Negative feedback (continued)

Sebaceous gland

Erector muscle

Free nerve endings

Sensory corpuscle

Adipose tissue

Blood vessel

Hair shaft

Hair papila

Hair follicle

Sweat pore

Sweat duct

Sweat gland

Epidermis

Dermis

Vasoconstriction

Narrowing of skin capillaries

Krause's corpuscles in skin detect drop in temperature

Nerve impulses are transmitted from skin to heat regulation centre in hypothalamus

Nerve impulses transmitted from hypothalamus to involuntary muscle layer of blood vessel in the skin causing vasoconstriction

More blood flows towards deeper skin layers

Less blood flows to skin surface, less heat lost by radiation, convection and conduction.

Less blood flow to sweat glands, less sweat production

Less sweat evaporates from skin surface, less cooling, heat loss reduced.

Ruffini's corpuscles in skin detect rise in temperature

Nerve impulses are transmitted from skin to heat centre in hypothalamus

Nerve impulses are submitted from hypothalamus to involuntary muscle layer of blood vessel in the skin causing vasodilation

Vasodilation

Widening of skin capillaries

More blood flows to skin surface, more heat lost by radiation, convection and conduction

More blood flow to sweat glands, more sweat production.

More sweat evaporates from skin surface, more cooling, increases heat loss.