Last of notes complete questions Flashcards
Cardiovascular Elements?
Heart, blood vessels, blood.
Main function of the cardiovascular system?
Delivers O₂/nutrients, removes CO₂/waste, transports hormones, regulates temperature/fluid balance, maintains acid–base balance, supports immunity.
Heart chambers?
Right atrium, right ventricle, left atrium, left ventricle.
Blood flow (right heart)?
Venae cavae → RA → RV → pulmonary valve → pulmonary arteries → lungs.
Blood flow (left heart)?
Pulmonary veins → LA → LV → aortic valve → aorta → body.
Why is the LV thick?
It pumps blood to the entire body and must generate high pressure.
Myocardium features?
Highly oxidative, dense capillaries, many mitochondria, intercalated discs for coordinated contraction.
Difference: Cardiac vs. Skeletal muscle?
Cardiac: small, branched, single nucleus, continuous involuntary contractions; Skeletal: large, long, multinucleated, voluntary intermittent contractions.
Coronary arteries?
Right coronary (supplies right heart) and left coronary (supplies left heart).
Intrinsic control of the heart?
Cardiac conduction system: SA node, AV node, AV bundle, and Purkinje fibers.
Intrinsic HR value?
Approximately 100 beats/min.
Role of the SA node?
Initiates the heartbeat with spontaneous depolarization.
Function of the AV node?
Delays the electrical signal to allow atrial contraction before ventricular contraction.
Purpose of Purkinje fibers?
Rapidly distribute impulses to ensure coordinated ventricular contraction.
Define the cardiac cycle.
The sequence of electrical and mechanical events during one heartbeat (systole and diastole).
Systole vs. diastole?
Systole: contraction/ejection phase; Diastole: relaxation/filling phase (diastole is about 2/3 of the cycle).
Stroke volume (SV) formula?
SV = EDV − ESV (e.g., 100 mL EDV − 40 mL ESV = 60 mL).
What is ejection fraction?
The ratio SV/EDV (e.g., 60 mL/100 mL = 60%).
Cardiac output formula?
CO = HR × SV (e.g., 70 bpm × 70 mL = 4900 mL/min, ~5 L/min).
Typical resting HR?
Between 60 and 100 beats/min; trained athletes may be as low as 35–40 bpm.
Estimated maximal heart rate?
220 minus age (e.g., for a 20-year-old: 220 − 20 = 200 bpm).
Extrinsic control: Parasympathetic NS?
Via the vagus nerve; decreases HR and contractility using acetylcholine.
Extrinsic control: Sympathetic NS?
Releases norepinephrine to increase HR and contractility.
Normal resting blood pressure?
Systolic: ~110–120 mmHg; Diastolic: ~70–80 mmHg.
Mean arterial pressure (MAP) estimate?
MAP ≈ (2/3 × DBP) + (1/3 × SBP).
Vascular resistance factors?
Depends on vessel length, blood viscosity, and especially radius (r⁴ relation).
Role of arterioles?
They regulate blood flow by vasoconstriction and vasodilation.
Local blood flow control?
Intrinsic mechanisms: metabolic (by-products, O₂/CO₂ levels), endothelial (NO, prostaglandins), and myogenic responses.
Functional sympatholysis?
Local reduction in sympathetic vasoconstriction in active muscles, allowing increased blood flow.
Mechanisms aiding venous return?
Venoconstriction, the skeletal muscle pump (with valves), and the respiratory pump.
Four steps in respiration?
Pulmonary ventilation, pulmonary diffusion, gas transport in blood, and capillary diffusion.
Air pathway through the respiratory system?
Nose/mouth → nasal cavity → pharynx → larynx → trachea → bronchi → alveoli.
Primary inspiratory muscles?
Diaphragm and external intercostals.
How does inspiration work?
Inspiratory muscles contract to expand the thoracic cavity, decreasing intrapulmonary pressure and drawing air in.
Accessory muscles for forced inspiration?
Scalenes, sternocleidomastoid, and pectorals.
Expiration process?
Normally passive via muscle relaxation and lung recoil; forced expiration involves active muscle contraction.
Muscles for forced expiration?
Internal intercostals, latissimus dorsi, quadratus lumborum, and abdominal muscles.
Pulmonary volumes measured by?
Spirometry (tidal volume, vital capacity, residual volume, and total lung capacity).
Define pulmonary diffusion.
Gas exchange between alveoli and blood across the alveolar-capillary membrane.
Alveolar-capillary membrane thickness?
Approximately 0.5–4 µm for efficient gas exchange.
Dalton’s law?
The total pressure equals the sum of the partial pressures of individual gases.
Atmospheric partial pressures?
At 760 mmHg: PN₂ ≈ 600.7 mmHg, PO₂ ≈ 159.1 mmHg, PCO₂ ≈ 0.2 mmHg.
Henry’s law significance?
The amount of gas dissolved in a liquid is proportional to its partial pressure.
Fick’s law?
Diffusion rate ∝ (Surface area × Pressure gradient) / Membrane thickness.
Alveolar O₂ exchange: key pressures?
Alveolar PO₂ ~105 mmHg, capillary PO₂ ~40 mmHg, resulting in pulmonary vein PO₂ ~100 mmHg.
CO₂ diffusion gradient?
Approximately 6 mmHg (from ~46 mmHg in pulmonary arteries to ~40 mmHg in alveoli).
Why does CO₂ diffuse efficiently?
Its diffusion constant is roughly 20 times greater than that of O₂.
Main oxygen transport method?
> 98% of O₂ is bound to hemoglobin; <2% is dissolved in plasma.
O₂–Hb dissociation curve in the lungs?
High PO₂ leads to nearly complete hemoglobin saturation.
O₂–Hb curve in tissues?
Lower PO₂ causes significant unloading of O₂ from hemoglobin.
Myoglobin’s role in muscles?
Stores oxygen and releases it when tissue PO₂ is very low.
Effect of pH and temperature on O₂ release?
Lower pH and higher temperature shift the curve right, enhancing O₂ unloading.
Central chemoreceptors?
Located in the medulla; respond to increased CO₂/H⁺ levels in cerebrospinal fluid.
Peripheral chemoreceptors?
Found in the carotid and aortic bodies; sensitive to changes in PO₂, PCO₂, and pH.
How does increased CO₂ affect breathing?
It raises H⁺ levels, stimulating an increase in the rate and depth of ventilation.
Anticipatory HR response?
HR increases slightly before exercise due to reduced vagal tone and increased sympathetic stimulation.
HR behavior during exercise?
HR increases with exercise intensity until reaching a plateau at maximal effort.
Steady-state HR?
The constant HR maintained during a steady exercise intensity.
Factors increasing stroke volume?
Higher preload, increased contractility, and decreased afterload.
Frank-Starling mechanism?
Increased EDV stretches the heart muscle, enhancing contractility and SV.
Example calculation of SV?
If EDV = 100 mL and ESV = 40 mL, then SV = 60 mL.
Example ejection fraction?
SV/EDV = 60 mL/100 mL = 60%.
Cardiac output at rest?
Approximately 5 L/min (e.g., 70 bpm × 70 mL ≈ 4900 mL/min).
Oxygen carrying capacity?
Approximately 20 mL O₂ per 100 mL of blood.
Max SBP during exercise?
May reach about 200 mmHg; trained athletes can reach 240–250 mmHg.
Maximal stroke volume ranges?
Typically 60–130 mL/beat; athletes may have 160–200 mL/beat.
Pulmonary diffusion capacity example?
At rest, about 21 mL O₂/min/mmHg; with an 11 mmHg gradient, ≈231 mL O₂/min.
Role of body position on SV?
Supine position increases venous return and SV compared to upright posture.
Importance of blood flow redistribution?
Directs more blood to active muscles and reduces flow to less active organs during exercise.
Local control of blood flow?
Adjusts vessel diameter via metabolic by-products, endothelial factors, and myogenic responses.
HR recovery significance?
A faster drop in HR post-exercise indicates better autonomic regulation and fitness.
Training effects on submaximal HR?
Trained individuals have a lower HR at the same workload due to increased SV and efficiency.
Maximal HR changes with training?
Maximal HR remains largely unchanged by training; it decreases primarily with age.
Training impact on cardiac output?
Maximal CO increases (mainly due to increased SV), while resting CO stays similar.
Pulmonary diffusion with exercise?
Improved lung perfusion increases diffusion capacity during maximal effort.
Capillarization adaptation?
Increased capillary density improves oxygen delivery and waste removal in muscles.
Role of the skeletal muscle pump?
Contractions help return blood to the heart by compressing veins.
Role of the respiratory pump?
Changes in intrathoracic pressure during breathing aid in venous return.
Definition of preload?
The end-diastolic volume stretching the ventricles prior to contraction.
Definition of afterload?
The pressure the ventricle must overcome to eject blood.
How is contractility increased?
Through sympathetic stimulation (norepinephrine/epinephrine) independent of EDV.
Types of cardiac hypertrophy?
Non-pathological (exercise-induced) and pathological (due to high blood pressure).
Intercalated discs function?
They connect cardiac cells for synchronized contraction.
How do gap junctions work?
They enable rapid electrical communication between cardiac cells.
Role of desmosomes?
They mechanically hold cardiac cells together during contraction.
Function of the pericardium?
Protects the heart and reduces friction via pericardial fluid.
Why is blood volume important?
It affects venous return, preload, and overall cardiac output.
How does exercise affect blood pressure?
SBP increases significantly; DBP changes little, leading to a higher MAP.
Effect of sympathetic stimulation on vessels?
It causes vasoconstriction, increasing resistance and blood pressure.
Effect of local vasodilation in muscles?
It overcomes sympathetic constriction, increasing blood flow to active muscles.
How does training affect plasma volume?
Training increases plasma volume, which enhances EDV and SV.
Why is the O₂ diffusion gradient critical?
It drives the movement of O₂ and CO₂ across the alveolar-capillary membrane.
How do alveolar and capillary PO₂ values drive O₂ uptake?
A high alveolar PO₂ relative to capillary PO₂ forces O₂ into the blood.
Key gas exchange law?
Fick’s law: Diffusion rate ∝ (Surface Area × Pressure Gradient) / Membrane Thickness.
How does exercise alter alveolar diffusion capacity?
Enhanced lung perfusion increases the effective surface area for gas exchange.
Why does the lung have zones?
Zones (1, 2, 3) describe variations in blood flow and ventilation across the lung.
Zone 3 of the lung?
Normal blood flow: capillary pressure exceeds alveolar pressure.
Zone 1 of the lung?
No perfusion when alveolar pressure exceeds arterial pressure.
Key aspect of respiratory regulation?
Maintaining homeostasis of PO₂, PCO₂, and pH.
How do central chemoreceptors detect CO₂?
They sense changes in H⁺ concentration in cerebrospinal fluid.
Where are peripheral chemoreceptors located?
In the carotid and aortic bodies.
Role of afferent feedback in ventilation?
Muscle metabolites signal the respiratory center to adjust ventilation.
Importance of the respiratory center?
It integrates signals to regulate the rate and depth of breathing.
How does VO₂max reflect fitness?
It measures the maximal capacity for oxygen uptake and utilization during exercise.
Effect of exercise on the O₂–Hb curve in tissues?
Lower tissue PO₂ promotes O₂ unloading for metabolism.
Why is blood flow redistribution crucial during exercise?
It directs more oxygen and nutrients to active muscles while conserving flow elsewhere.
