Body Organization and Structure Body Organization and Structure Homeostasis – the ability of your body to maintain a stable internal environment Your internal environment is always changing, so your body has to be able to adapt to these changes. Every single cell in your body has a special job to help maintain homeostasis. Cells are organized into groups called tissues. There are 4 main kinds of tissues in your body: 1) Epithelial tissue – covers and protects (skin cells) 2) Nervous tissue – sends signals through the body (nerves) 3.) Muscle tissue – contracts and relaxes to produce movement 4.) Connective tissue – joins, supports, protects, insulates, nourishes and cushions organs (the glue that holds your organs together) Nervous Tissue - nerve Epithelial Tissue - (skin) Smooth muscle tissue Cardiac muscle tissue Connective tissue Tissues make up organs. See diagram of stomach on page 581 Organs make up organ systems. Stomach works with other organs to make up the digestive system. Your body has 12 major organ systems. See p. 582-583. List all 12. 1. Integumentary 9. Nervous 2. Muscular 10. Digestive 3. Skeletal 11. Lymphatic 4. Cardiovascular 12. Endocrine 5. Circulatory 6. Respiratory 7. Urinary 8. reproductive Skeleton System • Made up of bones, cartilage, and the connective tissue that holds bones together Baby is born with over 300 bones. Most are soft and flexible. During childhood, most bones still have growth plates of cartilage. As you grow bones fuse together. Average adult has 206 bones. Fused skeleton happens by age 25. Closed plates Open plates Open plates Unfused baby skull Two main parts of the skeleton 1. Axial skeleton – skull, vertebral column, ribs, and sternum 2. Appendicular skeleton – arms, legs, shoulder, hip bones, wrists, ankles, fingers, toes, etc. Function of the Bones • Support and protection • Work with your muscles for movement • Store minerals • Make blood cells (The marrow in your bones help make blood cells.) Bone Structure • Several different tissue (connective tissue and minerals) • Minerals are deposited by living cells called osteoblasts • Compact bone – no visible open spaces; rigid and dense • Spongy bone – many open spaces; provides most of the strength and support for a bone Osteoblasts – deposit mineral – form bones Compact and Spongy bone structure • Soft tissue in bone is called marrow. Red marrow produces red and white blood cells. Yellow marrow in central cavity stores fat. • See page 585, figure 2 Bone Marrow In vertebrates joints are found where two or more bones meet. Joints are often held together by ligaments. Tendons are thick bands of connective tissue that attach muscles to bones. Kinds of Joints 1. Gliding – allows bones to glide over one another (hand, vertebrae) 2. Ball and socket – allows you to move in all directions (shoulder) 3. Hinge joint – allows you to flex and extend (elbow, knee) 4. Pivot joint – allows you to turn your head 5. Immovable joint – bone is fused together (skull) Cartilage Skeletal System Injuries and Diseases 1. Bones may be fractured or broken 2. Joints can be dislocated 3. Sprains can occur if ligaments are stretced too far 4. Osteoporosis is a disease that causes bones to become less dense and break easily. Age and poor eating habits play a role in causing this disease. 5. Arthritis is a disease that affects the joints. The joints swell or become stiff – very painful. Osteoporosis Arthritis Dislocation Major bones Muscular System Perform many functions: digesting food, breathing, standing upright Without muscles, your body would collapse. Three Kinds of Muscles 1. Smooth – found in digestive tract and walls of blood vessels 2. Cardiac – only in your heart 3. Skeletal – attached to your bones for movement Muscle action can be voluntary or involuntary. When you move, the muscle cells contract and get shorter. Tendons connect your muscles to bones. Your muscles usually work in pairs. The muscle that bends part of your body is called a flexor (bicep). The muscle that straightens a part of your body is called an extensor (triceps). flexor extensor To make your muscles stronger, you have to exercise. Two kinds of exercise can increase strength and endurance. Examples of resistance: using weights Example of endurance: any aerobic exercise like jogging, skating, swimming. Aerobic exercise mostly increases the strength of the heart. (aerobic – with oxygen) Injuries to Muscles • Strain – muscle or tendon is overstretches or torn. Occurs when not warmed up or overworked. • Tendonitis – when tendons become injured and get inflamed People that try to make their muscles stronger by taking drugs called anabolic steroids can cause long-term health problems to their heart, liver, and kidneys. They can also cause high blood pressure and taken too early can cause bones to stop growing! Integumentary System • Made up of skin, hair and nails • Covers body and helps maintain homeostasis • Largest organ in your body!!! Covers 2 m2 Function of Skin • Protect – keeps H2O in and foreign particles out • Nerve endings – sense of touch • Regulates temp – sweat glands release salty liquid that cools • Gets rid of wastes – chemical wastes removed in sweat Skin color determined by pigment called melanin. Purpose of melanin is to absorb UV light from the sun. 2 Main layers of skin: 1. Epidermis – top; made of several layers; thick as 2 sheets of paper; thicker on palms of hands and soles of feet • Most of the cells are dead • Filled with protein called keratin that makes the skin tough 2. Dermis – thicker layer; fibers made of collagen which makes skin strong; also allow skin to bend without tearing Hair and Nails • Made of living and dead cells • Only living cells in hair are around the base at the hair follicle • Hair gets color from melanin • Hair regulates body temp • Fingers and toes sensitive to touch so protected by nails Skin can repair itself. Some damage is serious enough to damage the genetic material. This is called cancer. • Skin cancer Acne can result when too much oil is secreted from hormones and combines with dead skin cells and bacteria to clog follicles.