Therefore they have very well developed endoplasmic reticulum and Golgi body. Secretory epithelial cell Skin protects us against the environment. It also cools the body with sweat, warms it with its hair and serves as excretion organ for some substances. Excitation travels through the nerve surounded by a myelin sheath. On the periphery lies compact bone which as a tube surrounds the spongy bone tissue lying more centrally.
Bone contains also the bone cells and blood vessels.
We have 32 teeth. Each tooth has an enamel coat of hardened calcium, dentin layer which is more bonelike and inner pulp which contains blood vessels that provide the nutrition and nerve that innervates the tooth. A tooth - longitudinal section We have 32 teeth. Each tooth has an enamel coat of hardened calcium, dentin layer which is more bonelike and inner pulp which contains blood vessels that provide the nutrition and nerve that innervates the tooth. Arrangement of human teeth Bones of the skull protect brain and sensory organs.