Systems of the Body 7th Grade Science

11 Body Systems Skeletal System Muscular System Cardiovascular System Digestive System Endocrine System Nervous System Respiratory System Immune/Lymphatic Systems Urinary System Integumentary System Reproductive Systems (Male and Female)

Skeletal System The skeletal system is all of the bones in the body and the tissues (tendons, ligaments, and cartilage) that connect them. Teeth are also considered part of the skeletal system, even though they are not made of bone.

What does the skeletal system do? The skeletal system has three main jobs: Support Protection Movement

Job #1: Support The main job of the skeletal system is to give our bodies support Without your bones your body would collapse into a pile on the floor, a puddle of skin and guts The human skeleton is extremely strong for how light it is

Job #2: Protection Your skeleton helps to protect your internal organs and other fragile tissues Your skeleton protects your brain, eyes, heart, lungs, and very importantly your spinal cord Your skull protects your brain and your eyes Your ribs protect your heart and lungs Your vertebrae (spine or backbone) protect your spinal cord

Job #3: Movement Bones are what your muscles attach to so that they can move your body Without bones your muscles would be useless! Tendons are tough bands that attach your muscles to your bones Tendons are not very flexible

Fun Facts Bones contain more calcium than any other organ Bones stop growing in length in early adulthood but they can continue to increase in thickness throughout life due to increased weight The adult skeleton has 206 bones, but babies have around 300 that fuse together during growth and development

Muscular System The purpose of the muscles found in your body is to help your body move! Muscles are responsible for everything from moving your legs when walking, to beating your heart, and even contracting tiny blood vessels inside of your brain You have three different types of muscles in your body: Skeletal Cardiac Smooth

Skeletal Muscle Tissue Responsible for helping you move! It is the only voluntary muscle tissue in your body, or the only one that you can control This is why you can walk, run, smile, frown, etc.

Smooth Muscle Tissue Helps moves food and liquids throughout your body Found in your blood vessels, bladder, and digestive system These are involuntary, you don’t think about them to make them move

Cardiac Muscle Tissue This muscle tissue is responsible for making your heart beat It is found only in the heart It is involuntary, after all, you don’t have to tell your heart to beat!

Muscles and Bones Working Together Muscles need to connect to your bones to allow you to move Tendons connect muscles to your bones at insertion points Ligaments are connective tissue that bind bones to each other Flexors are muscles that force your joints to bend (think biceps) Extensors are muscles that make your limbs to straighten (think triceps)

Flexors vs. Extensors

Lab Time!