Unit 3: Muscles

Unit 3:

Muscles

Biology for Grade 8th

by Steviana Amalia Ratih, S.Pd.

Feeling your muscles

• Rest your arm on the table in front of you, keeping it straight.

• Put the fingers of your other hand on your upper arm, where your biceps muscle is.

• Slowly and steadily, bend your arm upwards. Do this several times.

Open Ended

What can you feel happening in your upper arm, when you do this?

Learning Objectives

After doing the learning session, I can:

• Investigate how a pair of muscles moves the arm at the elbow.

• Classify the three types of muscles tissue based on their location and function.

Muscle

• Muscles are the movers of body parts, so muscles are referred to as active locomotion.

• Muscles can only pull, can't push.

• Muscles are made of specialised cells. These cells are able to make 

  themselves shorter. This is called contraction. When a muscle is not contracting, it relaxes. 

• Muscles use energy to contract. 

• They get this energy from 

  nutrients, especially glucose.

• The more you ask your muscles to contract, the more energy 

  they use, and therefore the more glucose they use.

• Many muscles are attached to bones, by strong cords called tendons. 

Biceps and Triceps

• Biceps. 'Bi' means two, because it has two tendons that attach it to the scapula.

• Triceps. 'Tri' means three, because it has two tendons that attach it to the humerus and one tendons that attach it to the scapula.

Multiple Choice

Which bones is the biceps attached to?

• Scapula and radius

• Radius and ulna

• Scapula and ulna

• Humerus and radius

Multiple Choice

Muscles use energy to contract. They get the energy from nutrients, especially ....

• Water

• Vitamin

• Glucose

• Lipid

Bending The Elbow Joint

• When you bend your arm, biceps muscle respond by contracting.

• The contraction makes the whole muscle get shorter.

• So when it gets shorter, these bones are pulled closer together. 

Straightening The Elbow Joint

• Triceps pull the arm straight again.

• Triceps can straightening the arm by getting shorter, or contracting.

Antagonistic Muscles

• The biceps muscle and the triceps muscle work as a team. To bend the arm, the biceps contracts and the triceps relaxes. And vice versa.

• Two muscles that work together like this are called antagonistic muscles. 

Multiple Choice

When the arm is bent, which muscle contracts?

• Triceps

• Biceps

Three Types of Muscle Tissue

Multiple Choice

Which muscles work voluntarily?

• Cardiac muscles

• Intestinal muscles

• Skeletal muscles

• Stomach muscles