The outer layer of the epidermis is made up of dead cells

1. The outer layer of the epidermis is made up of dead cells • The inner layer of the epidermis is made up of living cells that undergo rapid cell division and also make keratin, a tough, fibrous protein • The epidermis also contains melanocytes: cells that produce melanin, a dark brown pigment • There are no blood vessels in the epidermis Hair Sweat Pore Epidermis Nerve Dermis Oil gland Hair follicle Sweat gland Fat tissue Dermis: contains collagen fibers, blood vessels, nerve endings, glands (sweat and oil) and hair follicles Helps regulate body temperature: Hot: blood vessel dilate, produce sweat Cold: blood vessel constrict

2. Capillaries Renal Cortex Bowman’s capsule Glomerulus Renal artery Renal Medulla Renal vein Collecting tubule Ureter Vein Artery Loop of Henle To ureter

3. Reabsorption: • As the filtrate flows through the renal tubule, most of the water and nutrients are reabsorbed into the blood • The concentrated fluid that remains is called urine • Filtration: • Most filtration occurs in the glomerulus • Blood pressure forces water, salt, glucose, amino acids and urea into Bowman’s capsule • Proteins and blood cells are too large to cross • The fluid that enters the renal tubule is called the filtrate Secretion: - Substances such as hydrogen ions are transferred from the blood to the filtrat