The Skeletal System Chapter 8 1
Introduction Movement is essential for animals. This is done by moving muscles with the skeleton. 2
Functions of the skeleton 1. Gives shape and support to the body. The skeleton keeps the body upright. 2. Movement Muscles pull on bones to cause movement. 3
Functions of the skeleton 3. Protection Protects organs of the body Ribs protect heart, lungs Skull protects the brain 4. Manufactures blood cells Red and white cells are made in bone marrow 4
The Human Skeleton Humerus Radius Ulna Pelvis Femur Tibia Skull Collar Bone Shoulder Blade Ribs Spine Vertebra Sternum Fibula 5
Skeleton of a Cow Skull Vertabra Shoulder Blade Spine Femur Pelvis Humerus Radius & Ulna Sternum Ribs Tibia & Fibula 6
Skeleton of a Sheep Skull Vertabra Shoulder Blade Spine Femur Pelvis Humerus Radius & Ulna Ribs Tibia & Fibula 7
Skeleton of a Horse - Test yourself Skull Shoulder Blade Spine Vertabra Pelvis Ribs Humerus Radius & Ulna Sternum Femur Tibia & Fibula 8
Skull Spine Vertabra Shoulder Blade Humerus Radius Ulna Ribs Bones of the skeleton 9
Pelvis Femur Tibia Fibula Sternum Collar Bone 10
Composition of bone Bone is made of living part Organic Bone made of minerals. Calcium Phosphorus. 11
Structure of a long bone Bone must be light but strong. Has a cavity in centre called a medullary cavity. Marrow produces white cells Outside this is compact bone Bone cells packed tightly together. For strength and rigidity 12
Structure of a long bone 13
At the ends is spongy bone Contains bone cells separated by spaces. Spaces are filled with red marrow. Produces red blood cells. On the ends is Cartilage Tough, flexible material Reduces friction between bones. 14
To find the amount of minerals in bone
To find the amount of minerals in bone 1. Find the mass of two clean fresh bones. 2. Put one in Hydrochloric acid. 3. Leave for a week. 4. Find the mass of both again. 5. Test for flexibility. 6. As a control put the second bone in water.
Result The mass of the bone in the Hydrochloric Acid will go down. The mass of the bone in water will remain the same. 17
To find the amount of Organic Matter in bones
To find the amount of Organic Matter in bones 1. Find the mass of a clean fresh bone 2. Burn the bone in a Bunsen burner. 3. Find the mass again at the end of the experiment. 4. All the organic matter has been burned when two consecutive weights are the same. 5. As a control, leave a bone unburned
Result The mass will go down Because all organic matter has been burned out. It will break easily.
Result The mass will go down. Minerals have been dissolved out by Hydrochloric acid. Bone will be very flexible.
Joints There are three types of joints 1. Immovable. Bones held tightly together E.g. Bones of skull 2. Slightly movable. Little flexibility E.g. Bones in the vertebral column 3. Freely movable 22
Freely moveable joints Called Synovial joints. There are 4 types of joint: 1. Ball and socket - Hip, Shoulder 2. Hinge joint - Elbow, Knee 3. Gliding joint - Wrist, Ankle 4. Pivot joint - Between top two vertebrae 23
Muscle Muscles are attached to bones by tendons. For movement there are two muscles connected to each limb. This is because while one contracts, the other relaxes and vice versa. These muscles are said to be antagonistic muscles. Example Biceps and Triceps. 24
Muscles There are three types of muscle in the body: Striated Muscle Voluntary muscle attached to bones. Smooth Muscle Involuntary muscle found in our stomachs and intestines. Cardiac Muscle Involuntary muscle only found in the heart. 25
Muscle 2 Muscle is an extremely contractile connective tissue. The contraction of muscle performs four important functions: Movement Posture maintenance Support the joints Heat production Skeletal muscle is connected to the skeleton by tendons. It is under conscious control. Its contraction is fast and strong. Skeletal muscle tires easily. 26
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