Thermoregulation and Heat Balance Quiz

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Questions and Answers

What contributes to body heat production?

Respiration and heart rate

Muscular exercise, assimilation of food, and Basal Metabolic Rate (BMR) (correct)

Digestion and absorption of nutrients

Sweating and shivering

How is body heat primarily lost?

Radiation, conduction, convection, and evaporation of water (correct)

Absorption and metabolism of nutrients

Digestion and excretion

Respiration and sweating

What determines body temperature?

The level of physical activity

The balance between heat production & heat loss (correct)

The rate of breathing

The amount of food consumed

Why is it important for the body to regulate body temperature?

Normal body function depends on a relatively constant body temperature Signup and view all the answers

What is the primary heat loss mechanism at room temperature?

Evaporation of fluid from the skin Signup and view all the answers

What is the temperature set point determined by?

The hypothalamic control Signup and view all the answers

How much heat is removed when 1 liter of water evaporates from the skin surface?

580 kcal Signup and view all the answers

What innervates the sweat glands?

Sympathetic cholinergic nerves Signup and view all the answers

What can result from thermoregulatory failure?

Heat stroke Signup and view all the answers

What regulates heat loss primarily at temperatures above 36ᵒC?

Evaporation Signup and view all the answers

What is the location of the thermoregulatory center?

Anterior hypothalamus Signup and view all the answers

What can prolonged exposure to heat, high ambient humidity, or physical exertion lead to?

Hyperthermia Signup and view all the answers

What does the evaporation rate depend on?

Ambient temperature and humidity Signup and view all the answers

What can severe hypothermia be defined as?

Below 28ᵒC Signup and view all the answers

What is the primary neurotransmitter involved in the hypothalamic control of thermoregulation?

Acetylcholine Signup and view all the answers

What are the thermoregulatory responses to changes in core body temperature controlled by?

Hypothalamic heat-promoting and heat-loss centers Signup and view all the answers

What is the range of homeostatically regulated core body temperature (Tb)?

35 - 37.5 ᵒC (95 - 99.5 ᵒF) Signup and view all the answers

What is the approximate heat energy required to increase the body temperature of a 70 kg individual by 1 ᵒC?

70 kcal Signup and view all the answers

What accounts for 50-70% of daily energy expenditure in heat production?

Basal metabolic rate (BMR) Signup and view all the answers

Which mechanism is the primary heat loss mechanism at high ambient temperatures and during strenuous physical activity?

Evaporation Signup and view all the answers

What controls the regulation of skin temperature?

Autonomic nervous system Signup and view all the answers

What is the primary heat production mechanism mainly through?

Metabolism Signup and view all the answers

What is the body's high heat capacity primarily due to?

Water content Signup and view all the answers

What leads to increased heat storage?

Heat gain > loss Signup and view all the answers

What is the range of skin temperature (Ts) that varies widely with changes in ambient temperature and cutaneous blood flow?

32 - 34 ᵒC (89.6 - 93.2 ᵒF) Signup and view all the answers

What is the primary mechanism of heat loss at room temperature?

Radiation Signup and view all the answers

What leads to vasodilation and heat loss?

Parasympathetic activity Signup and view all the answers

What is the approximate increase in body temperature during the luteal phase of the menstrual cycle?

0.5 ᵒC Signup and view all the answers

Study Notes

Thermoregulation and Heat Loss Mechanisms

Radiative heat loss decreases as the temperature gradient between the skin and ambient air decreases
At temperatures above 36ᵒC, heat loss occurs primarily through evaporation, regulated by sweat production
1 liter of water evaporated from the skin surface removes 580 kcal of heat
Sweat glands are innervated by sympathetic cholinergic nerves and can deliver up to 6L fluid/hr to the skin surface
Evaporation rate depends on ambient temperature and humidity
The thermoregulatory center is located in the anterior hypothalamus and determines the temperature set point
The hypothalamic control of thermoregulation involves cholinergic and adrenergic mechanisms
The thermoregulatory responses to changes in core body temperature involve heat-loss and heat-promoting centers in the hypothalamus
Hyperthermia can result from prolonged exposure to heat, high ambient humidity, or physical exertion
Hypothermia can be mild, moderate, or severe, with severe hypothermia below 28ᵒC
Heat stroke can result from thermoregulatory failure, leading to CNS dysfunction and even death
The primary heat loss mechanism at room temperature is evaporation of fluid from the skin

Thermoregulation and Heat Balance

Core body temperature (Tb) is homeostatically regulated at 37ᵒC (98.6 ᵒF) with a range of 36 - 37.5 ᵒC (97 - 99.5 ᵒF).
Tb varies with activity and ambient temperature, increasing during exercise to ~40 ᵒC and decreasing in extreme cold weather to ~35 ᵒC.
Skin temperature (Ts) varies widely with changes in ambient temperature and cutaneous blood flow.
Rhythmic changes in body temperature include circadian and monthly rhythms, with a 0.5 ᵒC increase during the luteal phase of the menstrual cycle.
Heat balance is maintained when heat gain equals heat loss, with gain > loss leading to increased heat storage and gain < loss leading to decreased heat storage.
The body's high heat capacity, primarily due to its water content, requires approximately 70 kcal of heat energy to increase the body temperature of a 70 kg individual by 1 ᵒC.
Heat production is mainly through metabolism, with basal metabolic rate (BMR) accounting for 50-70% of daily energy expenditure and influenced by factors such as age, sex, hormones, and digestive state.
Muscular activity and non-shivering thermogenesis in brown adipose tissue are other mechanisms of heat production.
Heat loss occurs through radiation, conduction, convection, and evaporation, with evaporation being the primary mechanism at high ambient temperatures and during strenuous physical activity.
Heat transfer between the core and the environment involves convection and conduction, with heat dissipation occurring from areas of high temperature to areas of lower temperature.
Regulation of skin temperature is controlled by the autonomic nervous system, with sympathetic activity leading to vasoconstriction and heat storage, and decreased sympathetic tone leading to vasodilation and heat loss.
Naked individuals in rooms with different ambient temperatures lose heat predominantly by radiation to surrounding solid objects, with increased evaporative heat loss at higher temperatures.

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Description

Test your knowledge of thermoregulation and heat balance with this quiz. Explore the mechanisms of heat loss, the role of the hypothalamus in temperature regulation, and factors influencing core body temperature. Gain insights into heat production, heat transfer, and the impact of ambient temperature on heat loss.