Slide 1: Overview of Bone Tissue
Magnification: Low (4x or 10x objective)
Staining: H&E (Hematoxylin and Eosin) or Masson's trichrome
Description: The slide provides an overview of bone tissue, showing both compact and spongy bone. In compact bone, dense lamellar structures can be observed, with osteons arranged in parallel lines. Spongy bone appears as a mesh-like network of trabeculae, with spaces between filled with bone marrow. Blood vessels and osteocytes may also be visible within the bone tissue.
Slide 2: Osteon Structure
Magnification: Medium (20x or 40x objective)
Staining: H&E or Masson's trichrome
Description: This slide focuses on the structure of an osteon, the basic functional unit of compact bone. Osteons appear as cylindrical structures with concentric lamellae surrounding a central Haversian canal. Osteocytes are embedded within lacunae between the lamellae, connected to each other and the central canal by canaliculi. Blood vessels and nerves may be visible within the Haversian canal.
Slide 3: Trabecular Bone
Magnification: Medium (20x or 40x objective)
Staining: H&E or Masson's trichrome
Description: This slide highlights the structure of trabecular or spongy bone. Trabeculae are observed as delicate bony struts arranged in a lattice-like network, with spaces between filled with bone marrow. Osteocytes may be seen embedded within lacunae along the surface of trabeculae. Blood vessels and hematopoietic cells may also be present within the bone marrow spaces.
Slide 4: Bone Development
Magnification: Medium (20x or 40x objective)
Staining: H&E or Alizarin Red for mineralized bone
Description: This slide illustrates the process of bone development through endochondral ossification. Areas of cartilage undergoing ossification are visible, with calcified cartilage being replaced by bone tissue. Osteoblasts may be observed depositing bone matrix onto the calcified cartilage, forming primary ossification centers. Blood vessels and osteoprogenitor cells from the surrounding tissue may also be seen invading the developing bone.
Slide 5: Bone Remodeling
Magnification: High (40x or 100x objective)
Staining: H&E or Von Kossa for mineralized bone
Description: This slide demonstrates the process of bone remodeling, showing areas of bone resorption and formation. Osteoclasts may be observed resorbing old or damaged bone tissue, creating resorption lacunae. Adjacent to the resorption lacunae, osteoblasts may be seen depositing new bone matrix, forming osteoid. The presence of osteocytes within lacunae and canaliculi connecting them may also be evident.
Each description should provide a concise overview.
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"Exploring Bone Tissue: A Microscopic Journey into Structural Integrity and Functionality" (1).pdf
1. Brief lesson plan
▪ Mondays 11h40 to 15h25: Lectures
▪ Wednesdays 09h50 to 10h35: Quiz
▪ Fridays 08h00 to 08h45: Q&A
1
2. Assessment
Test 1: 45% of DP
Test 2: 45% of DP
Quiz: 10% of DP
DP: 50% of Final mark
Exam: 50% of Final mark
Pass mark = 50%
Example:
Test 1 = 60% Test 2 = 70% Quiz Av. = 65%
DP = (60x0.45) + (70x0.45) + (65x0.1) = 65%
Exam mark = 61%
Final mark = (65x0.5) + (61x0.5) = 63%
2
3. Recommended textbooks
▪ Human Anatomy and Physiology – EN. Marieb & K. Hoehn (2007). Pearson
International Edition.
▪ Dynatomy: Dynamic Human Anatomy – WC. Whiting & S. Rugg (2006). Human
Kinetics.
3
6. Functions of Bone and Skeletal System
◼ Support
◼ Protection
◼ Assistance in Movement
◼ Mineral Homeostasis
◼ Blood Cell Production
◼ Triglyceride Storage
7. Functions of Bone and Skeletal System
◼ Support
❑ Structural framework of the body
◼ Supports soft tissues
◼ Provides attachment points for tendons of skeletal
muscle
◼ Protection
❑ Protects important internal organs
◼ Cranium protects brain
◼ Vertebrae protects spinal cord
◼ Ribs protect lungs and heart
8. Functions of Bone and Skeletal System
◼ Assistance in Movement
❑ Skeletal muscle attaches to bone
◼ Skeletal muscle contraction pulls on bone producing
movement
◼ Mineral Homeostasis
❑ Bone tissue stores several minerals
◼ Acts to serve as a reservoir of critical minerals
❑ Calcium (99% of body’s content)
❑ Phosphorus
9. Functions of Bone and Skeletal System
◼ Blood Cell Production
❑ Red bone marrow produces (Hemopoiesis)
◼ Red blood cells
◼ White blood cells
◼ Platelets
◼ Triglyceride Storage
❑ Yellow bone marrow
◼ Triglycerides stored in adipose cells
❑ Serves as a potential chemical energy reserve
10. Structure of Bone
❑ Diaphysis - Shaft
❑ Epiphysis – Growing end
❑ Metaphysis
◼ Epiphyseal growth plate
❑ Articular cartilage
◼ Perforating fibers
❑ Periosteum - Covering
❑ Medullary cavity – inner space,
contain bone marrow
❑ Endosteum – lining of medullary
◼ Long Bone Anatomy (Humerus)
11. Histology of Bone Tissue
◼ Extracellular matrix surrounding widely
separated cells
❑ Matrix
◼ 25% water
◼ 25% collagen fibers
◼ 50% crystallized mineral salts
◼ The most abundant mineral salt is
calcium phosphate
12. Histology of Bone Tissue
◼ A process called calcification is initiated
by bone-building cells called osteoblasts
◼ Mineral salts are deposited and crystalize
in the framework formed by the collagen
fibers of the extracellular matrix
◼ Bone’s flexibility depends on collagen
fibers
13. Histology of Bone Tissue
◼ Four types of cells are present in bone tissue
◼ Osteogenic cells
❑ Undergo cell division; the resulting cells develop
into osteoblasts
◼ Osteoblasts
❑ Bone-building cells
❑ Synthesize extracellular matrix of bone tissue
◼ Osteocytes
❑ Mature bone cells
❑ Exchange nutrients and wastes with the blood
14. Histology of Bone Tissue
◼ Osteoclasts
❑ Release enzymes that digest the mineral
components of bone matrix (resorption)
❑ Regulate blood calcium level
15. Histology of Bone Tissue
◼ Bone may be categorized as:
❑ Compact
❑ Spongy
16. Histology of Bone Tissue
◼ Compact Bone
❑ Resists the stresses produced by weight and
movement
❑ Components of compact bone are arranged
into repeating structural units called osteons
or Haversian systems
❑ Osteons consist of a central (Haversian) canal
with concentrically arranged lamellae,
lacunae, osteocytes, and canaliculi
17. Histology of Bone Tissue
◼ Osteon
❑ Central canals run longitudinally through bone
❑ Around the central canals are concentric
lamellae
◼ Rings of calcified matrix (like the rings of a tree
trunk)
❑ Between the lamellae are small spaces called
lacunae which contain osteocytes
❑ Radiating in all directions from the lacunae are
tiny canaliculi filled with extracellular fluid
18. Histology of Bone Tissue
◼ Osteon
❑ Canaliculi connect
lacunae, forming a system
of interconnected canals
◼ Providing routes for
nutrients and oxygen to
reach the osteocytes
❑ The organization of
osteons changes in
response to the physical
demands placed on the
skeleton
19. Histology of Bone Tissue
◼ Spongy Bone
❑ Lacks osteons
❑ Lamellae are arranged in a lattice of thin
columns called trabeculae
◼ Spaces between the trabeculae make bones
lighter
◼ Trabeculae of spongy bone support and protect
the red bone marrow
◼ Hemopoiesis (blood cell production) occurs in
spongy bone
20. Histology of Bone Tissue
◼ Spongy Bone
❑ Within each trabecula are lacunae that
contain osteocytes
❑ Osteocytes are nourished from the blood
circulating through the trabeculae
❑ Interior bone tissue is made up primarily of
spongy bone
❑ The trabeculae of spongy bone are oriented
along lines of stress
◼ helps bones resist stresses without breaking
21. Blood and Nerve Supply of Bone
◼ Bone is richly supplied with
blood
❑ Periosteal arteries
accompanied by nerves
supply the periosteum and
compact bone
❑ Epiphyseal veins carry
blood away from long bones
◼ Nerves accompany the
blood vessels that supply
bones
❑ The periosteum is rich in
sensory nerves sensitive to
tearing or tension
22. Bone Formation
◼ The process by which bone forms is
called ossification
◼ Bone formation occurs in four situations:
❑ 1) Formation of bone in an embryo
❑ 2) Growth of bones until adulthood
❑ 3) Remodeling of bone
❑ 4) Repair of fractures
23. Bone Formation
◼ Formation of Bone in an Embryo
❑ Cartilage formation and ossification occurs
during the sixth week of embryonic
development
24. Bone Formation
◼ Formation of Bone in an Embryo
❑ Bone formation follows one of two patterns
◼ Intramembranous ossification
❑ Flat bones of the skull and mandible are formed in this
way
❑ “Soft spots” that help the fetal skull pass through the
birth canal later become ossified forming the skull
◼ Endochondral ossification
❑ The replacement of cartilage by bone
❑ Most bones of the body are formed in this way including
long bones
25. 1 Development of
cartilage model
Hyaline
cartilage
Perichondrium
Proximal
epiphysis
Distal
epiphysis
Diaphysis
1 Development of
cartilage model
Growth of
cartilage model
2
Hyaline
cartilage
Uncalcified
matrix
Calcified
matrix
Perichondrium
Proximal
epiphysis
Distal
epiphysis
Diaphysis
1 Development of
cartilage model
Development of
primary ossification
center
Growth of
cartilage model
2 3
Hyaline
cartilage
Uncalcified
matrix
Calcified
matrix
Nutrient
artery
Perichondrium
Proximal
epiphysis
Distal
epiphysis
Diaphysis
Periosteum
Primary
ossification
center
Spongy
bone
1
Hyaline
cartilage
Calcified
matrix
Periosteum
(covering
compact bone)
Uncalcified
matrix
Calcified
matrix
Medullary
cavity
Nutrient
artery and vein
Nutrient
artery
Perichondrium
Proximal
epiphysis
Distal
epiphysis
Diaphysis
Development of
cartilage model
Development of
primary ossification
center
Development of
the medullary
cavity
Growth of
cartilage model
Periosteum
Primary
ossification
center
2 3 4
Spongy
bone
Uncalcified
matrix
1 Development of
cartilage model
Development of
primary ossification
center
Development of
the medullary
cavity
Growth of
cartilage model
2 3 4
Hyaline
cartilage
Calcified
matrix
Periosteum
(covering
compact bone)
Uncalcified
matrix
Calcified
matrix
Medullary
cavity
Nutrient
artery and vein
Nutrient
artery
Perichondrium
Proximal
epiphysis
Distal
epiphysis
Diaphysis
Periosteum
Primary
ossification
center
Secondary
ossification
center
Nutrient
artery and vein
Uncalcified
matrix
Epiphyseal
artery and
vein
Development of secondary
ossification center
5
Spongy
bone
Uncalcified
matrix
1
Articular cartilage
Spongy bone
Epiphyseal plate
Secondary
ossification
center
Nutrient
artery and vein
Uncalcified
matrix
Epiphyseal
artery and
vein
Formation of articular cartilage
and epiphyseal plate
Development of secondary
ossification center
Development of
cartilage model
Development of
primary ossification
center
Development of
the medullary
cavity
Growth of
cartilage model
2 3 4
5 6
Hyaline
cartilage
Uncalcified
matrix
Calcified
matrix
Periosteum
(covering
compact bone)
Uncalcified
matrix
Calcified
matrix
Medullary
cavity
Nutrient
artery and vein
Nutrient
artery
Perichondrium
Proximal
epiphysis
Distal
epiphysis
Diaphysis
Periosteum
Primary
ossification
center
Spongy
bone
26. Bone Growth During Infancy, Childhood
and Adolescence
◼ Growth in Length
◼ The growth in length of
long bones involves two
major events:
❑ 1) Growth of cartilage
on the epiphyseal
plate
❑ 2) Replacement of
cartilage by bone
tissue in the
epiphyseal plate
27. Bone Growth During Infancy, Childhood
and Adolescence
◼ Osteoclasts dissolve the
calcified cartilage, and
osteoblasts invade the area
laying down bone matrix
◼ The activity of the epiphyseal
plate is the way bone can
increase in length
◼ At adulthood, the epiphyseal
plates close and bone replaces
all the cartilage leaving a bony
structure called the epiphyseal
line
28. Bone Growth During Infancy, Childhood
and Adolescence
◼ Growth in Thickness
❑ Bones grow in thickness at the outer surface
◼ Remodeling of Bone
❑ Bone forms before birth and continually renews
itself
❑ The ongoing replacement of old bone tissue by
new bone tissue
❑ Old bone is continually destroyed and new bone is
formed in its place throughout an individual’s life
29. Bone Growth During Infancy, Childhood
and Adolescence
◼ A balance must exist between the actions of
osteoclasts and osteoblasts
❑ If too much new tissue is formed, the bones become
abnormally thick and heavy
❑ Excessive loss of calcium weakens the bones, as
occurs in osteoporosis
❑ Or they may become too flexible, as in rickets and
osteomalacia
30. Factors Affecting Bone Growth and Bone
Remodeling
◼ Normal bone metabolism depends on several factors
◼ Minerals
❑ Large amounts of calcium and phosphorus and
smaller amounts of magnesium, fluoride, and
manganese are required for bone growth and
remodeling
◼ Vitamins
❑ Vitamin A stimulates activity of osteoblasts
❑ Vitamin C is needed for synthesis of collagen
❑ Vitamin D helps build bone by increasing the
absorption of calcium from foods in the gastrointestinal
tract into the blood
❑ Vitamins K and B12 are also needed for synthesis of
bone proteins
31. Factors Affecting Bone Growth and Bone
Remodeling
◼ Hormones
❑ During childhood, the hormones most important to
bone growth are growth factors (IGFs), produced by
the liver
◼ IGFs stimulate osteoblasts, promote cell division at the
epiphyseal plate, and enhance protein synthesis
❑ Thyroid hormones also promote bone growth by
stimulating osteoblasts
❑ Insulin promotes bone growth by increasing the
synthesis of bone proteins
32. Factors Affecting Bone Growth and Bone
Remodeling
◼ Hormones
❑ Estrogen and testosterone cause a dramatic
effect on bone growth
◼ Cause of the sudden “growth spurt” that occurs
during the teenage year
◼ Promote changes in females, such as widening of
the pelvis
◼ Shut down growth at epiphyseal plates
❑ Parathyroid hormone, calcitriol, and calcitonin
are other hormones that can affect bone
remodeling
33. Fracture and Repair of Bone
◼ Fracture Types
❑ Open (compound) fracture
◼ The broken ends of the bone protrude through the skin
❑ Closed (simple) fracture
◼ Does not break the skin
❑ Comminuted fracture
◼ The bone is splintered, crushed, or broken into pieces
❑ Greenstick fracture
◼ A partial fracture in which one side of the bone is broken and the other side
bends
❑ Impacted fracture
◼ One end of the fractured bone is forcefully driven into another
❑ Pott’s fracture
◼ Fracture of the fibula, with injury of the tibial articulation
❑ Colles’ fracture
◼ A fracture of the radius in which the distal fragment is displaced
❑ Stress fracture
◼ A series of microscopic fissures in bone
35. Fracture and Repair of Bone
◼ Calcium and phosphorus needed to strengthen and
harden new bone after a fracture are deposited only
gradually and may take several months
◼ The repair of a bone fracture involves the following
steps
❑ 1) Formation of fracture hematoma
◼ Blood leaks from the torn ends of blood vessels, a clotted
mass of blood forms around the site of the fracture
❑ 2) Fibrocartilaginous callus formation
◼ Fibroblasts invade the fracture site and produce collagen
fibers bridging the broken ends of the bone
❑ 3) Bony callus formation
◼ Osteoblasts begin to produce spongy bone trabeculae joining
portions of the original bone fragments
❑ 4) Bone remodeling
◼ Compact bone replaces spongy bone
36. Compact bone
Spongy bone
Periosteum
Fracture hematoma
Fracture
hematoma
Bone
fragment
Osteocyte
Red blood
cell
Blood vessel
Formation of fracture hematoma
Phagocyte
Osteon
1
Phagocyte
Osteoblast
Fibroblast
Fibrocartilaginous
callus
Collagen fiber
Chondroblast
Cartilage
Fibrocartilaginous callus formation
2
Compact bone
Spongy bone
Periosteum
Fracture hematoma
Fracture
hematoma
Bone
fragment
Osteocyte
Red blood
cell
Blood vessel
Formation of fracture hematoma
Phagocyte
Osteon
1
Bony callus
Spongy bone
Osteoblast
Bony callus formation
Osteocyte
3
Compact bone
Spongy bone
Periosteum
Fracture hematoma
Fracture
hematoma
Bone
fragment
Osteocyte
Red blood
cell
Blood vessel
Formation of fracture hematoma
Phagocyte
Osteon
1
Phagocyte
Osteoblast
Fibroblast
Fibrocartilaginous
callus
Collagen fiber
Chondroblast
Cartilage
Fibrocartilaginous callus formation
2
Spongy bone
Osteoblast
Osteoclast
New compact
bone
Bony callus formation Bone remodeling
Osteocyte
3 4
Compact bone
Spongy bone
Periosteum
Fracture hematoma
Fracture
hematoma
Bone
fragment
Osteocyte
Red blood
cell
Blood vessel
Formation of fracture hematoma
Phagocyte
Osteon
1
Phagocyte
Osteoblast
Fibroblast
Fibrocartilaginous
callus
Collagen fiber
Chondroblast
Cartilage
Fibrocartilaginous callus formation
2
Bony callus
37. Bone’s Role in Calcium Homeostasis
◼ Bone is the body’s major calcium reservoir
◼ Levels of calcium in the blood are maintained
by controlling the rates of calcium resorption
from bone into blood and of calcium deposition
from blood into bone
❑ Both nerve and muscle cells depend on
calcium ions (Ca2+) to function properly
❑ Blood clotting also requires Ca2+
❑ Many enzymes require Ca2+ as a cofactor
38. Bone’s Role in Calcium Homeostasis
◼ Actions that help elevate blood Ca2+ level
❑ Parathyroid hormone (PTH) regulates
Ca2+ exchange between blood and bone
tissue
◼ PTH increases the number and activity of
osteoclasts
◼ PTH acts on the kidneys to decrease loss of
Ca2+ in the urine
◼ PTH stimulates formation of calcitriol a
hormone that promotes absorption of
calcium from foods in the gastrointestinal
tract
40. Bone’s Role in Calcium Homeostasis
◼ Actions that work to decrease blood Ca2+
level
❑ The thyroid gland secretes calcitonin (CT)
which inhibits activity of osteoclasts
❑ The result is that CT promotes bone
formation and decreases blood Ca2+ level
41. Exercise and Bone Tissue
◼ Bone tissue alters its strength in response to
changes in mechanical stress
❑ Under stress, bone tissue becomes stronger through
deposition of mineral salts and production of collagen
fibers by osteoblasts
❑ Unstressed bones diminishes because of the loss of
bone minerals and decreased numbers of collagen
fibers
◼ The main mechanical stresses on bone are
those that result from the pull of skeletal muscles
and the pull of gravity
◼ Weight-bearing activities help build and retain
bone mass
42. Aging and Bone Tissue
◼ The level of sex hormones diminishes during
middle age, especially in women after
menopause
❑ A decrease in bone mass occurs
❑ Bone resorption by osteoclasts outpaces bone
deposition by osteoblasts
◼ Female bones generally are smaller and less
massive than males
❑ Loss of bone mass in old age has a greater
adverse effect in females
43. Aging and Bone Tissue
◼ There are two principal effects of aging on bone tissue:
❑ 1) Loss of bone mass
◼ Results from the loss of calcium from bone matrix
◼ The loss of calcium from bones is one of the symptoms in
osteoporosis
❑ 2) Brittleness
◼ Results from a decreased rate of protein synthesis
◼ Collagen fibers gives bone its tensile strength
◼ The loss of tensile strength causes the bones to become very brittle
and susceptible to fracture