Block 7 Temp Reg & Cancer

Radiation is the correct answer because it refers to the transfer of heat through electromagnetic waves, such as infrared radiation. Unlike conduction and convection, which require physical contact or movement of matter, radiation can occur even when objects are not in direct contact. This type of heat transfer is commonly observed in situations where heat is transferred from the Sun to the Earth, or when objects are heated by a fire or a hot object nearby.

Glutamine is the correct answer because it is an amino acid that can be converted into alpha-ketoglutarate, a key intermediate in the TCA cycle. Glutamine serves as a carbon source and "fills up" the TCA cycle with carbon compounds, allowing it to continue functioning. This process is important for energy production and the synthesis of other molecules in the cell.

During fever, the rise in core temperature is due to an increased thermal setpoint. This means that the body's internal thermostat is set to a higher temperature, causing the body to generate and retain more heat. On the other hand, during exercise, the rise in core temperature is primarily caused by increased metabolic activity and energy production, leading to an increased basal metabolic rate. Additionally, during exercise, sweat formation is increased to help cool down the body, whereas in fever, sweat formation may be reduced. Non-shivering thermogenesis and reduced skin blood flow are not specific to either fever or exercise.

Tumor cells use Malic enzyme to generate enough NADPH to keep fatty acid and nucleotide synthesis going. NADPH is required for these processes as it acts as a reducing agent. Malic enzyme is involved in the malate-aspartate shuttle, which transfers reducing equivalents from the cytosol into the mitochondria, where NADPH is generated. This NADPH can then be used in various biosynthetic pathways, including fatty acid and nucleotide synthesis.

Radiation is the correct answer because it refers to the heat transfer mechanism that occurs between the sun and the outer layer of the skin. Radiation involves the transfer of heat through electromagnetic waves, such as infrared radiation, without the need for direct contact between objects. In this case, the sun emits radiation in the form of sunlight, which is absorbed by the outer layer of the skin, resulting in the sensation of warmth.

In a temperate climate under normal conditions, the greatest loss of body heat occurs through radiation. This means that when the environmental temperature is lower than the body temperature, heat is transferred from the body to the surroundings through the process of radiation. Other mechanisms of heat loss, such as conduction, convection, and evaporation, may also contribute to regulating body temperature, but in a temperate climate, radiation is the primary method of heat loss.

Sweat secretion is a human thermoregulatory response controlled by cholinergic sympathetics. When the body temperature rises, the cholinergic sympathetics stimulate the sweat glands to produce sweat. Sweat then evaporates from the skin, which helps to cool down the body as the heat is carried away. This response helps to regulate body temperature and prevent overheating.

When someone is experiencing heat exhaustion, their body is unable to cool itself properly, leading to symptoms such as heavy sweating, dizziness, and fatigue. However, if their skin suddenly becomes very dry, it is a definitive indication that they are now at risk for heat stroke. Heat stroke is a more severe condition where the body's temperature regulation system fails, and the lack of sweating and dry skin are key signs of this dangerous condition.

Profuse sweating can lead to heat exhaustion because when we sweat excessively, our body loses a large amount of water and electrolytes. This can lead to dehydration and an imbalance in the body's temperature regulation system. Heat exhaustion occurs when the body is unable to cool itself effectively, leading to symptoms such as dizziness, fatigue, nausea, and rapid heartbeat. Therefore, it is important to stay hydrated and take breaks in a cool environment when sweating excessively to prevent heat exhaustion.

Acclimatization to a hot environment involves the body adapting to the heat by increasing sweat production. Sweating helps to cool down the body by evaporating the sweat from the skin surface. In order to efficiently cool down the body, the sweat becomes more dilute, meaning that it contains a higher amount of water and fewer electrolytes. This allows for more efficient evaporation and cooling of the body. Therefore, the correct answer is "More dilute".

The heat transfer mechanism that occurs between arteries and veins in a countercurrent exchange is called convection. Convection refers to the transfer of heat through the movement of a fluid, such as blood, which carries heat from the arteries to the veins. In countercurrent exchange, the warm blood flowing in the arteries transfers its heat to the cooler blood flowing in the veins, maximizing the efficiency of heat exchange. This process helps to maintain a constant body temperature and is essential for the proper functioning of the circulatory system.

The HK2-VDAC interaction on the outer mitochondrial membrane provides a readily available source of ATP for HK2 to phosphorylate glucose. This allows cancer cells to efficiently produce ATP, which is essential for their rapid growth and proliferation. By having a constant supply of ATP, cancer cells can sustain their high energy demands and support their uncontrolled growth.

When the environmental temperature increases moderately, blood flow to the skin increases as part of the body temperature regulatory mechanisms. This is because the body needs to dissipate heat and maintain its internal temperature within a narrow range. By increasing blood flow to the skin, the body can release heat through radiation and convection, helping to cool down the body. This is an important mechanism to prevent overheating and maintain homeostasis.

Pyruvate Kinase M2 is the correct answer because it is an enzyme that is known to play a key role in the regulation of glucose metabolism in cancer cells. It is highly expressed in tumors and is involved in promoting the nonoxidative pentose phosphate pathway (PPP), which is a metabolic pathway that generates important cellular building blocks and antioxidants. By increasing the flux through the nonoxidative PPP, Pyruvate Kinase M2 helps cancer cells meet their increased demand for nucleotides and antioxidants, promoting their growth and survival.

Convection is the principal physical mechanism that accounts for the transfer of heat within the body. Convection involves the movement of heat through the circulation of fluids, such as blood, within the body. As the fluids circulate, they carry heat from one area to another, helping to regulate body temperature. This process is essential for maintaining a stable internal body temperature and ensuring that heat is distributed evenly throughout the body.

When pathogens produce fever, one of the responses of the body is shivering. Shivering is a mechanism by which the body generates heat in order to increase the body temperature and reach the new set-point temperature established by the hypothalamus. Shivering involves rapid muscle contractions, which generate heat as a byproduct. This helps to increase the body temperature and fight off the infection caused by the pathogens.

When p53 is mutated, it leads to a decrease in the amount of NADPH produced by the pentose phosphate pathway (PPP). The PPP is responsible for generating NADPH, which is essential for various cellular processes, including antioxidant defense and biosynthesis of fatty acids and nucleotides. A decrease in NADPH production can disrupt these processes and lead to cellular dysfunction. This mutation does not directly affect glycolysis or the entry of pyruvate into the mitochondria.

The correct answer is that both thermoregulatory skin blood flow and sweating responses in the arm would be abolished. This is because a surgical sympathectomy completely interrupts the sympathetic nerves, which are responsible for controlling these responses. Without the sympathetic nerves, the blood vessels in the skin would not constrict or dilate appropriately to regulate temperature, and the sweat glands would not be activated to produce sweat. Therefore, both responses would be abolished in the affected arm.

Skeletal muscle is the major heat source to retain body temperature in a nude 65-kg adult person in a 29oC/84.2oF environment. Skeletal muscles generate heat through metabolic processes, such as muscle contractions and cellular respiration. When the body is exposed to cold temperatures, skeletal muscles contract involuntarily, known as shivering, to generate heat and maintain body temperature. This heat production helps to counteract the heat loss from the body to the environment and keep the body warm.

At the beginning of the rising phase of fever, the mean skin temperature is below normal. This is because during fever, the body's temperature regulation system is disrupted, causing the body temperature to rise. As a result, the blood vessels near the skin constrict, reducing blood flow to the skin and causing the skin temperature to decrease. This is a physiological response aimed at conserving heat and raising the overall body temperature.

When the mean skin temperature of a person reaches 40.5oC/104.9oF, the body will initiate physiological responses to cool down. One of these responses is to increase cardiac output, which means that the heart pumps more blood per minute. This is done to increase blood flow to the skin, where heat can be dissipated through sweating and radiation. At the same time, the body will decrease blood flow to the splanchnic region (organs of the digestive system) to redirect blood to the skin. This is because the body prioritizes cooling down over digestion during heat stress. Therefore, the correct answer is increased cardiac output and decreased splanchnic blood flow.

The esophageal temperature at the cardia is the most accurate reflection of changes in human core temperature caused by immersion in a warm body bath. This is because the esophagus is located close to the core of the body and is not affected by external factors such as ambient temperature or skin temperature. Therefore, measuring the temperature at the cardia of the esophagus provides a more reliable indicator of core temperature changes compared to other methods such as oral, rectal, axillary, or tympanic temperature measurements.