INB 365 - Exam 3

Flashcard 1
Q: At what age does the heart start working and how long does it continue?
A: The heart begins working at 3 weeks old and continues until death.

Flashcard 2
Q: What are the main components of the cardiovascular system?
A: Pumps (the heart) and pipes (blood vessels).

Flashcard 3
Q: How does the sympathetic nervous system affect the heart and blood vessels?
A: It makes the heart pump harder and causes blood vessel dilation.

Flashcard 4
Q: List the major parts of the heart's anatomy needed for understanding its function.
A: Left and right atrium, left and right ventricle, four valves (AV and semilunar), and four main vessels connected to these valves.

Flashcard 5
Q: What is the pathway of blood through the heart starting from the vena cava?
A: Vena cava → Right atrium → Tricuspid valve → Right ventricle → Pulmonary semilunar valve → Pulmonary trunk → Lungs → Pulmonary veins → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta.

Flashcard 6
Q: What is the function of valves in the cardiovascular system?
A: They prevent the backflow of blood, ensuring unidirectional flow.

Flashcard 7
Q: What unique feature connects heart muscle fibers and what is its function?
A: Intercalated discs, which pin the cells together and allow coordinated contraction.

Flashcard 8
Q: Define the role of gap junctions in heart muscle fibers.
A: They connect cells and function as ion channels to help generate action potentials, allowing the whole heart to contract together.

Flashcard 9
Q: What factors influence blood flow and pressure in the cardiovascular system?
A: Pressure gradient, resistance in blood vessels, and vessel radius.

Flashcard 10
Q: What is the relationship between flow, pressure, and resistance?
A: Flow depends on the pressure gradient and inversely on resistance.

Flashcard 11
Q: Where is blood pressure highest and lowest in the cardiovascular system?
A: Highest in the aorta and arteries, lowest in veins and the vena cava.

Flashcard 12
Q: Why is low velocity of blood in capillaries important?
A: It allows for efficient nutrient exchange.

Flashcard 13
Q: What causes muscle contraction in the sarcomere?
A: Myosin binds to actin when troponin binds calcium, moving tropomyosin aside.

Flashcard 14
Q: What is the function of the sarcoplasmic reticulum (SR) in muscle cells?
A: It stores calcium and releases it to trigger contraction.

Flashcard 15
Q: What prevents the heart from experiencing tetanus?
A: The long refractory period of contractile cells.

Flashcard 16
Q: What is an EKG and what does it measure?
A: An EKG (electrocardiogram) measures the electrical activity of the heart in two dimensions, focusing on the shape and intensity of the curves.

Flashcard 17
Q: What does the P-wave on an EKG represent?
A: Atrial depolarization.

Flashcard 18
Q: Explain what the QRS complex indicates.
A: It represents the depolarization of the ventricles.

Flashcard 19
Q: Why is atrial repolarization not visible on an EKG?
A: It occurs at the same time as ventricular depolarization and is masked by the QRS complex.

Flashcard 20
Q: Describe first-degree heart block and its effect on the EKG.
A: It occurs when the signal from the SA node to the AV node is delayed, shown by a prolonged PR interval.

Flashcard 21
Q: What pathway does the electrical signal in the heart follow starting from the SA node?
A: SA node → Both atria (P-wave) → AV node (PR segment for delay) → Bundle branches → Purkinje fibers → Ventricles (QRS complex).

Flashcard 22
Q: What is the significance of the PR interval on an EKG?
A: It indicates the time for electrical conduction from the SA node to the AV node and reflects atrial contraction.

Flashcard 23
Q: What does the QT interval represent?
A: The time from the start of ventricular depolarization to the end of ventricular repolarization, covering the refractory period.

Flashcard 24
Q: What are the roles of alpha-1 and beta-1 receptors in the cardiovascular system?
A: Beta-1 receptors increase heart pump function, while alpha-1 receptors cause vasoconstriction and vasodilation, affecting blood pressure.

Flashcard 25
Q: What happens when the sympathetic nervous system is activated during exercise?
A: Increased heart rate and pressure gradient, leading to increased blood flow to support higher oxygen and nutrient demands.

Flashcard 26
Q: Describe the process of muscle contraction from a motor neuron signal to myosin binding actin.
A: 1. Motor neuron releases acetylcholine → 2. Binds to nicotinic receptors on motor end plate → 3. Graded potential triggers action potential → 4. Travels through T-tubules → 5. DHP receptor activates RyR on SR → 6. Calcium is released → 7. Binds to troponin → 8. Tropomyosin moves → 9. Myosin binds to actin → 10. Power stroke.

Flashcard 27
Q: What is the role of ATP in muscle contraction and relaxation?
A: ATP binds to myosin to release it from actin, and ATP-driven pumps return calcium to the SR for muscle relaxation.

Flashcard 28
Q: What characterizes the refractory period of action potentials in skeletal and heart muscles?
A: Skeletal muscle: 2-4 ms, allowing for rapid action potentials and potential tetanus.
Heart muscle: 200-300 ms, preventing tetanus and ensuring proper relaxation.

Flashcard 29
Q: How do pacemaker cells generate action potentials?
A: Pacemaker cells in the SA node spontaneously depolarize due to fast sodium inflow, followed by calcium channel activation and potassium outflow for repolarization.

Flashcard 30
Q: Why are valves crucial in the heart, and how do they function?
A: Valves prevent the backflow of blood, ensuring it moves in one direction. They only open when pressure pushes them correctly and cannot open backward.

Flashcard 31
Q: What is the equation for mean arterial pressure (MAP) and why is it important?
A: MAP = (1/3 systolic BP) + (2/3 diastolic BP). It represents the average blood pressure in arteries and is vital for assessing tissue perfusion.

Flashcard 32
Q: How does a complete heart block affect the EKG?
A: P waves and QRS complexes are dissociated; more P waves appear compared to QRS complexes due to independent AV node firing.

Flashcard 33
Q: What leads to ventricular fibrillation, and why is it dangerous?
A: Uncoordinated electrical signals cause the ventricles to quiver, preventing effective blood pumping and drastically reducing cardiac output.

Flashcard 34
Q: Explain calcium's role in muscle contraction.
A: Calcium binds to troponin, causing tropomyosin to move away from actin's binding site, allowing myosin to bind and initiate contraction.

Flashcard 35
Q: What is tetanus in muscle physiology, and what can cause it?
A: Tetanus is sustained muscle contraction due to continuous action potential generation. Causes include ion imbalances, ATP depletion, high temperatures, and lactic acid excess.

Flashcard 36
Q: What is the role of the sodium-calcium exchanger in heart cells?
A: It pumps calcium out of the cell after contraction, using secondary active transport, to help reset the cell for the next cycle.

Flashcard 37
Q: Why does blood flow from high to low pressure, and how is velocity affected by cross-sectional area?
A: Blood flows down a pressure gradient. As cross-sectional area increases (e.g., in capillaries), velocity decreases to facilitate nutrient exchange.

Flashcard 38
Q: How does the structure of cardiac muscle contribute to its function?
A: Cardiac muscle fibers are interconnected via intercalated discs with gap junctions, allowing for coordinated contraction and action potential propagation.

Flashcard 39
Q: What is the function of tropomyosin during muscle relaxation?
A: Tropomyosin covers the binding sites on actin, preventing myosin from binding when the muscle is relaxed.

Flashcard 40
Q: How do sarcomeres shorten during muscle contraction?
A: The thick (myosin) and thin (actin) filaments slide past each other as myosin heads pull on actin, shortening the sarcomere from one Z-disc to another.

Flashcard 41
Q: How does blood flow into the ventricles, and what percentages are passive vs. active?
A: 80% through passive filling, 20% via atrial contraction.

Flashcard 42
Q: Describe the pressure-volume curve for the left ventricle from end-systolic to end-diastolic points.
A: Starts at low volume (~65 mL) and low pressure post-contraction. AV valve opens, filling increases volume, and atrial contraction boosts volume/pressure. Pressure rises further with no volume change until the aortic semilunar valve opens and blood is ejected.

Flashcard 43
Q: When are the first and second heart sounds heard, and what do they signify?
A: First sound at the AV valve closing, second at the semilunar valve closing, marking the beginning and end of ventricular contraction.

Flashcard 44
Q: What do points B and D represent on the pressure-volume loop?
A: B: End-diastolic volume. D: End-systolic volume.

Flashcard 45
Q: What happens to ventricular pressure and volume during isovolumetric contraction?
A: Volume remains constant, but pressure rises sharply as the ventricles contract.

Flashcard 46
Q: How is stroke volume defined, and what is a typical value?
A: Stroke volume is the difference between end-diastolic and end-systolic volumes, typically 70 mL.

Flashcard 47
Q: What is the equation for cardiac output, and what influences it?
A: Cardiac output = Stroke volume × Heart rate. It increases with exercise or increased heart rate.

Flashcard 48
Q: How does the body increase venous return during exercise?
A: Through skeletal muscle contraction and the respiratory pump, which boosts venous return and stroke volume.

Flashcard 49
Q: Explain the dual innervation of the SA node and its effects.
A: Parasympathetic (acetylcholine on muscarinic receptors) decreases heart rate; sympathetic (norepinephrine on beta-1 receptors) increases heart rate.

Flashcard 50
Q: What is the function of funny channels in pacemaker cells?
A: They allow a net sodium influx, aiding in depolarization and heart rate regulation.

Flashcard 51
Q: What is Starlings' Law of the Heart?
A: The greater the preload (stretch from incoming blood), the stronger the subsequent contraction.

Flashcard 52
Q: How does norepinephrine affect cardiac contractility?
A: It binds to beta-1 receptors, enhancing calcium influx, which increases the force and speed of contractions.

Flashcard 53
Q: Define preload and afterload and their impacts on cardiac function.
A: Preload: blood volume entering ventricles, boosting cardiac output when increased. Afterload: resistance ventricle overcomes to eject blood; high afterload hinders output.

Flashcard 54
Q: What mechanisms regulate blood pressure in response to high blood pressure?
A: Baroreceptors signal the medulla, prompting parasympathetic activity, reducing heart rate and causing vasodilation.

Flashcard 55
Q: How is mean arterial pressure (MAP) calculated?
A: MAP = Diastolic pressure + 1/3 Pulse pressure or 2/3 Diastolic + 1/3 Systolic pressure.

Flashcard 56
Q: What is the role of the aorta’s elastic layer?
A: To handle stroke volume by expanding and recoiling to maintain continuous blood flow.

Flashcard 57
Q: Explain the relationship between cardiac output, resistance, and blood flow.
A: Flow depends on pressure gradients and vessel resistance. Increasing resistance or lowering cardiac output reduces flow.

Flashcard 58
Q: How do capillaries facilitate nutrient exchange?
A: With a thin, one-cell-thick layer of epithelium for easy diffusion of gases and nutrients.

Flashcard 59
Q: How does hypertension affect the heart?
A: Increases workload, forcing the heart to contract more strongly to maintain blood flow.

Flashcard 60
Q: Describe the baroreflex when blood pressure drops.
A: Baroreceptors signal the medulla to activate the sympathetic system, raising heart rate and causing vasoconstriction to restore pressure.

Flashcard 61
Q: What is the sequence of events during the cardiac cycle in relation to the pressure-volume loop?
A: The cycle starts at low volume and pressure post-contraction. The AV valve opens (passive filling), volume increases with the atrial contraction (B), pressure rises (C) as the aortic semilunar valve opens and blood is ejected, then pressure remains high until the semilunar valve closes (D).

Flashcard 62
Q: What do points A, B, C, D, and E represent in the pressure-volume curve?
A:

• A: End-diastolic volume (maximum volume before contraction)

• B: Volume increases with atrial contraction; pressure starts to rise

• C: Aortic semilunar valve opens, blood ejection begins

• D: End-systolic volume (minimum volume after contraction)

• E: Systolic pressure (pressure during ejection)

• F: Diastolic pressure (pressure in arteries when the heart is at rest)

Flashcard 63
Q: How do the heart sounds correlate with the cardiac cycle?
A: The first heart sound occurs at point C (closure of the AV valves) during isovolumetric contraction, and the second heart sound at point D (closure of the semilunar valves) during isovolumetric relaxation.

Flashcard 64
Q: How does exercise affect cardiac output?
A: Exercise increases heart rate and stroke volume, leading to a higher cardiac output. Increased venous return during exercise enhances preload, thus increasing stroke volume.

Flashcard 65
Q: What factors contribute to venous return and how do they influence preload?
A: Factors include:

• Skeletal Muscle Contraction: Squeezes veins, pushing blood back to the heart.

• Respiratory Pump: Changes in thoracic pressure during breathing facilitate blood return.

• Sympathetic Activation: Increases venous tone, enhancing return and preload.

Flashcard 66
Q: Explain the role of the cardiovascular control center (CVCC) in blood pressure regulation.
A: Located in the medulla oblongata, the CVCC integrates signals from baroreceptors and adjusts heart rate and vessel diameter to maintain blood pressure homeostasis.

Flashcard 67
Q: What are the mechanisms of the sympathetic and parasympathetic nervous systems on heart rate?
A:

• Sympathetic: Norepinephrine binds to beta-1 adrenergic receptors, increasing heart rate and contractility.

• Parasympathetic: Acetylcholine binds to muscarinic receptors, decreasing heart rate by slowing depolarization.

Flashcard 68
Q: Describe the process of cardiac contractility and its regulation.
A: Contractility refers to the heart's strength of contraction, influenced by calcium availability. The sympathetic nervous system increases calcium influx, enhancing contractility. Increased contractility leads to more effective ejection of blood.

Flashcard 69
Q: How does preload affect stroke volume and cardiac output?
A: Increased preload enhances stroke volume due to greater ventricular stretch, resulting in stronger contractions and higher cardiac output.

Flashcard 70
Q: What is the relationship between afterload and cardiac output?
A: Afterload is the pressure the heart must overcome to eject blood. Higher afterload decreases stroke volume and cardiac output since the heart has to work harder against increased resistance.

Flashcard 71
Q: How is blood pressure influenced by vessel diameter?
A: Blood pressure is inversely related to vessel diameter; vasodilation decreases resistance and pressure, while vasoconstriction increases resistance and pressure.

Flashcard 72
Q: What is mean arterial pressure (MAP), and how is it calculated?
A: MAP is the average blood pressure in the arteries during one cardiac cycle. It is calculated as MAP = Diastolic pressure + 1/3 (Systolic pressure - Diastolic pressure).

Flashcard 73
Q: Explain the significance of pulse pressure and its calculation.
A: Pulse pressure is the difference between systolic and diastolic pressure (Systolic - Diastolic) and indicates the force that the heart generates each time it contracts.

Flashcard 74
Q: Describe how the body responds to increased blood volume and the resultant effects on blood pressure.
A: Increased blood volume raises blood pressure, which triggers baroreceptors to activate the parasympathetic system, leading to decreased heart rate, increased vasodilation, and reduced blood pressure.

Flashcard 75
Q: What is the anatomical dead space in the respiratory system?
A: The anatomical dead space refers to the air in the conducting zones (nose, trachea, bronchi) that does not participate in gas exchange, accounting for about 150 mL in a typical adult.

Flashcard 76
Q: What are the four lung volumes and capacities that are essential for understanding respiratory physiology?
A:

• Tidal Volume (TV): ~600 mL (volume of air inhaled/exhaled during normal breathing)

• Inspiratory Reserve Volume (IRV): ~3000 mL (additional air inhaled after a normal inspiration)

• Expiratory Reserve Volume (ERV): ~1400 mL (additional air exhaled after a normal expiration)

• Residual Volume (RV): ~1000 mL (air remaining in lungs after maximal exhalation)

• Total Lung Capacity (TLC): Sum of all lung volumes (~6000 mL).

Flashcard 77
Q: Describe the mechanics of breathing and how pressure changes facilitate airflow.
A: During inhalation, diaphragm and intercostal muscles contract, increasing lung volume and decreasing intrapleural pressure, allowing air to flow in. Exhalation occurs when these muscles relax, decreasing volume and increasing pressure, pushing air out.

Flashcard 78
Q: Explain how surfactant functions in the lungs and its importance.
A: Surfactant reduces surface tension in the alveoli, preventing collapse and aiding in lung compliance. It is secreted by type II alveolar cells and is critical for normal respiratory function, especially in premature infants.

Flashcard 79
Q: What occurs during pneumothorax, and what are its consequences?
A: Pneumothorax occurs when air enters the pleural space, causing a loss of intrapleural pressure, leading to lung collapse. This can severely impair ventilation and gas exchange.