BIO201 Osseous Tissue Review Guide

Compare and contrast compact bone with spongy bone.

Although compact bone appears solid, it actually consists of tightly packed, concentric rings. Blood vessels flow through the center canal. Other spaces within the compact bone, called lacunae, contain osteocytes, a type of cell that assists in bone remodeling. Compact bone tissue provides the strength and structure necessary to prevent bones from breaking. Unlike the dense structure of compact bone, spongy bone contains spaces throughout its structure. These spaces contain bone marrow that produces red blood cells for the body. Spongy bone helps to strengthen and support compact bone. SEER training models from the National Cancer Institute state that when stress is placed on the bone, the structures that make up the spongy tissue can realign to provide support.

What are the two major divisions of the human skeleton?

Appendicular and Axial

Describe the causes and symptoms of osteoporosis.

Bones lose mass and become brittle (loss of organic matrix and minerals) a. risk of fracture of hip, wrist and vertebral column b. complications (pneumonia and blood clotting) Postmenopausal white women at greatest risk c. by age 70, average loss is 30% of bone mass

Compare and contrast the following in regards to calcitriol, calcitonin, and PTH (Parathyroid Hormone). a. Where each hormone is produced. b. How each hormone is produced (especially if there are multiple steps). c. What each of these hormones does, including the target organs/regions of the body for each hormone. d. How the rise or fall of calcium levels in the blood will affect the release of these hormones. In other words, be able to predict how hypocalcemia and hypercalcemia are corrected.

Calcitriol - UV radiation and epidermal keratinocytes convert steroid derivative to cholecalciferol D3 -liver converts it to calcidiol kidney converts that to calcitriol (vitamin D) Calcitriol behaves as a hormone that raises blood calcium concentration MAIN ACTIONS: -increases intestinal absorption of calcium -promotes urinary reabsorption of calcium ions LESS SIGNIFICANT ACTIONS: -increases stem cell differentiation into osteoclasts, leading to bone resorption -Abnormal softness (rickets) in children and (osteomalacia) in adults without vitamin D Calcitonin Secreted by (C cells of thyroid gland) when calcium concentration rises too high. -Calcitonin is a hormone that lowers blood calcium concentration -reduces osteoclast activity as much as 70% -increases the number and activity of osteoblasts • Important in children, little effect in adults, osteoclasts more active in children Salmon Calcitonin - Reduces bone loss in osteoporosis Parathyriod Hormone (PTH) -4 glands on posterior surface of thyroid -Released with low calcium blood levels PTH raises blood calcium levels -causes osteoblasts to release osteoclast-stimulating factor (RANKL) increasing osteoclast population -promotes calcium reabsorption by the kidneys -promotes calcitriol synthesis in the kidneys -inhibits collagen synthesis and bone deposition by osteoblasts

Explain the importance of calcium and phosphate in the human body.

Calcium serves two important functions in the body the building of bones and teeth and regulating certain body processes. The need for calcium in the building of the skeleton is of course, grater during the year of. However the need doesn't end when full growth is attained. Once the bone is formed, it continues to change with the processes of building new bone and maintaining the old. The normal behavior of heart muscles, nerves and the blood clotting processes all depend on the presence of calcium.

Sketch Compact and Spongy Bone

Draw

Bone Marking

For lab

What is the function of the Haverisan Canal and Volkmann's canal? What are the other names for each of these canals?

Haverisan Canal: central cannal, contain blood vessels that run vertically Volkmann's Canal: perforating, perpendicular to the central canal - carry blood vessels into bone and marrow

Compare and contrast hypocalcemia and hypercalcemia, focusing on how each of these imbalances might present clinically.

Hypocalcemia: is deficiency of blood calcium. Causes excitability of nervous system if too low -muscle spasms, tremors or tetany -laryngospasm and suffocation with less calcium, sodium channels open more easily, sodium enters cell and excites neuron Hypercalcemia: is excess of blood calcium -binding to cell surface makes sodium channels less likely to open, depressing nervous system -muscle weakness and sluggish reflexes, cardiac arrest ~12 mg/dL

Explain how a bone lengthens, making sure to include the importance of the epiphyseal line.

Importance of Epiphyseal Line: This happens when an individual reaches their adult stature. Once bone growth ceases, the epiphyseal plate's cartilage is replace by bone and the epiphyseal line is left as a remainder of the epiphyseal plate.

What type of marrow is found in the medullary cavity of adults? Of children?

In adults: Red marrow is found mainly in the flat bones hip bone, breast bone, skull, ribs, vertebrae and shoulder blades In the cancellous ("spongy") material at the proximal ends of the long bones femur and humerus. Yellow marrow is found in the medullary cavity the hollow interior of the middle portion of long bones. In a child, all bone marrow is red bone marrow and can be found in nearly all flat and long bones, including the epiphysis and diaphysis. As the child ages the red bone marrow in the diaphysis of the long bones will be replaced with yellow bone marrow

Compare and contrast IN DETAIL WITH DRAWINGS intramembranous and endochondral ossification.

Intramembranous ossification [flat bones] & endochondral ossification [long bones].The essential between them is the presence or absence of cartilaginous phase. Intramembranous ossification occurs when mesenchymal precursor cells proliferate & subsequently differentiate directly into osteoblasts w/c mineralize an immature bone tissue called woven bone, characterize by irregular bundles of randomly oriented collagen fibers & an abundance of partially calcified immature new bone called asteoid. At later stages this woven bone is progressively remodeled to mature, lamellar bone. Endochondral ossification entails the conversion of a cartilaginous template into bone. Mesenchymal cells condense & differentiate into chondrocytes w/c secrete the cartilaginous matrix. This embryonic cartilage is avascular,& during its early developmental ring of woven bone is formed by intramembranous ossification in the future mid shaft area. .

Compare and contrast the types of bone found in the diaphysis and epiphysis of a long bone.

Knobby ends of a long bone are referred to as the epiphyses, and the diaphysis is the shaft or middle section of the long bone. Separating them is a part of the bone known as the metaphysis. Differences between the epiphysis and diaphysis is their shape. The swollen rounded ends of the long bone are the epiphyses. These structures look somewhat similar to a clenched fist. Tubular and centrally positioned, the diaphysis makes up the main shaft of the long bone. On a long bone, the diaphysis is much larger than the epiphysis. Structurally, the epiphysis and diaphysis are also distinct. The epiphysis is composed of compact or cortical bone on the outside and spongy, or trabecular, bone on the inside. Compact bone is fairly dense, providing strength. In the epiphysis, the spongy bone is slightly porous, leaving some space for red bone marrow and blood vessels. The porous nature of spongy bone also lightens the weight of the bone. The diaphysis is composed of compact bone surrounding a marrow cavity filled with a fairly porous yellow marrow. Functionally, the epiphysis and diaphysis are very different. The epiphysis is the site of bone growth and is also often the place where a tendon anchors onto the long bone. In children, an epiphyseal plate is located between the epiphysis and the metaphysis. Long bones elongate when new cartilage, produced in the epiphyseal plate, is pushed to the edge of the epiphysis while older cartilage, located at the diaphysis side of the epiphysis plate, gets converted into bone.

Compare and contrast ligaments and tendons.

Ligaments: bone to bone Tendons: bone to muscle

Compare and contrast the processes of osteogenesis, ossification, and calcification.

Osteogenesis is formation of bone. Ossification is specifically the conversion of connective tissue into bone tissue. Calcification is the depositing of calcium salts in any tissue, including bone.

List AND describe some important factors affecting bone growth.

These include nutrition, exposure to sunlight, hormonal secretions, and physical exercise. For example, vitamin D is necessary for proper absorption of calcium in the small intestine. In the absence of this vitamin, calcium is poorly absorbed, and the inorganic salt portion of bone matrix lacks calcium, softening and thereby deforming bones. In children, this condition is called rickets, and in adults, it is called osteomalacia.

What is the name given to the region of bone in which osteocytes reside?

lacunae

Describe in words examples of the six classifications of bones.

long bones, short bones, flat bones, irregular bones, suture bones (found between the flat bones of the skull), sesamiod bones (inside tendons near the joints of knee, hands and feet)

Compare and contrast the roles of osteocytes, osteoblasts, osteoclasts, and osteoprogenitor cells.

osteocytes: do not divide, assit in repair of damaged bone, live in lacunae, communicate via canaliculi osteoblasts: blast - builds, makes bone osteoclasts: break down bone matrix, dissolve martix by secretion acids and certain enzymes osteoprogentior cells: stem cells that undergo mitosis producing daughter cells that become osteoblasts, aid in repair and located in endostem

What is the functional unit of mature compact bone called?

osteon

Which region(s) of a long bone is periosteum NOT found?

parts of enclosed joint capsules

List AND describe the six functions of bone.

support, protection, leverage, mineral storage, blood cell formation

Describe in detail how osteoclasts break down bone. Using this knowledge, describe how braces work.

the braces make pressure form on the sides of teeth, this simulates osteoclasts to remove some bone, then when the pressure is decreased, osteoblasts are stimulated to bring back the bone that was lost but is in the right postion

Label the following regions of a long bone AND know the functions of each of these regions: a.Diaphysis b.Metaphysis c. Epiphyisis (proximal and distal) d. Articular cartilage e. Compact bone f. Spongy bone g. Epiphyseal line h. Medullary cavity i. Periosteum j. Endosteum k. Sharpy's Fibers

diaphysis: shaft of bones, composed of compact bone epiphysis: has a proximal and distal region on each bone, ends of bone, composed of spongy bone that is surrounded by compact bone, purpose is for articulation with other bones metaphysis: where diaphysis and epiphysis meet, where the growing cartilage is articular cartilage: covers the external surface of the epiphysis, make of hyaline cartilage and decreases friction on joint surfaces epiphyseal line: line that replaces the epiphyseal growth plate medullary cavity: where marrow is stored, in the shaft, marrow can be red for blood cells or yellow for fat periostium: outside covering of the diaphysis endosteum: lines in the marrow cavity, active is bone growth and repair sharpery's fiber: any of the thready processes of the periosteum that penetrate the tissue of the superficial lamellae of bones

Discuss some treatments for osteoporosis AND why these treatments may be contraindicated in some patients.

a. ERT (estrogen replacement therapy) slows bone resorption, but increases risk breast cancer, stroke and heart disease b. best treatment is prevention -- exercise and calcium intake (1000 mg/day) between ages 25 and 40

Discuss the importance of bone remodeling, making sure to mention Wolff's Law.

architecture of bone determined by mechanical stresses -dont use it you loose it

What does it mean that compact bone is homogenous and spongy bone is heterogeneous?

homogenous: it is dense and does not have any open spaces heterogeneous: has many open spaces

List AND describe the chemical makeup of osseous tissue. Be generally familiar with the abundances of each of the components of bone.

calcium (most), potassium (least), sodium, magnesium, carbonate, phosphate, protein (almost most) components of bone: 2/3 calcium phosphate, 1/3 of bone matrix is proteins (collagen),

What passageway connects the central canal to the lacunae? What are the functions of these passageways?

canaliculi, form a transport system to exchange nutrients and waste

What are the two other names that could be used to describe spongy bone?

cancellous and trabecular

Describe tooth structure, types of teeth and dental succession.

Study

List, describe, AND draw the common bone fractures discussed in class.

Study

How does bone repair itself after it is fractured? Use drawings as necessary.

When a bone breaks, the fissure also severs the blood vessels running down the length of the bone. Blood leaks out of these veins and quickly forms a clot called a fracture hematoma. This helps to stabilize the bone and keep both pieces lined up for mending. Swelling and inflammation follow due to the work of cells removing dead and damaged tissue. Tiny blood vessels grow into the fracture hematoma to fuel the healing process. After several days, the fracture hematoma develops tougher tissue, transforming it into a soft callus. Cells called fibroblasts begin producing fibers of collagen, the major protein in bone and connective tissue. Chondroblasts then begin to produce a type of cartilage called fibrocartilage. This transforms the callus into a tougher fibrocartilaginous callus, which bridges the gap between the two pieces of bone. This callus generally lasts for about three weeks. Next, osteoblasts move in and produce bone cells, transforming the callus into a bone callus. This hard shell lasts three to four months, and it provides necessary protection and stability for the bone to enter the final stage of healing. At this point, the body establishes the position of the bone within the flesh, begins reabsorbing bits of dead bone, and creates a hard callus to bridge the gap between the two pieces of bone. Osteoclasts and osteoblasts spend months remodeling bone by replacing the bone callus with harder compact bone. These cells also decrease the callus bulge, gradually returning the bone to its original shape. The bone's blood circulation improves and the influx of bone-strengthening nutrients, such as calcium and phosphorus, strengthen the bone.

What exactly does appositional bone growth refer to? How about interstitial bone growth?

When cartilage grows in length, this is called interstitial growth. When cartilage grows in thickness, this is called appositional growth.