7.4-7.5 Notes

Bone Function

A. Examples of Support and Protection

1. Bones give shape to the head, thorax, and limbs.

2. Bones such as the pelvis and lower limbs provide support for the body.

3. Bones of the skull protect the brain, ears, and eyes.

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B. Body Movement 1. Bones can act as levers

(mechanical device).a. A lever has four

components: a rigid bar, a pivot or fulcrum, an object that is moved against resistance, and a force that

supplies energy. b. Rigid rod-forearm; elbow is

fulcrum; hand is the object of resistance; force is supplied by biceps MOVE HAND UP

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Hematopoiesis

Blood cell formationBegins in the yolk sac of the human embryo; later they are made in the liver and spleen; eventually form in bone marrowHemoglobin-red oxygen carrying pigment

C. Blood Cell Formation 1. Two kinds of marrow occupy

the medullary cavities of bone.

a. Red marrow functions in the formation of red blood cells, white blood cells, and platelets, and is found in the spongy bone of the skull,

ribs, sternum, clavicles, vertebrae, and

pelvis.(mostly in infants-later turns into yellow)

b. Yellow marrow, occupying the cavities of most bones, stores fat.

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Bone Marrow TransplantRemoved from spongy bone of donor or umbilical cord of new born (these are stem cells)Donor selected –molecule pattern on red blood cells must be close to recipientCells are injected into the bloodstream (marrow has been destroyed by chemo or radiation); cells travel to the spaces where there is no marrow.

Graft-versus-host-disease-immune system rejects transplant and attacks recipientTreats disorders like leukemia and sickle cell diseaseCells they are using are stem cells.

D. Storage of Inorganic Salts 1. Calcium is

important for metabolism.

2. when blood levels are low, osteoclasts release calcium from

bone and break bone down.

3. High calcium causes osteoblasts to form bone tissue.

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4. Bone also stores magnesium, sodium, potassium, and carbonate ions.

5. Bones can also accumulate harmful elements, such as lead,

radium, and strontium.

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Skeletal OrganizationA. The axial skeleton consists

of the skull, thorax, and vertebrae.

B. The appendicular skeleton consists of the bones that make up arms and legs.

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Osteoporosis

Loss of bone tissueThese bones fill with fibrous and fatty tissue and are easy to break. They can no longer take the weight.Bone mass peaks 35.No drinking, smoking, take calcium supplements, exercise

Pg 131 Fracture and hematoma

Fracture-break in the boneHematoma-break with a blood clotPhagocytic cells clean up blood clot and osteoclasts clean up boneDoctors immobilize bone; use rods, wires, and nails to align the bone