TOPIC OF PRESENTATION . THERMOREGULATION IN MAMMALS

WHAT IS THERMOREGULTION? IT IS THE ABILITY OF AN ORGANISM TO KEEP ITS BODY TEMPERATURE WITHIN CERTAIN BOUNDARIES ,EVEN WHEN TEMPERATURE SURROUNDING IS VERY DIFFERENT..

WHAT IS HEAT STROKE? If the body is unable to maintain a normal temperature and it increases significantly above normal ,a condition called heat stroke.

What is hypothermia? The opposite condition, when body temperature decreases below normal levels, is known as hypothermia.

Mammals are endothermic. They are warm blooded. They are homeotherms

IN HOT CONDITIONS. 1.By sweating. Sweat glands under the skin secrete sweat on to the surface of the skin .This causes heat loss by a evaporation.

By relaxing these muscles hairs on the skin become flat which BY RELAXING THE ERRECTOR PILI MUSCLES By relaxing these muscles hairs on the skin become flat which increase the flow of hair by trapping it next to the skin, increasing heat loss by convection.

ARTERIOLES VASODILATION In arterial walls the smooth muscles relax allowing increase blood flow which comes to the superficial Capillaries in the skin increasing heat loss byradiation and conduction.

PANTING Many animals pant rather than sweat .This is the because of the large area of lungs and highly vascularised.

IN COLD CONDITIONS….. Sweat stops being produced. By contraction of errector pili muscles. By contraction of these muscles attach hair on the skin become erect ad standing on end which acts as an insulating layer, trapping heat

Arteries present on the superficial surface of the BY VASOCONSTRICTION Arteries present on the superficial surface of the skin constrict as a result blood is rerouted away from the skin and towards the warme r core of the body.

BY SHIVERING THERMOGENESIS Muscles can also receive messages from the thermoregulatory centre of the brain (the hypothalamus) to cause shivering.

THERMOREULATION IN OTHER MAMMALS. Insulation by pelage or fat deposits. By lowering the temperature of surface tissue . Heat loss by poorly insulated patches of skin . By countercurrent mechanism.

Winter sleep. Hibernation . Hibernation is a period of winter inactivity in which the hypothalamus of the brain slows the metabolic ,heart, and respiratory rates. Following changes takes place during hibernation,

These mammals accumulate large quantitites of body fat before hibernations. They retreat to a burrow or a nest during hibernation. Their hypothalamus sets the thermostat of body at about 2C . The respiratory rate of a hibernating ground squirel falls from 100 to 200 breaths per minute to about four breaths per minute.

The heart rate falls from 200 to 300 beats per minute to about 20 beats per minute. A mammal may lose one third of its body weight during hibernation.