Unit 2: Skeletal System Flashcards
Functions of Skeletal System
Support
Protection
Movement
Blood formation
Mineral Reservoir
pH balance
Describe the mineral deposition process
-Minerals removed from blood plasma
-Minerals deposited in bone tissue
-Fibroblasts deposit collagen fibers along osteons
-Osteoblasts encrust the fibers with minerals
Define osteogenic tissue
Beginning of bone cells found in connective tissue, go through mitosis to create osteoblasts
Define osteoblast cell
Bone-producing cell which mineralizes organic matter of the matrix
Define osteocyte cell
Describe the significance of lacunae and canaliculi
Osteoblast cell trapped in a mineralized, tough matrix
Osteocytes are found in lacunae in the bone, which are connected by canaliculi so that they can communicate with eachothers and with osteoblasts/osteoclasts
Define lacunae
A “cave” in the bone where osteocytes reside
Define canaliculi
Passage between lacunae “caves” where osteocytes can send signals to other osseous cells
Define osteoclast cell
(where they come from, purpose, location)
Form of white blood cell which develops from fused stem cells
Lowers the pH to degrade bone tissue
Reside in resorption bays
Main 3 minerals found in bone tissue
Phosphate, Calcium, Bicarbonate
Purpose of phosphate
Component in DNA, RNA, ATP, and phospholipids
Purpose of Calcium
Needed for communication between neurons, muscle contractions, blood clotting, exocytosis, and more
Purpose of Bicarbonate
Regulates pH of bodily fluids
The ECM of bone is what portion organic and what portion inorganic?
1/3 organic
2/3 inorganic
What is the organic matter in osseous tissue?
Collagen, glycosaminoglycans, proteoglycans, glycoproteins
What is the inorganic matter in osseous tissue?
85% hydroxyapatite
10% calcium carbonate
Fluoride, sulfate, potassium, magnesium
What is hydroxyapatite?
Crystallized calcium phosphate salt
Why is bone a combination of organic and inorganic matter?
Minerals give the bone strength to resist compression
Collagen gives the bone resilience to resist tension
What are the 3 hormones which regulate calcium homeostasis?
Calcitriol, Calcitonin, Parathyroid
What is Calcitriol?
How is it produced?
What is its function?
Vitamin D, blood borne messenger hormone
Produced by UV radiation on skin or digestion which is processed by kidney or liver
Helps intestine absorb calcium, phosphate, magnesium more
Promotes urinary resorption of calcium
Promotes osteoclast acitivty
Boosts calcium levels in blood
What is Calcitonin?
How is it produced?
What is its function?
Hormones secreted by C cells in thyroid gland
Is released when calcium levels in blood are too high
Reduces osteoclast activity
Increases osteoblast # and acitivity
What is Parathyroid?
How is it produced?
What is its function?
Hormones secreted by parathyroid gland
Is released when calcium level in blood are too low
Increases osteoclast activity
Increases calcium reabsorption and calcitriol synthesis
Decreases osteoblast activity
Describe the process of mineral resorption
Osteoclasts dissolve bone to release minerals into the blood
High acidity in space between osteoclast and bone dissolves tissue
Bones are ______ tissue
Connective
The 2 structures of bones are
Compact and spongey
Where is red bone marrow found?
Spongey bone
The shapes of bones are
Long
Short
Flat
Irregular
Describe long bone shape
Example of a long bone:
Longer than wide with expanded ends
Humerus, radius, ulna
Describe short bone shape
Example of a short bone:
Equal length and height
Carpals, tarsals
Describe flat bone shape
Example of flat bone:
Platelike
Ribs, frontal, parietal
Describe irregular bone shape
Example of irregular bone:
Wide variety of shapes
Vertebrae, coccyx, sphenoid, ethmoid
Define epiphysis
Enlarged ends of a long bone
Spongey bone covered with articular cartilage and some compact bone
Define diaphysis
Shaft of a long bone covered in periosteum
Compact bone with a marrow cavity (medullary cavity) lined with endosteum
Define periosteum
Outer surface of bone
Define endosteum
Inner lining of medullary cavity
Define medullary cavity
Cavity within long bone where yellow bone marrow is found, is lined with endosteum
Define epiphyseal plate/line
Epiphyseal plate (children) / line (adults) is where epiphysis meets diaphysis on a long bone
Describe the appearance of flat bones
Covered exteriorly and interiorly by compact bone
Spongey middle layer, but no medullary cavity
Compact bones are made of
Osteons
Define osteon
“Bricks”
Cylinders of tissue that form layers of matrix (lamellae) arranged around central canal
Define lamellae
Layers of matrix
The central canal holds
Blood vessels
Osteocytes are connected to eachother and the blood supply through
Canaliculi
Define perforating canals
Canals which run perpendicularly to connect central canals
Spongey bone is made of
Trabeculae
Define trabeculae
Rods and plates of bone with spaces filled with red bone marrow
Trabeculae always form along
Stress lines
Red bone marrow is located in
Trabeculae in spongey bone
Yellow bone marrow is located in
Medullary cavity of long bones, contain fatty adipose marrow
Intramembranous ossification produces _____ bones found where
Flat
Skull and clavicle
Endochondral ossification produces bone from
A cartilage model
Define stress fracture
Break caused by abnormal trauma to bone
Define pathological fracture
Break caused by weakness of bone due to disease
Bone usually heal in ________ weeks
8-12 weeks
Name the stages of bone repair:
Hematoma
Granulation tissue
Callus formation
Remodeling
Describe the Hematoma step of bone repair
Broken blood vessels form a clot
Describe the Granulation tissue step of bone repair
Fibrous tissue formed by fibroblasts are infiltrated by capillaries
Describe the Callus formation step of bone repair
Soft callus of fibrocartilage forms, is replaced by hard callus on bone in 6 weeks
Describe the Remodeling step of bone repair
Bone “overgrows” so over the next 6 month, spongey bone is replaced by compact bone
Describe Osteoporosis and its risk factors
Bone loses mass and becomes brittle (most common)
Risk Groups:
Lower estrogen (menopause)
Lack of calcium and protein
Lack of Vitamin D
Lack of weight-bearing exercise
Smoking
Describe Rickets and its risk factors
Lack of Vitamin D results in softness of bones in children (bowlegged)
Risk Groups:
Dietary Restrictions (lactose intolerant, vegan)
Celiac disease
Dark skin
Lack of sun
Can be genetic
Describe Osteomalacia and its risk factors
Lack of Vitamin D results in muscle and bone pain in adults
Risk Groups:
Lack of sun
Lack of Vitamin D in diet
Celiac disease
Medications for seizures
Gastric Surgery
Kidney/Liver disease
Describe Osteogenesis Imperfecta and its risk groups
“Brittle Bone Disease,” - inability to produce collagen
Bones fracture easily, hearing loss, and blue tint to sclera
Risk Groups:
Autosomal dominant genetic disease
Congenital (born with it)
What hormone activates when you need more calcium in your bloodstream?
Parathyroid
What hormone activates when you need less calcium in your bloodstream?
Calcitonin
Define hypercalcemia and its effects
Too much calcium in blood stream, can cause coma and death
Define hypocalcemia and its effects
Not enough calcium in blood stream, can cause muscle spasms and seizures
What process creates flat bones and how?
Intramembranous Ossification
Creates osteoblasts cells from connective tissue, which gather on trabeculae. Calcium phosphate is deposited onto the matrix and creates osteocytes. Marrow spaces are made in the center of bone (spongey) and hardened compact bone forms on the outside periosteum.
What process creates bones other than flat bones?
Endochondral ossification
Uses cartilage model to form bones. The cartilage model contains chondrocytes in center which create primary ossification center. Bony collar is made and chondrocytes die leaving a marrow cavity. Osteoblasts calcify on the trabeculae.
Where are the osteogenic layers of bone?
Periosteum
What different connective tissues make up the skeletal system?
Bones, cartilage, tendons, ligaments
What is the function of canaliculi in compact bone?
Supply nutrients via blood vessels, remove cellular wastes, and channels for communication between osteocyte
