| Question | Answer |
| Is there a fluid layer between the periosteum and the bone? | No. |
| Describe the life span of osteoclasts. | They have a short life span. |
| What is an osteoblast? | The bone-forming cells. Their primary function is to lay down new bone.
Once this function is complete,
osteoblasts become osteocytes. |
| Some minerals are stored in the bones, and when the blood levels of these minerals decrease, they are released from the bone. What are the top two minerals stored in the bone? | Calcium and phosphorus. |
| What allows us to move? | Displacement of body segments after contraction of muscle. |
| Perforating canals(in the bone) run perpendicular to osteons and are called? | Volkmann's canals. |
| Where are epiphyseal plates? | The point where the epiphysis joins the diaphysis. |
| An osteon is also known as a... | Haversian system. |
| What are canaliculi? | Minute channels within compact bone. |
| Skeletal muscles attach to bones by tendons, which are strong bands of connective tissue. How do they produce movement? | Contraction of the skeletal muscles moves the bones, producing body movements. |
| What is stored in the bones and can be released into the body as a source of energy? | Fat(adipose tissue). |
| What runs through an osteon? | A central vascular structure, which is a combination of an artery and a vein with tissue around it. |
| What stimulates osteoblasts to produce osteocalcin? | 1,25-dihydroxyvitamin D. |
| What are the five functions of the skeleton? | Support, protection, movement, storage, and blood cell production. |
| Osteoblasts are responsive to what hormone? | Parathyroid hormone(PTH). |
| True or false: Osteoclasts are the major resorptive cells of bone. | True. |
| What are osteocytes? | These cells are osteoblasts that have become imprisoned within the mineralized bone matrix. They help maintain bone by synthesizing new bone matrix molecules. |
| What are osteoclasts? | Osteoclasts function primarily to resorb (remove) bone during the process of growth and repair. They cause causes destruction of bone and extraction of Ca++ to increase the calcemia in the blood. |
| What are lysosomes? | Digestive vacuoles. |
| What is the connective tissue that surrounds the bone? | Periosteum. |
| Where are osteoblasts active? | Osteoblasts are active on the outer surface of bones, where they form a single layer of cells. |
| What do ligaments do? | Allow some movement between bones but prevent excessive movement. |
| What do bones store? | Calcium and phosphates and fats – yellow fat. |
| Joints permit and control the
movement between bones. Where are they formed? | Where two or more bones come together. |
| Fracture is rupture of bone. What happens first in the healing process? | Break –> severe bleeding. Vessels inside of osteon break and form hematoma in area. |
| The function of osteocytes is not fully known, but they do... | Synthesize certain matrix molecules assisting
bone calcification. |
| Where is blood formed? | In red bone marrow. |
| What are delicate bridges of bone that interlace marrow and vessels within a bone? | Trabecula. |
| What are intersitial lamallae? | Lamallae that fill in the spaces between the circular Haversian canals(osteons). |
| How are epiphyseal plates sealed? | There is a point after surge in sexual hormones when epiphyseal plates are sealed and there is no possibility for more growing. When seal is calcified you cannot create more bone and the longitudinal growth is impossible. |
| Where is red bone marrow found? | Mostly in flat bones – sternum, hip, skull, long bones. In fetus, many bones are capable of hematopoesis. |
| What are the two divisions of skeleton? | Axial and appendicular. |
| What happens as a result of a hematoma forming at a break in bone? | This brings chondroblasts to create a pattern of the broken plate in cartilage. Then osteoblasts deposit minerals in area. |
| What is a lamellae? | One of the layers of bone around a Haversian canal. |
| What do osteoblasts do when stimulated by 1,25-dihydroxyvitamin D? | Produce osteocalcin. |
| What is an example of flat bone? | Parietal bone from roof of skull. |
| What is an example of short bone? | Carpels from wrists. |
| What is hematopoiesis? | The formation of blood in the bones. |
| What is osteoid? | Non-mineralized bone matrix. |
| How do osteoblasts make new bone? | They bring about the formation of new bone by their synthesis of osteoid. |
| What is an osteocyte? | A transformed osteoblast that is trapped or surrounded in osteoid as it hardens from minerals that enter during calcification. |
| What is the head of the bone? | Epiphysis. |
| Bones break easily with either... | Too much or too little Ca++. |
| The bone contains three types of cells: | Osteoblasts, osteocytes, and osteoclasts. |
| Bones are constantly changing Ca++. How long to completely replace a bone? | 5-9 years. |
| Every organ has two components... | Parenchyma, which is the functional part of the organ. Stroma, which is support. |
| Why is there no skeletal protection around the abdominal organs? | Because we store fat in the abdomen and it needs room to grow. |
| What is bone? | Rigid, strong bone is well suited for bearing weight and is the major supporting tissue of the body. |
| Osteocytes synthesize and replace needed elements of the matrix, thus... | Helping to maintain mineral homeostasis with the help of the PTH and osteoblast cells. |
| How many times does the skeleton completely turn over in a lifetime? | At least 3 times. |
| What in the bone make up the osteon by forming rings around a blood vessel? | Concentric lamellae. |
| Periosteum has how many layers? What are they called? | Two. Inner and outer. |
| Osteoclasts contain <blank> filled with <blank>. | Lysosomes (digestive vacuoles) filled with hydrolytic enzymes. |
| How long to complete remodeling of bone? | At least 45 days. |
| Osteocytes obtain nutrients from... | Capillaries in the canaliculi and help concentrate them in the matrix. |
| Where do osteoclasts come from? | They develop from the hematopoietic stem cell in the bone marrow stroma and adjacent vessels and from mononuclear phagocytic cells. |
| What runs through the middle of a central(Haversian) canal? | Blood vessels. |
| What makes up the appendicular skeleton? | Appendicular skeleton includes pectoral girdle: clavicle, scapula, upper extremities. Pelvic girdle: coccyl bones, hips, lower extremities. |
| What are concentric lamallae? | Lamallae that encircle a Haversian canal(osteon). |
| What is a blood vessel perforating perpendicularly between two osteons (haversian systems)? | Volkmann's canal. |
| How many nucleuses do osteoclasts have? | Multiple. |
| Marrow found in some bone cavities gives rise to blood cells and... | Platelets. |
| What are the two ways bone is classified? | Histalogically and by shape. |
| What are the three types of skeletal support? | Bone, cartilage, and ligament. |
| Define osteoclasts: | They are large, multinucleated cells with a short life span which develop from the hematopoietic stem cell in the bone marrow stroma and adjacent vessels and from mononuclear phagocytic cells. |
| What is the functional unit of bone? | Osteon, or Haversian system. |
| What are examples of irregular bone? | Vertebra, sphenoid bone from skull. |
| What are examples of long bone? | Femur, humerus. |
| Bone is hard and protects the organs it surrounds. What are some examples of bone acting as protection? | The skull encloses and protects the brain, and the vertebrae surround the spinal cord.
The rib cage protects the heart, lungs, and other organs of the thorax. |
| What is the cavity that contains marrow(either red or yellow) called? | Medullary cavity. |
| What are the four shape classifications of bone? | Long, flat, irregular, short. |
| Cancellous bone is found in between... | Compact bone. |
| What are the two histalogical classifications of bone? | Compact and cancellous. |
| An osteoblast is a cell that produces... | Type I collagen. |
| What is cartilage? | Cartilage provides a firm, yet flexible support within certain structures, such as the nose, external ear, rib cartilages, and trachea. |
| How do osteocytes help to maintain mineral homeostasis with the help of the PTH and osteoblast cells? | By synthesizing and replacing needed elements of the matrix. |
| What are lysosomes inside osteoclasts filled with? | Hydrolytic enzymes. |
| What substance covers the ends of bones within some joints, allowing the bones to move freely? | Smooth cartilage. |
| Yellow bone marrow contains fat. Where is it found? | Everywhere. |
| What makes up the axial skeleton? | Skull, spinal column, and ribcage. |
| True or false: young people have more red bone marrow in their long bones than adults. | True. |
| What are ligaments? | Ligaments are strong bands of fibrous connective tissue that attach to bones and hold them together. |
