Ch. 19 Review

Question 1

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

Answer 1

All are true statements

Question 2

Label the coverings of the heart

Answer 2

Question 3

What is the function of the pericardial fluid?

Answer 3

Protects the heart from friction.

Question 4

Label the following structures of the heart

Answer 4

Question 5

Label the heart structures

Answer 5

Question 6

Trace the pathway of blood starting from the right atrium.

Answer 6

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.

Question 7

What does the coronary circuit deliver?

Answer 7

Blood to the heart muscle itself.

Question 8

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

Answer 8

Oxygen poor blood is pumped out of the right ventricle into the right and left pulmonary veins.
(pumped into the pulmonary arteries)

Question 9

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

Answer 9

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)

Question 10

What type of epithelium lines the heart chambers?

Answer 10

Simple squamous epithelium.

Question 11

Which direction does the apex of the heart point?

Answer 11

Towards the left hip.

Question 12

The diagram shows action potential found in a contractile cardiac muscle cell. Describe what happens in 3 steps

Answer 12

Question 13

How is the action potential of cardiac contractile cells different from those seen in skeletal muscle?

Answer 13

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

Question 14

What is the composition of the walls of the heart?

Answer 14

Cardiac muscle called myocardium.

Question 15

True or False: Cardiac muscle cells are striated and interconnected.

Answer 15

True.

Question 16

True or False: Cardiac muscle cells require innervation to contract.

Answer 16

False.

Question 17

Cardiac muscles cells are short and fat as compared to muscle cells

Answer 17

True

Question 18

Cardiac muscles cells contract via a sliding filament model

Answer 18

True

Question 19

The plasma membranes of cardiac muscle cells are connected via desmosomes

Answer 19

True

Question 20

Desmosomes allow electrical current to pass from one heart cell to another

Answer 20

False
Gap junctions do this, desmosomes are fibrous connection between cells

Question 21

List the three primary mechanical differences between cardiac and skeletal muscle cells.

Answer 21

• Do not require innervation
• Contract as a single unit
• Exhibit a long refractory period.

Question 22

What occurs during the depolarization phase of cardiac muscle action potential?

Answer 22

Na+ influx through fast-gated sodium channels.

Question 23

What happens during the plateau phase of cardiac muscle action potential?

Answer 23

Ca++ influx through slow Ca++ channels.

Question 24

What is the role of gap junctions in cardiac muscle?

Answer 24

Allow electrical currents to pass from one heart cell to another.

Question 25

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

Answer 25

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

Question 26

Put the components of the intrinsic conduction system in order.

Answer 26

SA Node 🡪 AV node 🡪 AV bundle 🡪 bundle branches 🡪 Purkinje fibers (subendocardial conducting network)

Question 27

How do the SA node, AV node, and AV bundle regulate heart activity?

Answer 27

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

Question 28

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)

Answer 28

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

Question 29

What are the stages of the cardiac cycle?

Answer 29

* Ventricular filling (diastole) * Ventricular relaxation (systole) * Isovolumetric relaxation.

Question 30

What is taking place in Ventricular filling?

Answer 30

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%

Question 31

What is taking place during ventricular systole?

Answer 31

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)

Question 32

During which phase of the cardiac cycle are the semilunar valves open?

Answer 32

Ventricular ejection.

Question 32

What is taking place during isovolumetric relaxation?

Answer 32

Occurs in diastole ventricles relax, drop pressure causses backflow of blood in aorta and pulmonary trunk, which closes the SL valves

Question 33

What is cardiac output?

Answer 33

The amount of blood pumped out by the heart in one minute.

Question 34

What is stroke volume?

Answer 34

The amount of blood pumped by one ventricle each heartbeat.

Question 35

What is end diastolic volume?

Answer 35

Volume of blood in each ventricle at the end of ventricular diastole.

Question 36

What is end systolic volume?

Answer 36

Volume of blood in each ventricle at the end of ventricular systole.