Cardio - System overview and the Heart

Question 1

What are the components of the circulatory system?

Answer 1

heart
blood vessels
blood

Question 2

Blood = ___ ___ (cells and cell fragments) + ___ (plasma).

Answer 2

formed elements; liquid

Question 3

What cells are found in the blood?

Answer 3

red blood cells, white blood cells. (neutrophils, B and T cells, monocytes, eosinophils, basophils), and platelets

Question 4

What makes up the buffy coat?

Answer 4

leukocytes and platelets

Question 5

The ___ is a rapid assessment of blood composition. It is a percent of the blood volume that is composed of RBCs.

Answer 5

hematocrit

Question 6

Total volume = ___ + ___ ___ + ___.

Answer 6

plasma; buffy coat; erythrocytes

Question 7

Estimate the hematocrit of a person with a plasma volume of 3L and a total blood volume of 4.5L?

Answer 7

Total volume = plasma + buffy coat + erythrocytes
4.5L = 3L + X
X=1.5L erythrocyte volume

Hematocrit = Erythrocyte volume / total volume

1.5L / 4.5L = Hematocrit (33%)

Question 8

The ___ is a pump that propels the blood through the systemic and pulmonary circuits.

Answer 8

heart

Question 9

T/F. Arteries carry blood back to the heart and veins carry blood away from the heart.

Answer 9

False, Arteries carry blood AWAY to the heart and veins carry blood BACK TO the heart.

Question 10

T/F. The red color indicates that blood is fully oxygenated. The blue color indicates that blood is only partially oxygenated.

Answer 10

True.

Question 11

Blood flows from arteries to ___ to ___ to ___.

Answer 11

arterioles; capillaries; venules

Question 12

What is microcirculation?

Answer 12

Arterioles + capillaries + venules

Question 13

At what level is oxygen, carbon dioxide, nutrients and metabolic end products exchanged in the circulation?

Answer 13

capillaries blood and the interstitial fluid by diffusion

Question 14

What does flow equal?

Answer 14

F = change in P / R

Question 15

If you decrease the R but keep the change in P the same, what happens to F?

Answer 15

It will increase.

by increasing the radius (vasodilation)

Question 16

How can you change the resistance?

Answer 16

by changing the radius (vasodilate or vasoconstrict)

Question 17

In addition to changing the radius, what else can alter resistance?

Answer 17

blood viscosity

Question 18

What is the function of intercalated discs?

Answer 18

they have gap junctions which are electrically coupled to cause cells to contract
these junctions allow proteins to diffuse through them

Question 19

Parasympathetic (vagus) neurons synapse on ___ cell receptors found in the ___ and release ___.

Answer 19

muscarinic; atria; acetylcholine

Question 20

Sympathetic ___ fibers from the ___ spinal nerves release the neurotransmitter ___. The hormone, ___, travels in the ___ from the adrenal ___. Both molecules bind to _-___ 1 receptors on both the ___ and ___.

Answer 20

postganglionic; thoracic; norepinephrine; epinephrine; blood; medulla; Beta-adrenergic; atria; ventricles

Question 21

What coronary artery do we need to know for this class?

Answer 21

left anterior descending coronary artery

Question 22

What is the pacemaker of the heart?

Answer 22

SA node because it initiates each wave of excitation with atrial contraction

Question 23

The ___ _ ___ delivers the excitation to the ___ of the heart so that the ventricular contraction occurs in an ___ sweep.

Answer 23

Bundle of His; apex; upward

Question 24

What does the P wave represent?

Answer 24

current flow during atrial depolarization (atrial contraction)

Question 25

What does the QRS wave represent?

Answer 25

ventricular depolarization (contraction of the ventricles)

Question 26

What does the T wave represent?

Answer 26

ventricular repolarization (relaxation of the ventricles)

Question 27

What happened to atrial repolarization?

Answer 27

It is not evident on a ECG because it occurs at the same time as the QRS complex.

Question 28

On a myocardial ventricular cell, what is responsible for the rapid depolarization phase seen when recording membrane potential?

Answer 28

the rapid opening of voltage gated Na+ channels

Question 29

The prolonged “___” of depolarization is due to the slow but prolonged opening of voltage-gated ___ channels PLUS the closure to ___ channels.

Answer 29

plateau; Ca2+; K+

Question 30

T/F. Voltage-gated calcium channels open faster than voltage-gated sodium channels in a myocardial ventricular cell.

Answer 30

False, Voltage-gated calcium channels open SLOWER than voltage-gated sodium channels in a myocardial ventricular cell.

Question 31

The opening of ___ channels results in the repolarization phase.

Answer 31

potassium

Question 32

T/F. The action potentials of atrial muscle cells are similar in shape to those for ventricular cells, but the duration of their plateau phase is shorter.

Answer 32

True.

Question 33

T/F. The SA node cell has a steady resting potential.

Answer 33

False, the SA nodes does NOT have a steady resting potential, but instead, undergoes a slow depolarization due to funny channels. This depolarization is known as the pacemaker potential.

Question 34

What causes a threshold graded depolarization in the SA node?

Answer 34

1. sodium ions “leaking” in through the F-type [funny] channels
2. calcium ions moving in through the T [calcium] channels

Question 35

In the SA node, the rapid depolarization phase is due to the rapid opening of voltage-gated ___ channels.

Answer 35

calcium

Question 36

What two process are involved in the repolarization phase?

Answer 36

1. Reopening of potassium channels

2. closing of calcium channels

Question 37

What does a purkinje cell action potential have?

Answer 37

it has funny channels therefore it looks like a nodal graph, but it is not as fast as the SA node

Question 38

Describe a second degree (partial) block.

Answer 38

The atria and ventricles are not communicating because the AV node is in refractory. Damage to the AV node permits only every other atrial impulse to be transmitted to the ventricles. Not every P wave is followed by a QRS and T.

Question 39

Describe a third degree (complete) block.

Answer 39

The atria and ventricles are completely separate. There is no synchrony between atrial and ventricular electrical activities and the ventricles are being driven by a very slow pacemaker cell in the bundle of His. The QRS comes from the purkinje fibers because the AV node is dead

Question 40

What happens in patients who have a lethal defect of ventricular muscle where the current through the voltage-gated K+ channels is delayed or reduced? How does the electrical signal transfer to contractile force?

Answer 40

This delays the repolarization of ventricular muscle cell action potentials. Thus, the T wave is delayed relative to the QRS. This is known as long QT syndrome.

this leads to arrythmias

Question 41

Explain Excitation-Contraction Coupling, which links the cardiac muscle cell action potentials to contraction via control of calcium within the myocardium.

Answer 41

1. Excitation (depolarization of the plasma membrane) opens Ca2+ channels in T-tubules
2. Ca2+ flows into the cytosol (TRIGGER calcium)
3. Calcium induced calcium release from the sarcoplasmic reticulum
4. Muscle contraction

Question 42

The plateau phase depends on ___ Ca2+ causing contraction PLUS a ___ period, which allows the ventricles to fill with blood and prevents ___ of cardiac muscle.

Answer 42

trigger; refractory; tetanus