Term
| Describe the structure of the heart, the pattern of blood flow through the valves and chambers of the heart, how the heart as a muscle is supplied with blood and what happens when the resting heart must suddenly supply an exercising body. |
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Definition
| The heart has two atria that serve as receiving chambers and two ventricles that serve as pumping chambers. It's enclosed in a tough membranous sac called the pericardium. The cavity between it and the heart is filled with pericardial fluid, which reduces friction between the sac and beating heart. The right side pumps deoxygenated blood to the lungs while the left side pumps oxygenated blood to all other tissues. During sudden exercise, the left ventricle has an increased demand to deliver blood, leading to hypertrophy. |
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Term
| What events take place that allow the heart to contract and how is heart rate controlled? |
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Definition
| An electrical signal is generated by the cardiac muscle, allowing the heart to contract on its own. The SA node creates an electrical impulse that is sent through the atria, triggering the atrial myocardium to contract. The sympathetic, parasympathetic, and endocrine nervous systems control heart rate. |
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Term
| What is the difference between systole and diastole and how do they relate to SBP and DBP? |
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Definition
| The difference between systole and diastole is that the former is a ventricular contraction. The latter is ventricular relaxation. SBP and DBP together make up one's blood pressure, where the higher pressure in the artery means a higher ventricular contraction and low ventricular relaxation means low arterial pressure. |
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Term
| What is the relationship between pressure, flow and resistance? |
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Definition
| Blood flows from high to low pressure, and pressure differences from opposite ends of a vessel is what causes blood to flow. Resistance creates a difference in pressure and provides blood flow resistance. |
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Term
| How is blood flow to the various regions of the body controlled? |
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Definition
| Blood flow is primarily controlled by vasoconstriction and vasodilation. These processes divert blood flow to where it's needed most. Changes in blood vessel size can direct both blood pressure and flow to supply it to specific parts of the body. |
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Term
| Describe the three important mechanisms for returning blood back to the heart when someone is exercising in an upright position. |
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Definition
| The three important mechanisms for returning blood back to the heart while exercising upright are metabolic regulation, endothelium and the myogenic response. Metabolic regulation causes arterioles to dilate by releasing vasodilating chemicals to allow more blood to flow to the area. The endothelium triggers mediated vasodilation, initiating the process in vascular smooth muscles, delivering blood containing nitric oxide. The myogenic response creates pressure inside the vessels which causes both vasodilation and vasoconstriction. |
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Term
| Describe the primary functions of blood. |
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Definition
| The primary functions of blood include transporting oxygen and substrates in the circulatory system to be used through the entire body, temperature regulation during physical activity due to heat production from the muscles, and buffers acids formed during anaerobic metabolism, maintaining pH homeostasis. |
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Term
| Describe and differentiate between external and internal respiration. |
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Definition
| External respiration moves gases from outside of the body into the lungs, and then the blood. Internal respiration is the gas exchange between the blood and the tissues. Both being linked through the circulatory system, the two combined described the process of getting oxygen from outside the body to the tissues. |
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Term
| Describe the mechanisms involved in inspiration and expiration. |
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Definition
| Inspiration uses intercostal muscles and the diaphragm. The ribs and sternum are moved by the intercostals while the diaphragm contracts, flattening it in the process. Expiration relates to the relaxing of elastic recoil of the lungs. The diaphragm returns to its normal position when relaxed, and as the intercostals relax, the sternum and ribs also return. |
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Term
| What is a spirometer? Describe and define the lung volumes measured using spirometry. |
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Definition
| A spirometer is a tool used to measure volumes of inspired and expired air, which shows the changes in lung volume. The lung volumes measured include tidal volume, the amount of air that enters and leaves the lungs with one breath, vital capacity, the greatest amount of air that can be expired after maximum inspiration, and residual volume, the remaining amount of air in the lungs after a maximal expiration. |
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Term
| Explain the concept of partial pressures of respiratory gases- oxygen, carbon dioxide, and nitrogen. What is the role of gas partial pressures in pulmonary diffusion? |
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Definition
| Partial pressure is defined as the individual pressure from each gas in a mixture, referring to the air inhaled in this case. Oxygen is 20.93% of the mixture while CO2 is 0.03% and nitrogen is the most plentiful gas at 79.04%. This creates a pressure gradient that creates gas exchange. Oxygen exchange then takes place where the body needs it most, while CO2 can cross membranes easier than oxygen. |
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Term
| Where in the lung does the exchange of gases with the blood occur? Describe the role of the respiratory membrane. |
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Definition
| The exchange of gases with the blood occurs in the respiratory membrane of the lung. It's made up of the alveolar wall, capillary wall and their basement membranes, and creates a pressure gradient that forms gas exchange diffusion. |
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Term
| How are oxygen and carbon dioxide transported in the blood? |
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Definition
| Oxygen and carbon dioxide are transported in the blood when oxygen either combines with hemoglobin or is disolved in plasma, and when carbon dioxide is carried as bicarbonate ions, dissolved in plasma or is bound to hemoglobin. |
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Term
| How is oxygen unloaded from the arterial blood to the muscle and carbon dioxide removed from the muscle into the venous blood? |
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Definition
| Oxygen is transported in the muscle to the mitochondria via myoglobin. The myoglobin then releases oxygen when PO2 is low. An increase in blood flow due to exercise leads to more oxygen being carried to the muscles. Simple diffusion leads to CO2 leaving the muscle cells and entering back into the blood and eventually to the lungs. |
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Term
| What is meant by the arterial-mixed venous oxygen difference? How and why does this change from resting conditions to exercise conditions? |
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Definition
| The arterial mixed venous oxygen difference means the difference in oxygen content between the venous and arterial blood. During intense exercise, the active muscle needs more oxygen, so more is brought to them since PO2 is lower than in the arterial blood. |
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Term
| Describe how pulmonary ventilation is regulated. What are the chemical stimuli that control the depth and rate of breathing? How do they control respiration during exercise? |
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Definition
| Respiratory centers control motor neurons. This in turn controls the respiratory muscles. Located in the brain stem and used to establish breathing rate and depth, changes in CO2 and H+ levels alter breathing to get rid of excess CO2 and H+. Forceful breathing during exercise means more expiration of CO2 and H+. |
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