When a person exercises, their body temperature rises. How does the body maintain homeostasis in response to this change?
By dilating blood vessels and increasing sweat production
By increasing metabolic rate
By decreasing the heart rate
By constricting blood vessels and reducing sweat production
The Correct Answer is A
A. By dilating blood vessels and increasing sweat production: This is the primary cooling response. Vasodilation of cutaneous blood vessels increases blood flow to the skin to dissipate heat; sweating and subsequent evaporation remove heat from the body surface. Together these actions lower core temperature and restore homeostasis.
B. By increasing metabolic rate: Increasing metabolic rate would produce more heat, which would worsen hyperthermia rather than cool the body. Metabolic rate typically increases during exercise (which raises temperature), but it is not a homeostatic response to reduce body temperature.
C. By decreasing the heart rate: During exercise, heart rate increases to meet oxygen demand; decreasing heart rate would impair heat dissipation and cardiovascular support for exercise. It is not a thermoregulatory mechanism to cool the body.
D. By constricting blood vessels and reducing sweat production: Vasoconstriction and reduced sweating conserve heat and reduce heat loss - an appropriate response in cold stress, not when body temperature is elevated. This would counteract cooling and worsen hyperthermia.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Providing energy:Carbohydrates are broken down into glucose, which is the body’s preferred and most efficient fuel source for cellular respiration (ATP production), especially for the brain and muscles during exercise.
B. Building tissues:While some carbohydrates are found in cell markers, the primary "building blocks" of body tissues (muscles, skin, organs) are proteins.
C. Regulating hormones:While some hormones are glycoproteins, the major class of molecules used to synthesize steroid hormones are lipids (specifically cholesterol), and many others are protein-based.
D. Insulating organs:Thermal insulation and physical cushioning of organs is the primary function of lipids (adipose tissue/fat).
Correct Answer is B
Explanation
A. Cardiac muscle:Cardiac muscle is found only in the heart. It is striated and involuntary with unique intercalated discs and autorhythmicity; it is notthe muscle that lines most hollow organs (like intestines, bladder, blood vessels).
B. Smooth muscle:Smooth muscle is non-striated, involuntary muscle located in the walls of hollow organs (e.g., gastrointestinal tract, bladder, uterus), blood vessel walls, and bronchi. It generates slow, sustained contractions for peristalsis, vasomotion, and other automatic functions.
C. Skeletal muscle:Skeletal muscle is striated and under voluntary control, attached to bones to produce movement; it is not the primary muscle of hollow organ walls.
D. Striated muscle:“Striated muscle” is a descriptive term that includes skeletal and cardiac muscle (both have striations). Since the question asks specifically about involuntary muscle in hollow organs, striated muscle is not the correct category.
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