The skeletal and mascular systems

Reflections and Exam tips

The masculo-skeletal system

Recap

Cells are arranged into tissues, which are arranged into organs, which work together to form organ systems that make up the whole organism.

An example of a system is the masculo-skeletal system. This system is made up of the mascular system (muscles) and the skeletal system (Bones).

The skeletal system

• The skeletal system is made up of bones.
• There are over 300 bones in a human adult.
• The bones are held together by tough fibrous tissue called ligaments, otherwise they would fall apart!
• Most bones are hollow inside- This makes them light and makes movement easy, however they are still very strong enough to support body weight and resist gravity.
• Bones are joined together at joints. Joints enable movement and bending.
• To avoid direct contact and to absorb pressure, the end of each bone is covered with smooth coushining called cartilage. Cartilage prevents friction and absorbs pressure, otherwise movement would be painful.

The mascular system

• Muscles are made of muscle tissue.
• The cells of muscle tissue are adapted to contract (shorten) and relax (lengthen).
• The contraction and relaxation help muscles move bones.
• Each muscle is attached to 2 bones, using tough inelastic material called tendons. Tendons do not stretch, otherwise muscles wouldn't be able to move the bones.

Antagonistic pairs

Muscles work in opposing pairs. When one contracts, the other one relaxes, this is antagonistic (opposing) action. An example of an antagonistic pair are the upper arm muscles-Biceps, top ones and Triceps. Biceps are attached to the collar bone using 2 tendons (2=bi), triceps are attached with 3 tendons (3= tri).

When you raise your lower arm, biceps contract to pull on it, triceps relax.

When lowering the arm, triceps contract to pull it down, biceps relax. This shows the antagonistic action.

The skeletal system is for support.

The mascular system moves bones.

Ligaments hold bones together.

Tendons join muscles to bones.