WK 4: Balancing Heat Gain and Volume Loss

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What is the primary function of arterio-venous anastomoses in apical regions of skin?

To increase blood pressure in the skin

To increase heat loss through sweating

To reduce blood flow to the skin during low ambient temperature

To facilitate countercurrent heat exchange (correct)

Which of the following is NOT a mechanism of heat production in the body?

Sweating (correct)

Adrenaline release

Shivering

Thyroid hormone production

What is the primary location of thermal sensors in the body?

In the hypothalamus

In the brainstem

Throughout the skin surface (correct)

In the spinal cord

What is the primary role of the hypothalamic control centre in thermoregulation?

To integrate thermal information from the body Signup and view all the answers

Which neurotransmitter is released by sympathetic nerves to stimulate sweat glands?

Acetylcholine Signup and view all the answers

What is the effect of rising core temperature on blood flow through the skin?

Vasodilation of dermal blood flow Signup and view all the answers

What is the primary function of the hypothalamic control centre in thermoregulation?

To detect changes in core body temperature Signup and view all the answers

What is the main mechanism of heat transfer between the body and environment?

Evaporation through sweat glands Signup and view all the answers

Which of the following is a peripheral thermal sensor?

Nerve endings in the skin Signup and view all the answers

Where are thermal sensors highly concentrated in the body?

In both the skin and preoptic anterior hypothalamus Signup and view all the answers

What is the role of the autonomic nervous system in thermoregulation?

To regulate blood flow and vasodilation to control heat loss Signup and view all the answers

What is the primary function of T3 and T4 hormones in thermoregulation?

To control the body's rate of heat production Signup and view all the answers

What is the function of thermal sensors in the skin?

To detect ambient temperature Signup and view all the answers

What is the role of shivering in thermoregulation?

To increase heat production through muscle contraction Signup and view all the answers

What is the role of the hypothalamic control centre in thermoregulation?

To integrate thermal information and regulate body temperature Signup and view all the answers

What is the effect of infections on the body's thermoregulatory system?

It raises the set-point temperature Signup and view all the answers

Which of the following is an efferent nerve fibre response in thermoregulation?

All of the above Signup and view all the answers

What is the purpose of anticipatory reflexes in thermoregulation?

To stabilise heat loss/gain prior to changes in core temperature Signup and view all the answers

What is the primary mechanism of Ach mediated vasodilatation?

Endothelial cell dependent formation of vasoactive molecules Signup and view all the answers

What is the estimated rate of total-body water loss through evaporation of perspiration in a hot environment?

2 L/hour Signup and view all the answers

What is the role of osmoreceptors in detecting volume loss?

Sense changes in plasma osmolality Signup and view all the answers

What is the effect of hyperosmolality on AVP output?

Increased AVP output Signup and view all the answers

What is the name of the hormone that promotes water retention in the kidneys?

Vasopressin Signup and view all the answers

What is the clinical consequence of losing more than 3% of body weight due to dehydration?

Lightheadedness and disorientation Signup and view all the answers

What is the primary indicator of circulating volume in the body?

Left-atrial pressure Signup and view all the answers

What is the primary response to low arterial pressure in terms of AVP secretion?

Increased AVP secretion Signup and view all the answers

What is the primary function of ANP in terms of blood pressure regulation?

Increased sodium excretion Signup and view all the answers

What is the primary mechanism of regulating body fluid status when salt is given with water?

Delayed urine production Signup and view all the answers

What is the primary role of the kidneys in blood pressure regulation in the long term?

Regulation of sodium excretion Signup and view all the answers

What is the primary effect of AVP on urine production?

Decreased urine production Signup and view all the answers