Lecture 1 - Bone Structure Flashcards
Functions of bone and skeletal system
- supports soft tissues and provides attachment for skeletal muscles
- protects internal organs
- assists in movement
- mineral homeostasis
- blood cell production (hematopoiesis)
- triglyceride storage
- endocrine function
what hormones are involved in mineral homeostasis?
- PTH
- calcitonin
- vitamin D
where does hematopoiesis occur?
red bone marrow (produces red blood cells, white blood cells, and platelets)
where is triglyceride storage at?
yellow bone marrow
what hormones do bones secrete?
- osteocalcin
- lipocalin
osteocalcin function
regulates blood glucose levels by increasing insulin secretion from beta cells and increase insulin sensitivity in surrounding tissues. stimulates testosterone secretion. role in fight or flight response
lipocalin function
suppresses appetite
diaphysis
shaft of long bone
epiphyses
distal and proximal ends of the bone, covered with hyaline cartilage
what kind of cartilage is the epiphyses covered with?
articular cartilage
metaphyses
section between diaphysis and epiphyses
epiphyseal plate
layer of hyaline cartilage found in metaphyses allows for bone to grow in length
epiphyseal line
cartilage is replaced with bone (no longer grow in length). found in metaphyses
periosteum
sheath of dense irregular connective tissue surrounding bone surface
function of periosteum
- protect bone
- assists in fracture repair
- helps nourish bone tissue
- serves as attachment point for ligaments and tendons
medullary cavity
space within diaphysis
endosteum
thin membrane that lines the medullary cavity
nutrient artery
- principle artery that supplies shaft of bone
- the branches of the nutrient artery snake though the canals of haversian systems and other cavities of the bone
- the nutrient artery enters the diaphysis via nutrient foramen
bone matrix
inorganic mineral salts deposited on organic framework (osteoid)
what is the bone matric made of?
- 25% water
- 25% collagen fibers (organic matrix/osteoid)
- 50% crystallized mineral salts
inorganic mineral salts
- hydroxyapatite
- magnesium hydroxide
- fluoride
- sulfate
what is hydroxyapatite composed of
calcium phosphate and calcium carbonate
which is the most abundant inorganic mineral salt?
hydroxyapatite
crystalized salts give bone _ while the collagen gives it _ and _
hardness, flexibility, tensile strength
osteogenic cells
- undifferentiated stem cells
- derived from mesenchyme
- differentiate into osteoblasts
- found in periosteum, endosteum, and in cancals within bone that contain blood vessels
osteoblasts
- build bone by making and secreting collagen fibers (osteoid)
- Initiates calcification by secreting alkaline phosphatase (enzyme that will calcify mineral salts after they bind to osteoid)
osteocytes
- mature osteoblasts
- play role in bone remodeling by acting as mechanosensory receptors
- play role in calcium homeostasis-can “hold” Ca and release into the blood quickly
osteoclasts
- derived from stem cells in the bone marrow that give rise to monocytes
- differentiation and fusion of monocyte like cells form osteoclasts
- responsible for bone resorption
- have ruffled border that forms a seal with bone surface
- release lysosomal enzymes and acids to digest matrix
- when active, the ruffled border is more pronounced
compact bone (_)
cortical bone
how is compact bone arranged?
in units called osteons (haversian systems)
Central (haversion canal)
runs longitudinally through bone and through osteon; contains blood vessels, lymphatic vessels, and nerves
Perforating (volkman’s) canal
connects central canals to each other, to medullary cavity, and to the periosteum
Concentric lamellae and inner & outer circumferential lamellae
rings of hard calcified matrix
Lacunae
spaces in matrix that house osteocytes
Canaliculi
small channels filled with extracellular fluid connecting adjacent lacunae; contain fingerlike processes of osteocytes which communicate via gap junctions with neighboring osteocytes
spongy bone (cancellous/trabecular bone)
- contains more spaces
- in certain bones, it houses red bone marrow
- not arranged in osteons
- contains trabeculae
- bone tissue arranged into lamellae
- contains lacunae and canaliculi
- Makes up most of bone tissue of short, flat, irregular shaped bones, epiphyses of long bone, and narrow rim around medullary cavity
red bone marrow function
- Produces red and white blood cells and platelets via hemopoiesis
- Contains developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fibers
yellow bone marrow function
- located within medullary cavity
- contains mostly adipocytes
- stores triglycerides for energy source
- with increasing age, much of the bone marrow changes from red to yellow
Blood and nerve supply
- Bone is richly supplied with blood vessels
- Nutrient artery and vein pass through nutrient canal and sends branches into the central canals of osteons to provide for osteocytes
- Nerves follow vessels into bone tissue where they sense damage and transmit pain messages
- Which hormone is secreted from bone?
a. Parathyroid Hormone
b. Calcitonin
c. Vitamin D
d. Osteocalcin
e. A, B, C
f. All of the above
D
- What is the major organic component of the matrix?
a. Hydroxyapatite
b. Magnesium Hydroxide
c. Collagen
d. A & B
e. All of the above
C
- What is the function of osteoclasts?
a. Bone formation
b. Bone resorption
B
- How do osteoclasts arise?
a. Maturation of osteoblasts
b. Fusion of monocytes
c. From division and differentiation of osteocytes
d. Differentiation of osteogenic cells
B
- How do osteoblasts arise?
a. Division of osteoclasts
b. Fusion of monocytes
c. Differentiation of osteogenic cells
C
- Compact bone and spongy bone are both organized into osteons?
a. True
b. False
B
- Osteoclasts:
a. Secrete collagen
b. Secrete alkaline phosphatase
c. Secrete lysosomal enzymes
d. A & B
e. All of the above
C
