skeletal system 6 functions - class webpage · skeletal system 6 functions - - - - - -functions 5...
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Skeletal System 6 Functions
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Functions 5 & 6
• Site of blood cell production – ____________ bone
marrow produces red blood cells from a process called hemopoiesis.
– _____________ bone marrow stores lipids (fats) for energy
Parts of a Long Bone• _________________________________________:
the shaft or long, main cylindrical portion of the bone
• _________________________________________: the extremities or ends of the bone
• _________________________________________: in mature bone, the region where the diaphysis joins the epiphysis.
• _________________________________________: a thin layer of hyaline cartilage covering the epiphysis where the bone forms an joint with another bone
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• ______________________________: A membrane around the surface of the bone not covered by articular cartilage.
• _____________________(marrow cavity): The space within the diaphysis that contains the fatty yellow bone marrow.
• _____________________________: The lining of the medullary cavity that consists of osteoprogenitor cells.
Histology• The skeletal system consists of four types
of connective tissue -
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Osseous (Bone) Tissue
• Contains lots of extracellular matrix surrounding widely separated cells.
• The matrix consists of inorganic components -
• And organic components -
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4 Types of Cells in Bone1. _________________________________________:
cells that undergo mitosis to become osteoblasts.
2. _________________________________________: cells that form bone, but do not have the ability to divide by mitosis.
3. _________________________________________: a mature bone cell, and maintain the daily cellular activities of bone tissue.
4. _________________________________________: function in bone reabsorption, which is important in the development, growth, maintenance, and repair of bone.
Unique to Bone
• Unlike other connective tissue the matrix of bone contains an abundance of ______________________________________.
• These salts are deposited by osteoblasts in the internal framework formed by collagen fibers.
• The tissue then hardens through a process called _____________________________.
2 Types of Osseous Tissue
• ________________________________ – Contains very few spaces – Forms the external portion of the bones – Provide protection and support
• ______________________________ – Usually does not contain true osteons
(tree ring structures) – Consists of irregular latticework of thin
plates called _______________________________
– These spaces are filled with red bone marrow
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How does bone form?
• When a human fetus is developing it is composed of mainly fibrous connective tissue and hyaline cartilage.
• ____________________________________________ (the process by which bones form) begins typically around the sixth or seventh week of embryonic life and continues throughout adulthood.
Endochondral Ossification• The replacement of
____________________________________________.
• Most bones are formed this way by the process is best observed in long bones.
1.
2.
3.
4.
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5. 6.
7. Growth and Maintenance• Growth occurs when cartilage cells are
_____________________________ on the epiphyseal side of the plate while the cartilage cells on the diaphyseal are being ________________________________ and turned into bone.
• The thickness of the plate will remain relatively constant while the bone of the diaphyseal side of the plate __________________________________________ in length.
• This process is controlled by the __________________________________________________.
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• The regulatory signals that send out HGH slow down as we get older.
• This causes the cartilage on the epiphyseal side to the plate to stop dividing and eventually the diaphyseal side catches up.
• When the epiphysis and diaphysis _________________________ together then no more bone growth can occur.
Still Growing?
Remodeling
• Like your skin, bone is constantly being ____________________ throughout your life.
• This process goes from the _______________.
• Osteoclasts are responsible for the ________________________________ of bone tissue.
Minerals and Vitamins
• Sufficient amounts of calcium, phosphorus, and sodium are what make the bone matrix _____________________________________.
• _______________________is required for the absorption of calcium from the digestive tract.
• Vitamin C, A and B12 also play a role in bone growth and remodeling.
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Mineral Storage
• Your bones are not the only organs that need calcium and therefore act as a storage site for this mineral.
• Your bones also store ___________________________which are required to produce nucleic acids (DNA and RNA).
Calcitonin (CT) and Parathyroid (PTH)• ___________________________ is a hormone released
from the thyroid gland in response to ____________ levels of calcium in the blood.
• It ____________________ osteoclastic activity and promotes bone growth and calcium storage, which brings the levels in the blood down.
• In response to _____________ levels of calcium in the blood, your parathyroid glands secrete a hormone called ____________________________________.
• This ________________________________ the activity of osteoclasts which will release calcium into the blood.
Exercise and Bone
• The bones in your body will alter their strength in response to mechanical stress.
• Bones become stronger under this stress because they increase the deposition of mineral salts.
• However, if mechanical stress is not applied then reabsorption does not happen and your bones become weaker through a process called ____________________________________.
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Demineralization• The main mechanical stress on bones results
from weight bearing exercise, and the force of ___________________________.
• If a person is bedridden or is in a cast the strength of the unstressed bone diminished because the ______________________________ of minerals has stopped.
• This is why when astronauts experience weightlessness they lose bone strength (mass) quickly because there is nothing acting on them.
Aging
2 principal events happen to our bones as we age.
1. A loss of calcium from bones – Starts at age ___________for females and accelerates
quickly around age 40-45 because estrogen levels start to decrease.
– In males loss does not typically begin until age _________ – The loss of calcium from bones causes osteoporosis.
2. A decreased rate in protein formation which results in a decreased ability to produce organic bone matrix. This causes more accumulation of inorganic matrix making the bones __________________________.
Osteoporosis• An age related disordered characterized as a
_________________________________ in bone mass resulting in an increased susceptibility to fractures.
• The sex hormone _________________________ normally promote bone formation by stimulating osteoblasts.
• But as we age (especially females) these estrogen levels decrease and bone formation slows down.
• Women are more susceptible to this disordered because estrogen promotes bone formation without the need for an increased amount of calcium deposition.
Symptoms
• Causes shrinkage of back bone and height loss
• Affects entire skeleton even teeth!
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Other Factors that cause Osteoporosis
1. Body build (shorter people have greater risk because they have less total mass)
2. Weight (since adipose is a good source of estrogen that slows bone loss)
3. Smoking 4. Calcium deficiencies and malabsorption 5. Vitamin D deficiency 6. Exercise 7. Certain drugs (alcohol, diuretics, cortisone,
etc.) 8. Premature menopause
Rickets
• A __________________________deficiency in children in which the body does not absorb calcium and phosphorus.
• This results in the bones in the leg _____________________ because the weight of the upper body is too much for them to support.
Herniated (Slipped) Disc
• A _________________________ (sticking out) of the inner, soft elastic material of an intervertebral disc.
Fractures
• A fracture is
• We will look at 6 different kinds – Partial (incomplete) – Complete – Closed (simple) – Open (compound) – Comminuted (multifragmentary) – Compressed
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Partial (Incomplete)
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Complete
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Closed (Simple)
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Open (Compound)-
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Comminuted (multifragmentary)
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Compressed
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