Anatomy: Bones and Bone Tissue

Anatomy: Bones and Bone Tissue

28 April 2021

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Passing Grades Flashcards

Functions of the skeletal system

1.) Protection
2.) fat storage
3.) mineral storage and acid base homeostasis
4.)blood cell formation
5.) movement
6.) support

How are bones classified?

1.) Long Bones
2.) Short Bones
3.) Flat Bones
4.) Irregular Bones
5.) Sesamoid Bones

- Named for overall shape not their actual size.
-longer than they are wide
-include most bones in arms and legs.

-Named shape rather than size.
-Roughly cube-shaped or about as long as the are wide
-include bones of wrist or carpals and ankles and tarsals.

-thin and broad bones
-include pelvis, rbs, sternum, and most bones in the skull.

Irregular Bones

-include vertebrae and certain skull bones.
-do not fit into other classes because of irregular shape.

-specialized bones located on within tendons.
-usually small, flat, and oval-shaped which give tendons a mechanical advantage. and gives muscles better leverage.
-patella is an example.

Structure of a long bone

-periosteum
-perforating fibers
-diaphysis
-compact bone
-spongy bone
-endosteum
-epiphyseal lines

- forms a covering, rich with blood vessels and nerves and surrounds outer surface of long bones.

Perforating Fibers (sharpey's fibers)

-anchors periosteum firmly to the underlying bone surface by penetrating deep into the bone (part of structure of long bone)

Image: Perforating Fibers (sharpey's fibers)

-shaft of long bone with each end is its epiphyses(long Bone structure)

Image: Diaphysis

-covered with a thin layer of hyaline cartilage
-found within the joints between bones
(long Bone structure)

Image: Epiphysis

- a hollow cavity that contains either red or yellow bone marrow, depending on bone or age (long Bone structure)

Image: Marrow cavity

-the hard, dense outer region that allows bone to resist linear compression and twisting forces among other stresses (long Bone structure)

Image: Compact bone

Spongy bone (cancellous bone)

-found inside cortical bone
-honeycomb-like framework
-like bony strust that allows long bones to resist forces from many directions
-provides cavity for bone marrow

Image: Spongy bone (cancellous bone)

-bony struts of spongy bone and all inner surfaces of bone are covered by this thin membrane (long Bone structure)
-involved of maintenance of homeostasis of bone

Image: endosteum

Epiphyseal lines

-found seperating both proximal and distal epiphyses from disphysis.
-these are remanants of epiphyseal plates (growth plates), a line of hyaline cartilage found in developing bones in children.

Structure of Short, Flat, Irregular, and sesamoid bones

-covered by periosteum
-diploe
-sinuses

-internal structure composed of two outer layers of thin comact bone with middle layer of spongy bone called this and is associated with bone marrow

Image: Diploe

-some flat and irregular bones of skull contain hollow, air-filled spaces called this which reduces bone weight.

Red bone marrow

-consists of loose connective tissue that supports islands of blood-forming hematopoietic cells
-amount of red marrow decreases as a person ages.

red marrow in and adult is found where

-is only found in pelvis, proximal femur and humerus, vertebrae, ribs, sternum, clavicles, scapula, and some bones of skull.

why do children need more red marrow?

-to assist in their growth and development

yellow bone marrow

-composed of triglycerides, blood vessels, and adipocytes (fat cells)

makeup of inorganic matrix

-predominatly made up of calcium salts
-hydroxyapatite
-crystalline structure
-biocarbonate
-potassium
-magnesium
-sodium

hydroxyapatite crystals

-calcium and phosphorus salts exist as large molecules known as...

crystalline structure

-makes bone one of the hardest substances in the body and makes it string and resistant to compression.
-allows bone to be protective and supportive

makeup of organic matrix

-protein fibers
-proteoglycans
-glycosaminoglycans
-glycoproteins
-bone specific proteins

-found in the organic matrix
-predominant protein fiber

functions of collagen in organic matrix

-forms cros-links with one another
-helps bone resist torsion and tensile forces.

three types of bone cells

-osteoblasts
-osteocysts
-osteoclasts

-metabolically active bone cells found in periosteum and endosteum.

osteogenic cells

-type of osteoblast cell.
-flattened stem cells that differentiate into osteoblasts when stimulated by soecific chemical signals

function of osteoblast cell

-bone building cells that perform bone deposition

bone deposition

-process where osteoblasts secrete organic matrix materials and assisst in formation of inorganic matrix

-when osteoblasts surround themselves with the bone matrix in a small cavity known as the lacuna they become this...

functions of osteocytes

-no longer actively synthesize bone matrix
-no longer active except for need to maintain bone extracellular matrix
-ability to recruit osteoblasts to build up or reinforce bone under tension

-responsible for resorption
-resemble jelly fish

Image: Osteoclasts

process in which cell secretes hydrogen ions and enzymes that break down bone matrix

-process of bone formation

when does ossification occur

-begins in embryonic period and continues through childhood and most bones completing the process by age 7

intramembranous ossification

-when bones are built on a model(starting material) made of a membrane of embryonic connective tissue

endochondral ossification

-bones formed by this are built on a model of hyaline cartilage
-begins in fetal stage

bones formed by intramembranous ossification

-forms many flat bones, incuding bones of the skull and clavicles, during fetal development

-formed within a mesenchymal membrane composed of embryonic connective tissue and richly supplied with blood and populated with mesenchymal

bones formed by endochondral ossification

-all bones below the head

How do long bones grow?

-lengthen by a process called longitudinal growth

Longitudinal growth

-involves division of chondrocytes in epiphyseal plate

where does bone growth take place?

-at the epiphysis side closet to diaphysis

what is the epiphyseal plate composed of

-hyaline cartilage that did not ossify

Zone of reserve cartilage

-found closest to epiphysis
-contains cells that are not directly invoved in bone growth but can be recruited for cell division

zone proliferation

-consists of actively dividing chondrocytes by endochondral ossification
-contains five different lucunae

zone of hypertrophy and maturation

-contains mature chondrocytes

Zone of calcification

-contains dead chondrocytes, some of which have been calcified

zone of ossification

-consists of calcified chondrocytes and osteoblasts

1st step in longitudinal growth

-chondrocytes divide in zone of proliferation forcing cells ahead of them into next zones, moving toward diaphysis.
-once chondrocytes reach zone of hypertrophy and maturation enlarge and stop dividing

2nd step in longitudinal growth

-chondrocytes that reach zone of calcification die and their matrix calcifies

3rd step in longitudinal growth

-calcified cartilage is replaced with bone in zone of ossification

4th step in longitudinal growth

-osteoblasts invade calcified cartilage and begin to lay down bone

5th step in longitudinal growth

-eventually calcified cartilage and primary bone is resorbed by osteoclasts and completely replaced with mature bone

Appositional growth

-bones growing in width
-does not result in immediate formation of osteons
-new circumferential lamellae are formed

Bone remodeling

-when the bone undergoes a continuous process of formation and loss

-new bone is formed by this process

-the bone is removed by this process

why does bone remodeling occur

-maintenance of calcium ion homeostasis
-replacement of primary bone with secondary bone
-bone repair
-replacement of old brittle bone
-adaption to tension and stress

process of bone deposition

-carried out by osteoblasts
-found in both periosteum and endosteum
-secrete proteoglycans and glycoproteins that bind calcium ions
-secrete vesicle containing calcium ions, ATP, an enzymes
-bind to collagen fibers
-calcium ions eventually crystallize rupturing vesicles and beginning calcification

what is bone remodeling a response to?

tension and stress

-squeezing or pressing together
-occurs when bones are pressed between body's weight and ground
-stimulates bone deposition

-stretching force
-bone deposition occurs in regions in of bones exposed to tension

-continuous downward force
-bone resorption is stimulated in regions of bones exposed to continuous pressure

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