Lec 1

Question 1

Function of Bones

Answer 1

Support – form the framework that supports the body and cradles soft organs

 Protection – provide a protective case for the brain, spinal cord, and vital organs

 Movement – provide levers for muscles

 Mineral storage – reservoir for minerals, especially calcium and phosphorus

 Blood cell formation – hematopoiesis occurs within the
marrow cavities of bones

Question 2

Bone marrow cavities found in ?

Answer 2

In ADULT
Most flat and some long bone like Head humerus and femur
in CHILDREN
All long bone

Question 3

Composition of Bone Organic

Answer 3

Osteoblasts – bone- forming cells

Osteocytes – mature bone cells

Osteoclasts – large cells that resorb or break down bone matrix

Question 4

Bone Textures

Answer 4

Compact bone: dense outer layer

Spongy bone:
honeycomb of trabecular filled with yellow bone marrow

Question 5

True or false

High density ->Low Porosity ->Less flexbility

Answer 5

True

Question 6

Structure of Compact Bone called

Answer 6

Haversian system , or osteon

Question 7

The components of Haversian system or osteon

Answer 7

Lamella: weight-bearing, column-like matrix tubes composed mainly of
collagen

Haversian , or central canal : central channel containing blood vessels
and nerves

Question 8

Structure of Long Bone

Answer 8

Diaphysis

Tubular shaft that forms the
axis of long bones
 Composed of compact bone
that surrounds the medullary
cavity
 Yellow bone marrow (fat) is
contained in the medullary
cavity

Epiphyses

Expanded ends of long bones
 Exterior is compact bone, and
the interior is spongy bone
 Joint surface is covered with
articular (hyaline) cartilage

*Epiphyseal line separates the
diaphysis from the epiphyses

Question 9

Long Bone Growth and Remodeling

Answer 9

Growth in length ( from outside):
cartilage continually grows and is replaced by bone as shown.

Remodeling ( from inside):
bone is resorbed and added by appositional growth as shown

Osteoclasts تأكل العظام من جوا عشان توسع medullary cavity

Question 10

Two control loops regulate bone remodeling

Answer 10

Hormonal mechanism maintains calcium homeostasis in the blood
like thyroid and parathyroid

Mechanical and gravitational forces acting on the skeleton

Question 11

Structure of Short, Irregular, and Flat Bones

Answer 11

Thin plates of compact
bone on the outside (diploë ) with
spongy bone the inside

 Have no diaphysis or epiphyses

 Contain Red bone marrow between the trabeculae

Question 12

Location of Hematopoietic Tissue (Red Marrow)

Answer 12

In infants
 Found in the medullary cavity and all areas of spongy bone

In adults
 Found in the diploë of flat bones, and the head of the femur and humerus

Question 13

Importance of Ionic Calcium in the Body

Answer 13

Calcium is necessary for:
 Transmission of nerve impulses
 Muscle contraction
 Blood coagulation
 Secretion by glands and nerve cells
 Cell division

Question 14

Hormonal Mechanism

Answer 14

Rising blood Ca2+ levels trigger the thyroid to release calcitonin.

 Calcitonin stimulates calcium salt deposit in bone.

 Falling blood Ca2+ levels signal the parathyroid glands to release PTH.

 PTH signals osteoclasts to degrade bone matrix and release Ca2+ into the
blood.

Question 15

Wolff’s law

Answer 15

a bone grows or remodels in response to the forces or demands placed upon it.

Question 16

Observations supporting Wolff’s law
include

Answer 16

 Long bones are thickest midway
along the shaft (where bending
stress is greatest).

 Curved bones are thickest where
they are most likely to buckle.

 Trabeculae form along lines of
stress.

 Large, bony projections occur where heavy, active muscles attach.

Question 17

Homeostatic Imbalances

Answer 17

Osteomalacia in ADULT

 Bones are inadequately mineralized causing softened, weakened bones.

 Main symptom is pain when weight is put on the affected bone.

 Caused by insufficient calcium in the diet, or by vitamin D deficiency.

Rickets in CHILDREN

 Bones of children are inadequately mineralized causing softened, weakened bones.

 Bowed legs and deformities of the pelvis, skull, and rib cage are common.

 Caused by insufficient calcium in the diet, or by vitamin D deficiency.

Question 18

Treatment for osteomalacia and Rickets

Answer 18

• Ca+ and vitD supplements.
• Hormonal.
• exercises like: walking, swimming for mechanical effects.

Question 19

True or false

By age 25, nearly all bones are completely ossified?

Answer 19

True

Question 20

Axial and Appendicular Skeletons

Answer 20

Axial skeleton – bones of the skull, vertebral column, and rib cage
(80 bone).

Appendicular skeleton – bones of the upper and lower limbs, shoulder, and
hip (126 bone).

Question 21

The Axial Skeleton

Answer 21

Skull:
 8 cranial bones
 14 facial bones
 6 auditory ossicles
 Hyoid bone

Vertebral column:
 24 vertebrae
 Sacrum
 Coccyx

 Thoracic cage:
 24 ribs
 Sternum

 Supports and protects organs in body cavities.

 Attaches to muscles of:
 Head, neck, and trunk
 Respiration
 Appendicular skeleton

Question 22

The Vertebral Column

Answer 22

 Formed from 26 irregular bones
(vertebrae) connected in such a way
that a flexible curved structure results

 Cervical vertebrae – 7 bones of the
neck.

 Thoracic vertebrae – 12 bones of the torso.

 Lumbar vertebrae – 5 bones of the
lower back.

 Sacrum – bone inferior to the lumbar vertebrae that articulates with the hip bones.

Question 23

The Vertebral Column

Answer 23

Posteriorly concave curvatures –
cervical and lumbar.

Posteriorly convex curvatures –
thoracic and sacral.

Question 24

All Synovial joints have the following

Answer 24

1. Articular cartilage
2. Joint (synovial) cavity
3. Articular capsule
4. Synovial fluid
5. Reinforcing ligaments

Question 25

True or false
Synovial Joints All are freely movable diarthroses

Answer 25

True

Examples – all limb joints, and most joints of the body.