Skin, Skeletal & Muscle Anatomy Lec 3 PDF

Dr.Ali Alkhafajy Anatomy Lec 3 Skin, Skeletal & Muscle 1  Dr.Ali Alkhafajy Anatomy Lec 3 What is the skin? The skin is the body’s largest organ, made of water, protein, fats and minerals. Your skin protect...

Dr.Ali Alkhafajy Anatomy Lec 3 Skin, Skeletal & Muscle 1  Dr.Ali Alkhafajy Anatomy Lec 3 What is the skin? The skin is the body’s largest organ, made of water, protein, fats and minerals. Your skin protects your body from germs and regulates body temperature. Nerves in the skin help you feel sensations like hot and cold. Your skin, along with your hair, nails, oil glands and sweat glands, is part of the integumentary system. “Integumentary” means a body’s outer covering. What are the layers of the skin? Three layers of tissue make up the skin:  Epidermis, the top layer.  Dermis, the middle layer.  Hypodermis, the bottom or fatty layer. What does the epidermis (top layer of skin) do? Your epidermis is the top layer of the skin that you can see and touch. Keratin, a protein inside skin cells, makes up the skin cells and, along with other proteins, sticks together to form this layer. The epidermis: Acts as a protective barrier: The epidermis keeps bacteria and germs from entering your body and bloodstream and causing infections. It also protects against rain, sun and other elements. Makes new skin: The epidermis continually makes new skin cells. These new cells replace the approximately 40,000 old skin cells that your body sheds every day. You have new skin every 30 days. Protects your body: Langerhans cells in the epidermis are part of the body’s immune system. They help fight off germs and infections. 2  Dr.Ali Alkhafajy Anatomy Lec 3 Provides skin color: The epidermis contains melanin, the pigment that gives skin its color. The amount of melanin you have determines the color of your skin, hair and eyes. People who make more melanin have darker skin and may tan more quickly. What does the dermis (middle layer of skin) do? The dermis makes up 90% of skin’s thickness. This middle layer of skin:  Has collagen and elastin: Collagen is a protein that makes skin cells strong and resilient. Another protein found in the dermis, elastin, keeps skin flexible. It also helps stretched skin regain its shape.  Grows hair: The roots of hair follicles attach to the dermis.  Keeps you in touch: Nerves in the dermis tell you when something is too hot to touch, itchy or super soft. These nerve receptors also help you feel pain.  Makes oil: Oil glands in the dermis help keep the skin soft and smooth. Oil also prevents your skin from absorbing too much water when you swim or get caught in a rainstorm.  Produces sweat: Sweat glands in the dermis release sweat through skin pores. Sweat helps regulate your body temperature.  Supplies blood: Blood vessels in the dermis provide nutrients to the epidermis, keeping the skin layers healthy. What does the hypodermis (bottom layer of skin) do? The bottom layer of skin, or hypodermis, is the fatty layer. The hypodermis:  Cushions muscles and bones: Fat in the hypodermis protects muscles and bones from injuries when you fall or are in an accident.  Has connective tissue: This tissue connects layers of skin to muscles and bones.  Helps the nerves and blood vessels: Nerves and blood vessels in the dermis (middle layer) get larger in the hypodermis. These nerves and blood vessels branch out to connect the hypodermis to the rest of the body.  Regulates body temperature: Fat in the hypodermis keeps you from getting too cold or hot. 3 Dr.Ali Alkhafajy Anatomy Lec 3 What is the skeletal system? The skeletal system gives your body its shape and holds your organs in place. In the simplest terms, your skeletal system is your body’s most important support structure. But it’s more than just your skeleton and bones. Your skeletal system also includes connective tissue that helps you stay supported and safe while you’re moving and still. It includes muscles that help you move and creates new blood cells that keep you healthy. The skeletal system is also called the musculoskeletal system. What are the functions of the skeletal system? The skeletal system has several jobs, some of which are easier to see and feel than others. But they’re all important to your body and health. Your skeletal system’s major functions include: 1. Giving your body shape: Your skeleton supports the weight of your body. It’s also the anchor for all the tissue that connects to it. 2. Helping you move: Your joints, connective tissue and muscles all work together to push and pull parts of your body every time you move. 3. Protecting your organs: The human skeleton is like a built-in suit of armor for organs throughout your body. Your skull protects your brain, your ribs shield your heart and lungs, and the vertebrae in your spine keep your spinal cord safe. 4. Creating new blood cells: Bone marrow at the center of some of your bones produces new red blood cells and white blood cells your body needs to stay healthy. 5. Storing minerals: Your bones hold your body’s supply of important minerals like calcium and vitamin D. 4 Dr.Ali Alkhafajy Anatomy Lec 3 What are the main parts of the skeletal system? 1. Bones: Bones are your body’s main form of structural support. Adults have between 206 and 213 bones in their bodies. 2. Muscles: Muscles are made of tightly woven, stretchy fibers. You have more than 600 muscles in your body that help you do everything from walking, running and jumping to breathing and digesting food. 3. Cartilage: Cartilage is strong, flexible tissue that acts like a shock absorber in joints throughout your body. 4. Ligaments: Ligaments are bands of tissue that connect bones to other bones. 5. Tendons: Tendons are cords that connect muscles to bone. 6. Joints: A joint is any place two bones meet. It contains some of (or all) the pieces listed above. TYPES OF BONE TISSUE  Compact bone looks solid but is very precisely structured. Compact bone is made of osteons or haversian systems, microscopic cylinders of bone matrix with osteocytes in concentric rings around central haversian canals.  Spongy bone, which does look rather like a sponge with its visible holes or cavities. Osteocytes, matrix, and blood vessels are present but are not arranged in haversian systems. The cavities in spongy bone often contain red bone marrow, which produces red blood cells, platelets, and the five kinds of white blood cells. CLASSIFICATION OF BONES 1. Long bones—the bones of the arms, legs, hands, and feet (but not the wrists and ankles). 2. Short bones—the bones of the wrists and ankles. 3. Flat bones—the ribs, shoulder blades, hip bones, and cranial bones. 4. Irregular bones—the vertebrae and facial bones. 5 Dr.Ali Alkhafajy Anatomy Lec 3 What are muscles? Muscles are pieces of soft tissue throughout your body. They help you do everything from holding your body still to running a marathon. Muscles also move and support your organs. Your heart is a hard-working muscle that beats thousands of times a day to keep you alive. What is the anatomy of muscles? Your muscles are made of thousands of small fibers woven together. These fibers stretching and pressing together is what moves your organs or body. Your muscles weave together like a quilt that covers your body. They run in all directions and work together to move you. What are the types of muscles? Healthcare providers organize muscles by tissue type. There are three types of muscle tissue in your body:  Skeletal.  Cardiac.  Smooth. Skeletal muscles: - Skeletal muscles are part of your musculoskeletal system. They work with your bones, tendons and ligaments to support your weight and move you. Tendons attach skeletal muscles to bones all over your body. Cardiac muscle: - Cardiac muscle (myocardium) makes up the middle layers of your heart. It doesn’t exist anywhere else in your body. Cardiac muscle squeezes and relaxes to pump blood through your cardiovascular system. 6 Dr.Ali Alkhafajy Anatomy Lec 3 Smooth muscles: - Smooth muscles are involuntary muscles that line the inside of some organs. They do essential jobs like moving waste through your intestines and helping your lungs expand when you breathe. Smooth muscles play an important role in many body systems, including the:  Female reproductive system and male reproductive system.  Urinary system.  Respiratory system.  Digestive system. 7