Human Body: Tissues, Skeleton and Muscles

There are 4 types of tissue in the human body.

Tissue	Example
Epithelial	skin, lining of the intestine
Connective	bone, blood
Muscle	biceps, heart
Nervous	neuron, glial cell

Connective tissue includes: bone, cartilage, blood, fat.

There are three types of muscle tissue:

• Striated: skeletal muscles, contract voluntarily.
• Smooth: walls of internal organs, involuntary.
• Cardiac muscle: striated, but involuntary.

The human skeleton consists of ≈ 206 bones. It is divided into the skeleton of the head, the trunk, and the limbs.

Structure of bone: on the outside is the periosteum (it ensures growth in thickness), inside are compact and spongy bone tissue, and in the cavity is the marrow. Organic substances give flexibility, inorganic ones (Ca and P salts) give hardness.

Key Facts

• Vertebral column: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), 4-5 coccygeal vertebrae.
• In children organic substances predominate (bone is flexible), in the elderly inorganic substances predominate (bone is brittle).
• Antagonist muscles: the biceps flexes, the triceps extends. The contractile unit of a muscle: the sarcomere.
• Red bone marrow produces blood, yellow marrow stores fat.
• Joints: movable (knee, elbow), partially movable, immovable (sutures of the skull).