar valve, aortic semilunar valve
This is an atrioventricular valve between the right atrium and the right ventricle.
Tricuspid
This is an atrioventricular valve between the left atrium and the left ventricle.
Bicuspid
This valve is between the right ventricle and the pulmonary trunk.
Pulmonary semilunar valve
This valve is between the left ventricle and the aorta.
Aortic semilunar valve
The sound of the heart beat consists of what kind of noise that is loud enough to be heard by a stethoscope.
Two sounds
What is the first sound in the heart? It is caused by?
Lubb caused by the closure of the atrioventricular valves.
The second sound in the heart is? It is caused by?
Dupp caused by the closure of the semilunar valves
This is abnormal heart sound that sometimes indicates a valve disorder.
Heart murmur
What are the two closed pathways in which a heart pumps blood.
Systemic and pulmonary circulation
In this closed pathway in which the heart pumps blood, the left ventricle pumps OXYGENATED blood to all areas of the body and DEOXYGENATED blood from all areas of the body (back to the heart)
Systemic circulation
In this closed pathway in which the heart pumps blood, the right ventricle pumps DEOXYGENATED blood to the lungs to pick up oxygen and OXYGENATED blood back to the heart.
Pulmonary circulation
These carry blood away from the heart
Arteries
These are small arteries
Arterioles
These carry blood towards the heart.
Veins
These are small veins
Venues
It’s arteries carry what kind of blood?
Oxygenated
What kind of blood do most veins carry?
Deoxygenated
These are microscopic blood vessels located between arteries and veins; these vessels have very thin walls through which materials are exchanged with the interstitial fluid.
Capillaries
What is the path of blood through the body?
Right atrium ➡ tricuspid valve ➡ right ventricle ➡ pulmonary semilunar valve ➡ pulmonary trunk ➡ right and left pulmonary arteries ➡ pulmonary capillaries ➡ pulmonary veins ➡ left atrium ➡ bicuspid valve ➡ left ventricle ➡ aortic semilunar valve ➡ aorta ➡ systemic arteries ➡ systemic capillaries ➡ systemic veins ➡ superior and inferior vena cava
Why does the myocardium receive its own blood supply?
Nutrients cannot diffuse quickly enough from the blood within the heart chambers to supply the cells that make up the wall of the heart.
These branch from the ascending aorta and encircle the heart.
Coronary arteries
The left coronary artery passes inferior to? It divides into?
The left auricle / Anterior interventricular branch (within the anterior interventricular sulcus) & the circumflex branch (within the coronary sulcus)
The right coronary artery passes inferior to? It divides into?
Right auricle / posterior interventricular branch and marginal branch.
What is the function of capillaries?
Supplies blood containing oxygen and nutrients to cells and receives carbon dioxide and wastes from cells.
After passing into capillaries, blood then moves into?
Coronary (or Cardiac) veins
Most of the blood drains into? It then empties?
Coronary sinus (within the coronary sulcus) / right atrium
Partial obstruction of blood flow in the coronary arteries may cause what 2 things to happen?
Ischemia (reduced blood flow) & hypoxia (reduced oxygen supply)
This is pain that sometimes accompanies myocardial ischemia
Angina pectoris
This is ischemia without pain.
Silent myocardial ischemia
This is the death of an area of myocardial tissue due to complete blockage of coronary artery; blood flow to cells beyond the blockage is obstructed so the cells die.
Myocardial infarction (MI) or heart attack
After a heart attack, what eventually happens to the dead myocardial tissue?
It is eventually replaced by scar tissue and the heart muscle loses some of its strength.
Depending on the size and location of the affected area, what can happen?
A MI may disrupt the conduction system and cause sudden death by ventricular fibrillation
Name some treatments for heart attacks.
Anti clotting medications, angioplasty, or bypass surgery.
Heart muscle can remain alive in a resting individual if it receives what percentage of its normal blood supply?
Even 10-15%
Is cardiac muscle voluntary or involuntary? Striated or non striated?
Involuntary / striated
The individual muscle fibers if cardiac muscle is similar to?
Skeletal muscle
How is cardiac muscle similar to skeletal muscle?
Same arrangement of actin, myosin and similarly structure as ands and zones, etc
In what ways are cardiac muscle fibers different than skeletal muscle fibers?
Fibers are shorter in length and contain more mitochondria than skeletal muscle fibers.
Cardiac muscle fibers are branched and separated from one another by? What do these allow the fibers to do?
Intercalated discs / allows the fibers to better communicate with one another
Most cardiac muscle fibers are just normal?
Contractile fibers
What percentage of cardiac muscle fibers are autorhythmic?
About 1%
The 1% of autorhythmic cardiac muscle fibers do not have a stable? For this reason, what do they do? This generates?
Resting membrane / spontaneously depolarize / action potential
What happens to the action potential generated by the autorhythmic cardiac muscle fibers?
It spreads and causes the heart to contract for awhile even when removed from the body.
The autorhythmic cells are concentrated where?
In 5 main areas of the heart
The 5 main areas that contain autorhythmic cells of the heart form? What does this enable?
A conduction system which enables the chambers of the heart to contract in a coordinated manner to make the heart an effective pump.
What are the 5 components to the conduction system of the heart? (Cardiac action potentials propagate through the conduction system in the following sequence)
Sa node, AV node, AV bundles (bundle of His), right and left branches, Purkinje fibers.
This is a small mass of cardiac muscle fibers located in the right atrial wall (just below the opening of the superior vena cava)
Sinoatrial node (SA node)
The SA node serves as?
The pacemaker for the heart
What does the SA node generate? How many times per minute? What results?
Action potential / 100 per minute / propagates throughout both atria and causes the to contract
What slows the pace at which the SA node generates action potentials? It is released by? It causes the SA node to release an action potential how many times per minute?
Acetylcholine / released by the parasympathetic division of the ANS / 75 time per minute
This is a mass of conducting cells located in the interatrial septum.
Atrioventricular node (AV node)
From the SA node, to where does the action potential travel?
AV node
From the AV node, the action potential enters this area that is within the interventricular septum
AV bundle (bundle of His)
From the AV node, the action potential travels to this area which extend from the AV bundle through the interventricular septum and toward the apex of the heart.
Right and left bundle branches
What is the job of the Purkinje Fibers?
To conduct action potentials from the apex of the heart upward to the rest of the ventricular myocardium
When the ventricles contract, blood moves where?
Out of the semilunar valves
This refers to contraction
Systole
This refers to relaxation
Diastole
The atria and ventricles contract and relax at different times due to?
The conduction system pathway
The contraction of cardiac muscle is similar to that of?
Skeletal muscle
The action potential initiated by the SA node travels alone the conduction system to?
Contractile fibers in the atria and ventricles
Contractile fibers have a stable resting membrane potential of?
about -90mV
When stimulated by a threshold-level actions potential, what happens to the contractile fibers?
Na+ ion influx and depolarization occur (to a membrane potential of at least 0 mV)
Compared to skeletal muscles, what is the length of contraction of cardiac muscle fibers?
Much longer
Where does blood travel after it passes through coronary arteries?
Into capillaries
Most parts of the body receive blood from branches of? This allows for what to happen if one vessel becomes blocked?
More than one artery / another vessel can supply the cells with blood
During cardiac muscle contraction what causes depolarization to be maintained?
Ca2+ ions enter cardiac muscle fibers from interstitial fluid, as well as from the sarcoplasm is reticulum (as in skeletal muscle fibers). Ca2+ ion concentration increases in the sarcoplasm. (The Ca2+ inflow balances the K+ outflow)
The extended retried of depolarization in cardiac muscle contraction is called?
Plateau phase
Do skeletal muscle fibers go through a plateau phase?
No
Name the steps of cardia muscle contraction (5)
Ca2+ binds to troponin and actin myofilaments are able to slide past myosin, the sarcomere shortens, contraction of cardiac muscle occurs, K+ outflux and repolarization occurs, the membrane potential returns to its resting level of -90mV
This is the time interval during which a second contraction cannot occur
Refractory period
How long does the refractory period last?
Until relaxation and repolarization are underway in cardiac muscle
How long does the refractory period last in cardiac muscle? I skeletal muscle? Which is shorter?
300 milliseconds / 5 millisecond / skeletal
Because of the longer refractory period in cardiac muscle, what cannot happen that normally happens in skeletal muscle?
Tetanus
What would happen if tetanus occurred in cardiac muscle?
It would stop the heart’s pumping action
As action potentials travel through the heart, what is created? What is used to detect this activity?
Electrical currents that can be detected at the body surface / electrocardiogram (EKG or ECG)
What is the purpose of EKG’s?
They are used to determine if the conduction system of the heart is working normally and if the heart is damaged
What does a normal EKG record consists of?
P wave, qrs complex, t wave
This on the EKG represent atrial depolarization which spreads from the SA node to the AV node and causes atrial systole.
P wave
This on the EKG represents ventricular depolarization as the action potential spreads from the AV bundle through the bundle branches and Purkinje fibers, and to the myocardium of both ventricles. This causes ventricular systole (and atrial diastole).
QRS complex
This on the EKG represents ventricular repolarization and causes ventricular diastole
T wave
