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0 - Dr. Hung's Kaplan MCAT Decks > 🌱 MCAT Biology Review - 7 > Flashcards

🌱 MCAT Biology Review - 7 Flashcards

(163 cards)

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1
Q

What is the correct sequence of a cardiac impulse?

A

SA node β†’ atria β†’ AV node β†’ bundle of His β†’ Purkinje fibers β†’ ventricles

This sequence is critical for normal heart rhythm.

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2
Q

True or False: Erythrocytes have nuclei located in the middle of the biconcave disc.

A

False

Erythrocytes do not contain nuclei.

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3
Q

What is the primary function of hemoglobin?

A

To transport oxygen

Hemoglobin’s affinity for O2 varies with conditions like pH and PaCO2.

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4
Q

Which blood type should an unconscious patient receive if there is no time to check blood type?

A

O-

O- is the universal donor and can be given in emergencies.

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5
Q

What is the effect of losing albumin due to kidney disease on capillary oncotic pressure?

A

Decreased oncotic pressure

Albumin helps maintain oncotic pressure in capillaries.

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6
Q

Fill in the blank: The _______ valve prevents backflow of blood from the right ventricle into the right atrium.

A

tricuspid

The tricuspid valve has three leaflets.

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7
Q

The right side of the heart is less muscular than the left side because it pumps blood to the _______.

A

lungs

The left side pumps blood throughout the body, requiring more muscle power.

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8
Q

What structure in the heart prevents backflow of blood from the ventricles into the atria?

A

Atrioventricular valves

These include the tricuspid and mitral valves.

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9
Q

What is the primary role of the cardiovascular system?

A

Movement of respiratory gases, nutrients, and wastes

It plays a crucial role in maintaining homeostasis.

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10
Q

Which vascular structure creates the most resistance to blood flow?

A

Arterioles

They regulate blood flow and pressure in the circulatory system.

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11
Q

During the last minute of breath-holding, what is likely to happen to the blood pH?

A

Decreased pH

Increased CO2 levels during breath-holding lead to acidosis.

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12
Q

What are the four humors according to the humoralism theory?

A
  • Black bile
  • Yellow bile
  • Phlegm
  • Blood

Humoralism was a dominant medical theory until the 19th century.

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13
Q

What was one of the primary treatments associated with humoralism?

A

Bloodletting

This practice involved withdrawing blood to restore balance among the humors.

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14
Q

True or False: The left side of the heart is more muscular than the right side.

A

True

This is necessary to maintain blood pressure throughout the body.

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15
Q

What is the name of the valve that separates the left ventricle from the aorta?

A

Aortic valve

It is a semilunar valve with three leaflets.

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16
Q

How does the cardiovascular system contribute to gas exchange?

A

By transporting oxygen and carbon dioxide to and from tissues

This is essential for cellular respiration.

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17
Q

What is the primary function of the heart?

A

Pumping blood into the systemic circulation

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18
Q

Why is the left side of the heart more muscular than the right side?

A

Blood leaving the left side must travel a considerable distance, requiring higher pressure

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19
Q

What is the pathway of electrical conduction in the heart?

A

SA node β†’ AV node β†’ bundle of His β†’ Purkinje fibers

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20
Q

What is the role of the SA node?

A

Generates 60-100 electrical signals per minute

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21
Q

What is the term for the additional volume of blood forced into the ventricles by atrial contraction?

A

Atrial kick

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22
Q

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

A

5-30 percent

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23
Q

What is the function of the AV node?

A

Delays the electrical signal to allow ventricles to fill completely

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24
Q

What allows for coordinated ventricular contraction?

A

Intercalated discs and gap junctions connecting muscle cells

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25
What is myogenic activity in cardiac muscle?
Ability to contract without neurological input
26
What is an electrocardiogram (ECG or EKG)?
A recording of the heart's electrical impulses
27
What does the P-wave in an EKG represent?
Atrial contraction
28
What does the QRS complex in an EKG represent?
Ventricular contraction
29
What does the T-wave in an EKG represent?
Ventricular repolarization
30
What are the two phases of a heartbeat?
Systole and diastole
31
What occurs during systole?
Ventricular contraction and closure of AV valves
32
What occurs during diastole?
Ventricles relax and fill with blood from the atria
33
What is cardiac output (CO)?
Total blood volume pumped by a ventricle in a minute
34
How is cardiac output calculated?
CO = HR Γ— SV (Heart Rate Γ— Stroke Volume)
35
What are the heart sounds referred to as?
Lub dub
36
What does the first heart sound (S1) signify?
Closure of the AV valves at the start of systole
37
What does the second heart sound (S2) signify?
Closure of the semilunar valves at the end of systole
38
What condition features a very rapid rate of ventricular contraction?
Ventricular tachycardia (v-tach)
39
What is the normal cardiac output for humans?
About 5 liters per minute
40
What are the three major types of blood vessels?
* Arteries * Veins * Capillaries
41
Which blood vessel carries blood away from the heart?
Arteries
42
What do capillaries branch into?
Venules
43
What is the function of coronary arteries?
To perfuse the heart musculature
44
What do arterioles lead to?
Capillaries
45
What is the function of coronary arteries?
To send blood to perfuse the heart musculature
46
What do capillaries join together to form?
Venules
47
What is the role of endothelial cells in blood vessels?
Help maintain the vessel by releasing chemicals for vasodilation and vasoconstriction
48
What happens to endothelial cells during an inflammatory response?
They allow white blood cells to pass through the vessel wall into the tissues
49
What is a heart attack also known as?
Myocardial infarction
50
What causes a heart attack?
Lack of blood flow through the coronary arteries
51
What do Ξ²-blockers do during a heart attack?
Block sympathetic stimulation of the heart, lowering heart rate and contractility
52
What is the primary function of arteries?
To move blood away from the heart
53
Which arteries contain deoxygenated blood?
Pulmonary arteries and umbilical arteries
54
What is the structure of capillaries?
Vessels with a single endothelial cell layer
55
What allows for easy diffusion of gases and nutrients in capillaries?
Thin walls
56
What type of blood do veins generally carry?
Deoxygenated blood
57
What is the role of valves in veins?
Prevent backflow of blood
58
What can result from failure of venous valves?
Varicose veins
59
What is deep vein thrombosis (DVT)?
A clot in the deep veins of the leg
60
What does pulmonary embolism refer to?
Clots that travel to the lungs
61
What external force helps propel blood forward in veins?
Skeletal muscles
62
What is the definition of circulation?
Circular movement of blood through the body
63
What is the pathway of blood flow starting from the venae cavae?
Right atrium β†’ Right ventricle β†’ Pulmonary arteries β†’ Lungs β†’ Pulmonary veins β†’ Left atrium β†’ Left ventricle β†’ Aorta
64
What is the purpose of the hepatic portal system?
To allow blood from the gut to pass through the liver
65
What is the primary component of plasma?
Liquid portion of blood
66
What are the three major categories of blood cells?
* Erythrocytes * Leukocytes * Platelets
67
What is the primary function of erythrocytes?
Oxygen transport
68
What is the liquid portion of blood called?
Plasma
69
What is serum?
Plasma without clotting factors
70
What is the main role of leukocytes?
Defense against infection
71
How are platelets produced?
From megakaryocytes in the bone marrow
72
What type of blood cells do not contain a nucleus?
Erythrocytes
73
What is the composition of blood by volume?
* 55% liquid * 45% cells
74
What is the primary function of erythrocytes?
Oxygen transport ## Footnote Erythrocytes also carry carbon dioxide and other wastes from peripheral tissues.
75
How many molecules of hemoglobin does each erythrocyte contain?
About 250 million molecules ## Footnote Each hemoglobin molecule can bind four molecules of oxygen.
76
What is the shape of red blood cells and why is it beneficial?
Biconcave ## Footnote This shape assists in traveling through capillaries and increases surface area for gas exchange.
77
What organelles do mature red blood cells lack?
Nuclei, mitochondria, and other membrane-bound organelles ## Footnote This allows more space for hemoglobin and prevents the cell from consuming oxygen it carries.
78
What is the lifespan of erythrocytes in the bloodstream?
120 days ## Footnote After which, they are phagocytized by cells in the liver and spleen.
79
What two measures are commonly used for red blood cells in a complete blood count?
Hemoglobin and hematocrit ## Footnote Hemoglobin measures the quantity of hemoglobin, while hematocrit measures the percentage of blood volume that consists of red blood cells.
80
What is a normal hemoglobin range for phenotypical males?
13.5 to 17.5 g/dL ## Footnote For females, the range is 12.0 to 16.0 g/dL.
81
How many leukocytes are typically found per microliter of blood?
4,500-11,000 leukocytes ## Footnote This is less than 1 percent of total blood volume.
82
What are the two main classes of leukocytes?
Granulocytes and agranulocytes ## Footnote Granulocytes include neutrophils, eosinophils, and basophils; agranulocytes include lymphocytes and monocytes.
83
What is the role of lymphocytes?
Specific immune response ## Footnote They act against particular pathogens and help maintain long-term memory of pathogen recognition.
84
Where do B-cells and T-cells mature?
B-cells mature in the bone marrow; T-cells mature in the thymus ## Footnote B-cells are responsible for antibody generation, and T-cells kill virally infected cells.
85
What are monocytes renamed when they enter an organ?
Macrophages ## Footnote Macrophages play a role in phagocytizing foreign matter.
86
What are thrombocytes and their function?
Platelets; assist in blood clotting ## Footnote Thrombocytes are cell fragments released from megakaryocytes in the bone marrow.
87
What is hematopoiesis?
The production of blood cells and platelets ## Footnote Triggered by hormones, growth factors, and cytokines.
88
What are the two major antigen families relevant for blood groups?
ABO antigens and Rh factor ## Footnote These antigens are crucial for blood type compatibility.
89
What is the genotype of type O blood?
ii ## Footnote Type O blood does not express A or B antigens.
90
Who are considered universal donors?
People with type O blood ## Footnote Type O blood does not cause ABO-related hemolysis.
91
What is the significance of the Rh factor?
Indicates the presence or absence of the D antigen ## Footnote Rh-positivity follows autosomal dominant inheritance.
92
What condition can arise from Rh incompatibility during pregnancy?
Erythroblastosis fetalis ## Footnote Occurs when an Rh-negative mother produces antibodies against Rh-positive fetal blood cells.
93
How can erythroblastosis fetalis be prevented?
By administering Rh-immunoglobulin (RhoGAM) ## Footnote This prevents the mother from producing anti-Rh antibodies.
94
What is erythroblastosis fetalis?
A condition that can occur in subsequent Rh-mismatched pregnancies, typically avoided by administering Rh-immunoglobulin (RhoGAM) to the Rh– parent during pregnancy and after delivery. ## Footnote Erythroblastosis fetalis occurs when an Rh– mother carries an Rh+ fetus, leading to the mother's immune system attacking the fetus's red blood cells.
95
What are the components of plasma?
Water, electrolytes, proteins, hormones, nutrients, and waste products. ## Footnote Plasma is the liquid component of blood and makes up about 55% of its volume.
96
An individual with B+ blood could receive blood from which types?
* B+ * B– * O+ * O– ## Footnote B+ individuals can receive blood from B+ and B– donors, as well as O+ and O– donors due to the presence of Rh factor.
97
What does a hematocrit measure?
The proportion of blood volume that is occupied by red blood cells, expressed as a percentage. ## Footnote Normal hematocrit values are typically around 38-46% for women and 40-54% for men.
98
Which types of leukocytes are involved in the specific immune response?
* B cells * T cells ## Footnote B cells are responsible for antibody production, while T cells are involved in cell-mediated immunity.
99
Where do platelets come from?
They originate from megakaryocytes in the bone marrow. ## Footnote Platelets play a crucial role in blood clotting.
100
What is the normal range for blood pressure?
90/60 to 120/80 mmHg. ## Footnote Blood pressure is expressed as systolic over diastolic pressure.
101
True or False: The largest drop in blood pressure occurs across the veins.
False. ## Footnote The largest drop in blood pressure occurs across the arterioles, not veins.
102
What does the pressure differential equation in circulation represent?
Ξ”P = CO x TPR ## Footnote Where Ξ”P is the pressure differential, CO is cardiac output, and TPR is total peripheral resistance.
103
What happens to blood pressure when baroreceptors detect low pressure?
They stimulate the sympathetic nervous system, causing vasoconstriction to increase blood pressure. ## Footnote Baroreceptors are specialized neurons that sense mechanical changes in blood vessels.
104
What is the role of antidiuretic hormone (ADH)?
It increases water reabsorption in the kidneys, thus increasing blood volume and pressure. ## Footnote ADH is produced in the hypothalamus and stored in the posterior pituitary.
105
Fill in the blank: Oxygen is primarily carried in the blood by _______.
hemoglobin ## Footnote Hemoglobin is a protein that binds oxygen molecules in red blood cells.
106
What is the normal range for partial pressure of oxygen (PaO2) in the blood?
70-100 mmHg. ## Footnote PaO2 is a measure of the amount of oxygen dissolved in arterial blood.
107
What is the oxyhemoglobin dissociation curve?
A graph that shows the relationship between the partial pressure of oxygen and the saturation of hemoglobin with oxygen. ## Footnote The curve typically has a sigmoidal shape due to cooperative binding.
108
What is the Bohr effect?
A right shift in the oxyhemoglobin dissociation curve due to increased carbon dioxide and decreased pH, leading to reduced hemoglobin affinity for oxygen. ## Footnote This effect allows more oxygen to be released to tissues during high metabolic activity.
109
How is carbon dioxide primarily transported in the blood?
As bicarbonate ions (HCO3–) formed from carbonic acid (H2CO3). ## Footnote Carbon dioxide reacts with water in red blood cells to form carbonic acid, which dissociates into bicarbonate and protons.
110
What is the function of carbonic anhydrase?
It catalyzes the conversion of carbon dioxide and water into carbonic acid. ## Footnote This reaction is crucial for the transport of CO2 in the bloodstream.
111
What is the significance of a right shift in the oxyhemoglobin dissociation curve?
It represents greater unloading of oxygen into the tissues during conditions like exercise. ## Footnote A right shift occurs at a partial pressure of 20 mmHg O2, typical for exercising muscle.
112
What physiological changes cause a right shift of the oxyhemoglobin curve during exercise?
* Increased PaCO2 * Increased [H+] (decreased pH) * Increased temperature ## Footnote Mnemonic: 'Exercise is the right thing to do.'
113
What is the effect of fetal hemoglobin compared to adult hemoglobin on the oxyhemoglobin dissociation curve?
Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin, resulting in a left-shifted curve. ## Footnote This allows fetal red blood cells to effectively extract oxygen from maternal hemoglobin.
114
What is the bicarbonate buffer system's role in blood pH regulation?
It links the respiratory and renal systems, helping maintain blood pH by adjusting bicarbonate and CO2 levels. ## Footnote Hyperventilation can lead to respiratory alkalosis, while renal tubular acidosis type I leads to metabolic acidosis.
115
What are the two opposing pressure gradients that maintain fluid balance in the bloodstream?
* Hydrostatic pressure * Osmotic (oncotic) pressure ## Footnote Hydrostatic pressure pushes fluid out, while osmotic pressure pulls fluid back in.
116
What causes edema in the tissues?
An imbalance between hydrostatic and osmotic pressures, leading to excess fluid accumulation in the interstitium. ## Footnote Blockage of lymph nodes can also contribute to edema.
117
What initiates the coagulation cascade in blood clotting?
Exposure of subendothelial compounds, including collagen and tissue factor. ## Footnote Platelets aggregate and release contents in response to injury.
118
What is the role of thrombin in blood clotting?
Thrombin converts fibrinogen into fibrin, forming a stable clot. ## Footnote The clot captures red blood cells and platelets, preventing blood loss.
119
What is the main function of platelets in the vascular system?
To protect the vascular system by forming clots to minimize blood loss during injury. ## Footnote Clots consist of coagulation factors and platelets.
120
What is the pathway of blood flow through the heart and circulatory system?
right atrium β†’ right ventricle β†’ pulmonary artery β†’ lungs β†’ pulmonary veins β†’ left atrium β†’ left ventricle β†’ aorta β†’ arteries β†’ arterioles β†’ capillaries β†’ venules β†’ veins β†’ venae cavae β†’ right atrium ## Footnote The left side of the heart contains more muscle due to higher resistance.
121
What is the primary difference in structure between arteries and veins?
Arteries are thick, muscular, and elastic; veins are thin-walled, inelastic, and have valves. ## Footnote Arteries propel blood forward while veins accommodate large volumes.
122
What are the components of cardiac output?
Heart rate and stroke volume. ## Footnote Cardiac output reflects the volume of blood the heart pumps per minute.
123
What is the role of carbonic anhydrase in the blood?
It catalyzes the conversion of carbon dioxide to bicarbonate ions and vice versa. ## Footnote This process is crucial for CO2 transport in the blood.
124
What is the structure of capillaries?
Capillaries have walls that are one cell thick and are sites of gas and solute exchange.
125
What type of blood vessels are veins?
Veins are inelastic, thin-walled structures that transport blood to the heart.
126
What is a portal system?
A portal system is one in which blood passes through two capillary beds in series.
127
What is the function of the hepatic portal system?
In the hepatic portal system, blood travels from the gut capillary beds to the liver capillary bed via the hepatic portal vein.
128
What is the function of the hypophyseal portal system?
In the hypophyseal portal system, blood travels from the capillary bed in the hypothalamus to the capillary bed in the anterior pituitary.
129
What is the renal portal system?
In the renal portal system, blood travels from the glomerulus to the vasa recta through an efferent arteriole.
130
What is blood composed of?
Blood is composed of cells and plasma, an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins.
131
What are erythrocytes?
Erythrocytes are red blood cells that lack mitochondria, a nucleus, and organelles to make room for hemoglobin.
132
What are leukocytes?
Leukocytes are white blood cells formed in the bone marrow and are crucial for the immune system.
133
What role do granular leukocytes play?
Granular leukocytes such as neutrophils, eosinophils, and basophils play a role in nonspecific immunity.
134
What are thrombocytes?
Thrombocytes are cell fragments from megakaryocytes required for coagulation.
135
What are blood antigens?
Blood antigens include the surface antigens A, B, and O, as well as the Rh factor (D).
136
What is the relationship between IA (A) and IB (B) alleles?
IA (A) and IB (B) alleles are codominant, while the i (O) allele is recessive.
137
What happens in Rh factor compatibility?
Positive Rh factor is dominant; an Rh-negative individual will create anti-Rh antibodies after exposure to Rh-positive blood.
138
What is blood pressure?
Blood pressure is the force per unit area exerted on the walls of blood vessels by blood.
139
How is blood pressure maintained?
Blood pressure is maintained by baroreceptor and chemoreceptor reflexes.
140
What are Starling forces?
Starling forces consist of hydrostatic pressure and osmotic (oncotic) pressure.
141
What is cooperative binding in hemoglobin?
Cooperative binding refers to the phenomenon where each successive oxygen bound to hemoglobin increases the affinity of the other subunits.
142
How is carbon dioxide transported in the blood?
Carbon dioxide is largely carried in the blood as carbonic acid, bicarbonate, and hydrogen ions.
143
What causes a right shift in the oxyhemoglobin dissociation curve?
A right shift can be caused by high PaCO2, high [H+], low pH, high temperature, and high concentration of 2,3-BPG.
144
What is the role of the coagulation cascade?
The coagulation cascade results in the formation of a clot over a damaged area of a blood vessel.
145
What stabilizes a clot?
Clots are stabilized by fibrin, which is activated by thrombin.
146
What is the function of plasma?
Plasma is an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins.
147
What is hematocrit?
Hematocrit measures the percentage of a blood sample occupied by red blood cells.
148
What happens if all autonomic innervation to the heart is lost?
The heart would continue beating at the intrinsic rate of the pacemaker (SA node), but heart rate could not be modified.
149
What is the function of the sinoatrial (SA) node?
The SA node initiates the electrical impulse for heart contractions.
150
What is the relationship between arteries and veins regarding wall thickness?
Arteries are thick-walled, while veins are thin-walled.
151
What is the role of valves in veins?
Valves in veins maintain one-way flow of blood toward the heart.
152
What is the significance of the Bohr effect?
The Bohr effect describes how decreasing pH lowers hemoglobin's affinity for oxygen.
153
What can cause a left shift in the oxyhemoglobin dissociation curve?
A left shift can be seen in fetal hemoglobin compared to adult hemoglobin.
154
What happens to oxygenation and Pa CO2 when holding one's breath for a prolonged period?
Oxygenation drops and Pa CO2 increases ## Footnote This leads to physiological changes in the blood chemistry.
155
What does increased carbon dioxide associate with to form?
Carbonic acid ## Footnote This reaction is part of the body's response to elevated CO2 levels.
156
What does carbonic acid dissociate into?
A proton and a bicarbonate anion ## Footnote This dissociation is crucial in regulating blood pH.
157
What metabolic process occurs due to low oxygen saturation in tissues?
Anaerobic metabolism ## Footnote This can lead to an increase in lactic acid.
158
What is the effect of anaerobic metabolism on blood pH?
It causes a decrease in pH ## Footnote Increased lactic acid contributes to acidosis.
159
Where does the cardiac conduction system start?
SA node ## Footnote The SA node is located near the top of the right atrium.
160
What is the location of the AV node in the cardiac conduction system?
Between the two AV valves ## Footnote The AV node plays a crucial role in electrical conduction in the heart.
161
Where is the bundle of His located?
Within the wall between the ventricles ## Footnote Damage to this area can affect cardiac function.
162
What is the greatest amount of resistance in the circulatory system provided by?
Arterioles ## Footnote Arterioles are muscular and can regulate blood pressure through contraction and dilation.
163
True or False: The left ventricular muscle is part of the cardiac conduction system.
False ## Footnote The left ventricular muscle is not involved in the conduction pathway.

0 - Dr. Hung's Kaplan MCAT Decks (36 decks)

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