Define/Explain the following terms:
$(1)$ Sweat gland
$(2)$ Uremia

(N/A) $(1)$ Sweat glands are present in the skin of mammals. Their secretion contains water,salts,minerals,urea,lactic acid,and a small amount of amino acids,which are excreted through the skin in the form of sweat.
$(2)$ The presence of an excessive amount of urea in the blood is known as uremia.