A & P Ch. 6

7) What is the structure of a typical long bone

A long bone is lined with a sheet of vascularized connective tissue called the periosteum. This has layer has blood vesicles, sensory nerves, and lymphatic vessels that provides nutrients for the bone. The long body of the bone is called the diaphysis. The diaphysis has a hallow cavity on the inside as well as a yellow substance called endosteum which is the yellow bone marrow. On the ends of the long bone is the epiphysis. The epiphysis includes a epiphyseal plate which contains hyaline cartilage and is the sight off bone growth. This cartilage ossifies (stops growing and turns to bone) and turns into the epiphyseal line. The connection or junction between the epiphysis and the diaphysis is called the metaphysis. Within the bones there are pore-like openings called nutrient foramen. The nutrient foramen contains arteries and veins that go into and out of the bones.

c. Osteoprogenitor cells

Osteoprogenitor cells are stem cells that function to create new osteoblasts.

9) What is the difference between red bone marrow and yellow bone marrow

Red bone marrow is vascular and involved in producing blood cells. Yellow bone marrow is adipose tissue and helps with energy reserve because off its storage of lipids.

15) How do parathyroid and calcitonin hormones help maintain bone integrity

Calcitonin helps maintain bone integrity by decreasing the amount of calcium in the blood. It is produced in the thyroid gland by C cells when the calcium level in our blood gets too high. This hormone inhibits osteoclasts so that they stop releasing calcium from our bones and reduces the rate of its absorption from food. It also signals the kidneys to release the calcium into the urine and out of the body. Parathyroid hormone on the other hand increases the amount of calcium in the blood. This hormone stimulates osteoclasts which harvests calcium out of the bone, increases calcium absorption from food, and reclaims the calcium found in the kidneys.

8) What is the structures of compact vs spongy bone

Compact bone is the dense regions that make up the shaft of the bone. Compact bone contains circles of Osteons which are regions which arrange around blood vessels. One osteon is made up of multiple lamellae and the canals of blood vessels that connects all of the osteons are called perforating canals. Spongy bone on the other hand is composed of a dense network of trabeculae which are highly porous and has a spider web like structure. The thin columns of bone contain osteocytes and have open spaces in order to house the red bone marrow.

13) What is the dietary and hormonal factors that affect bone growth

Diet affects bone growth in that the vitamins from diet have essential roles in bone functioning. For example, vitamin C helps with collagen, K and B12 with protein synthesis, A stimulates osteoblasts and D helps in calcium reabsorption. Hormones also effect bone growth in that growth hormones promotes cartilage growth in the epiphyseal plate which results in a taller person. An excessive amount of such hormone would result in someone with gigantism or a lack of the hormone which would result in someone with dwarfism.

11) What is the process of endochondral ossification

Endochondral Ossification is the process in which cartilage is ossified and often turns into long bones. In this process, the cartilage enlarges and pushes away from each other in order to elongate. It then starts producing spongy bone which will eventually be broken down by osteoclasts leaving a medullary cavity. There will then be secondary ossification centers in which spongy bone is produced at opposite ends of the bone surrounded by epiphyseal cartilage and continues growth. Eventually with puberty the epiphyseal cartilage will narrow until it disappears.

4) What is the importance of hydroxyapatite

Hydroxyapatite is important because it makes up the bone and bone matrix and gives bone its rigidity and inflexible nature.

12) What is the process of bone growth (both interstitial and appositional)

Interstitial bone growth is growth in length that happens when chondrocytes grow, multiply, and turn to bone. This growth produces long bones and usually occurs until age 18-25 years old. This bone growth occurs in the epiphyseal plate on the diaphysis side. Appositional bone growth is the process in which the bone grows in thickness. In this process osteoblasts form layers around the outside of the bone and cover themselves with hydroxyapatite and become osteocytes. This appositional growth can either happen to increase its thickness or even to remove layers of thickness.

10) What is the process of intramembranous ossification

Intramembranous Ossification is the process where bone (that will make up the skull and the jaw) forms during embryonic development usually at about the eighth week. During this process, mesenchymal cells differentiate into osteoblasts in the embryos connective tissue. This process occurs within the layers of the dermis and therefore results in the formation of dermal bones.

a. Osteoblasts

Osteoblasts functions to form bones and produces the compounds to makeup the hydroxyapatite.

d. Osteoclasts

Osteoclasts function to break down bones (to release the stored minerals).

b. Osteocytes

Osteocytes functions to provide maintenance and repair the bone.

3) What is the composition of the bone matrix

The bone matrix is composed of 33% organic fibers (collagen) and 67% inorganic salts (hydroxyapatite). Some of the inorganic compounds include calcium, carbonate, and phosphate.

2) What are the major functions of bone

The major functions of bones is to provide support, to serve as a storage place for minerals, to produce blood cells, to protect some of the major organs, and finally they provide a form of leverage in which they attach to muscles and therefore aid in moving the body.

14) What are the sex hormones that play a role in bone growth and how can we use that knowledge to differentiate between a male and female pelvic bone

The sex hormones involved in bone growth are estrogen (female) or testosterone (male). Sex hormones are involved in increasing the growth of bone. Estrogen is stronger than testosterone. We can differentiate between male and female pelvic bone because the female will have a wider pelvis than the male due to estrogens stronger influence on its bone growth.

1) What makes up the skeletal system

The skeletal system is made up off bone (which makes up the skeleton) and cartilage (which makes up the joints).

6) What are the different bone types

The types off bones are flat bones (parietal), sutural bones (parts of skull), long bones (Humerus), irregular bones (Vertebra), sesamoid bones (patella), and short bones (wrist).