Page 5 - Fundamentals of anatomy physiology

Spotlight Figures

Spotlight Figures SPOTLIGHT Figure 6–11
Endochondral Ossification
are one- or two-page presentations
that integrate text and art to Endochondral ossification begins with the formation of a hyaline
communicate physiological, cartilage model. This model serves as the pattern for almost all bone
organizational, or clinical development. Limb bone development is a good example of this
information in a visually process. By the time an embryo is six weeks old, the proximal bones
effective format. of the limbs, the humerus (upper limb) and femur (lower limb),
have formed, but they are composed entirely of cartilage.
Clear steps use text These cartilage models continue to grow by expansion of
the cartilage matrix (interstitial growth) and the
and art to guide ­students production of more cartilage at the outer surface
through complex processes. (appositional growth).

Initiation of Ossification in the Developing Bone (Steps 1–4)

1 As the cartilage 2 Blood vessels grow 3 Blood vessels penetrate 4 Remodeling occurs as
enlarges, chondrocytes around the edges of the cartilage and invade growth continues, creating
near the center of the the cartilage, and the the central region. a medullary cavity. The
shaft increase greatly cells of the perichon- Fibroblasts migrating osseous tissue of the shaft
in size. The matrix is drium convert to with the blood vessels becomes thicker, and the
reduced to a series of osteoblasts. The shaft differentiate into cartilage near each
small struts that soon of the cartilage then osteoblasts and begin epiphysis is replaced by
begin to calcify. The becomes ensheathed producing spongy bone shafts of bone. Further
enlarged chondrocytes in a superficial layer of at a primary ossification growth involves increases
then die and disinte- bone. center. Bone formation in length and diameter.
grate, leaving cavities then spreads along the
within the cartilage. shaft toward both ends
of the former cartilage
model.

Enlarging Perichondrium
chondrocytes within

calcifying matrix

Epiphysis

Bone collar

Blood Diaphysis Medullary Medullary
vessel cavity cavity

Hyaline Periosteum Primary Metaphysis
cartilage formed from ossification
perichondrium center
Disintegrating
chondrocytes Superficial
of the cartilage bone

model Spongy
bone

190

NEW The Tenth Edition SPOTLIGHT Figure 3–23 SPOTLIGHT Figure 9–2
has 18 new Spotlight DNA Replication Joint Movement
Figures for a total of 50,
including at least one in For cell division to be 1 KEY SIMPLE MODEL OF ARTICULAR MOTION AXES OF MOTION CLASSIFICATION OF SYNOVIAL JOINTS
every chapter. successful, the genetic
material in the nucleus must DNA replication begins when helicase enzymes Adenine Take a pencil as your model and stand it Movement of joints can also be described by the Synovial joints are freely movable diarthrotic joints, and they are classified by the type and range of motion
be duplicated accurately, unwind the strands and disrupt the hydrogen bonds Guanine upright on the surface of a desk. The pencil number of axes that they can rotate around. A joint permitted. Synovial joints are described as gliding, hinge, condylar, saddle, pivot, or ball-and-socket on
and one copy must be between the bases. As the strands unwind, molecules Cytosine represents a bone, and the desk is an that permits movement around one axis is called the basis of the shapes of the articulating surfaces, which in turn determine the joint movement.
distributed to each daugh- of DNA polymerase bind to the exposed nitrogenous Thymine articular surface. A lot of twisting, pushing, monaxial, a joint that permits movement around
ter cell. This duplication of bases. This enzyme (1) promotes bonding between and pulling will demonstrate that there are two axes is called biaxial, and one that permits Gliding joint Movement: Examples:
the cell’s genetic material is the nitrogenous bases of each separated strand with only three ways to move the pencil. movement around three axes is called triaxial. Gliding. Clavicle t "DSPNJPDMBWJDVMBSBOE
called DNA replication. complementary DNA nucleotides in the nucleoplasm Gliding joints, or plane joints, Slight nonaxial
and (2) links the nucleotides by covalent bonds. Moving the Point Superior–inferior axis have flattened or slightly curved or multiaxial claviculosternal joints
surfaces that slide across one t *OUFSDBSQBMKPJOU
1 Linear motion Lateral–medial axis another, but the amount of Manubrium t 7FSUFCSPDPTUBMKPJOU
2 Possible movement 1 shows the pencil can move. movement is very slight. t 4BDSPJMJBDKPJOU
If you hold the pencil upright, without securing the Anterior–posterior axis
3 2 point, you can push the pencil across the surface. Hinge joint Movement: Humerus Examples:
As the two original strands This kind of motion is called gliding. You could "OHVMBS t &MCPXKPJOU
4 gradually separate, DNA slide the point forward or backward, from side to Hinge joints permit angular Monaxial t ,OFFKPJOU
5 polymerase binds to the side, or diagonally. motion in a single plane, t "OLMFKPJOU
6 strands. DNA polymerase can like the opening and Ulna t *OUFSQIBMBOHFBMKPJOU
987 work in only one direction closing of a door.
along a strand of DNA, but the
Each DNA Segment 2 DNA nucleotide two strands in a DNA molecule Changing the Shaft Angle Condylar joint Movement: Example:
molecule consists Segment 1 are oriented in opposite direc- Condylar joints, or ellipsoidal "OHVMBS t 'JSTUDBSQPNFUBDBSQBMKPJOU
of two nucleotide 1 23 4 5 tions. The DNA polymerase Angular motion joints, have an oval articular Biaxial
strands joined by 6 bound to the upper strand Possible movement 2 shows the pencil face nestled within a Scaphoid
hydrogen bonds 7 shown here adds nucleotides shaft can change its angle with the depression on the opposing Radius bone
between their to make a single, continuous surface. With the tip held in position, you surface.
complementary complementary copy that can move the eraser end of the pencil
nitrogenous bases. grows toward the “zipper.” forward and backward, from side to side, Saddle joint
or at some intermediate angle. Saddle joints have complex
8 3 articular faces and fit together
DNA polymerase on the other Circumduction MJLFBSJEFSJOBTBEEMF&BDI
original strand, however, can Possible movement 3 shows a complex angular face is concave along one axis Ulna
work only away from the movement. Grasp the pencil eraser and move the and convex along the other.
4 unzipping site. In the lower pencil in any direction until it is no longer vertical. Movement: Examples:
strand, the first DNA Now, swing the eraser through a complete Pivot joint "OHVMBS t 3BEJPDBSQBMKPJOU
Thus, a second molecule of DNA polymerase must bind polymerase to bind to it must circle in a movement called circumduction. Pivot joints only permit Biaxial t .FUBDBSQPQIBMBOHFBM
closer to the point of unzipping and assemble a work from left to right, adding rotation.
complementary copy that grows in the sequence until it nucleotides in the sequence Rotating the Shaft III II Metacarpal joints 2–5
bumps into the segment created by the first DNA 12345. But as the original bone of thumb t .FUBUBSTPQIBMBOHFBM
polymerase. Enzymes called ligases (liga, to tie) then splice strands continue to unzip, Rotation
together the two DNA segments. additional nucleotides are Possible movement 4 shows that the pencil shaft Trapezium joint
continuously exposed. This can rotate. If you keep the shaft vertical and the
5 Duplicated DNA molecule of DNA polymerase point at one location, you can still spin the pencil Movement: "UMBT Examples:
double helices cannot go into reverse. It can around its longitudinal axis in a movement called Rotation. t "UMBOUPBYJBMKPJOU
Eventually, the unzipping completely only continue working from rotation. No joint can freely rotate because this Monaxial t 1SPYJNBMSBEJPVMOBSKPJOU
separates the original strands. The copying left to right. would tangle blood vessels, nerves, and
and last splicing are completed, and two muscles as they crossed the joint.
identical DNA molecules are formed. Once "YJT
the DNA has been replicated, the centrioles 270
duplicated, and the necessary enzymes and Ball-and-socket joint Movement: Examples:
proteins have been synthesized, the cell "OHVMBS
t 4IPVMEFSKPJOU
leaves interphase and is ready to proceed In a ball-and-socket joint, circumduction, t )JQKPJOU
to mitosis. the round head of one and rotation.
bone rests within a Triaxial
cup-shaped depression Scapula
in another. Humerus

271

DNA Replication Joint Movement
Chapter 3, page 128 Chapter 9, pages 296-297