Biology: Topic 2J Coordination and Response (Part 1A The Skin)

Why is homeostasis important?

To maintain optimal conditions for cell function and enzyme activity.

What type of action is thermoregulation?

Involuntary action.

What is the process of thermoregulation?

Controlled by the thermoregulatory centre (TRC), which is contained in the hypothalamus region in the brain.

TRC contains thermoreceptors, which are receptors sensitive to the temperature of blood. Thermoreceptors are found in skin and brain.

Mechanism of increasing heat loss - What is sweating?

Sweat is secreted by sweat glands.

Sweat evaporates, transferring heat energy from skin to the surroundings

Mechanism of increasing heat loss - What is vasodilation?

Muscles in arterioles relax.

Arterioles near skin surface dilates

Blood flow in skin capillaries increases. → More heat is lost to surroundings through radiation.

Mechanism of increasing heat loss - What is flattening of hairs?

The hair erector muscles in skin relax.

Hairs lie flat - stops hair from trapping air which is a poor conductor of heat.

→ MORE heat is lost to surroundings through radiation.

Mechanism to decrease heat loss - What is shivering?

Skeletal muscles contract rapidly in. controlled manner.

MORE heat energy is released from respiration.

Mechanism to decrease heat loss - What is Vasoconstriction?

Muscles in arterioles contract.

Arterioles near skin surface constricts.

Blood flow in skin capillaries decreases → LESS heat is lost to surroundings through radiation.

Mechanism to decrease heat loss - What is erection of hairs?

Hair erector muscles in skin contract.

Hairs stand upright or become erect. - Traps layer of air, which is a poor conductor of heat between hairs.

→ LESS heat is lost to the surroundings through radiation.