Ch. 19 Review Flashcards
Which of the following is not true statement about the heart?
The heart is located in the mediastinum.
The heart chambers are lined with simple squamous epithelium
The apex of the heart points toward the left hip
the walls of the heart are composed of cardiac muscle cells called myocardium
All are true statements
All are true statements
Label the coverings of the heart
What is the function of the pericardial fluid?
Protects the heart from friction.
Label the following structures of the heart
Label the heart structures
Trace the pathway of blood starting from the right atrium.
Right atrium 🡪 tricuspid valve 🡪 right ventricle 🡪 pulmonary semi-lunar valve 🡪 pulmonary trunk (pulmonary arteries) 🡪 lungs 🡪 pulmonary veins 🡪 left atrium 🡪 mitral valve 🡪 left ventricle 🡪 aorta 🡪 body.
What does the coronary circuit deliver?
Blood to the heart muscle itself.
Which statement about the pulmonary circuit is NOT true?
The pulmonary circuit consists of blood vessels carrying blood to the and from the lungs
Oxygen poor blood is pumped out of the right ventricle into the right and left pulmonary veins.
Oxygen rich blood returns to the heart via the right and left pulmonary veins
Blood from the lungs empties into the left atrium
All are true statements
Oxygen poor blood is pumped out of the right ventricle into the right and left pulmonary veins.
(pumped into the pulmonary arteries)
Which statement about the systemic circuit is NOT true?
The systemic circuit consists of blood vessels carrying blood to and from the body
Oxygen poor blood returns to the right atrium via the inferior and superior vena cava
Oxygen rich blood leaves the heart from the vena cava and return to the body via the aorta
Gas and nutrients exchange occurs at the capillary beds
All are true statements
Oxygen rich blood leaves the heart from the vena cava and return to the body via the aorta
(leaves via the aorta and returns via the vena cava)
What type of epithelium lines the heart chambers?
Simple squamous epithelium.
Which direction does the apex of the heart point?
Towards the left hip.
The diagram shows action potential found in a contractile cardiac muscle cell. Describe what happens in 3 steps
How is the action potential of cardiac contractile cells different from those seen in skeletal muscle?
Very fast depolarization
The presence of Ca++ channels which cause a plateau phase
Very long refractory period - this allows time for the chambers to fill before the next contraction
What is the composition of the walls of the heart?
Cardiac muscle called myocardium.
True or False: Cardiac muscle cells are striated and interconnected.
True.
True or False: Cardiac muscle cells require innervation to contract.
False.
Cardiac muscles cells are short and fat as compared to muscle cells
True
Cardiac muscles cells contract via a sliding filament model
True
The plasma membranes of cardiac muscle cells are connected via desmosomes
True
Desmosomes allow electrical current to pass from one heart cell to another
False
Gap junctions do this, desmosomes are fibrous connection between cells
List the three primary mechanical differences between cardiac and skeletal muscle cells.
- Do not require innervation
- Contract as a single unit
- Exhibit a long refractory period.
What occurs during the depolarization phase of cardiac muscle action potential?
Na+ influx through fast-gated sodium channels.
What happens during the plateau phase of cardiac muscle action potential?
Ca++ influx through slow Ca++ channels.
What is the role of gap junctions in cardiac muscle?
Allow electrical currents to pass from one heart cell to another.
Which of the following statements are not true?
The intrinsic conduction system of the heart is comprised of non-contractile cells called pacemaker cells
Pacemaker cells have an unstable resting potential that continually depolarize towards the threshold
Action potentials initiated in pacemaker cells initiate action potentials that spread throughout the cardiac contractile cells
The pattern of ion channel opening and closing in pacemaker cells is identical to that seen in cardiac contractile cells
The pattern of ion channel opening and closing in pacemaker cells is identical to that seen in cardiac contractile cells
depolarization, (after the pacemaker potential reaches threshold) is due to Ca++ channels opening and influx
Put the components of the intrinsic conduction system in order.
SA Node 🡪 AV node 🡪 AV bundle 🡪 bundle branches 🡪 Purkinje fibers (subendocardial conducting network)
How do the SA node, AV node, and AV bundle regulate heart activity?
SA node generates impulses at 75per/min impulse spreads to AV node depolarizing it, conducted through the rest of the heart via the AV bundle and other fibers (depolarizing in return). These depolarizations spread to the contractile cells of the heart (generating action potentials there) causing the myocardium to contract
The intrinsic conduction system set the basic heart rate- but it can be modified extrinsically by the nervous system. Explain these extrinsic controls and how they can effect the heart rate (and ultimately cardiac output)
The sympathetic nervous system can increase both rate and force of the heartbeat – sympathetic neurons can stimulate impulses in hearts SA and AV nodes, heart muscle and coronary arteries
The parasympathetic nervous system slows the heart. Parasympathetic neurons can send impulses to motor neurons in the heart wall fibers, SA and AV nodes
What are the stages of the cardiac cycle?
- Ventricular filling (diastole)
- Ventricular relaxation (systole)
- Isovolumetric relaxation.
What is taking place in Ventricular filling?
takes place in mid to late diastole
pressure in the heart is low, AV valves are open and 80% of blood passively flows into ventricles
atrial systole occurs (increasing pressure, delivering the remaining 20%
What is taking place during ventricular systole?
atria relax and ventricles begin to contract
rising ventricular pressure results in closing of the AV valves
ventricular pressure exceeds pressure in the large arteries, forcing the SL valve open (=ejection phase)
During which phase of the cardiac cycle are the semilunar valves open?
Ventricular ejection.
What is taking place during isovolumetric relaxation?
Occurs in diastole
ventricles relax, drop pressure causses backflow of blood in aorta and pulmonary trunk, which closes the SL valves
What is cardiac output?
The amount of blood pumped out by the heart in one minute.
What is stroke volume?
The amount of blood pumped by one ventricle each heartbeat.
What is end diastolic volume?
Volume of blood in each ventricle at the end of ventricular diastole.
What is end systolic volume?
Volume of blood in each ventricle at the end of ventricular systole.
