Because dogs and cats do not sweat through the skin, the respiratory system also plays an important role in regulation of temperature. The urinary system is responsible for removing waste products from blood and eliminating them as urine. The genital organs are involved in reproduction. The nervous system includes the brain, spinal cord and all the nerves that communicate between tissues and the brain and spinal cord. The endocrine system includes several glands that produce hormones.
Hormones are substances that travel through the blood stream and affect other organs.
Endocrine organs include the thyroid glands, parathyroid glands, adrenal glands and part of the pancreas. The hematopoietic system includes the bone marrow which is located inside the bones.