Chapter 20 Flashcards
What are the three types of blood vessels and their functions?
Arteries: carry blood away from heart
Vein: carry blood to heart
Capillaries: network between arteries and veins.
What is the difference between the pulmonary circuit and the systemic circuit?
Systemic carries blood to and from body.
Pulmonary carries blood to and from gas exchange surfaces of the lungs.
Explain the function of each of the four chambers of the heart.
Right atrium: collects blood from systemic circuit (deoxygenated blood)
Right ventricle: pumps blood to pulmonary circuit.
Left atrium: collects blood from pulmonary circuit (oxygenated blood)
Left ventricle: pumps blood to systemic circuit.
The coronary sulcus divides _______.
Atria and ventricles
What are the wall layers of the heart from the innermost to the outermost?
Endocardium, myocardium, and epicardium
Intercalated discs interconnect __________.
Cardiac muscle cells.
Name the components of the right atrium.
Superior vena cava Inferior vena cava Coronary sinus Foramen ovale Pectin ate muscles
What is the purpose of the superior vena cava?
Receives blood from head, neck, upper limbs, and chest.
What is the purpose of the inferior vena cava?
Receives blood from trunk, viscera, and lower limbs.
The coronary sinus opens into _________.
Right atrium
Cardiac veins return blood to ____________.
Coronary sinus.
What is the difference between the foramen ovale and fossa ovalis.
Before birth, is an opening through interatrial septum
Connects the two atria. The foramen ovale seals off an birth, forming fossa ovalis.
This is present in the right ventricle but not the left ventricle.
Moderator band
The opening from the right atrium to right ventricle.
Right atrioventricular (AV) valve
Blood leaves left ventricle through aortic valve into ___________.
Ascending aorta
The atrioventricular valves connect _________.
Connect right atrium to right ventricle and left atrium to left ventricle.
Which side of the heart has the tricuspid valve and which side has the bicuspid valve?
Right side has tricuspid valve
Left side has bicuspid valve
What permits blood flow in only one direction, from the atria to the ventricles?
The atrioventricular (AV) valves
The opening between the 2 atria is called ______.
Foramen ovale
The moderator band is located in the right ventricle on ________
Trabeculae carneae
Blood flows from right ventricle to __________ through pulmonary valve.
Pulmonary trunk
Which ventricle is larger, thicker, and stronger?
The left ventricle.
Which ventricle holds more volume of blood?
Neither. Both hold same amount.
Why is there less pressure to right ventricle than left ventricle?
Because right ventricle only pumps blood to lungs, which is about the same level as the heart, while the left ventricle pumps blood throughout the entire body, and it takes more force to pump the blood over the heart to head and neck.
These valves have no muscle support.
Semilunar valves
What prevents the atrioventricular valves from opening the wrong way?
Chordae tendineae
When the ventricles are relaxed, what happens to the AV valves and the semilunar valves?
AV valves are open, semilunar valves are closed.
What happens to the AV and semilunar valves when the ventricles are contracting?
AV valves are closed, semilunar valves are open
When atria receives electrical signal, it can’t send it to the ventricles without this.
The cardiac skeleton
This stabilizes the heart valves because it has 4 bands around them.
The cardiac skeleton
The blood supply to the heart is called?
Coronary circulation
A single contraction of the heart is called ______.
A heartbeat
Electric events in the cardiac cycle can be recorded on an ________.
Electrocardiogram (ECG)
The cardiac cycle begins with action potential at the _______.
SA node
The entire heart contracts in series: first the ______, then the ________.
First the atria, then the ventricles.
What are the 2 types of cardiac muscle cells?
Conducting system and contractile cells.
What is the purpose of the conducting system?
Controls and coordinates heartbeat
What is the purpose of contractile cells?
Produce contractions that propel blood.
What is automaticity?
Cardiac muscle tissue contracts automatically without neural command.
How is heart rate determined?
Determined by the number of electrical impulses generated by SA node.
The SA node generates ______ action potentials per minute and AV node generates _______ action potentials per minute.
SA node = 80-100 action potentials per minute
AV node = 40-60 action potentials per minute
What is the purpose of the purkinje fibers?
Distributes the electrical impulse throughout the heart. If you don’t have the purkinje fibers, signal doesn’t spread and remains at bottom of the heart.
Abnormally slow heart rate is called ______
Bradycardia
Action potentials are propagated by ________.
Intercalated discs
The right atrium receives blood from the systemic circuit through these two great veins.
Superior vena cava
Inferior vena cava
The right atrioventricular(AV) valve is also called __________.
Tricuspid valve
The left atrioventricular valve (AV) is also called _________.
Bicuspid valve
In systemic circulation, blood leaves the left ventricle through the aortic semilunar valve into the _______
Ascending aorta.
The ascending aorta turns at this point and becomes descending aorta
Aortic arch
Sacs that prevent valve cusps from sticking to aorta are called ________
Aortic sinuses
The coronary arteries originate at ________.
Coronary sinus
The _________ supplies blood to the SA node and the AV node.
The right coronary artery
Each heartbeat begins with a conducted action potential at a pacemaker called _______.
SA node
Once an action potential reaches cardiac muscle cells, they contract. Which parts of the heart contact first?
The atria
When action potential causes cardiac muscle cells to contract, the atria contract first, forcing blood to pass through the _______ into the ventricles.
Atrioventricular (AV) valves
The conducting system includes:
SA node, AV node, and conducting cells
What is the purpose of conducting cells?
Distribute stimulus throughout myocardium.
The cells that distribute the contractile stimulus throughout the myocardium are called _________.
Conducting cells
Where is the SA node located?
In wall of right atrium
Where is the AV node located?
At the junction between atria and ventricles
The SA node contains _________, which establishes the heart rate. This is also the reason why the SA node is known as the natural pacemaker.
Contains pacemaker cells
The SA node is connected to the larger AV node by ________.
Internodal pathways
Trachycardia is ________.
Abnormally fast heart rate
What are the P wave, the QRS complex, and the T wave of an ECG?
P wave - atrial depolarization
QRS complex - ventricular depolarization
T wave - ventricular repolarization
Why isn’t atrial repolarization apparent on an ECG?
Because it takes place during the QRS complex.
What are the P-R and Q-T time intervals between ECG waves?
P-R = From start of atrial depolarization to start if QRS complex. Q-T = from start of ventricular depolarization to start of ventricular repolarization.
Which cells account for roughly 99% of the muscle cells in the heart?
Contractile cells.
During the conducting system, what distributes the stimulus to the contractile cells?
Purkinje fibers
What is the resting potential of an atrial cell?
-80 mV
What is the resting potential of a ventricular cell?
About -90 mV
What is the major difference between action potentials in cardiac muscle cells and skeletal muscle cells?
The plateau
Cardiac muscles store oxygen in _______.
Myoglobin
The energy for cardiac contractions comes from________.
Mitochondrial breakdown of fatty acids and glucose.
The period between the start of one heartbeat to the beginning of the next is called ________.
Cardiac cycle.
What are the phases of the cardiac cycle?
Systole (contraction), diastole(relaxation)
What happens to blood pressure during the phases of the cardiac cycle?
Rises during systole
Falls during diastole
The average cardiac cycle lasts about _______.
800 msec
What happens to the cardiac cycle if heart rate increases?
All phases of the cardiac cycle shorten, particularly diastole.
When are the AV valves open during the cardiac cycle?
During steps 1 and 2, atrial systole and atrial ejection of blood into ventricles.
When do the AV valves close?
When atrial systole ends. They remain closed until step 8: atrial pressure is higher than ventricular pressure.
