Antagonistic Muscles and Joints

Skeletal System

Main functions:

Provide support and structure, allow movement, and protect organs.

Movement: Joints

What are joints?

Joints occur where two or more bones join together. Most joints are flexible. However some bones in your skeleton are joined rigidly together and cannot move.

Rigidly means Firmly fixed or set

How do joints allow you to move?

Your Joints need to be strong enough to hold your bones together but flexible enough to let them move. Different types of joints allow movement in different directions

Bones are linked together by joints. Most joints allow different parts of the skeleton to move. The

human skeleton has joints called synovial joints.

If two bones just moved against each other, they would eventually wear away. This can happen in people who have a condition called arthritis. To stop this happening, the ends of the bones in a joint are covered with a tough, smooth substance called cartilage. This is kept slippery by a liquid called synovial fluid.

Tough ligaments join the two bones in the joint and stop the joint falling apart.

Ligament: a short band of tough, flexible, fibrous connective tissue that connects two bones or cartilages or holds together a joint.

The three types of joints are:● Hinge joints - for movement backwards and forwards, for

example the knee and elbow.● Ball-and-socket joints - for movement in all directions for

example, the hip and shoulder● Fixed joints - do not allow any movement for example the skull. ● Pivot Joints -consist of the rounded end of one bone fitting into

a ring formed by the other bone. This structure allows rotational movement, as the rounded bone moves around its own axis

Movement: Muscles

Muscular System

Allows movement by working with the skeletal system

Muscles in the body

Muscles are found all over your body. Muscles are a type of tissues that’s made up of lots of muscles cells working together to cause movement.

There are many types of muscles in your body. For example, your heart is a muscle made of cardiac muscle tissue. This muscle pumps blood around the body. Other muscles are found in your gut (stomach) to help squeeze the food along. The diagram shows the major muscle groups in your body that are used for movement.

How do muscles work

To make you move, muscles work by getting shorter -- they contract.

Muscles are attached to bones by tendons. When a muscle contracts it pulls on a bone. If the bone is part of a joint, the bone will move.

How do pairs of muscles work together?

Muscles can only pull. They cannot push. This means that two muscles have to work together at a joint. If you only had one muscle in your arm, you may be able to bend your arm but you would not be able to straighten it again.

Antagonistic Muscles

At each joint a pair of muscles work together to cause movement. These are used to bend and straighten the arm at the elbow joint by contracting or getting shorter.

Top photo - To bend the arm: ● The biceps muscle (on the

front of the upper arm) contracts

● The triceps muscle (on the back of the upper arm) relaxes

Bottom of photo - To straighten the arm: ● the biceps muscle relaxes● The triceps muscle

contracts.

More about Body Systems

Circulatory System

Main Function:

Allow you to breathe in oxygen and exhale carbon dioxide.

Heart: Pumps blood

Artery: Carries blood away from the heart

Veins: Carries blood to the heart

Digestive System

To absorb nutrients and get rid of waste

Nervous System

Sends messages to and from the brain and tells the body how to react