Chapter 2 — Science and Sports

Anatomy is the scientific study of the structure of the human body — it covers what body parts are and where they are located. Physiology is the study of how different organs and systems function to maintain life. Anatomy answers the 'what' and 'where'; physiology explains the 'how' and 'why' of bodily functions.

Long bones (e.g., humerus, femur) are tubular with a long axis and two ends that articulate with other bones. Flat bones (e.g., cranial bones, scapula) are flat and thin and protect internal organs. Irregular bones (e.g., vertebrae) have complex shapes. Sesamoid bones (e.g., patella) lie within tendons. Short bones (e.g., carpal bones) are cuboidal in shape.

Cartilage is a tough yet flexible connective tissue that helps protect bones and joints by absorbing shock. Found at the ends of bones, it minimises friction and keeps bones from grinding against each other during movement. In some areas it also provides form and shape to body structures. Cartilage can be damaged suddenly from sports injuries or gradually through overuse.

A tendon is a tough, flexible band of tissue that attaches muscles to bones, allowing limbs to move; it also absorbs part of the impact during activities like running and jumping. A ligament is a strong, fibrous band of connective tissue that links bones to one another, stabilises joints, guides and limits bone movement, and reduces the risk of injuries.

Fibrous joints connect bones by dense fibrous connective tissue (like collagen) with no direct movement — for example, the skull. Cartilaginous joints connect bones by cartilage, allowing limited movement — for example, the vertebrae. Synovial joints are freely moveable joints with a fluid-filled cavity covered by a synovial membrane — for example, the knee and shoulder.

Ball and socket joints allow movements in all directions (e.g., hip, shoulder). Hinge joints allow flexion and extension only (e.g., knee, elbow). Pivot joints allow rotational movement (e.g., atlanto-axial joint in the neck). Gliding joints allow sliding movements (e.g., wrist, ankle). Saddle joints allow movement in two planes (e.g., thumb). Condyloid joints allow movements in all directions but not rotation (e.g., knuckles).

Breathing (ventilation) is the physical act of inhaling oxygen and exhaling carbon dioxide, involving the lungs, chest muscles, and diaphragm. Respiration happens at the cellular level — it is the chemical process inside cells where oxygen is used in the mitochondria to break down glucose and release energy in the form of ATP, producing carbon dioxide and water as waste products.

Blood passes through the heart twice in one complete circuit. In pulmonary circulation, the right side pumps oxygen-deficient blood to the lungs, where carbon dioxide is removed and oxygen is added, then oxygen-rich blood returns to the left side. In systemic circulation, the left side pumps oxygen-rich blood to all body tissues, cells use oxygen and produce carbon dioxide, and oxygen-deficient blood flows back to the right side of the heart.

Cardiac output is the amount of blood the heart pumps into the aorta every minute. In an average adult, the cardiac output at rest is about 5 litres per minute. During exercise it can rise to up to 30 litres per minute, as the body needs to send more blood to active tissues.

Immediately, the heart beats faster and pumps more blood, breathing rate and depth increase, muscles use more oxygen, and blood vessels redirect blood to muscles. Long-term, the heart becomes larger, stronger, and more efficient; lungs develop greater capacity; muscles increase in size, strength, and endurance; more capillaries grow in muscles (capillarisation); and bones become stronger with better joint stability.

Force is the push or pull that muscles create. Strength is how much force a muscle can produce to overcome resistance. Power is strength combined with speed — for example, in sprinting or jumping — and may also be called explosive strength.

Skeletal muscles are voluntary muscles attached to bones; they are long, cylindrical, multinucleated, and striated, and consciously control movement (e.g., biceps, quadriceps). Smooth muscles are involuntary, found in the walls of hollow internal organs like the stomach and blood vessels; they are spindle-shaped and controlled by the Autonomic Nervous System. Cardiac muscles are found only in the heart's myocardium; they are branched, striated, and self-stimulating, pumping blood continuously throughout life.

PRICE stands for Protection, Rest, Ice, Compression, and Elevation. Protection prevents further damage; Rest means stopping pressure on the injured part; Ice is applied for 10–15 minutes every 2 hours (always wrapped in cloth) to reduce pain and swelling; Compression with an elastic bandage limits swelling and provides support; Elevation means keeping the injured limb raised above heart level to help fluid drain away and reduce swelling.

DRSABCD stands for: Danger (check the area is safe for yourself, bystanders, and the casualty), Response (check if the person responds), Send for help (call 112), Airway (check for obstruction; tilt the head back and lift the chin to open the airway), Breathing (look, listen, and feel for 10 seconds), CPR (30 chest compressions + 2 breaths if not breathing), and Defibrillation (attach an AED if available and follow its instructions).

The normal 'lub-dub' heart sound is caused by the closing of the heart's four valves in sequence. 'Lub' (S1) is the sound of the mitral and tricuspid valves closing as the ventricles begin to contract. 'Dub' (S2) is caused by the closing of the aortic and pulmonary valves as the ventricles finish contracting and relax. An abnormal sound called a heart murmur can occur from turbulent blood flow due to a leaky or stiff valve.

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