Structural and Functional Organisation of the body

• Atoms combine to form molecules.

• Cells are the smallest building blocks of living beings.

• Cells form tissues: epithelial, connective, muscular, and neural.

• Organs are composed of different types of tissues and perform specific functions.

• Organ systems consist of two or more organs that work together.

2.1 Body systems

• Integumentary system; skin and appendages (hair, fingernails); covering the body, protecting tissues, synthesising vitamin D, eliminating waste, regulating body temperature.

• Skeletal system; bones, cartilage, ligaments; protecting and supporting organs, providing a framework for muscles, producing blood cells, storing minerals.

• Muscular system; cardiac, smooth, and skeletal muscle tissue; locomotion, facial expression, posture maintenance, body heat production, digestion.

• Nervous system; brain, spinal cord, nerves, sensory receptors; fast-acting control system, responding to internal and external changes, activating muscles and glands.

• Endocrine system; endocrine glands; secretion of hormones into the bloodstream.

• Respiratory system; lungs, nasal passages, pharynx, larynx, trachea; oxygen supply, carbon dioxide removal, gas exchange in lung air sacs.

• Cardiovascular system; heart, blood vessels; pumping blood, transporting respiratory gases, nutrients, hormones, and wastes.

• lymphatic system; lymphatic vessels, nodes; collecting leaked fluid, returning it to the blood, disposing of debris, housing immune cells.

• Digestive system; oesophagus, stomach, intestines, and accessory organs; breaking down food, absorbing nutrients, removing indigestible waste.

• Urinary system; kidneys, bladder; eliminating nitrogen waste, regulating water, electrolyte and acid-base balance.

• Male reproductive system; testes, scrotum, penis; producing sperm, delivering viable sperm to the female reproductive tract.

• Female reproductive system; ovaries, uterus, vagina; producing eggs, site for fertilization and foetal development, milk production for nourishing newborns.