Skeletal System TEST #2 Flashcards

1
Q

How does compact (dense) bone differ from cancellous (spongy) bone?

A

Compact bone: tissue that is dense, hard, and forms the protective exterior portion of all bones; has bone cells embedded in extracellular matrix that is primarily collagen and inorganic salts; resists compressive forces

Cancellous bone: tissue inside compact bone which is very porous (full of tiny holes); has bone cells embedded in mineral salts and collagen fibers; has trabecular (branching, bony plates with irregular spaces between them); is on ends (and insides) of long bones; is strong and light; is subject to compressional forces

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2
Q

What is osteology?

A

The study of bones

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3
Q

What is an osteocyte?

A

Mature bone cell encased with body extracellular matrix

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4
Q

What is an osteoblast?

A

Cell which deposits (makes or builds) bone

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5
Q

What is an osteoclast?

A

Cell which resorbs (breaks down or cuts up) bone

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6
Q

Describe and locate the microscopic structures of compact bone

A

Osteocytes are located in tiny, bony chambers called lacunae

Osteocytes can communicate with one another through tiny channels known as canaliculi

Osteocytes and layers of extracellular materials are clustered around a central canal (housing blood vessels and nerves) to form a cylinder-shaped unit called the osteon

Each osteon (also called a Haversian system) is the structural and functional unit of compact bone

Many osteons cemented together form compact bone

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7
Q

How does the microscopic structure of spongy bone differ from that of compact bone?

A

Spongy bone doesn’t have central canals around which bones cells aggregate; instead, cells lie within bony ridges called trabeculae and get nutrients from substance diffusing through canaliculi that lead to the surface of the trabeculae.

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8
Q

Which of the four major tissue types (epithelial, connective, muscular, nervous) are found in bone?

A

Primarily connective and nervous: connective (dense fibrous connective–tendons; supportive connective–bone and cartilage; fluid connective–blood), nervous (nerve fibers)

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9
Q

When do bones first begin to form?

A

The first two weeks of prenatal development

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10
Q

How do intramembranous bones differ from endochondral bones?

A

Intramembranous bones: are mostly broad, flat bones like the skull bones

Endochondral bones:include most of the bones of the skeleton

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11
Q

How does the origin of intramembranous bones differ from the encochonfral bones?

A

Intramembranous bones: originated with sheet-like layers of connective tissue.

Endochondral bones: begin as masses of hyaline cartilage that act as a model upon which bone is later formed

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12
Q

What are the first steps involved in long bone development?

A

Hyaline cartilage acts as a model for long bone development that starts during the first weeks of prenatal development

Hyaline cartilage tissue breaks down and the periosteum (with osteoblasts and blood vessels) develops

Osteoblasts first form spongy bone in the primary ossification center (space previously occupied by the cartilage). Osteoblasts next deposit a thin layer of compact bone around the spongy bone. This will eventually become the diaphysis

Developing bone thickens as compact bone is deposited on the outside.

As compact bone forms on the outside, osteoclasts erode tissue on the inside, creating the medullary cavity

The epiphysis remain cartilaginous and grow. Secondary ossification centers appear in the epiphysis and spongy bone forms in all directions from them

A band of cartilage known as the epiphyseal plate remains between the primary ossification centers of the diaphysis and the secondary ossification center of the epiphyses.

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13
Q

How does the long bone increase in length? When does it stop lengthening?Growth at the epiphyseal plate causes the bone to grow in length

A

Actively dividing cartilage cells (nearer to the end of the plate than to the end of the bone) lay down layer upon layer of new cartilage cells which extend out from the epiphyseal plate

The cartilage cells become calcified.

Osteoblasts break down the calcified matrix

Osteoblasts deposit bone tissue in place of calcified cartilage

A long bone continues to lengthen as long as the cartilaginous cells of the epiphyseal plate are active

Once the ossification centers of the diaphysis (primary ossification center) and epiphysis (secondary ossification center) meet and the epiphyseal plates ossify, lengthening stops. The epiphyseal plates of children are very well defined, while those of adults whose bone growth has ceased are indistinct

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14
Q

What is meant by the phrase “homeostasis of bone tissue”?

A

Resorption (breaking down of bone by osteoclasts) and deposition (making bone by osteoblasts) are regulated so the total mass of bone tissue within an adult skeleton remains relatively constant throughout life

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15
Q

What organ system regulates bone resorption and deposition?

A

The endocrine system. Resorption occurs when parathyroid hormone stimulates osteoclasts to break down bone. Deposition occurs when calcitonin hormone from the thyroid gland stimulates osteoblasts to form bone. A negative feedback system is involved.

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16
Q

What factors affect bone growth, development, and repair? Explain.

A

go to notes

17
Q

What are the two types of incomplete fractures?

A

Greenstick:break occurs in the convex surface of the bend on the bone

Fissured:longitudinal break

18
Q

What are the four types of complete fractures?

A

Comminuted:fragments the bone

Transverse:break occurs at a right angle to the axis of the bone

Oblique:occurs at an angle other than a right angle to the axis of the bone

Spiral:caused by twisting a bone excessively

19
Q

Describe the steps involved in healing a fracture

A

Escaping blood from vessels forms a hematoma

New blood vessels begin to develop. Spongy bone forms close to them and fibrocartilage forms farther away from the blood vessels

A bony callus replaces the fibrocartilage

Osteoclasts remove the excess bony tissue, restoring the bone to its former likeness

20
Q

What is hematopoiesis?

A

The formation of blood cells: red, white, and platelets. It takes place in red bone marrow (found in most infant bones) and in adults in the spongy bone skull, ribs, sternum, clavicles, vertebrae, and hipbones)

21
Q

Name some life span changes that occur in the skeletal system as the body ages

A

Decrease in height at about age 30

Calcium levels fall

Bones become brittle

Osteoclasts outnumber osteoblast

Spongy bone weakens before compact bone

Bone loss rapid in menopausal women

Hip fractures common

Vertebral compression fractures common

22
Q

Tarsal bones

A

(superior, then clockwise on right foot) Talus, calcaneus, navicular, medial cuneiform, intermediate cuneiform, lateral cuneiform, cuboid

23
Q

Carpal bones

A

(Proximal row, then distal row) Scaphoid, luntae, triquetrum, pisiform, trapezium, trapezoid, cuboid, hamate