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Circulatory system mcq Flashcards

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1
Q
A
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2
Q

Which chamber of the heart pumps deoxygenated blood to the lungs via the pulmonary trunk?

A

Right ventricle

The right ventricle pumps oxygen-poor blood into the pulmonary trunk, which leads to the lungs for oxygenation.

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3
Q

Which heart valve prevents backflow of blood from the left ventricle into the left atrium?

A

Mitral (bicuspid) valve

The mitral valve closes during ventricular contraction to prevent regurgitation into the left atrium.

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4
Q

Which heart valve has only two cusps (flaps)?

A

Mitral valve

The mitral valve is also known as the bicuspid valve due to its two cusps.

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5
Q

What is the role of the chordae tendineae in the heart?

A

They prevent the AV valve cusps from inverting into the atria during ventricular contraction

Chordae tendineae anchor the AV valve cusps to papillary muscles to prevent valve prolapse.

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6
Q

Which part of the heart normally initiates the impulse that triggers a heartbeat?

A

Sinoatrial (SA) node

The SA node is the heart’s natural pacemaker, generating electrical impulses that establish the sinus rhythm.

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7
Q

Which sequence correctly represents the path of the cardiac electrical conduction system?

A

SA node → AV node → AV bundle (Bundle of His) → bundle branches → Purkinje fibers

This sequence ensures coordinated contraction of the heart.

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8
Q

What is the primary function of the atrioventricular (AV) node?

A

To delay the electrical impulse, allowing the atria to contract before the ventricles

This delay ensures efficient filling of the ventricles.

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9
Q

If the SA node fails to fire, which part of the heart can assume pacemaker function?

A

Atrioventricular (AV) node

The AV node can take over as an ectopic pacemaker at a slower rate.

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10
Q

Which heart chamber has the thickest myocardium (muscular wall)?

A

Left ventricle

The left ventricle must generate high pressure to pump blood through the systemic circuit.

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11
Q

What is the function of the coronary arteries?

A

They supply oxygenated blood to the heart muscle (myocardium)

The coronary arteries branch off the ascending aorta to provide blood to the heart muscle.

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12
Q

Most of the blood flow to the myocardium occurs during which phase of the cardiac cycle?

A

Ventricular diastole

Coronary perfusion primarily occurs during heart muscle relaxation.

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13
Q

What are intercalated discs, and what is their function in cardiac muscle?

A

Specialized gap junctions that connect cardiac muscle cells and enable synchronized contraction

Intercalated discs contain desmosomes and gap junctions for coordinated contraction.

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14
Q

What is one important function of the cardiac fibrous skeleton of the heart?

A

It electrically insulates the atria from the ventricles

The fibrous skeleton ensures proper conduction pathway for electrical impulses.

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15
Q

Which of the following statements about heart valves is INCORRECT?

A

The mitral valve is located on the right side of the heart

The mitral valve is actually the left AV valve.

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16
Q

On a normal ECG, what does the P wave represent?

A

Atrial depolarization

The P wave triggers atrial contraction shortly after it begins.

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17
Q

Which deflection on the ECG tracing corresponds to ventricular depolarization?

A

QRS complex

The QRS complex is larger due to the size of the ventricles compared to the atria.

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18
Q

What electrical event of the heart is represented by the T wave on an ECG?

A

Ventricular repolarization

The T wave reflects the recovery phase as the ventricles prepare for the next cycle.

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19
Q

Stimulation of the heart by sympathetic nerves will:

A

Increase heart rate and force of contraction

Sympathetic stimulation releases norepinephrine, enhancing cardiac output.

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20
Q

What effect does parasympathetic (vagal) stimulation have on the heart?

A

It decreases heart rate by releasing acetylcholine

Parasympathetic tone maintains the heart rate around 60–80 bpm.

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21
Q

Stroke volume is defined as:

A

The volume of blood ejected by a ventricle in one beat

Stroke volume is typically the difference between end-diastolic and end-systolic volume.

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22
Q

Cardiac output is the:

A

Volume of blood each ventricle pumps per minute

Cardiac output is calculated as stroke volume multiplied by heart rate.

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23
Q

“Afterload” refers to:

A

The force against which the heart must pump blood

Afterload is largely determined by arterial blood pressure and vessel resistance.

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24
Q

According to the Frank–Starling law of the heart, which factor increases stroke volume?

A

Increased venous return (greater end-diastolic volume)

More filling leads to stronger contractions, increasing stroke volume.

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25
“Preload” in cardiac physiology is best described as:
The degree of stretch of the ventricular myocardium before contraction ## Footnote Preload is influenced by the volume of blood in the ventricle at the end of diastole.
26
What does the Frank–Starling mechanism state?
The more the ventricle is filled, the more it stretches and the stronger it contracts on the next beat. ## Footnote Increased venous return and end-diastolic volume (preload) lead to a larger stroke volume.
27
What is 'preload' in cardiac physiology?
The volume of blood in the ventricle at the end of diastole (end-diastolic volume). ## Footnote A higher preload usually increases stroke volume via Frank–Starling mechanics.
28
Which vessels return systemic deoxygenated blood to the right atrium?
Superior and inferior venae cavae. ## Footnote The superior vena cava drains the upper body, and the inferior vena cava drains the lower body.
29
What causes the first heart sound ('lub')?
Closure of the atrioventricular (AV) valves at the onset of ventricular systole. ## Footnote This marks the start of ventricular systole.
30
What does the second heart sound ('dup') correspond to?
Closure of the semilunar valves (aortic and pulmonary) at the onset of ventricular diastole. ## Footnote It occurs as the ventricles relax.
31
During isovolumetric contraction of the ventricles, what is true?
All four heart valves are closed. ## Footnote This phase occurs just after the first heart sound.
32
When does most of the ventricular filling occur?
During early ventricular diastole, before the atria contract. ## Footnote About 70–80% of filling is passive.
33
At what point in the cardiac cycle is the volume of blood in the left ventricle the highest?
End of ventricular diastole (just before the ventricle contracts). ## Footnote This volume is the end-diastolic volume (EDV).
34
What causes the aortic pressure 'dicrotic notch' on a pulse pressure waveform?
Closure of the aortic valve and brief backflow of blood. ## Footnote This occurs at the onset of diastole.
35
The interval between the first heart sound (S1) and the second heart sound (S2) corresponds to what?
Ventricular systole (ejection phase). ## Footnote This is when the ventricles are contracting.
36
Compared to the right ventricle, what does the left ventricle do during systole?
Generates much higher pressure to overcome greater resistance. ## Footnote The left ventricular wall is thicker and stronger.
37
Arrange the following events of the cardiac cycle starting with atrial contraction: Atrial systole, Isovolumetric ventricular contraction, Ventricular ejection, Isovolumetric ventricular relaxation, Ventricular filling (passive).
2 → 4 → 1 → 3 → 5. ## Footnote This sequence reflects the correct order of events in the cardiac cycle.
38
During the ventricular ejection phase of the cardiac cycle, what happens?
Ventricular pressure rises above arterial pressure, forcing semilunar valves open. ## Footnote This allows blood to be ejected into the arteries.
39
What is the role of atrial systole in ventricular filling?
It 'tops off' the ventricular volume by adding a final 20–30% of blood to the ventricle. ## Footnote Atrial contraction becomes more important at high heart rates.
40
End-systolic volume (ESV) is defined as what?
The volume of blood remaining in a ventricle after it has contracted and ejected blood. ## Footnote For example, if a ventricle had 120 mL before contraction and ejected 70 mL, the ESV would be about 50 mL.
41
If a ventricle’s end-diastolic volume is 120 mL and its end-systolic volume is 50 mL, what is the stroke volume?
70 mL. ## Footnote Stroke volume = EDV – ESV.
42
At a normal resting heart rate (~75 beats per minute), how long does one cardiac cycle last?
0.8 second. ## Footnote This includes approximately 0.3 s of systole and 0.5 s of diastole.
43
The period from the second heart sound (S2) to the next first heart sound (S1) corresponds to what?
Ventricular diastole. ## Footnote This is when the ventricles are relaxing and refilling.
44
What type of blood vessel carries blood away from the heart?
Artery. ## Footnote This is true regardless of whether the blood is oxygenated or not.
45
Which vessels contain valves to prevent backflow of blood?
Veins (especially in the limbs). ## Footnote These valves assist venous return against gravity.
46
What type of vessels are primarily responsible for controlling the distribution of blood flow and systemic blood pressure?
Arterioles. ## Footnote They are the principal 'resistance vessels' affecting systemic vascular resistance.
47
What type of capillary is most common throughout the body and has uninterrupted endothelial lining?
Continuous capillaries. ## Footnote They allow only small molecules to pass between cells.
48
In which organ would you expect to find fenestrated capillaries?
Kidneys. ## Footnote Fenestrated capillaries allow rapid exchange of substances.
49
What type of capillaries are found in organs that require rapid exchange of substances?
Fenestrated capillaries ## Footnote Examples include the kidneys, small intestine, and endocrine glands.
50
What is a characteristic of fenestrated capillaries?
They have pores in their endothelial cells, allowing greater permeability to fluids and small solutes.
51
Which organ typically contains sinusoid capillaries?
Liver ## Footnote Sinusoids are found in organs like the liver, spleen, bone marrow, and some endocrine glands.
52
What is the thickest layer of a typical muscular artery?
Tunica media
53
In veins, which layer of the vessel wall is typically the thickest?
Tunica externa (adventitia)
54
Approximately what percentage of the blood volume is in the systemic veins at any given time?
~60%
55
Where does the greatest drop in blood pressure occur in the circulatory system?
Across the arterioles
56
What is the function of precapillary sphincters in the microcirculation?
They regulate the flow of blood into capillary beds.
57
Which statement is true regarding arteries compared to veins?
Arteries have thicker muscular walls and smaller, rounder lumens than veins.
58
What is an anastomosis in the circulatory system?
A direct connection between two blood vessels (bypassing the capillary bed)
59
A portal system is characterized by what?
Two capillary beds in series connected by a vein.
60
Which vessel carries nutrient-rich blood from the gastrointestinal tract to the liver?
Hepatic portal vein
61
Which side of the heart pumps blood into the pulmonary circulation?
Right side (right ventricle)
62
Which blood vessels in the pulmonary circuit carry oxygenated blood?
Pulmonary veins
63
How does pressure in the pulmonary circulation compare to the systemic circulation?
Pulmonary pressure is much lower than systemic pressure.
64
What unique feature do pulmonary arteries have compared to systemic arteries?
Pulmonary arteries carry deoxygenated blood, whereas systemic arteries carry oxygenated blood.
65
What occurs in left-sided heart failure?
Blood backs up into the pulmonary circulation, leading to pulmonary edema and shortness of breath.
66
What is considered a normal resting blood pressure for a healthy adult?
Approximately 120/80 mmHg
67
What do the top and bottom numbers of a blood pressure reading correspond to?
Pressure during heart contraction (systole) and pressure during heart relaxation (diastole)
68
How is pulse pressure (PP) calculated?
Systolic pressure minus diastolic pressure
69
If a person’s blood pressure is 120/80 mmHg, what is the approximate mean arterial pressure (MAP)?
~93 mmHg
70
What change will increase blood pressure?
An increase in heart rate or stroke volume (increased cardiac output)
71
What happens when baroreceptors in the carotid sinuses and aortic arch detect a rise in arterial blood pressure?
They increase their firing rate, which leads to decreased sympathetic output and lowering of blood pressure.
72
Where are the major arterial baroreceptors located?
In the carotid sinuses and aortic arch
73
Where are the major arterial baroreceptors located?
In the carotid sinuses and aortic arch ## Footnote The key baroreceptors are found in the carotid sinus (at the bifurcation of each common carotid artery) and in the aortic arch.
74
What does activation of the renin–angiotensin–aldosterone system (RAAS) tend to do?
Increase blood pressure ## Footnote The RAAS raises blood pressure by causing vasoconstriction and stimulating aldosterone secretion, which retains sodium and water.
75
Which hormone is released by the heart in response to high blood volume and pressure?
Atrial natriuretic peptide (ANP) ## Footnote ANP causes the kidneys to excrete more sodium and water, reducing blood volume and lowering blood pressure.
76
What effect does antidiuretic hormone (ADH) have on blood pressure?
It increases blood pressure by causing vasoconstriction and water retention ## Footnote ADH acts to conserve water and constrict blood vessels, helping restore blood pressure.
77
What does stimulation of the vasomotor center in the medulla oblongata do?
Increase sympathetic signals to blood vessels, causing vasoconstriction ## Footnote The vasomotor center controls vascular tone and raises blood pressure by increasing peripheral resistance.
78
What causes orthostatic hypotension?
An insufficient baroreceptor reflex causing delayed vasoconstriction upon standing ## Footnote This results in dizziness or fainting due to transient brain hypoperfusion.
79
Hypertension in adults is generally defined as a sustained blood pressure of at least:
140/90 mmHg ## Footnote This is a common clinical threshold for diagnosing high blood pressure.
80
Which organ plays the most important role in long-term regulation of blood pressure?
Kidneys ## Footnote The kidneys adjust blood volume by altering water and sodium excretion, directly influencing blood pressure.
81
What is the reflex response of peripheral chemoreceptors when they detect low oxygen or high CO₂?
Stimulate the cardiovascular center to increase heart rate and cause vasoconstriction ## Footnote This response raises blood pressure and improves blood flow to vital organs.
82
What is total peripheral resistance and what factor most influences it?
The resistance to blood flow in the systemic circulation, mainly determined by arteriolar diameter ## Footnote TPR is influenced by the caliber of systemic arterioles; constriction increases resistance.
83
How does widespread vasoconstriction affect blood pressure and blood flow?
It increases blood pressure by raising resistance, and it can decrease blood flow to tissues ## Footnote Higher resistance raises blood pressure but may reduce perfusion to less critical regions.
84
How does blood viscosity affect blood pressure?
Increased viscosity (thicker blood) raises resistance and tends to increase blood pressure ## Footnote Higher viscosity creates more internal friction, increasing peripheral resistance.
85
What is the vasomotor center?
A region in the medulla oblongata that regulates blood vessel diameter via sympathetic nerves ## Footnote It controls vessel tone and works with cardiac control centers to maintain hemodynamic stability.
86
What compensatory mechanisms help maintain blood pressure during significant hemorrhage?
Increased heart rate and contractility, vasoconstriction, and hormone release (e.g., ADH, angiotensin II) ## Footnote These mechanisms help sustain blood pressure and perfusion to vital organs despite reduced blood volume.
87
What portion of whole blood is plasma?
~55% plasma and ~45% formed elements ## Footnote Plasma is the liquid extracellular matrix of blood, while formed elements include cells and cell fragments.
88
What is the most abundant protein in blood plasma?
Albumin ## Footnote Albumin maintains osmotic pressure and helps transport various substances.
89
Which cells are the most numerous in blood?
Erythrocytes (red blood cells) ## Footnote RBCs make up about 99% of the formed elements in blood.
90
What is the primary function of mature red blood cells?
To transport oxygen (and some CO₂) between the lungs and tissues ## Footnote Erythrocytes are specialized for gas transport due to their hemoglobin content.
91
Why are red blood cells shaped as biconcave discs?
The biconcave shape increases surface area for gas exchange and flexibility ## Footnote This shape optimizes RBCs for efficient gas transport.
92
What is the shape of a red blood cell, and why is it important?
A red blood cell's biconcave disc shape increases surface area for gas exchange and flexibility ## Footnote This shape allows RBCs to squeeze through capillaries and maximizes oxygen-carrying capacity.
93
What is hemoglobin?
An iron-containing protein in red blood cells that binds and transports oxygen ## Footnote Each hemoglobin molecule can carry up to four oxygen molecules and also contributes to CO₂ transport.
94
Hematocrit refers to what?
The percentage of whole blood volume that is red blood cells ## Footnote Normal hematocrit is around 40-50% in males and 36-44% in females.
95
What does the buffy coat in centrifuged blood contain?
Leukocytes (WBCs) and platelets ## Footnote The buffy coat accounts for less than 1% of blood volume in a healthy sample.
96
Which type of white blood cell is the most abundant and specializes in phagocytizing bacteria?
Neutrophils ## Footnote Neutrophils comprise about 50-70% of leukocytes and are rapid responders to bacterial infections.
97
Which leukocytes are responsible for antibody production?
Lymphocytes (B lymphocytes, specifically) ## Footnote B lymphocytes differentiate into plasma cells that produce antibodies.
98
Which white blood cell leaves circulation to become a macrophage?
Monocyte ## Footnote Monocytes migrate into tissues and differentiate into macrophages, which are potent phagocytes.
99
Eosinophils are especially elevated during what conditions?
Parasitic worm infestations and allergic reactions ## Footnote Eosinophils combat parasites and modulate allergic inflammation.
100
Basophils in the blood function similarly to which cells in the tissues?
Mast cells; they release histamine (and heparin) to promote inflammation ## Footnote Basophils contribute to the inflammatory response during allergic reactions.
101
Platelets are defined as what?
Cell fragments that play a key role in blood clotting (hemostasis) ## Footnote Platelets are essential for forming a platelet plug and promoting coagulation.
102
What is the correct sequence of events for hemostasis after a blood vessel is cut?
Vascular spasm → Platelet plug formation → Coagulation (fibrin clot) ## Footnote This sequence helps in stopping the bleeding effectively.
103
Which vitamin is necessary for the liver to synthesize clotting factors?
Vitamin K ## Footnote Vitamin K is required for the post-translational modification of several clotting factors.
104
Why can a person with type O blood donate red blood cells to any ABO blood type?
Type O red cells lack A and B antigens on their surface ## Footnote This absence prevents an immune reaction in recipients with different blood types.
105
Which blood type is considered the universal recipient for red blood cell transfusions?
AB positive, because their plasma has no anti-A, anti-B, or anti-Rh antibodies to attack donor RBCs ## Footnote This tolerance allows AB positive individuals to receive RBCs from any type.
106
What hormone stimulates red blood cell production in response to hypoxia?
Erythropoietin (EPO) ## Footnote EPO is secreted by the kidneys to increase RBC formation in the bone marrow.

BIO 102 (16 decks)

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