Tissues, Organs, and Organ Systems Objectives :

1. Tissues, Organs, and Organ Systems Objectives: Explain the organization within more advanced organisms. Explain the role of each tissue type and list examples of it in the body Describe the composition of bone. Recognize major bones of the skeletal system. Identify different types of joints and their function. Evaluate the role of vitamins, minerals, and toxins in the health and maintenance of the skeletal system. Describe the cause, treatment, and symptoms of various skeletal disorders. Vocabulary: Tissues, Organs, Organ Systems, Exoskeleton, Endoskeleton, Axial skeleton, Appendicular skeleton, Pectoral girdle, Pelvic girdle, Osteoblast, Osteoclast, Osteoporosis, Arthritis, Rickets, Ligaments, Invertebrate, Vertebrae, Marrow, Superior, Inferior, Posterior, Cervical, Thoracic, Lumbar, Dorsal, Medial, Distal, Osteocytes, osteo-, arth-, Spongy bone, Compact bone, Anemia, Cartilage, Periosteum, Ossification, Epiphyseal plate Joints: Fixed, Ball & Socket, Hinge, Pivot

2. In more advanced organisms, there is organization of cells working together to form tissues (Ex: muscle tissue), and tissues working together to form organs (Ex: muscle, nervous, connective, tissue, etc. form the heart), and organs working together to form organ systems. Types of Tissues: Epithelial tissue - is the lining and covering of organs, including the skin Connective tissue - provides support, attachments, and insulation. This includes: collagen, elastin, adipose (fat), blood, cartilage, and bone. Nervous tissue - an electrical communication system including the brain, nerves, and sensory organs (eyes, etc). Muscle tissue - creates movement through contraction.

3. The Skeletal System Animals without a backbone are called invertebrates. Some of these have no skeleton at all, others have an exoskeleton (exterior skeleton), usually made of chitin, not bone. Those with an endoskeleton (interior skeleton) generally have bones made of numerous minerals, including calcium, magnesium, phosphorus, silicon, boron, etc. Some toxins, like lead can compete with calcium for absorption and end up in the bones. If the bones are later broken down to balance blood pH, etc. the lead will be released with all of the other minerals into the blood stream. The human skeleton has 206 bones. Of these, about 80 bones make up the axial skeleton which consists of the skull, sternum (breastbone), spine (26 vertebrae -backbones), ribs (12 pairs), and sacrum (at the base of the spine). The rest compose the appendicular skeleton which includes the pectoral girdle (shoulders: clavicles & scapulas, and arms) and the pelvic girdle (hips and legs).

4. The Axial Skeleton The skull consists of numerous bony plates that meet at fixed joints, also known as “sutures”. The forehead area is the frontal bone, the plates near the ears are the temporal bones, superior (above) and slightly posterior (toward the hind end, behind) to the temporal plates are the parietal bones, inferior (below) to these is the occipital bone. In addition, the upper jaw is known as the maxilla and the lower jaw is the mandible. The cheek bones are known as the zygomatic arches. The eye sockets are called “orbits”. The skull to neck is a pivot joint. The spine, located on our dorsal side (usually the top side, but our back side due to our upright position), has 7 cervical (neck) vertebrae, 12 thoracic (chest area) vertebrae, and 5 lumbar (lower back) vertebrae. Running through our vertebrae is a dorsal, hollow, nerve cord. Between vertebrae are cartilaginous, fluid-filled discs. The ribs protrude from the vertebrae and most circle around to the sternum(breast bone), attaching to it via cartilage. The 2 inferior ribs are sometimes called “floating ribs” due to their lack of attachment to the sternum.

6. The Appendicular Skeleton 1) The pectoral girdle consists of the clavicles (collar bones), scapulas (shoulder blades), the humerus (upper arm bone), the radius (lower arm bone on the thumb side), ulna (the other lower arm bone), the carpals (wrist bones), metacarpals (hand bones), and phalanges (finger bones). The wrist is an angular joint. The shoulder is a ball and socket joint. 2) The pelvic girdle consists of the ilium (top hip area, NOT ileum), the sacrum (5 fused into 1 vertebrae just below the lumbar vertebrae), coccyx (the “tailbone”), the ischium (just medial {closer to the center} to and inferior to the ball and socket joint where the femur attaches to the “hips”), the pubis, the femur (upper leg bone), the patella (knee cap), the tibia (larger of the 2 lower leg bones, the fibula (the other lower leg bone), the tarsals (ankle bones), calcaneus (heel bone), metatarsals (foot bones), and phlanges (toe bones). The knee is a hinge joint. The ankle is a gliding joint.

8. The bones are formed by osteoblasts which secrete collagen fibers for calcium phosphate and other minerals to deposit on. The first layer is laid down around the Haversian canal (a long hollow channel in the center of the bone, running the length of the bone) which houses blood vessels that nourish the osteocytes (bone cells). Bones are LIVING! They are constantly being torn down by osteoclasts and rebuilt by osteoblasts. If they were not living, broken bones would never heal. There are 2 forms of bones, compact and spongy. The compact bone is the outer, very dense layer. The spongy bone is on the inside and is riddled with pore spaces. Some of the pores are filled with red marrow, which makes red blood cells, white blood cells, and platelets. The hips are a good area to find red marrow. Other pores are filled with yellow marrow, which stores fat. Research has shown that low body temperature (Ex: due to hypothyroidism) can cause red marrow to convert to yellow marrow and result in anemia (low RBC count). The bone is covered by a tough membrane called the periosteum. (peri = around, surrounding, osteum = bone)

10. During fetal development, bone starts as cartilage but is eventually mostly replaced by bone as it becomes mineralized (ossification). As we grow, cartilage at the distal (far end) of bones forms the epiphyseal plate where new cartilage cells are formed and replaced by bone. Eventually the epiphyseal plates “close” and no more growth is possible. Although 99% of the calcium in the body is in the bones, it’s extremely important that the blood maintains its calcium levels so, if necessary, bone will be sacrificed. When calcium is released, so is the phosphorus it is bound to and many other minerals stored there including harmful metals like lead. The break down of bone can lead to osteoporosis (brittle bones). Lack of the proper nutrients during bone development can lead to soft, bowed bones as is the case with vitamin D deficiency causing rickets.

11. Notice bone related words use the prefix “osteo-”, which means “bone”. Whereas, the prefix “arth-” means joints. So, arthritis (-itis = inflammation) is inflammation of the joints. Rheumatoid arthritis often benefits from copper supplementation. This could be due to its role in one form of the anti-oxidant “super oxide dismutase” (SOD) or because copper has an anti-bacterial affect. On the other hand, osteoarthritis involves degeneration of the bones and/or cartilage at the joints. Many substances, such as glucosamine, chondroitin sulfate, etc. can help repair cartilage. Finally, ligaments are tough connective tissue that holds adjacent bones together at the joints. Ligaments can be torn or over stretched.