Internal Environment And Homeostasis Trivia Quiz

Homeostasis refers to the nearly constant conditions that are maintained in the internal environment of multicellular organisms. This includes the regulation of body temperature, pH levels, blood sugar levels, and other physiological processes to ensure optimal functioning of the organism. Homeostasis is essential for the survival and proper functioning of cells, tissues, and organs within the body.

With maximal expiratory effort, the volume of air in the lungs cannot be reduced to nearly zero. Even with maximum effort, there is always a residual volume of air that remains in the lungs to prevent them from collapsing completely. This residual volume is necessary for gas exchange and to maintain the structural integrity of the lungs. Therefore, the statement is false.

If more of a substance appears in the urine than was filtered at the glomerulus, it suggests that the substance was added to the urine after the filtration process. This indicates that the substance must have undergone tubular secretion, where it is actively transported from the blood into the renal tubules. Tubular reabsorption, on the other hand, involves the movement of substances from the renal tubules back into the blood. Therefore, tubular secretion is the most likely explanation for the increased presence of the substance in the urine.

If a decrease in blood pressure were the stimulus for a negative feedback control system, the response produced by the effector cells of the control system would be to increase blood pressure. In a negative feedback system, the response works to oppose the original stimulus and restore the system to its normal state. Therefore, when blood pressure decreases, the effector cells would work to increase it back to the normal level.

At high altitudes, the partial pressure of oxygen in the air decreases. This decrease in oxygen partial pressure leads to vasoconstriction in the pulmonary blood vessels, resulting in an increase in pulmonary vascular resistance. This is a physiological response to compensate for the reduced availability of oxygen at high altitudes. Therefore, the statement "The low oxygen partial pressure of air at high altitude leads to an increase in pulmonary vascular resistance" is true.

The interstitial fluid is a component of the extracellular fluid in the body and is larger in volume than the plasma volume. It is found between cells and is considered part of the internal environment. Therefore, all of the given statements are correct.

Cardiac action potentials are transmitted from the pacemaker region throughout the rest of the heart by gap junctions between adjacent cardiac muscle cells. Gap junctions are specialized protein channels that allow for direct electrical communication between cells, allowing the action potential to spread rapidly and efficiently. These gap junctions ensure that the depolarization wave is transmitted smoothly and synchronously, allowing for coordinated contraction of the entire heart. Nerves from the pacemaker region do not directly synapse on individual cardiac muscle cells, paracrine agents are not involved in transmitting action potentials, and synapses between adjacent cardiac muscle cells are not present in the heart.

If the SA node of the heart were destroyed, the atria and ventricles would still be able to contract, although not in a coordinated manner. This is because the SA node, also known as the natural pacemaker of the heart, initiates electrical impulses that regulate the heart's rhythm. However, if the SA node is destroyed, other cells in the heart, such as the AV node or Purkinje fibers, can take over the pacemaking function, albeit at a slower rate. This would result in a slower and less coordinated contraction of the atria and ventricles, but they would still be able to contract.

A decrease in blood vessel radius will increase resistance to blood flow. This is because the radius of a blood vessel directly affects its cross-sectional area. As the radius decreases, the cross-sectional area also decreases, resulting in a smaller space for blood to flow through. This leads to an increase in the velocity of blood flow and an increase in resistance. Conversely, an increase in blood vessel radius would result in a larger cross-sectional area, allowing for easier blood flow and decreased resistance.

Baroreceptor reflexes are responsible for rapid adjustments in systemic blood pressure. Baroreceptors are specialized nerve endings located in the walls of certain blood vessels, particularly in the carotid sinus and aortic arch. They detect changes in blood pressure and send signals to the brain to initiate appropriate responses to maintain blood pressure within a normal range. When blood pressure increases, the baroreceptors inhibit sympathetic activity and stimulate parasympathetic activity, causing vasodilation and decreased heart rate. Conversely, when blood pressure decreases, the baroreceptors stimulate sympathetic activity and inhibit parasympathetic activity, leading to vasoconstriction and increased heart rate. This reflex mechanism helps maintain blood pressure homeostasis.

After a severe hemorrhage, the body goes into a state of hypovolemia, where there is a decrease in blood volume. In response to this, the pituitary gland secretes antidiuretic hormone (ADH) to conserve water by reducing urine output. This helps in maintaining blood volume and blood pressure. Additionally, the decrease in blood volume also leads to a decrease in glomerular filtration rate (GFR), as the kidneys try to conserve fluid. To compensate for the decrease in blood volume, the kidneys also secrete renin, which initiates the renin-angiotensin-aldosterone system to increase blood pressure. Therefore, all of the above statements are correct.

Pulmonary surfactant is a substance produced by the cells in the lungs that helps to reduce the surface tension within the alveoli. By decreasing surface tension, surfactant prevents the collapse of the alveoli during expiration and allows for easier expansion during inspiration. This is important for efficient gas exchange in the lungs. Therefore, the correct answer is that pulmonary surfactant decreases alveolar surface tension.

If an individual has aortic stenosis, the ejection of blood through the valve during systole will be restricted. Aortic stenosis is a condition where the aortic valve, which allows blood to flow from the heart's left ventricle to the aorta, becomes narrowed. This narrowing obstructs the flow of blood, making it difficult for the heart to pump blood out to the body. As a result, the ejection of blood through the valve during systole, the contraction phase of the heart, will be restricted.

Aldosterone is a hormone that promotes the reabsorption of sodium and water in the kidneys, leading to an increase in blood volume and subsequently blood pressure. Angiotensin II is a hormone that constricts blood vessels, increasing peripheral resistance and therefore increasing blood pressure. Increased sodium intake can also lead to an increase in blood volume, which in turn increases blood pressure. Therefore, all of the given options - aldosterone, angiotensin II, and increased sodium intake - can contribute to an increase in blood pressure.

An opening in the right side of the chest wall that pierces the parietal pleura will cause the right lung to collapse because it disrupts the negative pressure in the intrapleural space. The negative pressure in the intrapleural space is necessary to keep the lungs inflated. When the pleural cavity is breached, air rushes in and equalizes the pressure between the intrapleural space and the alveolar pressure, causing the lung to collapse.

The correct answer is "the acidity of the extracellular fluid remains the same as diet changes." This response demonstrates homeostasis because it shows that the body is able to maintain a stable pH level in the extracellular fluid despite changes in the diet. Homeostasis is the body's ability to regulate and maintain a stable internal environment, and in this case, it is maintaining the acid-base balance within a narrow range.

The plasma osmolarity has a range of 290 to 310 mOsmoles, which means that it falls within this specific range. It is critical for maintaining fluid compartmentalization, as it helps to regulate the movement of fluids between different compartments in the body. Additionally, plasma osmolarity is important for proper cell function, as it affects the balance of water and solutes within cells. Lastly, plasma osmolarity is equal to extracellular fluid osmolarity, meaning that they have the same concentration of solutes. Therefore, all of the statements mentioned above are correct.

Increasing depth of respiration, vigorous walking, and an increase in ventricular contraction strength all contribute to an increase in venous return to the right atrium. When the depth of respiration increases, it enhances the negative intrathoracic pressure, which helps in pulling the blood towards the heart. Vigorous walking increases the venous return by promoting the contraction of skeletal muscles, which squeeze the veins and propel the blood towards the heart. An increase in ventricular contraction strength results in a more forceful ejection of blood from the ventricles, leading to an increased venous return. Therefore, all of these factors contribute to an increased venous return to the right atrium.

Both interstitial fluid and plasma constitute a portion of the internal environment. Interstitial fluid is the fluid that surrounds and bathes the cells, while plasma is the fluid component of blood. Both of these fluids play important roles in maintaining the internal environment of the body by transporting nutrients, oxygen, and waste products between cells and organs.

During the plateau phase of the cardiac action potential, there is a sustained depolarization of the cell membrane. This is primarily due to the increased membrane permeability to calcium ions. Calcium ions enter the cell through voltage-gated calcium channels, which prolongs the depolarization phase and allows for the contraction of cardiac muscle. The influx of calcium ions also triggers the release of additional calcium ions from the sarcoplasmic reticulum, leading to further muscle contraction. Therefore, the increased permeability to calcium ions is responsible for the plateau phase and the subsequent contraction of the heart.

Insufficiency of the left AV valve, also known as mitral valve regurgitation, occurs when the valve does not close properly during systole (contraction of the ventricles). This allows blood to flow back into the left atrium, causing a characteristic murmur that can be heard during systole. During diastole (relaxation of the ventricles), the valve should be closed, so a murmur would not be heard during this phase.

In individuals with COPD, such as asthma, there is a decrease in the ability to effectively exhale air, leading to a buildup of carbon dioxide (CO2) in the bloodstream. This increased CO2 levels cause a decrease in arterial pH, leading to acidosis. Therefore, it is expected to see increased arterial PCO2 and decreased arterial pH in individuals with COPD.

At an altitude of 10,000 feet, the atmospheric pressure is approximately 500 mm Hg. The question states that the atmosphere contains 20% oxygen. Since the partial pressure of a gas is directly proportional to its percentage in the mixture, the partial pressure of oxygen at this altitude would be 20% of 500 mm Hg, which is equal to 100 mm Hg.

Native high altitude dwellers have different physiological responses to the high altitude than native sea level dwellers. One of the responses they have in common is the hypercapnic ventilatory response. This refers to the increased ventilation in response to high levels of carbon dioxide (hypercapnia) in the blood. At high altitudes, there is lower oxygen availability, which can lead to an increase in carbon dioxide levels. The hypercapnic ventilatory response helps to remove excess carbon dioxide from the body and maintain the appropriate balance of gases in the blood.

The pulmonary veins carry oxygenated blood from the lungs back to the heart. This oxygenated blood enters the left atrium of the heart. From the left atrium, the blood will then pass through the mitral valve into the left ventricle before being pumped out to the rest of the body. Therefore, the correct answer is left atrium.

In the ischemic zone of the heart, the change in resting membrane potential is due to the limited action of the Na+/K+ ATPase pumps. These pumps are responsible for maintaining the concentration gradients of sodium and potassium ions across the cell membrane. In ischemia, there is reduced oxygen supply to the heart muscle, leading to a decrease in ATP production. As a result, the activity of the Na+/K+ ATPase pumps is compromised, leading to an imbalance in ion concentrations and a change in resting membrane potential.

Vasodilation of the afferent arterioles to the glomerular capillaries will increase the GFR. The afferent arterioles are responsible for supplying blood to the glomerulus, where filtration occurs. By dilating these arterioles, more blood can flow into the glomerulus, resulting in an increased glomerular filtration rate (GFR). This allows for more efficient filtration of waste products and reabsorption of necessary substances by the kidneys. Decreasing arterial blood pressure, decreased plasma concentration of ADH, and increased plasma concentration of angiotensin II would all have the opposite effect, reducing the GFR.

The majority of the CO2 transported in the blood is in the form of bicarbonate ions dissolved in the blood plasma. When CO2 enters the bloodstream, it combines with water to form carbonic acid (H2CO3), which then dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). The bicarbonate ions are highly soluble in the blood plasma and can easily be transported to the lungs for elimination. This form of CO2 transport is important in maintaining the acid-base balance in the body.

At high altitudes, the partial pressure of oxygen (PO2) decreases. This leads to a decrease in the amount of oxygen available for the body's tissues, including the lungs. In response, the body tries to compensate by constricting the blood vessels in the lungs, which increases pulmonary vascular resistance. This increase in resistance causes pulmonary hypertension, which is characterized by high blood pressure in the pulmonary arteries. As a result of the increased pressure, there is an increased filtration of fluid across the pulmonary capillaries, leading to pulmonary edema.

Starling's law of the heart states that the force of cardiac contraction increases with an increase in the length of the cardiac muscle fibers. This means that when the muscle fibers stretch, they generate a stronger contraction, allowing the heart to pump more blood with each beat. This mechanism helps the heart to adapt to changes in venous return and maintain an adequate cardiac output.

During systole, the contraction of the heart pushes blood into the arteries, causing them to stretch and expand. This stretching is due to the presence of elastic fibers in the arterial walls. These elastic fibers store potential energy during systole and then release it during diastole, helping to maintain the pressure in the arteries even when the heart is not actively pumping. This prevents the arterial pressure from falling to zero during diastole.

Afferent arteriolar vasoconstriction decreases blood flow into the glomerulus, which causes the glomerular capillary blood pressure to decrease, leading to a decrease in the net filtration pressure and a resultant decrease in the GFR.

Alveolar ventilation refers to the volume of fresh air that reaches the alveoli per minute. Minute ventilation, on the other hand, is the total volume of air breathed in and out per minute. It is possible for alveolar ventilation to decrease without changing minute ventilation if there is a decrease in the proportion of fresh air reaching the alveoli, while the total volume of air breathed in and out remains the same. This can occur, for example, if there is an increase in dead space ventilation, where air is not effectively reaching the alveoli.

Stroke volume refers to the volume of blood pumped by each ventricle during one cardiac cycle. It is the difference between the end diastolic volume (the volume of blood in the ventricle at the end of diastole) and the end systolic volume (the volume of blood in the ventricle at the end of systole). Therefore, stroke volume represents the amount of blood ejected from the ventricle with each heartbeat.

During isovolumetric ventricular contraction, all valves into and out of the heart are closed. This means that the atrioventricular (AV) valves, which separate the atria from the ventricles, are closed to prevent blood from flowing back into the atria. Additionally, the semilunar valves, which separate the ventricles from the major arteries (aorta and pulmonary artery), are also closed to prevent blood from flowing back into the ventricles. As a result, no blood is being ejected from the ventricles and no blood is flowing from the atria to the ventricles. Therefore, the correct answer is that all valves into and out of the heart are closed.

The ascending limb of the loop of Henle actively transports NaCl into the surrounding interstitial fluid and is impermeable to water. This means that it plays a crucial role in the reabsorption of sodium and chloride ions from the filtrate, while preventing the reabsorption of water. This helps to create a concentration gradient in the interstitial fluid, which is important for the reabsorption of water in the collecting ducts. Therefore, the correct answer is both A and B.

Increased circulating erythropoietin stimulates the production of erythrocytes by the bone marrow. Erythropoietin is a hormone produced by the kidneys in response to low oxygen levels in the blood. It acts on the bone marrow to increase the production and maturation of red blood cells, which carry oxygen throughout the body. Therefore, when circulating erythropoietin levels are increased, it signals the bone marrow to produce more erythrocytes, leading to an increase in red blood cell production.

Protein is present in a lower concentration in the glomerular filtrate than in the blood plasma. This is because the glomerular filtration barrier in the kidneys prevents larger molecules, such as proteins, from passing through into the filtrate. Glucose, potassium, sodium, and urea are all small enough to pass through the filtration barrier and are present in higher concentrations in the glomerular filtrate compared to the blood plasma.

Increased release of ADH is a probable mechanism to compensate for dehydration. ADH, or antidiuretic hormone, is released by the pituitary gland in response to low blood volume and increased osmolality. Its main function is to increase water reabsorption in the kidneys, which helps to conserve water and reduce urine output. By increasing the release of ADH, the body can retain more water and prevent further dehydration.

The T wave of the electrocardiogram corresponds with the relaxation of the ventricles. This is because the T wave represents the repolarization of the ventricles, which occurs during the relaxation phase of the cardiac cycle. During this phase, the ventricles are filling with blood and preparing for the next contraction. The T wave is an important marker on the ECG that helps in diagnosing various cardiac abnormalities.

An increase in left atrial pressure can lead to pulmonary congestion, as the increased pressure causes fluid to accumulate in the lungs. This can result in symptoms such as shortness of breath and coughing. Additionally, the increased left atrial pressure can cause an increase in right ventricular pressure, as the two chambers are connected. This can lead to right ventricular hypertrophy and eventually heart failure. Therefore, both options A and C are expected findings with an increase in left atrial pressure.

MAP stands for mean arterial pressure, which represents the average pressure in the arteries during one cardiac cycle. It is calculated by adding one-third of the difference between systolic and diastolic pressure to the diastolic pressure. Since MAP takes into account both systolic and diastolic pressure, but gives more weight to diastolic pressure, it is closer to diastolic pressure than systolic pressure.

Furosemide is a diuretic that is commonly used in the management of congestive heart failure (CHF) because it helps reduce the extracellular fluid volume. CHF is characterized by fluid overload, and diuretics like Furosemide help remove excess fluid from the body through increased urine production. By reducing the extracellular fluid volume, Furosemide helps alleviate symptoms of CHF such as edema and shortness of breath.

The contraction of the diaphragm decreases the pressure in the alveoli of the lungs. When the diaphragm contracts, it moves downward, causing the volume of the thoracic cavity to increase. This increase in volume leads to a decrease in pressure within the alveoli. As a result, air is drawn into the lungs to equalize the pressure, allowing for inhalation.

The vital capacity refers to the maximum amount of air that can be exhaled after a maximum inhalation. It represents the total volume of air that can be moved in and out of the lungs and is an important measure of lung function. Tidal volume refers to the amount of air inhaled or exhaled during normal breathing, while residual volume refers to the amount of air that remains in the lungs after a maximum exhalation. Respiratory volume is a general term that encompasses various measures of lung function.

The heart is innervated by both the autonomic nervous system and the peripheral nervous system. The autonomic nervous system controls the involuntary functions of the heart, such as heart rate and blood pressure, while the peripheral nervous system controls the voluntary functions, such as the sensation of pain in the heart. Therefore, both options A and C are correct.

Vasopressin, also known as antidiuretic hormone (ADH), increases the membrane permeability of the epithelial cells in the collecting ducts to water. This allows water to be reabsorbed from the urine back into the bloodstream, leading to a more concentrated urine and the conservation of water in the body.

Potassium is the ion principally responsible for the resting membrane potential. This is because there is a higher concentration of potassium ions inside the cell compared to outside. This concentration gradient creates an electrochemical gradient, where potassium ions tend to move out of the cell. However, the cell membrane is selectively permeable to potassium ions, allowing only a small fraction of them to leave. This results in a negative charge inside the cell, leading to the resting membrane potential.

Starvation or a protein-deficient diet can lead to a decrease in protein concentration in the body. This is because the body starts to break down its own proteins for energy when there is not enough protein intake from the diet. As a result, water accumulates in the tissue spaces as the decrease in protein concentration disrupts the balance of fluid in the body.

This question is asking which response is not a result of decreased systemic blood pressure from hemorrhage. The correct answer is arteriole dilation. When there is decreased blood pressure due to hemorrhage, the body typically responds by increasing heart rate and decreasing parasympathetic discharge to the heart in order to maintain blood flow. Arteriole dilation, on the other hand, would actually help to increase blood flow and therefore would not be a response to decreased blood pressure.