Regulation of Body Temperature

Vocabulary flashcards covering skin structure, mechanisms of thermoregulation, physiological responses to temperature changes, and related illnesses.

Enzyme activities

Processes that are kept steady by a stable body temperature to maintain a steady metabolic rate.

Heat gain sources

Mainly from metabolism inside the body, particularly respiration in the liver and skeletal muscles, as well as the environment.

Methods of heat exchange

Radiation, conduction, convection, and evaporation.

Epidermis

The outer thin layer of the skin that reduces water loss, protects against mechanical injury, prevents pathogen entry, and produces vitamin D.

Keratin

A substance that gradually replaces the cytoplasm of cells in the epidermis as they die and move to the outermost layer.

Melanin

A pigment in the epidermis that prevents ultraviolet light from harming the body.

Dermis

The inner thick layer of the skin containing sensory receptors, hair follicles, erector muscles, glands, and blood vessels.

Sebaceous glands

Glands in the dermis that secrete sebum to keep skin and hair supple and waterproof.

Sebum

A secretion that suppresses the growth of microorganisms and keeps skin and hair supple.

Sweat glands

Structures that secrete sweat to help regulate body temperature and remove metabolic wastes.

Subcutaneous fat

A layer below the dermis that acts as an insulating layer to reduce heat loss and serves as an energy reserve.

Thermoregulatory centre

A region in the hypothalamus consisting of the heat gain centre and the heat loss centre.

Hypothalamus thermoreceptors

Receptors that detect the temperature of the blood passing through the brain, representing internal temperature.

Skin thermoreceptors

Receptors that detect the external temperature of the skin.

Normal body temperature set point

The standard temperature the body maintains, typically $37\,^{\circ}\text{C}$.

Vasoconstriction

The constriction of arterioles under cold conditions, resulting in less blood flow to capillaries near the skin surface to reduce heat loss.

Vasodilation

The dilation of arterioles under hot conditions, resulting in more blood flow to capillaries near the skin surface to increase heat loss.

Erector muscles (cold response)

Muscles that contract to pull hairs upright, trapping a thicker layer of still air for better insulation.

Erector muscles (hot response)

Muscles that relax so hairs lie flat, trapping only a thin layer of still air to reduce heat insulation.

Shunt vessel

A blood vessel that connects the arteriole and venule; more blood flows through it during vasoconstriction to reduce heat loss.

Shivering

Involuntary, uncoordinated contraction of skeletal muscles to increase respiration and generate more heat.

Thyroxine

A hormone secreted by the thyroid gland that increases the metabolic rate of body cells to generate more heat.

Heat exhaustion and heatstroke

Illnesses resulting from prolonged exposure to high temperatures and the body's inability to regulate temperature.

Hypothermia

An illness resulting from prolonged exposure to low temperatures.