skeletal system part 1
The Skeletal System serves many important functions:
1. Support - Provide a hard framework.
2. Protection of many vital organs.
3. Movement - Act as levers with skeletal muscles moving them. Joints control possible movements.
4. Mineral storage
a. 99% of the bodys calcium is stored in bone.
b. 85% of the bodys phosphorous is stored in bone
c. Adipose tissue is found in the marrow of certain bones.
5. Hematopoiesis ( blood cell formation) - blood cells are made in the marrow of certain bones.
Bone classification
There are 206 named bones in the human body. Each belongs to one of 2 large groups:
1. Axial skeleton
2. Appendicular skeleton
the _______ consists of bones that form the long axis of the body and support and protect the organs of the head, neck, and trunk.
a. The Skull
b. The Sternum
c. The Ribs
d. The Vertebral Column
Axial skeleton
The ______ is composed of bones that anchor the appendages to the axial skeleton.
a.The Upper Extremities
b. The Lower Extremities
c. The Shoulder Girdle
d. The Pelvic Girdle--(the sacrum and coccyx are considered part of the vertebral column)
appendicular skeleton
4 types of bones according to Shape:
1. Long Bones
2. Short Bones
3. Flat Bones
4. Irregular Bones
- Much longer than they are wide.
- All bones of the limbs ( EXCEPT the patella or kneecap, and the bones of the wrist and ankle)
- It is composed of a Shaft plus 2 expanded ends.
- Shaft or middle part is known as the diaphysis.
- Expanded ends are epiphyses
1. Long Bones
are short, cube-shaped, and found in the wrists and ankles.
(ex. carpal of wrist)
Short Bones
are thin, flattened, and usually a bit curved. Ex. Scapulae, sternum, (shoulder blades), ribs and most bones of the skull.
Flat Bones
They have irregular shapes that fit none of the 3 previous classes. Ex the vertebrae, hip bones, 2 skull bones ( sphenoid and the ethmoid bones).
Irregular Bones.
๐จ๐๐๐๐ฉ or middle part is known as the _______.
diaphysis
Expanded ๐๐ฃ๐๐จ are ______
epiphyses
All bones consist of a dense, solid ๐ค๐ช๐ฉ๐๐ง ๐ก๐๐ฎ๐๐ง known as _______ and an ๐๐ฃ๐ฃ๐๐ง ๐ก๐๐ฎ๐๐ง of ๐จ๐ฅ๐ค๐ฃ๐๐ฎ ๐๐ค๐ฃ๐ฎ (________) a honeycomb of flat, needle-like projections or ______.
- compact bone
- cancellous bone/trabeculae
Within ๐๐ค๐ข๐ฅ๐๐๐ฉ ๐๐ค๐ฃ๐ is a system of canals that contain blood vessels, nerves, and lymph vessels. These canals form functional units called ______.
- osteons (Haversian systems)
The osteon is a ๐ฉ๐ช๐๐-๐ก๐๐ ๐ ๐จ๐ฉ๐ง๐ช๐๐ฉ๐ช๐ง๐ containing a central _________ (which runs longitudinally) and horizontal canals (______) through which nerves and blood vessels pass.
- Haversian canal
- perforating/Volkmanns
Surrounding the central canal is bone matrix, a substance produced by osteocytes. Within the osteon, osteocytes form _______, concentric layers of hard bone matrix. As osteoblasts create _______, these osteoblasts become trapped within the compact bone and are called osteocytes.
lamellae
-Osteocytes lie within _______, small pockets between the lamellae.
- space in the osteocytes
lacunae
______, tiny canals, connect the lacunae. it is also connect with the central canal. These connections allow nutrients to pass through the ______ to the trapped osteocytes within the dense lamellae.
Canaliculi
Bone cells:
1. Osteoprogenitor cells
2. Osteoblasts
3. Osteocytes
4. Osteoclastl
These are pluripotential mesenchymal stem cells, when properly stimulated, they have the capacity to undergo cell division and produce offspring that differentiate into osteoblasts.
Osteoprogenitor cells
Synthesize, transport, and arrange the protein bone matrix. It initiates the process of mineralization. It possesses surface receptors which bind many hormones (parathyroid hormone, Vit D and estrogen), and growth factors.
Osteoblasts
are mature bone cells made from osteoblasts that have made bone tissue around themselves. These cells maintain healthy bone tissue by secreting enzymes and controlling the bone mineral content;Live in holes called lacunae. Connect to each other and central canal via canaliculi, little canals. Pass nutrients, waste products
Osteocytes
- Responsible for bone resorption
- Bone-destroying cells
- Break down bone matrix for remodeling and release of calcium
- Bone remodeling is a process by both osteoblasts and osteoclasts
Osteoclast
Bone Matrix:
Consists of _______ and _____ components.
- organic
- inorganic
-______ component consists of several materials that are secreted by the osteoblasts:
- Type 1 collagen- Forms the backbone of matrix and accounts for 90 % of the organic component;
- it provides the bones its ๐ง๐๐จ๐๐ก๐๐๐ฃ๐๐ and the ability to resist ๐จ๐ฉ๐ง๐๐ฉ๐๐๐๐ฃ๐ and ๐ฉ๐ฌ๐๐จ๐ฉ๐๐ฃ๐.
I. Organic Matix
-๐๐๐ซ๐๐จ ๐๐ค๐ฃ๐ ๐จ๐ฉ๐ง๐๐ฃ๐๐ฉ๐ ๐๐ฃ๐ ๐๐๐ง๐๐ฃ๐๐จ๐จ
-๐๐ฉ๐ค๐ง๐๐๐ค๐ช๐จ๐ ๐ค๐ ๐พ๐๐ก๐๐๐ช๐ข 99%, ๐๐๐ค๐จ๐ฅ๐๐ค๐ง๐ค๐ช๐จ 85 %, ๐๐ค๐๐๐ช๐ข ๐๐ฃ๐ ๐๐๐๐ฃ๐๐จ๐๐ช๐ข 65%
๐๐. ๐๐ฃ๐ค๐ง๐๐๐ฃ๐๐ ๐ข๐๐ฉ๐ง๐๐ญ
๐พ๐๐ก๐๐๐ช๐ข ๐๐ฎ๐๐ง๐ค๐ญ๐ฎ๐๐ฅ๐๐ฉ๐๐ฉ๐
_________ are body's chemical messengers. They are secreted in a gland and travel in the bloodstream to distant tissues or organs. They work slowly, over time, and affect many different processes, including Growth and development and Metabolism ( how your body produces and utilizes energy)
Hormones
________play a critical role in the lifelong bone remodeling process. The following are some of those hormones, with a brief description of their complex roles in supplying necessary minerals for bone development, monitoring mineral blood levels, and maintaining or influencing bone homeostasis:
Regulatory hormones
- is produced by four small glands adjacent to the thyroid gland. These glands precisely control the level of calcium in the blood.
Parathyroid hormone (PTH)
PTH are sensitive to small changes in calcium concentration so that when calcium concentration decreases even slightly the secretion of PTH _______. PTH stimulates osteoclast proliferation and activity. As a result, calcium is released from the bones into circulation, increasing the calcium ion concentration in the blood. PTH also promotes calcium reabsorption by the kidney tubules, which can affect calcium homeostasis.
increases
Excessive production of PTH, usually due to a small tumor of the parathyroid glands, is called _______ and can lead to ๐๐ค๐ฃ๐ ๐ก๐ค๐จ๐จ.
hyperparathyroidism
- is a hormone that plays a role in regulating(control) the level of calcium in your blood by ๐๐๐๐ง๐๐๐จ๐๐ฃ๐ it.
- a calcium-regulating hormone produced by cells of the thyroid gland, although by different cells than those that produce thyroid hormones has some effects that counteract those of PTH.
- inhibits(๐ง๐๐๐ช๐๐๐ฃ๐) ๐ค๐จ๐ฉ๐๐ค๐๐ก๐๐จ๐ฉ activity and stimulates(๐๐ฃ๐๐ง๐๐๐จ๐) ๐๐๐ก๐๐๐ช๐ข uptake by the bones, reducing the concentration of calcium ions in the blood. As evidenced by their opposing functions in maintaining calcium homeostasis, PTH and calcitonin are generally not secreted simultaneously.
Calcitonin
- ____is a group of fat soluble vitamin responsible for increasing intestinal absorption of calcium magnesium and phosphate and multiple other biological effect.
- it helps increase the absorption of calcium from digestive system into the bloodstream without enough _______ your body can't absorb calcium efficiently which can lead to weak bone and condition like osteoporosis or ricket in children.
vitamin d
- is the hormone produced from vitamin D.
- also called 1,25 ๐๐๐๐ฎ๐๐ง๐ค๐ญ๐ฎ ๐ซ๐๐ฉ๐๐ข๐๐ฃ ๐ฟ, is formed from vitamin D by enzymes in the liver and kidney.
- acts on many different tissues, but its most important action is to ๐๐ฃ๐๐ง๐๐๐จ๐ ๐๐ฃ๐ฉ๐๐จ๐ฉ๐๐ฃ๐๐ก ๐๐๐จ๐ค๐ง๐ฅ๐ฉ๐๐ค๐ฃ ๐ค๐ ๐๐๐ก๐๐๐ช๐ข ๐๐ฃ๐ ๐ฅ๐๐ค๐จ๐ฅ๐๐ค๐ง๐ช๐จ, thus supplying minerals for the skeleton.
Calcitriol
Vitamin D deficiency leads to a disease of defective mineralization, called _____ in children and ______ in adults. These conditions can result in bone pain, bowing and deformities of the legs, and fractures. Treatment with vitamin D can restore calcium supplies and reduce bone loss.
- rickets
- osteomalacia
Sex hormones:
female hormones and male hormones
-Estrogen
-Testosterone
-is a key regulator of bone remodeling in women and men and acts on both osteoclasts and osteoblasts.
-The ______ produced in children and early in puberty can increase bone growth. The high concentration that occurs at the end of puberty has a special effectthat is, to stop further growth in height by closing the cartilage plates at the ends of long bone that previously had allowed the bones to grow in length.
- it acts on both osteoclasts and osteoblasts to inhibit bone breakdown at all stages in life. _____ may also stimulate bone formation. The marked decrease in estrogen at menopause is associated with rapid bone loss.
- it help protect bones by inhibiting osteoclast (reducing bone breakdown) and stimulating osteoblast (increase/promoting bone formation)
- a decrease and _____ such as during menopause can lead to an imbalance between osteoclast and osteoblast resulting in weakened bone and increase rest of fracture
Estrogen
- is important for skeletal growth and is also a source of estrogen in the body.
- is important for skeletal growth both because of its direct effects on bone and its ability to stimulate muscle growth, which puts greater stress on the bone and thus increases bone formation. ______ is also a source of estrogen in the body in men; it is converted into estrogen in fat cells. This estrogen is important for the bones of men as well as women. In fact, older men have higher levels of circulating estrogen than do postmenopausal women
Testosterone
-its production of the insulin-like growth factor (IGF-1) influences bone formation.
- also known as somatotropin
- is a hormone produced by the pituitary gland, a small gland located at the base of the brain
- this hormone play a key role in promoting growth development and solve regeneration throughout the body
- It acts by stimulating the production of another hormone called insulin-like growth factor-1 (IGF-1), which is produced in large amounts in the liver and released into circulation.
Growth hormone
- is a rare disorder resulting from an excess production of growth hormone (GH) in adults, occurring after the bones have stopped growing. In children in whom the bones are still growing, the excess in GH leads to ๐๐๐๐๐ฃ๐ฉ๐๐จ๐ข. The most common cause is a non-cancerous pituitary tumor that secretes excess GH
- the pituitary gland produce excess growth hormone in adulthood
Acromegaly
is caused by more bone cells being resorbed than being deposited. This imbalance results in a progressive loss of bone density and a thinning of bone tissue. _____ bones are more porous and therefore more vulnerable to fracture. _____ may result from disease, dietary or hormonal deficiency or advanced age. Regular exercise and vitamin and mineral supplements can reduce and even reverse loss of bone density.
Osteoporosis
is infection in the bones. Often, the original site of infection is elsewhere in the body, and spreads to the bone by the blood. Bacteria or fungus may sometimes be responsible for ______.
Osteomyelitis
is found in the marrow of certain bone
adipose tissue
- Forms the backbone of matrix and accounts for 90 % of the organic component;
โข Type 1 collagen
Calcitriol is the hormone produced from vitamin D. Calcitriol, also called __________, is formed from vitamin D by enzymes in the liver and kidney.
1,25 dihydroxy vitamin D3
Growth hormone and its production of the ________influences bone formation.
insulin-like growth factor-1 (IGF-1)
The pituitary gland produces Thyrotropin, also known as ________ that regulates thyroid function and metabolic processes in the body. Increase TSH secretion of the pituitary gland will lead to increase thyroid hormone release
thyroid-stimulating hormone (TSH)