Exercise Physiology Practice Final

Carbon dioxide is transported in three main forms in the blood: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions. Dissolved CO2 is the smallest fraction and is transported directly in the plasma. CO2 can also bind to hemoglobin, forming carbaminohemoglobin, which accounts for a small portion of CO2 transport. The majority of CO2 is converted to bicarbonate ions in red blood cells through the enzyme carbonic anhydrase. These bicarbonate ions are then transported in the plasma. Therefore, the statement that carbon dioxide is transported in only three blood forms is true.

The diaphragm is a muscle that plays a crucial role in respiration. It separates the thoracic and abdominal cavities and contracts during inhalation, allowing the lungs to expand and fill with air. Somatic motor neurons are responsible for controlling voluntary muscle movements, and the diaphragm is one such muscle. Therefore, it is correct to say that the diaphragm is innervated by somatic motor neurons.

The P wave represents atrial depolarization, which is the electrical activation of the atria. It is the first deflection seen on an electrocardiogram (ECG) and indicates the contraction of the atria. Atrial depolarization leads to the contraction of the atria, which helps in filling the ventricles with blood.

During incremental exercise, the diastolic pressure remains fairly constant because the relaxation phase of the cardiac cycle is not significantly affected by exercise. On the other hand, the systolic pressure increases due to the increased force of contraction of the heart during exercise, which leads to a higher pressure in the arteries.

When peripheral resistance decreases, blood pressure actually decreases. Peripheral resistance refers to the resistance that blood encounters as it flows through the small arteries and arterioles. When this resistance decreases, it allows blood to flow more easily, resulting in a decrease in blood pressure. Conversely, when peripheral resistance increases, it restricts blood flow and causes an increase in blood pressure. Therefore, the statement that blood pressure increases when peripheral resistance decreases is incorrect.

Atmospheric pressure at rest is commonly referred to as standard atmospheric pressure, which is defined as the pressure exerted by the weight of the atmosphere on a unit area. It is typically measured at sea level and under normal weather conditions. The unit of measurement for atmospheric pressure is millimeters of mercury (mmHg). The answer of 760 mmHg is considered correct because it represents the standard atmospheric pressure at sea level.

Muscle chemoreceptors are receptors that are sensitive to muscle metabolites. These receptors are responsible for detecting changes in the chemical composition of the muscles, such as the levels of oxygen, carbon dioxide, and lactic acid. When these metabolites reach certain levels, muscle chemoreceptors send signals to the brain, which then initiates appropriate responses, such as adjusting blood flow or respiration rate, to maintain homeostasis in the body. Therefore, muscle chemoreceptors are the correct answer as they specifically respond to muscle metabolites.

Drifts Upward

The amount of blood pumped by the heart each minute is known as cardiac output. This term refers to the volume of blood that is ejected by the heart from the left ventricle into the systemic circulation in one minute. It is calculated by multiplying the stroke volume (the amount of blood pumped with each heartbeat) by the heart rate (the number of heartbeats per minute). Cardiac output is an important measure of heart function and can be influenced by various factors such as exercise, stress, and certain medical conditions.

When carbon dioxide (CO2) is carried in the blood, it can bind to hemoglobin, a protein in red blood cells. This binding forms a compound called carbaminohemoglobin. This statement is true because carbaminohemoglobin refers to the complex formed when CO2 binds to hemoglobin.

During exercise, the primary drive to increase ventilation comes from higher brain centers. This means that the brain sends signals to the respiratory muscles to increase the rate and depth of breathing in order to meet the increased oxygen demand and remove carbon dioxide produced during exercise. This response is controlled by the respiratory centers in the brain, specifically the medulla oblongata and pons, which detect changes in blood pH, carbon dioxide levels, and oxygen levels, and adjust ventilation accordingly. Therefore, the statement "The primary drive to increase ventilation during exercise is from higher brain centers" is true.

receives blood from the coronary arteries

A decrease in blood pressure triggers the body's sympathetic nervous system, which is responsible for the "fight or flight" response. This response increases heart rate, constricts blood vessels, and releases stress hormones, all of which work to raise blood pressure back to normal levels. Therefore, an increase in sympathetic nervous system activity is a physiological response to low blood pressure, making the statement true.

Beta blocking drugs actually decrease the myocardial oxygen demand. These drugs work by blocking the beta receptors in the heart, which results in a decrease in heart rate and contractility. This reduction in heart rate and contractility leads to a decrease in the workload of the heart, thereby reducing the demand for oxygen. Therefore, the statement that beta blocking drugs increase the myocardial oxygen demand is false.

Dyspnea is the medical term used to describe shortness of breath. It is a symptom rather than a specific condition and can be caused by various underlying factors such as asthma, bronchospasm, or COPD. Therefore, dyspnea is the correct answer as it encompasses the general term for difficulty in breathing and does not specify a particular cause.

Excessive mucus blocked in the airways is a symptom commonly associated with chronic bronchitis. Chronic bronchitis is a long-term condition characterized by inflammation and irritation of the bronchial tubes, leading to excessive production of mucus. This excess mucus can block the airways, causing difficulty in breathing and coughing. Exercise-induced asthma is a condition where physical activity triggers asthma symptoms, but it does not specifically involve excessive mucus. Asthma is a chronic respiratory condition characterized by inflammation and narrowing of the airways, but it may or may not involve excessive mucus production. Emphysema is a lung disease primarily caused by smoking, where the air sacs in the lungs are damaged, leading to difficulty in breathing. While emphysema can cause mucus production, it is not the primary symptom. Therefore, chronic bronchitis is the most suitable answer.

Platelets

The correct formula for calculating Mean Arterial Pressure (MAP) is MAP = DBP + .33(SBP - DBP). This formula takes into account both the systolic blood pressure (SBP) and diastolic blood pressure (DBP) readings. The difference between SBP and DBP represents the pulse pressure, and adding one-third of this pulse pressure to the DBP provides an estimation of the average pressure in the arteries over a cardiac cycle.

known as diffusion

The statement is true because alveolar ventilation refers to the volume of fresh air that reaches the alveoli per minute, while dead space ventilation refers to the volume of air that is not involved in gas exchange. When these two values are added together, it gives the total volume of air that is involved in gas exchange in the lungs, which is known as pulmonary ventilation. Therefore, the statement is correct.

The brain stem is responsible for controlling essential bodily functions, including respiration. It regulates the rate and depth of breathing by sending signals to the muscles involved in the process. The cerebellum is primarily involved in coordinating movement and balance, while the frontal lobe is responsible for higher cognitive functions such as decision-making and problem-solving. The cerebrum is the largest part of the brain and is involved in various functions, including sensory perception and voluntary movement, but it is not specifically responsible for respiratory control.

resting systole is .3 sec while resting diastole is .5 sec

Hydrogen binds to hemoglobin (Hb) in red blood cells to prevent acidity. When there is an excess of hydrogen ions (acidic conditions) in the body, hydrogen ions bind to hemoglobin, which helps to maintain the pH balance and prevent a decrease in blood pH. This is an important buffering mechanism in the body to regulate acid-base balance and ensure proper functioning of various physiological processes. Therefore, the statement "Hydrogen binds to Hb to prevent acidity" is true.

Uses both negative and positive

The statement "Ventricular Systole is the first phase of the cardiac cycle" is incorrect. In the cardiac cycle, ventricular systole is the second phase, following the atrial systole. During ventricular systole, the ventricles contract, forcing blood out of the heart and into the arteries. Therefore, the correct answer is False.

During heavy exercise, the heart needs to pump more blood to meet the increased demand for oxygen and nutrients in the muscles. This is achieved by increasing the duration of systole, which is the phase of the cardiac cycle when the heart contracts and pumps blood out of the chambers. By prolonging systole, the heart has more time to pump a larger volume of blood. On the other hand, diastole, the phase when the heart relaxes and fills with blood, is shorter during heavy exercise to allow for more frequent contractions and maintain a higher heart rate. Therefore, the statement that systole is longer than diastole during heavy exercise is true.

Blood pressure above 140/90 mmHg is known as high blood pressure. Blood pressure is measured in millimeters of mercury (mmHg) and consists of two numbers: the top number represents systolic pressure (the pressure in the arteries when the heart beats) and the bottom number represents diastolic pressure (the pressure in the arteries when the heart is at rest). High blood pressure, also known as hypertension, can lead to serious health complications if left untreated.

The systemic circulation does not have lower pressure than the pulmonary circulation. In fact, the systemic circulation has higher pressure than the pulmonary circulation. This is because the systemic circulation is responsible for delivering oxygenated blood to the body's tissues and organs, while the pulmonary circulation is responsible for oxygenating the blood by exchanging carbon dioxide for oxygen in the lungs. To deliver blood to the entire body, the systemic circulation needs to generate higher pressure to overcome the resistance offered by the blood vessels throughout the body.

weak acid

5 L/m

Deoxyhemoglobin is not simply hemoglobin carrying carbon dioxide. Deoxyhemoglobin refers to the form of hemoglobin that has released its oxygen molecules, while still being bound to the iron atoms. It does not specifically carry carbon dioxide, as carbon dioxide is mainly transported in the blood in the form of bicarbonate ions or dissolved in plasma.

Central chemoreceptors are located in the medulla. These receptors are responsible for monitoring the levels of carbon dioxide and pH in the cerebrospinal fluid. When carbon dioxide levels increase, it diffuses across the blood-brain barrier and triggers the central chemoreceptors in the medulla to stimulate the respiratory centers, leading to an increase in breathing rate. Therefore, the medulla plays a crucial role in regulating respiratory function and maintaining acid-base balance in the body.

The statement suggests that training can change the structure of the lungs to increase their capacity to take up more oxygen. However, this is not true. While exercise and training can improve lung function and efficiency, they do not physically change the structure of the lungs. The lungs have a fixed size and capacity, and training cannot alter their anatomical structure.

The SA node, also known as the sinoatrial node, is responsible for initiating the electrical impulses that regulate the heart's rhythm. It is located in the right atrium of the heart and is often referred to as the "natural pacemaker" of the heart. The SA node consists of autorhythmic cells that generate electrical signals, causing the atria to contract and initiating the heartbeat.

Arterioles create the most resistance among the vessels listed. Arterioles are small blood vessels that regulate blood flow and control the distribution of blood to different tissues. They have a high degree of smooth muscle in their walls, which allows them to constrict or dilate, thereby regulating blood pressure and flow. When arterioles constrict, it increases the resistance to blood flow, leading to increased blood pressure. This constriction is an important mechanism in regulating blood flow to various organs and tissues in the body.

produced in the endothelium

The pulmonary circuit is responsible for carrying deoxygenated blood from the right side of the heart to the lungs, where it picks up oxygen and gets rid of carbon dioxide. Once the blood is oxygenated, it returns to the left side of the heart through the pulmonary veins. Therefore, the correct answer is that the pulmonary circuit pumps oxygenated blood to the left side of the heart via pulmonary veins.

double product increases

The tidal volume refers to the amount of air that is inhaled and exhaled during normal breathing. It is typically around 500 mL, which means that an average person breathes in and out 500 mL of air with each breath. This value can vary depending on factors such as age, gender, and physical activity level.

It does not

Fatty acids

The formula for Air Flow is given as Airflow = (P2 - P1)/resistance. This formula represents the difference in pressure (P2 - P1) divided by the resistance. This makes sense because air flow is directly proportional to the pressure difference and inversely proportional to the resistance. Therefore, as the pressure difference increases or the resistance decreases, the air flow will increase.

Pulmonary ventilation refers to the amount of air that is moved in and out of the lungs per minute. It is a measure of the overall ventilation of the lungs and is important for gas exchange. This includes the movement of both tidal volume, which is the volume of air inspired or expired with each breath, and dead space ventilation, which is the volume of air that does not participate in gas exchange. Therefore, pulmonary ventilation encompasses the total volume of air that is involved in the respiratory process.

The vital capacity refers to the maximum amount of gas that can be expired after a maximum inspiration. This means it is the total volume of air that can be inhaled and exhaled during a forced breathing maneuver. It represents the maximum amount of air that the lungs can hold and is an important measure of lung function.

During heavy exercise, the heart beats at 180 bpm. This is because during intense physical activity, the body requires more oxygen and nutrients to meet the increased demand. The heart pumps faster to deliver oxygen-rich blood to the muscles and organs, allowing them to function optimally. This increased heart rate helps to supply the necessary nutrients and remove waste products efficiently.

If the sympathetic neurons connecting to the heart are cut off, it would actually result in increased excitation of the heart. The sympathetic nervous system is responsible for the "fight or flight" response, which includes increasing heart rate and contractility. If these neurons are cut off, the parasympathetic nervous system would dominate, leading to a decrease in heart rate and overall cardiac activity. Therefore, the correct answer is False.

Resistance depends on the length of the vessel, radius of the vessel, and viscosity of the blood. The length of the vessel affects resistance because a longer vessel offers more surface area for friction to occur, increasing resistance. The radius of the vessel affects resistance because a narrower vessel increases the resistance to blood flow. Viscosity of the blood also affects resistance because thicker or more viscous blood increases resistance. Therefore, all three factors play a role in determining the resistance in a vessel.

The arteries in the coronary circulation originate behind the aortic semilunar valves. This is because the coronary arteries branch off from the ascending aorta, which is located behind the aortic semilunar valves. This positioning allows for oxygenated blood to be pumped into the coronary arteries and subsequently supply the heart muscle with the necessary nutrients and oxygen for proper functioning.

The central chemoreceptors are sensitive to increases in PCO2 and decreases in pH. PCO2 refers to the partial pressure of carbon dioxide in the blood, and it is an important indicator of respiratory function. When PCO2 levels increase, it leads to a decrease in pH, making the blood more acidic. The central chemoreceptors in the brainstem respond to these changes in PCO2 and pH by regulating the rate and depth of breathing, helping to maintain the balance of gases in the body.

only if greater that 2 mm

The correct answer is 200 ml O2/L blood. This is the typical O2 content of blood for males when their hemoglobin (Hb) saturation is at 100%.

The correct answer is 120 minutes. Current evidence suggests that respiratory muscles fatigue at prolonged exercise lasting more than 120 minutes. This means that after exercising for more than 120 minutes, the respiratory muscles become tired and may not function as efficiently as they did at the beginning of the exercise. This can lead to decreased breathing capacity and potentially impact performance.

Nitric oxide promotes smooth muscle relaxation. Nitric oxide is a signaling molecule that is produced by various cells in the body, including endothelial cells lining blood vessels. It acts as a vasodilator, meaning it causes blood vessels to relax and widen, leading to increased blood flow. In smooth muscle cells, nitric oxide activates an enzyme called guanylate cyclase, which increases the production of cyclic guanosine monophosphate (cGMP). cGMP then leads to the relaxation of smooth muscles, including those in blood vessels and the gastrointestinal tract. This relaxation allows for improved blood flow and helps to reduce muscle spasms and contractions.

parasympathetic

Emphysema is a condition characterized by the destruction of the air sacs in the lungs, leading to the collapse of the airways. This collapse prevents proper airflow and causes air to become trapped in the lungs. This results in difficulty breathing and shortness of breath, which are common symptoms of emphysema. Asthma, COPD (chronic obstructive pulmonary disease), and chronic bronchitis are also respiratory conditions, but they do not specifically cause airway collapse and trapped air in the lungs like emphysema does.

Sympathetic innervation

Alveolar ventilation refers to the volume of air that reaches the respiratory zone, specifically the alveoli, where gas exchange occurs. It is the amount of fresh air that is available for the exchange of oxygen and carbon dioxide in the lungs. This measurement excludes the dead space ventilation, which is the volume of air that fills the non-respiratory airways and does not participate in gas exchange. Therefore, alveolar ventilation is the most accurate measure of the volume of air that actually reaches the site of gas exchange in the lungs.

The parietal pleura is the correct answer because it is the membrane that lines the thoracic wall. The parietal pleura covers the inner surface of the chest cavity and is responsible for protecting and lubricating the lungs during breathing. It is separate from the visceral pleura, which covers the outer surface of the lungs. The endothelium is a type of tissue that lines blood vessels, not the thoracic wall. Therefore, the correct answer is parietal pleura.

Decreased pH and increased temperature both cause a rightward shift of the dissociation curve. A decrease in pH, which indicates increased acidity, results in a decrease in the affinity of hemoglobin for oxygen, causing it to release oxygen more readily to the tissues. Similarly, an increase in temperature also decreases the affinity of hemoglobin for oxygen, promoting oxygen release. Therefore, both factors contribute to a rightward shift of the dissociation curve, indicating a decreased affinity of hemoglobin for oxygen at a given partial pressure.

CO2 is primarily dissolved in the plasma in the form of bicarbonate ions. The concentration of dissolved CO2 in the plasma is regulated by the respiratory system, which controls the rate of CO2 removal through breathing. Normally, around 10% of the total CO2 produced in the body is dissolved in the plasma. This dissolved CO2 plays a crucial role in maintaining the acid-base balance in the body.

The correct answer is four. Current evidence suggests that the normal rhythm of breathing is generated by the interaction between four separate respiratory rhythm centers located in the medulla oblongata and the pons. These centers work together to regulate the timing and depth of each breath, ensuring that oxygen is taken in and carbon dioxide is expelled efficiently.

Each gram of Hb can transport 1.34 ml O2. This is because the oxygen-carrying capacity of hemoglobin is determined by its binding capacity to oxygen. Each gram of hemoglobin can bind to approximately 1.34 ml of oxygen. This capacity allows hemoglobin to efficiently transport oxygen throughout the body, ensuring the oxygen needs of tissues and organs are met.

The epicardium is the outermost layer of the heart and serves as a lubricative outer covering. It helps protect the heart and provides a smooth surface for the heart to beat against. The epicardium also contains blood vessels and nerves that supply the heart muscle.

3 phases
Ventricular Diastole
Ventricular Systole
Isovolumetric Relaxation

Acetylcholine does not enhance the strength of ventricular contraction. In fact, acetylcholine has an inhibitory effect on the heart, causing a decrease in heart rate and a weakening of the force of contraction. Therefore, the statement is false.

myoglobin has higher affinity to reserve O2 for muscles

During the Frank Starling mechanism, an increase in preload will stretch the sarcomere from 2.0 - 2.4. This is because the Frank Starling mechanism states that the force of contraction of the heart is directly proportional to the initial length of the cardiac muscle fibers. As the preload increases, the ventricles are filled with more blood, causing the sarcomeres to stretch. This stretching increases the overlap of the actin and myosin filaments, leading to a stronger force of contraction and a larger stroke volume.

The rough index of workload on the heart is known as the double product. This term refers to the product of heart rate and systolic blood pressure, which represents the amount of work the heart has to do to pump blood throughout the body. By calculating the double product, healthcare professionals can assess the heart's workload and evaluate its efficiency. It is an important measure in diagnosing and managing heart conditions.

60 percent

Plasma is the liquid component of blood and it contains ions, proteins, and hormones. Ions are electrically charged particles that are essential for various physiological processes in the body. Proteins in plasma play a crucial role in maintaining osmotic pressure, transporting nutrients, and regulating immune responses. Hormones are chemical messengers that are secreted by glands and transported through the bloodstream to regulate various bodily functions. However, red blood cells are not present in plasma as they are cellular components that are found in the formed elements of blood.

At rest, approximately 15-20% of blood is distributed to muscles. This means that a small portion of the blood circulating in the body is directed towards the muscles when the body is in a resting state. The majority of the blood is likely distributed to other organs and tissues that require a higher supply of oxygen and nutrients.

Tidal Volume x Breathing Frequency = Pulmonary Ventilaton

Peripheral chemoreceptors are specialized cells located in the aortic and carotid bodies that detect changes in the levels of oxygen, carbon dioxide, and pH in the blood. These chemoreceptors play a crucial role in regulating respiratory function by sending signals to the brainstem to adjust breathing rate and depth. They are called "peripheral" because they are located outside of the central nervous system. Central chemoreceptors, on the other hand, are located in the brain and primarily respond to changes in carbon dioxide levels. Baroreceptors are sensory receptors that detect changes in blood pressure. Therefore, the correct answer is peripheral chemoreceptors.

myocardial ischemia

At a heart rate of 150-200 beats per minute, it takes approximately 150 milliseconds to fill the heart. This means that the heart chambers are able to fill with blood in this time frame before the next heartbeat occurs. The heart rate determines the speed at which the heart pumps and fills with blood, and a higher heart rate means a shorter time to fill the heart.

The kidneys play a crucial role in long-term regulation of mean arterial blood pressure. They help maintain blood pressure by adjusting the volume of blood and the concentration of electrolytes in the body. The kidneys regulate blood pressure by filtering waste and excess fluid from the blood, which helps maintain the balance of sodium, potassium, and water in the body. This process, known as renal regulation, helps ensure that blood pressure remains within a normal range. Therefore, the kidneys have a significant influence on long-term regulation of mean arterial blood pressure.

The typical lung capacity is 6000 mL. This is the correct answer because it falls in the middle range of the given options and is a commonly accepted value for lung capacity in adults. Lung capacity refers to the maximum amount of air that can be inhaled or exhaled from the lungs, and 6000 mL is a reasonable average value for this measurement.

When HCO3- diffuses out of the RBC's into plasma, chloride ions (Cl-) diffuse into the RBC's to maintain electrical neutrality. This is known as the chloride shift or Hamburger phenomenon, where chloride ions enter the RBC's to balance the loss of bicarbonate ions. This process helps to maintain the electrochemical equilibrium and pH balance within the RBC's.

The correct answer is 99% because the majority of oxygen in the blood is transported by binding to hemoglobin molecules in red blood cells. This oxygen-hemoglobin complex allows for efficient delivery of oxygen throughout the body. Only a small fraction of oxygen dissolves directly into the blood plasma. Therefore, 99% is the most accurate choice as it represents the highest percentage of oxygen chemically bonded with hemoglobin.

ventilatory threshold

..lowers Hb-O2 affinity

During isovolumetric contraction, the ventricles of the heart are contracting but there is no change in the volume of blood in the ventricles. As the ventricles contract, the pressure within them increases, leading to ventricular pressure rising. At the same time, the AV valves, which separate the atria from the ventricles, close to prevent the backflow of blood into the atria. Therefore, the correct answers are ventricular pressure rises and AV valves close.

An ejection fraction of less than 55% indicates myocardial contraction. Ejection fraction is a measure of how well the heart is pumping out blood and is calculated by dividing the volume of blood pumped out of the heart with each beat by the total volume of blood in the heart. An ejection fraction of less than 55% suggests that the heart is not contracting efficiently and may be a sign of heart dysfunction or heart failure.

During incremental exercise, ventilation refers to the amount of air that is breathed in and out per minute. In an untrained subject, ventilation increases linearly up to around 50-75% of their maximum oxygen consumption (VO2 max). This means that as the intensity of the exercise increases, the individual's breathing rate also increases in a linear manner until they reach this range of VO2 max. Beyond this range, ventilation may increase disproportionately or plateau. Therefore, the correct answer is ~50 - 75% VO2 max.

The preBotzinger Complex is responsible for generating the basic rhythm of breathing. It contains pacemaker neurons that initiate the rhythmic pattern of breathing even in the absence of external stimuli. These neurons send signals to the respiratory muscles, coordinating the contraction and relaxation necessary for inhalation and exhalation. The other options mentioned, such as the pneumoraxic center, retrotrapezoidal nucleus, and caudal pons, are also involved in respiratory control, but the preBotzinger Complex is specifically known for its role in initiating the breathing rhythm.

Carotid bodies are more important than aortic bodies in regards to peripheral chemoreceptors. This is because carotid bodies are located in the carotid arteries, which are closer to the brain and play a crucial role in regulating respiratory responses to changes in oxygen levels. Aortic bodies, on the other hand, are located in the aortic arch, farther away from the brain. While both carotid and aortic bodies contribute to the regulation of respiratory responses, the proximity of the carotid bodies to the brain makes them more influential in this process.

The statement is false because chronic obstructive lung disease is actually linked with a decreased expiratory airflow and an increased inspiratory airflow due to constant airway narrowing. In this condition, the airways become narrowed and obstructed, making it difficult for air to be expelled from the lungs during exhalation. This leads to a decrease in expiratory airflow. Additionally, the constant narrowing of the airways can also result in an increased effort required to inhale air, leading to an increase in inspiratory airflow.

The statement suggests that receptors that are sensitive to an increase in PCO2 are believed to exist, but their existence has not been definitively proven. This means that while there is a hypothesis about their existence, further research and evidence are needed to confirm it.

Approximately 40-50% of elite endurance athletes experience hypoxemia during high-intensity exercise, specifically when their oxygen consumption is above 90% of their maximum capacity (VO2 max). Hypoxemia refers to a condition where there is a lower than normal level of oxygen in the blood. This can occur due to the increased demand for oxygen during intense exercise, which may exceed the body's ability to deliver an adequate supply. The high prevalence of hypoxemia among elite endurance athletes highlights the physiological challenges they face in maintaining oxygen levels during extreme physical exertion.

The ventricles contract approximately 0.1 seconds after the atria. This delay allows for the atria to fully empty their blood into the ventricles before the ventricles contract, ensuring efficient blood flow and proper functioning of the heart.

stimulated when too high

narrows the coronary arteries

15 - 25x

Sedentary individuals typically have a resting stroke volume (SV) of 50 - 60 ml. SV refers to the amount of blood pumped out by the heart with each contraction. Sedentary individuals, who engage in little to no physical activity, tend to have lower SV compared to individuals who are physically active. This is because regular exercise strengthens the heart, allowing it to pump more blood with each beat. Therefore, sedentary individuals would have a lower resting SV range of 50 - 60 ml.

tidal volume

not-available-via-ai

The heart at rest beats at 75 bpm. This is the normal resting heart rate for a healthy adult. The heart rate can vary depending on factors such as age, fitness level, and overall health. However, a resting heart rate of 75 bpm is considered within the normal range.

70% of CO2 is found in the blood is transported as bicarbonate. This is because CO2 reacts with water in the blood to form carbonic acid, which then dissociates into bicarbonate ions and hydrogen ions. The bicarbonate ions are transported in the plasma, while some CO2 is also transported bound to hemoglobin in red blood cells. This bicarbonate transport mechanism helps to maintain the pH balance in the blood and is an important part of the body's respiratory system.

Hypertension, or high blood pressure, can cause kidney damage, stroke, and atherosclerosis. When the blood pressure is consistently high, it puts strain on the blood vessels and organs, including the kidneys. Over time, this can lead to kidney damage and impair their ability to filter waste from the blood. Additionally, high blood pressure can cause damage to the blood vessels in the brain, increasing the risk of stroke. Atherosclerosis, a condition characterized by the buildup of plaque in the arteries, is also associated with hypertension and can further increase the risk of stroke and other cardiovascular complications.

Systolic pressure does not provide an indication of peripheral resistance. Systolic pressure refers to the maximum pressure in the arteries during a cardiac cycle, while peripheral resistance is the resistance to blood flow in the smaller arteries and arterioles. While systolic pressure can be influenced by factors such as cardiac output and arterial compliance, it does not directly indicate peripheral resistance. Therefore, the statement is false.

An increase in blood pressure triggers a reflex response known as the baroreceptor reflex. This reflex aims to restore blood pressure to its normal range. When blood pressure increases, the baroreceptors in the arteries detect the change and send signals to the brain. In response, the brain sends signals to decrease sympathetic nervous system activity. The sympathetic nervous system is responsible for the "fight or flight" response, which includes increasing heart rate and constricting blood vessels. By decreasing sympathetic activity, the body can counteract the increase in blood pressure and restore balance.

During exercise, the preBotzinger Complex interacts with the retrotrapezodial nucleus along with two additional regulatory centers in the pons to regulate breathing. The preBotzinger Complex is a group of neurons located in the medulla oblongata, which is responsible for generating the basic rhythm of breathing. The retrotrapezodial nucleus is also located in the medulla oblongata and plays a role in modulating the respiratory rhythm. Together, these two centers, along with the other regulatory centers in the pons, work to coordinate and regulate breathing during exercise.

The filling time of the heart at rest is the time it takes for the ventricles to fill with blood before they contract. The correct answer of 500 - 700 ms suggests that it takes approximately half a second to three-quarters of a second for the ventricles to fill with blood during rest. This time frame is within the normal range for filling time, indicating that the heart is functioning properly during periods of rest.

During heavy or submaximal exercise, the body requires more oxygen to meet the increased energy demands. This leads to an increase in ventilation, which helps to bring in more oxygen and remove carbon dioxide.

Increasing blood H+ (acidosis) is one of the factors that can stimulate an increase in ventilation during exercise. As exercise intensity increases, there is an increase in the production of carbon dioxide and lactic acid, which leads to an increase in blood acidity. This increase in acidity stimulates the chemoreceptors in the brain, triggering an increase in ventilation to remove excess carbon dioxide and restore the acid-base balance.

Body temperature also plays a role in the increase in ventilation during exercise. As the body temperature rises during exercise, it can stimulate the respiratory centers in the brain, leading to an increase in ventilation.

Blood catecholamines, such as adrenaline and noradrenaline, are released during exercise and can stimulate an increase in ventilation. These hormones help to increase the heart rate, blood pressure, and blood flow to the muscles, and they also stimulate the respiratory centers in the brain, leading to an increase in ventilation.

K+ (potassium) is not directly involved in the regulation of ventilation during exercise.

During isovolumetric relaxation, the ventricles of the heart relax, which causes the ventricular pressure to drop. As a result, the atria are able to refill with blood. Additionally, the semilunar valves close during this phase. This prevents the backflow of blood from the arteries into the ventricles. Therefore, all of the given statements are correct.

Ventilation control during exercise is fine-tuned by humoral chemoreceptors, higher brain centers, and neural feedback from muscles. Humoral chemoreceptors detect changes in the levels of chemicals such as oxygen and carbon dioxide in the blood, signaling the need for adjustments in ventilation. Higher brain centers, including the cerebral cortex and the respiratory centers in the brainstem, regulate breathing based on conscious control and feedback from the chemoreceptors. Neural feedback from muscles provides information about the level of exertion and helps adjust ventilation accordingly. Therefore, all of these factors play a role in fine-tuning ventilation during exercise.