Chapter 6 Flashcards
T/F: Bones are organs?
True
What tissues do bones contain?
-Bone Tissue
-Nervous Tissue
-Cartilage
-Fibrous connective tissue
- Muscle
- Epithelial cells in blood vessels
A skeleton is initially (blank) then replaced by (blank.)
Cartilage; bone
Perichondrium
contains blood vessels for nutrient delivery
What does all skeletal cartilage contain?
Chondrocytes and Extracellular matrix
What are the three types of skeletal cartilage?
- Hyaline
- Elastic
- Fibrocartilage
Hyaline cartilage function and location:
- provides support, flexibility, and resilience
- Articular (bones & joints) , Costal (breastbone), Respiratory (larynx), and Nasal Cartilage
Elastic cartilage function and location:
- provides support, flexibility, and resilience
- external ear and epiglottis
Fibrocartilage function and location:
- great tensile strength
-menisci of the knee; vertebral discs
Bones are divided into two groups.
1.Axial
2. Appendicular
What is the axial skeleton?
Skull, vertebral column, and rib cage
What is the appendicular skeleton?
- Bones of upper and lower limbs
- Girdles attaching limbs to axial skeleton
Long bones: description and location
Longer than they are wide
Limbs, tarsals, carpals
Short bones: description and location
Cube shaped bones (wrist and ankle)
Sesamoid bones (patella)
Flat bones: description and location
Thin, flat, and slightly curved
Sternum, scapula, ribs, most skull bones
Irregular bones: description and location
Vertebrae, coxal bones
What are the functions of bones?
- Support
- Protection
- Movement
- Mineral and growth factor storage
- Blood cell formation (hematopoiesis) in red marrow cavities of certain bones
- Triglyceride (fat) storage in bone cavities= energy source
- Hormone production
What are two types of bone textures?
- Compact
- spongy
Describe what a compact bone looks like.
smooth and solid, with a dense outer layer
Describe what a spongy bone looks like.
honeycomb structure
Diaphysis
tubular shaft; compact bone surrounding the medullary cavity
Epiphyses
bone ends; external compact bone and internal spongy bone
Periosteum
covers external surface; outer fibrous layer
Osteogenic cells
bone stem cells;
Five Major Cell Types of Bone Tissue
- Osteogenic cells
- Osteoblasts
- Osteocytes
- Bone lining cells
- Osteoclasts
Osteogenic cells are also called: (blank.) What are they?
Ostoeprogenitor cells; active stem cells in the periosteum and endosteum; differentiate into osteoblasts
What are osteoblasts and what do they do?
Bone forming cells; secrete unmineralized bone matrix (osteoid); differentiate into osteocytes
What are osteocytes and what do they do?
Mature bone cells in lacunae; monitor and maintain bone matrix; communicate stimuli to osteoblast and osteoclast so bone remodeling can occur
What is the function of bone lining cells and where are they located?
Help maintain matrix; periosteal cell and endosteal cells
What are osteoclasts and what do they do?
derive from stem cells that become macrophages; secrete digestive enzymes and hydrogen ions to breakdown tissue
What is the structural unit of a compact bone?
osteon or Haversian system
Three components of the compact bone:
Central (Haversian) canal
Perforating(Volkamann’s) canal
Lacunae
What does the central canal contain?
blood vessels and nerve fibers
What does the perforating canal contain? What does it connect?
endosteum; blood vessels and nerves of periosteum, medullary cavity, and central canal
What does the lacunae contain?
Osteocytes at lamelae junctions
How does the spongy bone appear?
Poorly organized.
What is the structural unit of the spongy bone?
Trabeculae
Organic components of a bone include:
connective tissue (cells + extracellular matrix)
bone cells (mentioned previously)
What do the organic components of a bone contribute to?
Structure and provision of tensile strength and flexibility
Difference between organic and inorganic bone.
Organic bone: include living components and secretion
Inorganic bone: include minerals and release when necessary
Inorganic components of bone include:
Hydroxyapatites
What is hydroxyapatite consist of? What is the function?
- 65% bone mass
- calcium phosphate crystals
- responsible for hardness and resistance to compression
What is ossification?
Process of bone tissue formation
What are the two types of ossification?
- Endochondral
- Intramembranous
What is endochondral ossification? What does it form?
- bone forms by replacing hyaline cartilage
- forms most of the skeleton; bony skeleton
What is intramembranous ossification? What does it form?
- bone develops from fibrous membrane
-forms flat bones; clavicle and cranial bones
5 steps involved in Endochondral ossification:
- Bone collar surrounds diaphysis of hyaline cartilage
- Cartilage in mid-diaphysis calcifies and develops cavities.
- Periosteal bud invades internal cavities and spongy bone forms.
- Diaphysis elongates and medullary cavity forms.
- Secondary ossification centers appear in the epiphysis - Ephysis ossify. Hyaline cartilage remains only in epiphyseal plates and articular cartilage
4 steps involved in Intramembranous ossification:
- Ossification center appear in the fibrous connective tissue membrane
- Osteoid is secreted within the fibrous membrane and calcified
- Woven bone and periosteum form.
- Lamellar bone replaces woven bone, just deep to the periosteum. Red marrow appears.
Interstitial Growth
- increase in length of long bones
- chondrocytes divide and form a new matrix; expansion of the cartilage tissue and replaced by the bone tissue.
Appositional growth
increase in bone thickness
When does the stop-in interstitial growth occur?
- end of adolescence (chondrocytes divide less)
- epiphyseal plate thins then replaced by bone
- females usually stop at 18 y/o and males 21 y/o
How long does appositional growth occur?
throughout life
What is growth hormone?
stimulates epiphyseal plate activity in infancy and childhood
What is thyroid hormone?
ensures proper proportions and modulates activity of growth hormones
How do testosterone and estrogen function? Which occurs in who?
- promote adolescent growth spurts; ended by inducing epiphyseal plate closure
-testosterone in males & estrogen in females
Bone homeostasis:
bone remodeling and bone repair
Approximately how often is spongy bone replaced?
Every 3-4 years
Approximately how often is compact boe replaced
Every 10 years
What happens to your bones as you get older?
- bones become more brittle
- fracture easily
- calcium salts crystalize
Bone Remodeling:
- bone deposit and bone resorption
- affected by calcium levels and mechanical stress
- osteoblast and osteoclast are the units involved
Importance of Calcium:
- essential for the body to keep in a specific range
- nerve impulse transmission, muscle contraction, blood coagulation, secretion by glands and nerve cells; cell division
Hormones involved in Control of Blood Calcium:
- PTH (parathyroid hormone)
- Calcitonin
What is the function of PTH? Where does it come from?
-removes calcium from bone regardless of bone integrity
- produced by parathyroid glands
What is the function of Calcitonin? Where does it come from?
- reduces blood calcium levels
- produced by parafollicular cells of thyroid gland
Stages of Bone Repair:
- Hematoma forms
- Fibrocartilaginous callus forms
- Bony callus forms
- Bone remodeling occurs
Bone Homeostatic Imbalances:
Osteomalacia
Rickets
Osteoporosis
What occurs in Osteomalacia?
- Bones poorly mineralized
- Calcium salts not adequate
- Soft, weak bones
- Pain upon bearing weight
What occurs in Rickets?
- bowed leg or bone deformities
- bones ends enlarged or abnormally long
- osteomalacia for children
- Vit D deficiency or insufficient calcium
Both osteomalacia and rickets are (blank) deficiencies?
calcium
What occurs in Osteoporosis?
- bone resorption outpaces deposit
- associated with age
- become porous and light
- spongy bone of spine and neck of femur most susceptible
