1. Skeletal
Physiology

2. Types of Bones
A) Long bones are easily identified by their extended
longitudinal axes and expanded and often uniquely shaped
articular ends. Examples are the femur of the thigh and the
humerus of the arm.
B) Short bones are often described as cube-or box-shaped
structures, which are about as broad as they are long.
Examples are the wrist (carpals) and ankle (tarsal) bones.
C) Flat bones are generally broad and thin with a flattened and
often curved surface. Examples are certain bones of the skull,
the shoulder blades (scapulae), ribs, and breastbone
(sternum).
D) Irregular bones are often clustered in groups and come in
various sizes and shapes. An example is the kneecap (patella).

3. The Long Bone
a) Diaphysis: main shaft like portion.
b) Epiphyses: both ends of a long bone.
c) Articular cartilage: thin layer of hyaline cartilage
that covers articular or joint surfaces of epiphyses.
d) Periosteum: dense, white fibrous membrane that
covers bone except at joint surfaces, where
articular cartilage forms the covering.
e) Medullary (or marrow) cavity: a tube like hollow
space in the diaphysis of a long bone.
f) Endosteum: a thin epithelial membrane that lines
the medullary cavity of long bones.

4. Bones Cont.
It consists of cells, fibers, and extracellular material
also known as matrix. Its extracellular components
are hard and calcified. In bone the extracellular
material, or matrix, predominates. The rigidity of
bone enables it to serve supportive and protective
functions. As a tissue, bone is ideally suited to its
functions, and the concept that structure and
function are interrelated is apparent in this tissue. It
has a tensile strength nearly equal to cast iron but
at less than one third the weight. Bone is organized
so that its great strength and minimal weight result
from the interrelationships of its structural
components.

5. The Haversian System
Lamellae- Concentric, cylinder-shaped layers of calcified
matrix.
Lacunae- Small spaced containing tissue fluid in which
bone cells lie imprisoned between the hard layer of the
lamellae.
Canaliculi- Ultrasmall canals radiating in all directions
from the lacunae and connecting them to each other and
into a larger canal (The Haversian Canal)
Haversian Canal- extends lengthwise through the center
or each Haversian System; contains blood vessels,
lymphatic vessels, and nerves from the haversian canal;
nutrients and oxygen move through canaliculi to the
lacunae and their bone cells

6. Cells in Bones
Osteoclasts: Osteoclasts are large cells that dissolve the bone. They
come from the bone marrow and are related to white blood cells. They
usually have more than one nucleus and are found on the surface of
the bone mineral.
Osteoblasts: Osteoblasts are cells that form new bones. They come
from bone marrow and are related to structural cells. They only have
one nucleus and they produce new bone called “osteoid” which is
made of bone collagen and other proteins. They also control calcium
and mineral deposition. They are found on the surface of new bone.
Old osteoblasts are called lining cells that regulate the passage of
calcium in and out of the bone. They also respond to hormones that
create protein that activate osteoclasts.
Osteocytes: These cells are found inside the bone that come from
osteoblasts. Some turn into osteocytes while the new bone is being
formed. These cells can sense pressures or cracks in the bone and
help direct where the osteoclasts will dissolve the bone.

7. Homeostatic Functions
1.Support: Bones are the supporting framework in the body and contribute to shape,
alignment, and positioning of the body parts. This involves homeostasis because without
support we would have nothing to hold our weight. We would be a glob of blood and
organs.
2.Protection: Bones protect the body from the external environment. Bones also protect
the structures that they enclose. Without protection from bones we would easily get hurt
because there would be nothing to prevent objects from hurting our organs or easily
crushing our internal parts. By having protection we can endure more difficult tasks and
participate in more rigorous activities.
3.Movement: Muscles are anchored to bones. As the muscles move, they pull on bones,
producing movement. Without movement it would be hard to maintain our body
temperature because we wouldn't be able to get warm when it’s cold or get cold when it’s
hot.
4.Mineral Storage: Bones serve as the major place for calcium, phosphorus, and other
minerals. Homeostasis of blood calcium concentration depends a lot on changes in the
rate of calcium movement between the blood and bones. For example, if blood calcium
moves faster out of the blood into bones and more slowly in the opposite direction, blood
calcium concentration decreases. This is essential for healthy survival.
5.Hematopoiesis: Hematopoiesis is another word for blood cell formation. This is the vital
process carried on by red bone marrow. This is important because it keeps the body in
balance. It helps regulate differences in the body such as infections or fevers.

8. Intramembranous and
Endochondral bone
Intramembranous Bone (flat bones): Membranous bones first
look like flat, membrane-like layers. These layers have a
continuing flow of nutrient blood supply from blood vessels
that are formed between the layers. In the beginning,
connective tissue cells situate themselves among the layers
and then form into osteoblasts which are bone-forming cells.
Osteoblasts remove calcium from the blood and put it in the
bone matrix. As a result, layers of spongy bone form around
the original cartilage. Later, spaces among the spongy bone fill
with bone matrix to become compact bone. The osteoblasts
keep depositing calcium supplements into the matrix until it is
completely surrounded by it. After, the osteoblasts are
considered to be in the lacunae and are called osteocytes.
Broad, flat skull bones are examples of intramembranous
ossification.

9. Intramembranous and
Endochondral bone
Endochondral bone(long bones). This ossification forms bone by
replacing a cartilaginous model that is earlier in embryonic
development. These models first undergo changes as the
connective tissue gets bigger, destroying surrounding matrix.
Soon after, connective tissue cells die. As the cells die, a
periosteum is formed on the outside of the developing structure.
Next, blood vessels and other cells rush into the dying tissue. Once
a significant amount of spongy bone is formed, growth in the
cartilage bones occurs. Thickness in cartilage bones is done by
intramembrous ossification. Beneath the layer of periosteum,
compact bone is formed and hardened with the help of
osteoblasts filling portions of the spongy bone with calcium
phosphate crystals. Sometimes the compact bone is formed on
the surfaces of existing bone tissue and osteoblasts must get rid
of them. The crystals are then delivered to blood and tissues.

10. Similarities
Similarities: Both processes create bone and
sometimes the creation of bone requires both
endochondral and intramembranous ossification.
When both processes are used, mesenchyme cells
develop into chondroblasts and increase in number
by cell division. The chondroblasts get bigger and
excrete a matrix which hardens due to presence or
inorganic minerals. Then, chambers form within the
matrix and osteoblasts and blood-forming cells
enter these chambers. The osteoblasts then
secrete minerals to form the bone matrix

11. Bone Fracture Repair
1. Fracture has
occured
2. Formation of a
fracture hematoma
3.Formation of an
internal and
external callus
4.Bone remodeling
completes

12. Types of Cartilage
Hyaline Cartilage- the most common type
of cartilage, it appears gelatinous and
glossy
Elastic Cartilage- cartilage with elastic, as
well as collagenous fibers; provides
elasticity and firmness
Fibrocartilage-cartilage with the greatest
number of collagenous fibers; strongest
and most durable type of cartilage

13. Types of Cartilage
Elastic Cartilage
Hyaline Cartilage
Fibrocartilage