Skeletal and Muscular System

Skeletal and Muscular System Wednesday, December 01, 2010 6:30 AM Slides Notes CC'd AUDIO FILE: n01 Title Now that we have covered some of the amazing diversity of life in Creation. Now it is times to take a look at the human body. Psalms 139:14 says that the human body is fearfully and wonderfully made, and indeed it is! From time to time, we will compare the human body with the structures of other organisms. While there may be life forms that are simpler than humans; there is no such thing as a simple life form. Even the simplest life form in Creation is much more complex and welldesigned than the most impressive human made technology. The body's superstructure is made up of the skeleton, the muscles, and the skin. CC'd n02 Characteriistics The skeletal system is as strong as steel, light al aluminum, grows as we do, and can heal itself when damaged. It is responsible to support the body and work with the muscles for movement. It also protects vital organs. The bone marrow actually produces the cells in your blood. It also stores minerals in case other reserves run out; though, loss of these minerals in the bone can compromise bone strength. General Science Page 1

CC'd n03 baby vs adult There are 206 separate bones in the adult body. Children actually have more because some of the bones that are fused together in the adult are separate still in children. Bones can be classified into two groups: appendicular and axial. The appendecular Skeleton attaches to the limbs. They consist of... Limbs (femur too) Pelvic girdle Pectoral girdle The axial Skeleton supports and protects the head, neck, and trunk. They include... Skull - The skull, in an adult, has 29 separate bones. Backbone Ribcage CC'd n04 Bone Anatomy Now let's look at bone anatomy. You will not have to memorize the anatomy of the bone, just the general information. The center of the bone is the medullary canal. It contains bone marrow and blood vessels. If the marrow is young, it will be red and produced the blood cells. If it is old, the marrow will be yellow and can no longer make blood cells. The medullary canal is surrounded by two types of bone: spongy bone and compact bone. Both are made from the same substance, but they differ in how mineral-hardened fibers are packed together. Though the spongy bone looks spongy, it is very hard, just with lots of air spaces. This lets the bone be strong yet the air spaces lighten the weight. It also contains the red marrow. Bone is alive, which means it needs oxygen and nutrients. The next layer is a sheath called the peristeum (pehr - ee - ah - stee - uhm). It contains nerves and blood vessels and will signal the brain if there is any damage to the bone. The smallest bone in the human body is in the middle ear and is a mere 1/10 " long. The longest bone is the femur and it makes up 25% of your height. General Science Page 2

CC'd AUDIO FILE: n05 Other Organisms The sum total of bones in the human body is called the endoskeleton. Endo means inside. Other organisms have skeletons as well. Birds have hollow bones so that they will be light enough to fly with ease. Some organisms have skeletons on the outside, exoskeletons. Exo means outside. Many of the organisms that have exoskeletons, do not have a backbone. Arthropods are like this. Their exoskeletons are made of chitin. What are arthropods? We call them invertebrates while organisms with backbones are called vertebrates. Other invertebrates are jellyfish and snails. Where do they get their body support from? What about bacteria, protists, and plants? CC'd AUIDIO FILE: n06 four joints There are 4 major joints Washer Ball-and-Socket Hinge Saddle CC'd AUDIO FILE: n07 washer joint The washer joint exists only in your backbone. Your backbone is made up of vertebrae. Each one is connected to each other with the washer joint. Each allows a small range of motion, but together you get a wide range of motion. The backbone is divided into the lumbar region (lower back) and the spine (mid to upper back). If you bend to the side, you will need to shift your hips to the side of the midline of balance or you will fall down. Without that shift, you will not be able to bend to the side more than about 35 degree without falling if your ankles are together. To bend forward or backward, if you bend only in the lumbar region, you can General Science Page 3

CC'd AUDIO FILE: n07 washer joint The washer joint exists only in your backbone. Your backbone is made up of vertebrae. Each one is connected to each other with the washer joint. Each allows a small range of motion, but together you get a wide range of motion. The backbone is divided into the lumbar region (lower back) and the spine (mid to upper back). If you bend to the side, you will need to shift your hips to the side of the midline of balance or you will fall down. Without that shift, you will not be able to bend to the side more than about 35 degree without falling if your ankles are together. To bend forward or backward, if you bend only in the lumbar region, you can bend 25 to 33 degrees. To bend further, you must also involve the spine and the hips or shift your feet from an ankle to ankle position. Muscles and fat that get in the way can also reduce the range of motion to a joint. CC'd AUDIO FILE: n08 ball and socket In the ball and socket joint, the ball-shaped part fits in to a bowl shaped socket. Hip range of motion is so extensive that you can do the splits forward and to the side if your muscles are flexible enough to stretch. The toes will point in an angle matching the hip/lumbar region. The hips also play a part in the range that the knee can swing inward and outward. Shoulder ball and socket joint is shallow. This gives it a larger range of motion than the ball and socket joint in the hip. The disadvantage to having a larger range of motion is that it isn't as strong a joint. The arm lock is effective because it puts the shoulder joint at the end of its range of motion. That lessens the leverage that the muscle can apply. Some people are flexible enough to touch their fingers together behind their back with one arm from above and one below. CC'd AUDIO FILE: n09 Hinge Joint The hinge joint in the third joint out of the four we will discuss. In one direction, the hinge joint has about 130 degrees of motion allowing that joint to nearly double back on itself. But, in moving the other direction, it can extend only a little way as a hyperextension or in a side to side motion. General Science Page 4

CC'd AUDIO FILE: n10 Saddle Joint The saddle joint is a bit in between a hinge and a ball and socket. The bones fit together in a saddle shaped way. They have left and right as well and up and down motion, but it doesn't have the range of motion of the ball and socket joint. CC'd AUDIO FILE: n11 cartilage Flex your nose and ears. That is what it mean to be rubbery. This is cartilage. It has a very high percentage of collagen. Now give your shin a good push. Not so flexible! That is that bone in front of the lower leg. Not so flexible is it?! The bone that is your shin has calcium salts that strengthen it. Bones have two things in the bone matrix: collagen and minerals. Collagen is a flexible, rubbery substance that belongs to a class of chemicals called proteins. Cartilage's flexibility makes it an excellent shock absorber and because it also has sort of a slick and smooth nature, it can reduce friction in joints. If the joints were to rub bone to bone when there was motion, a lot of damage would result because bones are not made to handle that kind of wear and tear. Another chemical called synovial fluid is coating the joints which reduced friction even more. If you have ever handled egg white, you will have an idea of what this fluid is like. The fluid is stored in a bag like structure called an articular capsule. Cartilage doesn't hold bones together though. An even muscles don't. There are tough, elastic-like bands that connect bone to bone at locations where movement occurs and the bones could otherwise slip out of alignment. These bands are called ligaments. Now, in this particular module, you've got a lab in which you will take a bone and soak it in vinegar over a period of days to weeks. I think you will find that something interesting will happen. General Science Page 5

CC'd AUDIO FILE: n12 Skeletal Muscles A skeleton gives the body structure and joints allow that skeleton to bend, but that cannot create movement. You need muscles for motion. There are three types of muscles: Skeletal - which there are 640 different kinds There are also smooth muscles and Cardiac muscles Skeletal muscles are the ones we most often think of when we thing of muscles. They are involved with moving your skeleton around. Interestingly, muscles do not attach directly to the bones. Instead they taper and end in a tendon which does attach to the skeleton. CC'd AUDIO FILE: n13 muscular To cause movement, your muscles typically come in pairs One muscle on one side of the joint and one on the other. They are attached ins such a way that if one contracts the other will relax. This combination of pull and relax lets the muscles move the joint. Let's take a look at the pairs related to the bending of the elbow. The muscles that pair up here are the bicep and triceps. The bicep is the one that you make really big when you try to make your arm look strong. The triceps are under the upper arm and they work to straighten the elbow. If a persons triceps were damaged and couldn't contract, what motion could still be performed and what motion could not? This example is a fairly simple one. In reality, muscles work in sets of 10, 20, or even more muscles in a group. General Science Page 6

CC'd Smooth muscles are quite different in both structure and function than skeletal muscles. They are smoother, hence their name. If you looked at skeletal muscles under a microscope, you would see a striped appearance. Smooth muscles do not have the rougher, striped texture. These muscles are not connected to bone. These muscles are the muscles of the stomach, intestinal muscles, etc. Unlike skeletal muscles, you do not have to 'think' to move them When you do not have to consciously think to move a muscle yet it does what it is supposed to do by moving such as the stomach muscle churning your food after you eat, we call it an involuntary muscle. Another involuntary muscle is the cardiac muscle. It is the muscle of your heart. It is a good thing that you do not have to think to make your heart pump blood. You wouldn't last long after going to sleep and you would be in trouble if you got distracted while awake. Though you do not have to think to make your heart beat, your brain does still control it - along with a patch of cells on the heart itself called the sinotorial node. The sinotorial node sets the pace for the heart and because of this it is often called the pacemaker. It does this by setting off an electrical signal about 100 times per minute. Place your finger over your wrist or over the artery in your neck and count how many beats you have in one minute. I will watch the time for you. Your heart doesn't beat 100 times per minute does it? Well that is because the pacemaker is also influenced by the brain. The brain gets feedback from receptors all over your body as to how much oxygen is needed. The brain can slow down or speed up the sinoatorial node's settings to match the body's need at any given time. Under a microscope, the cardiac muscle is striped, much like the skeletal muscle, but the it is much smaller. It is a cross between skeletal and smooth muscle types. General Science Page 7

CC'd AUDIO FILE: The basic structure and function of muscles are pretty much the same from organism to organism; however, the placement can be quite different. Our muscles lay over the tops of joints. Arthropods have muscles that reside inside the joints. In kingdom monera (bacteria), movement occurs via the flagella. They spin these little tails like an outboard motor. Some protists have little hairs called cilia that they wiggle like you would move oars in a boat to make it move. Plants use turgor pressure in their vacuoles to create movement. They will move in response to light and they also respond to gravity. This response to gravity is called gravitropism. It helps them sense which way is up and which way is down so that they send their roots and stems in the correct direction. Both of these movements are controlled by hormones. CC'd AUDIO FILE: The skin's job is to protect the body from invaders. It also is home to our sense of touch, temperature, and pain. Hair, fingernails, and toenails are a modified type of skin. Keratinization is the process by which skin goes from soft and supple to tough as nails. Your skin is composed of two basic layers. The outer layer is called the epidermis. It protects the inner tissues. The other layer is the dermis, it is composed of fibrous connective tissue. Below the dermis is the hypodermis which is composed mostly of fat. It isn't technically considered part of the skin. Its job is to provide insulations for your body. Notice that the epidermis is composed of two layers: a layer of dead cells and a layer of living cells. As a cell from the lower level moves to the outer layer, the cystoplasm is transformed into a waterproofing protein called keratin. The process is called keartization. This process kills the cell but makes it quite sturdy and a good barrier to pathogens. These dead cells are constantly flaking off. A large percentage of the dust in your home are actually these dead cells. You have hair on all skin surfaces except for the palms of your hand and the soles of your feet. Hair is also keratinized and will grow from the hair follicle into a cylindrical shape as a whole. The cells in hair are tougher than in skin. General Science Page 8

This growth will be at different rates in different places. The hair on your head is very active for months at a time. The hair on your arms and legs grow in short spurts and then they rest for along period of time. What purposes do you think hair serves? (insulation and sense of touch). Goose pimples are caused from the tiny muscles attached to each hair. When you get cold, the muscles contract and the hair stands up allowing greater amounts of air to become trapped between them to increase warmth. The sebaceous gland creates an oil that coats and softens the hair and skin. Often the glands become over active and create so much oil that the pores become blocked causing irritation and skin problems. Sweat glands allow moisture to get to the surface of the skin to be used for cooling the body due to evaporation. That might be surprising that the body wants to help the bacteria and fungi, but it all comes down to what type it is. The body just doesn't want pathogenic bacteria on the skin. One of the by-products of a good bacteria is that it produces lactic acid. This acid makes it hard for the pathogenic ones to do what they do. Symbiosis is a wonderful cooperation between two different organisms to benefit each other. Skin color is controlled by a substance called melanin which is a pigment. If someone has a lot of melanin, their skin will be dark. People with albinism have no melanin. They will have pink colored eyes, very white-ish pink skin, and pure white hair. Hair gets its color much the same way. Red hair is a mixture of melainin and a red pigment made by the bodies of people with that genetic trait. General Science Page 9

CC'd AUDIO FILE: If an organism's skin produces feathers, it is a bird. Arthropods and fungi have skin made of chitin. Bacteria just have their cell membrane and a sticky goo that is loaded with toxins. CC'd AUDIO FILE: Fish and reptiles have scales. CC'd AUDIO FILE: Amphibians can even breathe through their skin. It is one of four methods of respiration that they will have in their lifetime. CC'd AUDIO FILE: Plants have an epidermis too, but it more simple than our epidermis. In summary, the body is an amazing thing! General Science Page 10