Week 2 // Chapter 6 // Bone Tissue Flashcards
List functions of the skeletal system
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- Provides Support
- Protects internal organs
- Assists body movements (with muscles)
- Mineral homeostasis (calcium + phosphorus)
- Participates in blood cell production (hemopoiesis)
- Stores triglycerides in adipose cells of yellow marrow
Bone is an organ made up of several different tissues working together.
Name the tissues
bone, cartilage, dense connective tissue, adipose, and nervous tissue
Name the parts of a long bone
Long bones contain
Diaphysis (bone shaft), 2 epiphyses (both ends of the bone at the joints), 2 metaphyses (region between diaphysis and epiphysis), Articular cartilage covering both epiphyses, Periosteum (connective tissue surrounding the diaphysis), Medullary cavity (hollow space within diaphysis), Endosteum (thin membrane lining the medullary cavity)
The long bone shaft is called a
Diaphysis
The ends of the long bone are called the
epiphysis
The region between the diaphysis (shaft) and epiphysis (end) is called the ______
metaphyses
(this is where bone growth occurs!)
What covers both epiphysis in a long bone?
Articular cartilage
The connective tissue surrounding the diaphysis is called the _______
Periosteum
What is the hollow space within diaphysis and what does it contain?
The Medullary cavity contains the yellow bone marrow
This lines the medullary cavity
The Endostium
Spongy bone vs. Compact Bone
- Compact bone is good at providing protection and support; strongest
- Spongy bone is lightweight and provides tissue support; also called trabecular or cancellous bone
What are the 4 types of bone cells?
- Osteoprogenitor cells (bone stem cells able to differentiate into the other types of cells)
- Osteoblasts (bone-building cells that secrete matrix; initiate calcification)
- Osteocytes (mature bone cells)
- Osteoclasts (remodel bones and cause them to release calcium; bone resorption)
Bones are supplied with blood and nerves via
Periosteal arteries and nutrient arteries
How do Periosteal arteries enter the bone?
Periosteal arteries (accompanied by nerves) enter the diaphysis through Volkmann’s canals. They are accompanied by periosteal veins.
How do nutrient arteries enter the bone?
A nutrient artery enters the center of the diaphysis through a nutrient foramen.
Nutrient veins exit via the same canal.
Metaphysis and epiphysis also have their own arteries and veins that enter the ends of the bones
The process of bone formation is called
Ossification/ Osteogenesis
Bones form in these 4 situations
1) During embryological and fetal development
2) When bones grow before adulthood
3) When bones remodel
4) When fractures heal
What are the 2 types of ossification?
1) Intramembranous
2) Endochondral
What is Intramembranous ossification?
Intramembranous ossification occurs in flat bones when a connective tissue membrane is replaced by bone.
(It is the process of bone development from fibrous membranes. It is involved in the formation of the flat bones of the skull, the mandible, and the clavicles.)
When does Endochondral ossification happen?
Endochondral ossification replaces cartilage with bone in the developing embryo and fetus.
Endochondral ossification also occurs in epiphyseal plates of long bones as they grow in length
The cooperative action of osteoblasts and osteoclasts results in this
Bones thicken thanks to the cooperative action of osteoblasts and osteoclasts.
(Osteoblasts create bone and osteoclasts dissolve bones and initiate normal bone remodeling)
Bone fractures heal in these three stages
- The reactive phase is an early inflammatory phase.
- The reparative phase includes formation of a fibrocartilaginous callus first and a bony callus second.
- The bone remodeling phase is the last step as the bony callus is remodeled.
Factors affecting bone growth and remodelling
(Minerals, Vitamins, Hormones)
Minerals
calcium, phosphorus, magnesium, fluoride, manganese
Vitamins
Vitamins A, C, D, K and B12
Hormones
IGFs (stimulated by GH), T3 and T4,
sex hormones (estrogen in females, testosterone in males)
Types of fractures
Open, Communited, Potts, Greenstick, Colles, Vertebral Compression Fracture
Open / Compound (outside of skin),
Communited (splinters/crushed and small pieces between two main parts of bone)
Greenstick (only small children), Impacted (one end forcefully driven into other),
Pott (ankle rolled out, fibula borken with damage to the tibia joint),
Colles (distal end of tibia pushed posteriorly),
VCF (vertebra cracked adn compressed into a wedge shape)
Bones store ____% of the body’s calcium.
99%
What is the bone’s role in calcium homeostasis?
The parathyroid gland secretes parathyroid hormone (PTH) when calcium levels drop. Osteoclasts are stimulated to increase bone resorption and calcium is released. PTH also stimulates the production of calcitriol by the kidneys to increase calcium absorption in the intestines.
Bone remodelling and age
From birth through adolescence, more bone is produced than is lost during remodeling. In adults, the rates are the same. Older individuals, especially post-menopausal women, experience a decrease in bone mass when resorption outpaces deposition.
