Anatomy and Physiology Unit 2.1
(Chapter 7-2) pg 217
Histology of Osseous Tissue
Bone Cells: There are four principal types of bone cells:
1. Osteogenic cells: are __________________that develop from fibroblast and give rise to most other bone
cells. They are found in the_____________________ and the______________. Since they are stem cells they
Multiple constantly and some differentiate to become____________________.
Osteogenic means____________________________
2. Osteoblasts are __________________________. They line up in a single layer on the
________________
under the ________________and the________________________. These cells synthesize_______________
________________which then hardens by mineral deposition. THESE CELLS ARE NON-MITOTIC.
Osteoblast means__________________________
Bone Stress and Fractures stimulate _______________________cells to multiple rapidly to generate increased
numbers of ____________________-which rebuild and reinforce the bone.
3. Osteocytes are former_______________________ that have become trapped in the matrix they
deposited. They reside in tiny _____________________called_____________________which are
interconnected by slender channels called____________________. These cells have fingerlike projections
hat connect to other osteocytes and sometimes to also to osteoblasts. They exchange nutrients,and
____________________to one another and can pass ___________________________to the nearest blood
vessel in this way. Osteocyte means_____________________
Multi-functionality of Osteocytes:
some re-absorb bone matrix and others____________________
This is important in maintaining the homeostasis of _____________________and blood concentrations of
calcium and ___________________. They are Strain Sensors!!!!! When load is placed on bone, extracellular
fluid flows thru the ______________________and _____________________. This stimulates osteocytes to
secrete_________________________that stimulate bone remoldeling which is ______________________
_______________________.
1,2,&3 are all derived from stem cells, and one cell lineage……osteoclasts have independent
origin
Pg 218
4. Osteoclasts are bone _______________cells found on the bone_________________. They develop
from the fusion of several bone marrow stem cells. They are usually ______________and have 3-4 nucleui,
some having up to 50!! Some are visible to the naked eye they are so big. These cells have sides..one facing
the bone surface has a ____________________which increases the efficiency of______________________.
Bone remodeling is the result of bone dissolving______________________and bone depositing___________.
Illustrate the path of an osteogenic cell:
Illustrate the path of stem cells fusing to form osteoclasts:
The Matrix: The matrix of osseous tissue is about 1/3 organic matter and about ______________________.
Organic matter synthesized by ______________ is mostly collagen and _____________________________
such as gylcoproteins.
Inorganic matter is about 85% _______________________crystalized calcium phosphate salts and about 10%
calcium carbonate. The matrix is made up of collagen and hydroxyapatite. When bones are depleated of the
calcium salts, the bone matrix is very soft. These bones bend under the weight. (Rickets) Without the
protein, collagen, bones are brittle and would shatter. Is this what you noticed in the baked and acid treated
bones?
Compact Bone: This bone is composed of onion like __________________________, layers of matrix
arranged around a ______________________________ and connected to each other by canaliculi.
An Osteon is composed of __________________and its ____________________. This is the basic structural
unit of compact bone.
Pg 220
Collagen fibers corkscrew down the matrix. In the adjacent lamella, they angle in the opposite direction. This
gives ________________to the bone!
The skeleton receives about _____________________of blood per minute! Blood vessels along with _______
Enter the bone tissue thru nutrient foramina on the surface. These open into narrow canals ______________
___________________ that cross the matrix and feed into the central canals.
The inner and outer boundaries of dense bone (compact bone) are arranged in _______________________.
Spongy Bone: consists of slender rods, _____________and spines called____________________________.
It is hard and calcified but is permeated by ____________________filled with ________________________.
The matrix is arranged in ____________________like in compact bone but there are few_______________.
Central canals are not needed because________________________________________________________.
Osteocytes are close to the marrow so no need for central canals and the trabeculae are arranged
along__________________________________________.
Bone Marrow:
Marrow is _________________________that occupies the narrow cavity of a long bone. There are 2 kinds,
_________________________________ and __________________________.
In children almost every bone cavity is filled with ____________________________. It is said to be
_________________________and produces RBCs.
In adults, most of this red marrow turns to __________________________________. This no longer produces
blood, except in severe or chronic anemia. Red bone marrow in adults is only found in the ______________,
_________________, ____________, _________________, ___________________ and the proximal heads of
the humerus and femur.
Bone Development:
Pg 221
The formation of bone is called _____________________________ or_________________________. In the
human fetus, bone develops by 2 methods. ___________________________ and _____________________.
Intramembranous Ossification: produces bones of the ___________________and
______________________.
This process gives rise to the “sandwich like” arrangement typical of _________________________________.
Endochondral Ossification: produces bone from a pre-existing model composed of ____________________.
Most bones of the body develop in this way.
Bone Growth:
From infancy through adolescence, an epiphyseal plate is present at one or both ends of the long bones. At
this plate is the region of __________________from cartilage to bone, and functions as a growth zone where
bones elongate.
Pg 225 and 226
Bone growth is really the result of continually pushing the zone of reserve cartilage toward the ends of the
bone, so the bone elongates.
Bone elongation is really the result of cartilage growth frp wotjom by the multiplication of _____________ and
the deposition of new ______________. This is called ___________________________________.
Epiphyseal plates close at different ages in different bones. This information is often used in forensic science
to _________________________________________________.
Bones also continue to get thicker. This process is called______________________________________.
This process creates more surface layers of bone called _________________________________________.
Bone remodeling: This continues throughout life. This process replaces about ______________of bone
tissue each year! It repairs and reshapes bones in response to use and disuse.
Pg.227
If bone is not used often, osteoblasts and osteoclasts remove matrix to rid unnecessary mass.
If bone is heavily used, _____________________deposit new osseous tissue and thicken the bone.
Would athletes have heavier bones? Could you determine the type of work ancient peoples did by looking at
bone structure?
HW: Please answer the BYGO questions on page 221. Be prepared for a quiz covering Tissues and Organs of
the Skeletal System, the Histology of Osseous Tissue, and Bone Development on Monday 9/14/15.