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MCAT: Biology > Chapter 7: The Cardiovascular System > Flashcards

Chapter 7: The Cardiovascular System Flashcards

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1
Q

How many chambers does the heart contain?

A

4

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2
Q

Where does deoxygenated blood enter the heart? Where does oxygenated blood exit the heart?

A
  • Deoxygenated enters at the right side of the heart

- Oxygenated exits at the left side

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3
Q

How is deoxygenated blood moved to the lungs?

A

By way of the pulmonary arteries

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4
Q

How is oxygenated blood moved to the heart?

A

By way of the pulmonary veins

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5
Q

What are the two types of circulation?

A
  • Pulmonary circulation

- Systemic circulation

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6
Q

What are atria?

A

Thin-walled structures where blood is received

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7
Q

The atria may receive blood from what? (2)

A
  • Venae cavae (deoxygenated blood entering the right heart)

- Pulmonary veins (oxygenated blood entering the left heart)

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8
Q

The atria contract to push blood into the __________.

A

ventricules

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9
Q

What is the mnemonic for atrioventricular valves?

A

LAB: Left Atrium = Bicuspid (mitral)
RAT: Right Atrium = Tricuspid

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10
Q

The atria are separated from the ventricles by what?

A

Atrioventricular valves

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11
Q

The ventricles are separated from the vasculature by what?

A

Semilunar valves

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12
Q

What does the pulmonary valve separate?

A

The right ventricle from pulmonary circulation

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13
Q

What does the aortic valve separate?

A

The left ventricle from the aorta

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14
Q

How many leaflets do the semilunar valves have?

A

Three

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15
Q

Name the components of the electrical conduction system of the heart, in order.

A
  • Sinoatrial node (SA node)
  • Atrioventricular node (AV node)
  • His (AV bundle) and its branches
  • Purkinje fibers
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16
Q

Where does impulse initiation occur for the electrical conduction system of the heart? How many signals per minute are generated without requiring any neural input?

A
  • SA node

- 60-100 signals per minute

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17
Q

Where is the SA node located?

A

Wall of the right atrium

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18
Q

What percentage of cardiac output does the atrial kick account for?

A

5-30%

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19
Q

Where is the AV node located?

A

At the junction of the atria and ventricles

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20
Q

Where is the bundle of His?

A

Embedded in the interventricular septem

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21
Q

The muscle cardiac cells are connected by what?

A

Intercalated discs

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22
Q

The parasympathetic system slows down the heart rate, provided by the ______ nerve.

A

vagus

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23
Q

What happens during systole?

A

Ventricular contraction and closure of the AV valves occurs and blood is pumped out of the ventricles

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24
Q

What happens during diastole?

A

The heart is relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles

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25
Q

Contraction, which increases blood pressure, is during _________, while ________ is responsible for relaxation.

A

systole

diastole

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26
Q

What is the equation for cardiac output? What is the average cardiac output for humans?

A
  • CO = HR x SV
  • Heart Rate (beats per minute)
  • Stroke Volume (Volume of blood pumped per beat)
  • 5 liters per minute
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27
Q

When does the first sound (lub) appear?

A

When the two AV valves close at the start of systole to prevent backflow into the atria

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28
Q

When does the second sound (dub) appear?

A

When the two semilunar valves close at the end of systole to prevent backflow into the ventricles

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29
Q

What happens in terms of pressure and volume when the aortic valve opens?

A
  • Pressure increases

- Volume decreases

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30
Q

What happens in terms of pressure and volume when the aortic valve closes?

A
  • Pressure decreases

- Volume increases

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31
Q

Blood travels away from the heart in ________.

A

arteries

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32
Q

What is the largest artery?

A

Aorta

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33
Q

All blood vessels are lined with what kind of cells?

A

Endothelial cells

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34
Q

What are the functions of endothelial cells in the cardiovascular system? (3)

A
  • Helps to maintain the vessel by releasing chemicals that aid in vasodilatation and vasoconstriction
  • Allow white blood cells to pass through the vessel wall and into the tissues during an inflammatory response
  • Release chemicals when damaged that are necessary in the formation of blood clots to repair the vessel and stop bleeding
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35
Q

How are arteries and veins similar in terms of structure? How are they different?

A
  • They are composed of the same types of cells

- Arteries have much more smooth muscle than veins

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36
Q

Most arteries contain (oxygenated/deoxygenated) blood. What are the exceptions?

A
  • Oxygenated

- Pulmonary arteries and umbilical arteries

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37
Q

Smaller, muscular arteries are known as what?

A

Arterioles

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38
Q

Why must the left side of the heart generate much higher pressures?

A

To overcome the resistance caused by systemic arteries

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39
Q

How thin are the walls of capillaries? How do red blood cells travel through capillaries?

A
  • Single endothelial cell layer

- Single-file line

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40
Q

What is the interface for communication of the circulatory system with the tissues?

A

Capillaries

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41
Q

What causes a bruise?

A

When capillaries are damaged, blood can leave the capillaries and enter the interstitial space

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42
Q

Veins are (elastic/inelastic).

A

inelastic

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43
Q

Veins carry (oxygenated/deoxygenated) blood. What are the exceptions?

A
  • Deoxygenated

- Pulmonary and umbilical veins

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44
Q

_________ are smaller venous structures that connect capillaries to the larger veins of the body

A

Venules

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45
Q

Are veins or arteries able to stretch to accommodate greater amounts of blood?

A

Veins

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46
Q

The pressure at the bottom of the _______ ______ _____ can be quite high, going as high as 200 mmHg or more.

A

inferior vena cava

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47
Q

What structures do veins possess to push blood forward and prevent backflow?

A

Valves

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48
Q

What are varicose veins? Who is susceptible?

A
  • Veins that have valves that were unable to close

- Pregnant women

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49
Q

What is the external force that veins rely on to generate the pressure to push blood toward the heart?

A

Skeletal muscles, which squeeze the veins as the muscles contract

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50
Q

Blood returns to the heart from the body via the _______ ________

A

venae cava

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51
Q

What is the pathway of blood circulation?

A
  • Right atrium (tricuspid valve)
  • Right ventricle (pulmonary valve)
  • Pulmonary artery
  • Lungs
  • Pulmonary veins
  • Left atrium (mitrall valve)
  • Left ventricle (aortic valve)
  • Aorta
  • Arteries
  • Arterioles
  • Capillaries
  • Venules
  • Veins
  • Venae cavae
  • Right atrium
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52
Q

Which tree portal systems in the body have blood that pass through two capillary beds?

A
  • Hepatic portal system
  • Hypophyseal portal system
  • Renal portal system
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53
Q

What are the two capillary beds of the hepatic portal system?

A

Blood leaving the capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver

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54
Q

What are the two capillary beds of the hypophyseal portal system?

A

Blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary to allow for paracrine secretion of releasing hormones

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55
Q

What are the two capillary beds of the renal portal system?

A

Blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta

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56
Q

Which valve prevents backflow in the right atrium?

A

Tricuspid valve

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57
Q

Which valve prevents backflow in the right ventricle?

A

Pulmonary valve

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58
Q

Which valve prevents backflow in the left atrium?

A

Mitral (bicuspid) valve

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59
Q

Which valve prevents backflow in the left ventricle?

A

Aortic valve

60
Q

Do arteries, capillaries, or veins contain valves?

A
  • Arteries: no
  • Capillaries: no
  • Veins: yes
61
Q

Do arteries, capillaries, or veins contain much smooth muscle?

A
  • Arteries: yes, a lot
  • Capillaries: no
  • Veins: yes, a little
62
Q

Why does the right side of the heart contain less cardiac muscle than the left side?

A

The right side of the heart pumps blood into a lower-resistance circuit and must do so at lower pressures; therefore, it requires less muscle

63
Q

What percentage of plasma to cells is blood composed of?

A
  • 55% plasma

- 45% cells

64
Q

What is plasma?

A

The liquid portion of blood, which is an aqueous mixture of nutrients, salts, respiratory gases, hormones and blood proteins

65
Q

What are the three major categories of the cellular component of blood?

A
  • Erythrocytes
  • Leukocytes
  • Platelets
66
Q

Blood cells are all formed from what type of cell? Where do they originate from?

A

From hematopoietic stem cells, which originate in the bone marrow

67
Q

What is an erythrocyte?

A

Specialized cell designed for oxygen transport

68
Q

How is oxygen bound to an erythrocyte?

A
  • Each molecule of hemoglobin contained in a red blood cell can bind four molecules of oxygen
  • Oxygen does not dissolve in the aqueous cytoplasm of the cell as it is nonpolar
69
Q

What is the function of the biconcave structure of red blood cells?

A
  • The shape assists them in traveling through tiny capillaries
  • The shape increases the cell’s surface area, which allows for greater gas exchange
70
Q

What happens when red blood cells mature? Why?

A
  • When they mature, the nuclei, mitochondria, and other membrane-bound organelles are lost
  • Makes space for the molecules of hemoglobin
71
Q

What kind of biochemical mechanisms do red blood cells carry-out for energy purposes?

A

Glycolysis with lactic acid (arising from fermentation) as the main by-product

72
Q

Can red blood cells divide? Why or why not?

A

No, since they lack nuclei

73
Q

How long can erythrocytes survive in the bloodstream? How are they degraded?

A
  • 120 days

- The cells in the liver and spleen phagocytize old red blood cells and recycle them for their parts

74
Q

What is a hematocrit measure?

A

Measurement of how much of the blood sample consists of red blood cells, given as a percentage

75
Q

What is a normal hemoglobin amount for males and females?

A
  • Males: 13.5 and 17.5

- Females: 12.0 and 16.0

76
Q

What is a normal hematocrit amount for males and females?

A
  • Males: 41 and 53%

- Females: 36 and 46%

77
Q

What percent of total blood volume do leukocytes comprise?

A

Less than one percent

78
Q

What are the two classes of leukocytes?

A
  • Granulocytes

- Agranulocytes

79
Q

Name the three granulocytes.

A

Neutrophils, eosinophils, and basophils

80
Q

What are granulocytes?

A

Leukocytes that contain cytoplasmic granules that are visible by microscopy

81
Q

What is the function of the granules in granulocytes? What are they involved in?

A
  • The granules contain a variety of compounds that are toxic to invading microbes, and their contents can be released through exocytosis
  • Involved in inflammatory reactions, allergies, pus formation, and destruction of bacteria and parasites
82
Q

Name the two agranulocytes.

A

Lymphocytes and monocytes

83
Q

What is the primary function of lymphocytes?

A

Involved in the specific immune response, the body’s targeted fight against particular pathogens, such as viruses and bacteria

84
Q

Many vaccines work by training ___________, which help our body learn from experience and are prepared to mount a fast response upon repeated exposure to familiar pathogens.

A

lymphocytes

85
Q

Where do B-cells mature? What are they responsible for?

A
  • Spleen or in lymph nodes

- Responsible for antibody generation

86
Q

Where do T-cells mature? What are they responsible for?

A
  • Thymus

- Kill virally infected cells and activate other immune cells

87
Q

What is the primary function of monocytes?

A

Phagocytize foreign matter such as bacteria

88
Q

Once they leave the bloodstream and enter an organ, monocytes are renamed __________.

A

macrophages

89
Q

What is the macrophage population called in the central nervous system, skin, and bone?

A
  • CNS: microglia
  • Skin: Langerhans cells
  • Bone: osteoclasts
90
Q

What are thrombocytes (platelets)? What are they released from?

A

Cell fragments or shards released from cells in the bone marrow known as megakaryocytes

91
Q

What is the primary function of platelets?

A

Assist in blood clotting

92
Q

What is the production of blood cells and platelets called? What is it triggered by?

A
  • Hematopoiesis

- Hormones, growth factors, cytokines

93
Q

What is the function of erythropoietin? What is it secreted by?

A
  • Secreted by the kidney

- Stimulates mainly RBC development

94
Q

What is the function of thrombopoietin? What is it secreted by?

A
  • Secreted by the liver and kidney

- Stimulates mainly platelet development

95
Q

What are the two major antigen families relevant for blood groups?

A
  • ABO antigens

- Rh factor

96
Q

What are the four blood types?

A
  • A
  • B
  • AB
  • O
97
Q

Which ABO antigens are dominant, and which is recessive?

A
  • A and B are dominant

- O is recessive

98
Q

What are the antigens produced by O? What are the antibodies produced? What can it donate to? What can it receive from?

A
  • Antigens: none
  • Antibodies: anti-A and anti-B
  • Can donate to A, B, AB, O (universal donor)
  • Can receive from O only
99
Q

What are the antigens produced by A? What are the antibodies produced? What can it donate to? What can it receive from?

A
  • Antigens: A
  • Antibodies: anti-B
  • Can donate to A, AB
  • Can receive from A, O
100
Q

What are the antigens produced by B? What are the antibodies produced? What can it donate to? What can it receive from?

A
  • Antigens: B
  • Antibodies: anti-A
  • Can donate to B, AB
  • Can receive from B, O
101
Q

What are the antigens produced by AB? What are the antibodies produced? What can it donate to? What can it receive from?

A
  • Antigens: A and B
  • Antibodies: none
  • Can donate to AB only
  • Can receive from A, B, AB, O (universal recipient)
102
Q

What is the Rh factor?

A

The presence (+) or absence (-) of the specific allele D

103
Q

Rh-positivity follows what kind of inheritance?

A
  • Autosomal dominant inheritance

- One positive allele is enough for the protein to be expressed

104
Q

What is erythroblastosis fetalis?

A
  • If a women is Rh- and her fetus is Rh+, she will begin making antibodies against it
  • Any subsequent pregnancy in which the fetus is Rh+ will present a problem
  • Maternal anti-Rh antibodies can cross the placenta and attack the fetal blood cells, resulting in hemolysis of the fetal cells
105
Q

Which cell type(s) in blood do not contain nuclei?

A

Erythrocytes and platelets

106
Q

What is the definition of blood pressure? What is it measured with? How is it expressed?

A
  • A measure of the force per unit area exerted on the wall of the blood vessels
  • Measured with a sphygmomanometer
  • Expressed as a ratio of the systolic to diastolic pressures
107
Q

When does blood pressure drop during circulation? When is the largest drop?

A
  • Gradually drops from the arterial to venous circulation

- The largest drop occurs across the arterioles

108
Q

How can Ohm’s law (V = IR) be translated into circulation?

A
  • P = CO x TPR
  • P is the pressure differential across the circulation
  • CO is the cardiac output
  • TPR is the total peripheral resistance
109
Q

What is the effect of opening capillary beds that are all in parallel with each other?

A

Decreases vascular resistance (like adding another resistor in parallel) and, assuming the body can compensate, increase cardiac output

110
Q

How is blood pressure regulated?

A
  • Using baroreceptors in the walls of the vasculature

- Baroreceptors detect changes in the mechanical forces on the walls of the vessel

111
Q

What do baroreceptors signal when blood pressure is too low?

A

Stimulate the sympathetic nervous system, which causes vasoconstriction, increasing blood pressure

112
Q

What happens when chemoreceptors sense that blood osmolarity is too high? What does it indicate?

A
  • Possible dehydration
  • Promotes the release of ADH, which is made in the hypothalamus and stored in the posterior pituitary, which increases the reabsorption of water and blood pressure
113
Q

What is the function of atrial natriuretic peptide (ANP)?

A

Aids in the loss of salt within the nephron, acting as a natural diuretic with loss of fluid when blood pressure is too high

114
Q

What is a normal partial pressure of O2 (PaO2)? Why is it inconvenient?

A
  • 70 - 100 mgHg

- Since it involves taking a sample of blood from an artery

115
Q

What is oxygen saturation? How is it measured?

A
  • Percentage of hemoglobin molecules carrying oxygen (around 97%)
  • Easily measured using a finger probe
116
Q

Explain the feedback-like (spiralling forward) mechanism of oxygen bound to hemoglobin. What is it called?

A
  • As heme groups acquire an oxygen molecule, the affinity increases due to conformational changes
  • With the removal of one molecule of O, the affinity of heme for oxygen decreases, making it easier for oxygen to leave the groups
  • Cooperative binding
117
Q

The cooperative binding curve of oxygen to hemoglobin looks like what?

A

Sigmoidal (S-shaped)

118
Q

What is the partial pressure of O2 in the lungs, in the tissues at rest, and in tissues during exercise?

A
  • Lungs: 100%
  • Tissues during rest: 40%
  • Tissues during exercise: 20%
119
Q

The vast majority of CO2 exists in the blood as what? Why?

A
  • HCO3- (bicarbonate ion)

- As an ion, it has high solubility in water, making it an effective method of transport

120
Q

What happens when CO2 enters a red blood cell?

A

It encounters carbonic anhydrase, which catalyzes the combination reaction between CO2 and water to form carbonic acid (H2CO3)

121
Q

What does carbonic acid dissociate into?

A

A proton and the bicarbonate anion

122
Q

What happens when HCO3- enters the alveolar capillaries?

A

Combines with a proton to form H2CO3, and is catalyzed by carbonic anhydrase to CO2 (and excreted)

123
Q

What is the Bohr effect? How does it affect the oxyhemoglobin curve?

A
  • Increased CO2 production causes a right shift in the bicarbonate buffer equation, resulting in increased H+
  • H+ binds to hemoglobin, reducing its affinity for oxygen
  • Causes a right shift in the oxyhemoglobin curve
  • Results in greater unloading of oxygen into the tissues
124
Q

What are the five factors that can cause a right shift in the oxyhemoglobin dissociation curve? What does that reflect?

A
  • High partial pressure of CO2
  • High H+
  • Low pH
  • High temperature
  • High concentration of 2,3-biphosphoglycerate
  • Indicates a decreased affinity for oxygen
125
Q

How can the renal system compensate for hyperventilation (excess CO2 blown off)?

A

Increases the excretion of bicarbonate, which brings the pH back to normal

126
Q

How can the bicarbonate buffer system compensate for renal tubular acidosis type I, in which the kidneys are unable to excrete acid effectively?

A

The excess CO2 formed in the process can be exhaled, and the person may increase respiratory rate to compensate, bringing the pH back to normal

127
Q

How does fetal hemoglobin compare to adult hemoglobin? How does that affect the oxyhemoglobin dissociation curve?

A
  • Fetal hemoglobin has a higher affinity for oxygen

- Left-shifted curve compared to adult hemoglobin

128
Q

Where are carbohydrates and amino acids absorbed into the bloodstream? How do they enter systemic circulation?

A
  • Absorbed into the capillaries of the small intestine

- Via the hepatic portal system

129
Q

How are fats absorbed into the blood stream? How do they enter systemic circulation?

A
  • Absorbed into lacteals in the small intestine

- Bypassing the hepatic portal circulation to enter systemic circulation via the thoracic duct

130
Q

What happens when peptide hormones reach their target tissue?

A

They activate cell-surface receptors

131
Q

What happens when steroid hormones reach their target tissue?

A

They diffuse into the cell to activate intracellular or intranuclear receptors

132
Q

What are the two essential pressure gradients to maintain a proper balance of fluid volume and solute concentrations between the blood and the interstitium?

A
  • Hydrostatic pressure

- Osmotic pressure

133
Q

What is hydrostatic pressure?

A
  • The force per unit area that the blood exerts against the vessel walls
  • Pushes fluid out of vessels
  • Dependent on blood pressure driven by the heart and the elastic arteries
134
Q

What is osmotic pressure? What is it also called?

A
  • Pulls fluid back into the vessels
  • Dependent on the number of particles (usually proteins) dissolved in the plasma
  • Oncotic pressure
135
Q

At the arteriole end of a capillary bed, how does hydrostatic pressure compare to oncotic pressure?

A
  • Hydrostatic > oncotic

- Net efflux of water from the circulation

136
Q

At the venule end of the capillary bed how does hydrostatic pressure compare to oncotic pressure?

A
  • Hydrostatic < oncotic

- Net influx of water back into the circulation

137
Q

What are Starling forces?

A

Balance between the hydrostatic pressure and oncotic pressure, which is essential for maintaining proper fluid volumes and solute concentrations

138
Q

Accumulation of excess fluid in the interstitium results in a condition called ______.

A

edema

139
Q

How does lymphatic fluid returned to the central circulatory system?

A

By way of a channel called the thoracic duct

140
Q

What are clots composed of? What do they prevent?

A
  • Coagulation factors (proteins) and platelets

- Prevent blood loss

141
Q

What happens when the endothelium of a blood vessel is damaged?

A

Exposes the underlying connective tissue, which contains collagen and a protein called tissue factor

142
Q

What happens when platelets come into contact with exposed collagen?

A
  • They sense this as evidence of injury

- They release their contents and begin to aggregate

143
Q

What are coagulation factors secreted by? What is their function?

A
  • Secreted by the liver

- Sense tissue factor and initiate a complex activation cascade

144
Q

What is the endpoint of the coagulation activation cascade?

A
  • Activation of prothrombin to form thrombin by thromboplastin
  • Thrombin can then convert fibrinogen into fibrin
  • Fibrin acts as a net to capture RBCs and other platelets, which forms a stable clot
145
Q

How is a blood clot broken down?

A

Plasmin, which is generated from plasminogen

146
Q

In bacterial sepsis, a number of capillary beds throughout the body open simultaneously. What effect does this have on blood pressure?

A
  • Opening up more capillary beds, which are in parallel, will decrease the overall resistance of the circuit
  • Cardiac output will increase in an attempt to maintain constant blood pressure

MCAT: Biology (12 decks)

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