THE SKELETAL SYSTEM Skeletal System FUNCTIONS 1 Movement

THE SKELETAL SYSTEM

Skeletal System FUNCTIONS 1. Movement 2. Support and Protection 3. Mineral Storage 4. Red Blood Cell (RBC) production 5. Labelling the Bones

FIBULA RIBS TIBIA PHALANGES FEMUR ZYGOMATIC METACARPALS METATARSALS CARPALS MANUBRIUM TARSALS OCCIPITAL STERNUM MANDIBLE SCAPULA OS COXAE PATELLA MAXILLARY HUMERUS VERTABRAE ULNA COCCYX RADIUS PARIETAL PELVIS FRONTAL SACRUM NASAL XIPHOID PROCESS

THE HUMAN SKULL PARIETAL FRONTAL NASAL OCCIPITAL MANDIBLE MAXILLARY ZYGOMATIC

7 INTERVETEBRAL DISCS 12 5 5 4

SHAFT OR DIAPHYSIS COMPACT PERIOSTEUM SPONGY

BONE • Periosteum= The tough membrane covering long bones, it contains blood vessels and cells for growth and repair. • Compact Bone= beneath the periosteum, it is hard and dense which gives the bone its strength. It is thickest in the shaft. • Spongy bone= Located at either end of long bones, it is the bones shock absorber. • Cartilage= Tough, flexible connective tissue.

The Human MUSCULAR SYSTEM

Overview • Over 600 muscles in the human body • Without muscles we could not walk, talk, eat, breathe, digest food or reproduce. • Can be in our direct conscious control-Voluntary Muscles eg. Skeletal Muscles that move bones, or not under conscious control-Involuntary Muscles eg. Heart muscles. • Have 3 main functions – 1 - Movement – 2 - Posture – 3 - Heat production

FUNCTIONS (1) Movement VOLUNTARY MUSCLES • These are muscles that we can consciously control to create movement. • Our skeletal muscles, walking, lifting. INVOLUNTARY MUSCLES • These are muscles that work without our conscious control, they work by themselves. • Mainly involved in life support and internal organs of the body, i. e. heart, diaphragm, eye muscles etc.

(2) Posture • Position of the body and limbs, is dependant on the Musculoskeletal System. • Good posture relies on the skeletal muscles working together to overcome the constant pulling force of gravity. They continuously change their state of ‘tone’ or tension in-order to keep the body upright and straight. • Postural problems occur when the skeletal muscles become unbalanced and do not allow for correct alignment. This unbalance is generally caused by poor muscle tone.

(3) Body Heat • Muscles require energy in order to contract, producing movement and heat. • This heat produced by contracting muscles helps maintain the body’s normal temperature. • The natural body’s response to being cold is to shiver. This is tiny muscles contracting repeatedly to produce heat and help keep us warm.

Types of Muscle • 3 types in the human body. 1 - Skeletal Muscle= These are attached to bones and produce body movement. They are Voluntary Muscles (mostly*) 2 - Smooth Muscle= We have no control over smooth muscles (Involuntary). They are found in blood vessels, the walls of the intestine and stomach, where they move food through the digestive system. 3 - Cardiac Muscle= Found in the walls of the heart. Also Involuntary, ALL THESE MUSCLES WORK TOGETHER TO KEEP US ALIVE AND WORKING CORRECTLY, HOWEVER, THEY ARE ONLY CAPABLE OF 2 MOVEMENTS: CONTRACTION AND RELAXATION

The Three Types of Muscles Type of Muscle Appearance Voluntary or Involuntary Function Smooth Muscle Cardiac Muscle Skeletal Muscle Smooth Striated Involuntary Voluntary Controls movement of internal organs. Controls contractions of the heart. Moves bones. Skeletal muscles work in pairs. When one contracts, the other relaxes. They are attached to bone by bands of tissue called tendons.

Skeletal Muscles

• The "Sliding-Filament Theory of Muscle Action" explains how the movement of thick- and thin-filaments relative to each other leads to the contraction and relaxation of whole muscles hence ultimately to the movement of the limbs or tissues attached to those muscles: • As explained on the previous page (Structures of Muscle Filaments), there are two physical units that are important for the action of muscles. They are thick filaments and thin filaments. • Muscle tissue can be described in terms of units called sacromeres. These units are defined in terms of groups of overlapping filaments (the thin and thick filaments previously described). Sacromeres are arrangements of thick and thin filaments. • The length of a sacromere and the zones (H zone, I band A band) within each sacromere, are determined by the positions of the thick and thin filaments relative to each other. This is illustrated in the three diagrams below - showing the relative length and configuration of two sacromeres of relaxed muscle (top), partially contracted muscle (centre) and fully contracted muscle (bottom diagram). Note that although the length of the sarcomere changes, the lengths of the filaments remain the same - the length of the sarcomere is a consequence of the extent to which these filaments overlap.

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