Motor Mechanisms

1. Chapter 49 Motor Mechanisms By: Rodrigo Vilaro, Peyton Maclay, and Maria Walts

2. Introduction • Most organisms need some form of support. Many animals wear their support on the outside. They have • Exoskeleton- a hard covering or shell • Insects, for example, have exoskeleton made of chitin. All vertebrates (animals with backbones) possess an endoskelton- their entire skelton is on the inside. Examples: humans, fish, amphibians, reptiles, birds, and all other mammals are considered vertebrates Cicada’s Exoskelton

3. Hydrostatic Skeleton A hydrostatic skeleton consists of fluid held under pressure in a closed body compartment. Peristalsis- a type of movement on land produced by rhythmic waves of muscle contractions passing from front to back.

4. The Human Skeletal System In humans, the supporting skeleton is made of cartilage and bone. Cartilage is found in the embryonic stages of all vertebrates. It is later replaced by bone, except in your external ear or the tip of your nose. - Bone is a connective tissue that contains nerves and blood vessels. - Cartilage lacks nerves and blood vessels.

5. Bones • Bone is made up of two substances: 1. Collagen2. Calcium Salts • Bone is a dynamic tissue that changes shape when osteoblasts (bone-building cells) and osteoclasts(bone-breaking cells) remodel it. • Bones are held together by joints, like the ball-and-socket joint in your shoulder. • Bones not only serve as support but together with muscles also help move us. • The connective tissue that attach muscles to bones are called Tendons.

6. Joints Joints hold bones together. So what holds the joints together? They are held together by tough connective tissues called ligaments. Ligaments attach bone to bone. Ball and Socket: shoulder- enables rotation Hinge: allows only one type of movement Pivot: allows for rotation (neck)

7. Muscle Contraction • A nerve impulse is sent to a skeletal muscle. • The neuron sending the impulse releases a neurotransmitter onto the muscle cell. • The muscle depolarizes. • Depolarization causes the sarcoplasmic reticulum to release calcium ions. • These calcium ions cause the actin and myosin filaments to slide past each other. • The muscle contracts. • http://www.khanacademy.org/science/biology/v/anatomy-of-a-muscle-cell

8. Locomotion Swimming- Overcoming friction is a major problem for swimmers. Gravity is less of a problem for swimming animals than for those that move on land or fly. Locomotion on Land- Walking, running, hopping, or crawling on land requires an animal to support itself and to move against gravity.

9. Locomotion continued Flying- Flight requires that wings develop enough lift to overcome the downward force of gravity. Comparing Costs of Locomotion- Animals that are specialized for swimming spend less energy per meter traveled than equivalently sized animals specialized for flying or running.