Unit 4 - Osseous Tissue and Bone Structure Flashcards
How many bones does a normal human adult have?
206
What is bone?
Rigid structure Dense connective tissue Variety of shapes and sizes Serves a variety of functions Active tissue
What do ligaments attach?
Bone to bone
What do tendons attach?
Muscle to bone
7 functions of the skeleton
Support Protection Movement Electrolyte balance Acid-base balance Blood formation Metabolic functions
What is matrix?
Calcium hydroxyapatite and organic collagen
What makes the collagen fibers hard in bones?
When calcium and phosphorus comes together, they will precipitate on the collagen forming crystals. Those crystals harden and make the collagen fibers hard.
7 general features of bones
Cortical bone Diaphysis Marrow cavity Epiphyses Cancellous bone Articular cartilage Nutrient foramina
What are the 4 bone shapes?
Long bones
Short bones
Flat bones
Irregular bones
2 features of long bones
Longer than wide
Rigid levers acted upon by muscles
2 features of short bones
Equal in length and width
Glide across one another in multiple directions
What do flat bones protect and what is their shape?
Protect soft organs
Curved but wide & thin
7 structures of a long bone
Epiphyses Diaphysis Cortical Cancellous Marrow cavity Articular cartilage Periosteum
2 structures of a flat bone
Two layers of cortical bone enclosing middle layer of cancellous bone
Diploe
What is diploe?
Cancellous layer in cranium
4 principal types of bone cells
Osteogenic cells
Osteoblasts
Osteocytes
Osteoclasts
What are osteoblasts?
Bone forming cells
What are osteocytes?
Mature osteoblasts trapped in matrix they deposit
What are osteoclasts?
Cells that breakdown and reabsorb bone
How do lacuna maintain the matrix?
It uses an osteocyte
What is the function of canaliculi?
They carry nutrients to the bone cells
How many bones are in the skull?
22
What are 3 changes that affect bone?
Nutrition
Ratio of calcium to phosphate
Amount of trace minerals
2 types of bone
Cortical
Cancellous
Which layer of bone is the hard, outer layer?
Cortical
Percentage of cortical bone in total bone mass of adult human skeleton
80%
What is cortical bone covered by on the outer and inner surfaces?
Periosteum on outer surface, and endosteum on inner surface
The basic structural unit of cortical bone
Osteon
What is the physical appearance of cancellous bone?
Sponge-like
Cancellous bone consists of? (3)
Spicules
Trabeculae
Red bone marrow
Which bone type is the interior of cortical bone?
Cancellous bone
Percentage of cancellous bone in total bone mass of adult human skeleton
20%
Description of cancellous bone
Thin formations of osteoblasts covered in endosteum
2 types of bone marrow
Red and yellow
What does hemopoietic tissue produce?
Blood cells
What is hemopoietic tissue composed of?
Multiple tissues
Which age group is yellow marrow found in?
Adults
What does most red marrow turn into?
Fatty yellow marrow
When does the skeletal system begin to develop?
6 weeks
What are the 2 ways bones are developed?
Intramembranous ossification
Endochondral ossification
What happens during intramembranous ossification?
Bone is created by connective tissue
What happens during endochondral ossification?
Bone is created from cartilage
What types of bones does intramembranous ossification produce?
Flat bones of skull and clavicle
What does endochondral ossification start with?
The pre-existing cartilage model
During infancy and childhood, what do epiphyses fill with?
cancellous bone
by late teens to early twenties, what happens after all remaining cartilage in epiphyseal plate is consumed?
Gap between epiphyses and diaphysis closes
What happens to the bone when the gap between epiphyses and diaphysis closes?
The bone can no longer grow in length
What is osteogenesis?
Extracellular matrix laid down by osteoblasts
During osteogenesis, what do collagen fibers polymerize to form?
Collagen strands
4 cellular components of bone
Osteoblast
Osteoid
Osteocyte
Matrix
What are the 2 types of bone growth?
Bone elongation
Appositional growth
Why is bone always turning over?
In response to calcium homeostasis
5 zones of metaphysis
Reserve cartilage Proliferation Hypertrophy Calcification Bone deposition
Where does bone grow in length?
The metaphysis
What is the term for bones growing in length?
Interstitial growth
What is the term for bones increasing in width?
Appositional growth
What % of bone remodeling occurs yearly?
10%
2 types of dwarfism
Achondroplastic
Pituitary
Defining feature of achondroplastic dwarfism
Long bones stop growing in childhood
2 defining features of pituitary dwarfism
Lack of growth hormone
Normal proportions with short stature
What occurs during mineralization?
Osteoblasts produce collagen fibers and fibers become encrusted with minerals that harden matrix
What are abnormal calcifications?
Calcifications that are irregular in size or shape or are tightly clustered together in an otherwise soft organ
Where is hydrogen pumped during mineral resorption?
The space between osteoclast and bone surface
Mineral resorption is performed by _____ at the ___ ___
Performed by osteoclasts at the “ruffled border”
What is calcium homeostasis?
The mechanism the body uses to maintain adequate calcium levels
How many grams of calcium in an adult human?
1100
Term for blood calcium deficiency
Hypocalcemia
Term for blood calcium excess
Hypercalcemia
What is a carpopedal spasm?
Hypocalcemia demonstrated by muscle spasm of hands and feet
Calcium homeostasis depends on the balance between…? (3)
Dietary intake, urinary and fecal losses, and exchanges between osseous tissue
Calcium homeostasis is regulated by three hormones:
Calcitriol
Calcitonin
Parathyroid hormone
What is calcitriol produced by? (3)
Skin, liver, kidneys
How does calcitriol raise blood calcium dioxide concentration? (3)
Increases calcium absorption by small intestine.
Increases calcium resorption from the skeleton.
Promotes kidney reabsorption of calcium ions.
What is calcitriol necessary for?
Forming new bones
What happens without an adequate amount of vitamin D?
An abnormal softness of bones
How does the body lower blood calcium concentration?
Calcitonin
2 ways calcitonin lowers blood calcium concentration
Osteoclast inhibition
Osteoblast stimulation
How is calcitonin secreted?
By C cells in the thyroid gland
What secretes parathyroid hormone?
Parathyroid glands
Parathyroid hormones is released with…?
Low calcium blood levels
4 mechanisms parathyroid hormones use to raise calcium blood levels
- Binds to receptors on osteoblasts
- Promotes calcium reabsorption by the kidneys, less lost in urine
- Promotes calcitriol synthesis in kidneys
- Inhibits collagen synthesis by osteoblasts
When is bone growth rapid?
Puberty & adolescence
What do anabolic steroids do for growth?
Causes it to stop
What is a stress fracture?
Abnormal trauma to a bone
What is a pathological fracture?
Bone weakened by some other disease
What 3 characteristics are fractures classified by?
Direction of fracture line
Break in the skin
Multiple pieces
4 steps of fracture repair
- Fracture hematoma formation
- Callus formation
- Cancellous bone formation
- Cortical bone formation
Define osteoporosis
Bones lose mass and become brittle due to loss of organic matrix and minerals
Who is at the highest risk of osteoporosis?
Postmenopausal white women