A. They live in the polar regions of the Northern and Southern Hemispheres.
Probably to not contaminate food or accidentally poison it.
Answer:
Relaxation of the dartos muscle.
Explanation:
Testes are present in scrotum outside the pelvic cavity to maintain the temperature about 2-3 degrees Celsius below the body temperature as required for sperm production. Dartos muscle is the layer of smooth muscle located in the superficial fascia. The contraction of dartos muscle serves to make the skin of the scrotum wrinkled and tight.
During hot weather, the dartos muscle relaxes and makes the surface of scrotum less wrinkled to increase the loss of the heat from its surface. The increased heat loss from the surface of scrotum due to relaxed dartos muscles keeps the testes protected from heat.
The cardiovascular system is a system of organs that facilitates the circulation of blood to all parts of the body. Blood is required to reach all living cells as the blood carries essential elements for cell life and regulation, such as nutrients, amino acids, electrolytes,oxygen and hormones. The blood also has a role in maintaining body temperature, fighting diseases, maintaining a stable pH and maintaining homeostasis. The blood also carries carbon dioxide away from the cells. The cardiovascular system consists of a network of arteries, veins and capillaries, as well as the heart, which acts to pump blood around the body, Blood leaves the heart via arteries and return via veins. The lymphatic system transports lymph, typically at a much slower rate than blood. The lymphatic system is an important part of the immune system. Unlike the cardiovascular system, the lymphatic system is not a closed system. The cardiovascular system processes a lot of blood each day through capillary filtration, which separates the blood cells from the plasma. Not all plasma is re-absorbed into the blood vessels, and the lymphatic system is responsible for returning the remaining plasma to the cardiovascular system. <span> </span>
