The skeletal System Flashcards
1
Q
- What does the skeletal system include
A
- Bones of the sksleton
- Connective tissues of the skeleton:
- Tendons
- Ligaments
- cartilage
2
Q
Connective tissues of the skselton
- what are the connective tissues of the skeleton
A
- Tendons and ligaments = connective tissue proper (dense and regular) as well as fibroblast, colagen fibers and viscous gel matrix
- Cartilage (Supporting connective tissue) = matrix is a firm gel
- Bone (Supporting connective tissue = matrix is calcified
3
Q
Cartilage Histology
Cartilage (Chondro)
A
- Matrix - firm gel - chondrotin sulfate & collagen ,elastic, and reticular fibers
- Cells - chondrocytes, located in lacunae
- Perichondrium - seperated cartilage from surrounding tissues
- Three types of cartilage:
- Hyaline - collagen fibers and ground substrate
- Elastic - collagen and elastic fibers
- Fibrocartilage - dense collagen, little ground sub
4
Q
Cartilage
Cartilage Growth and Repair
A
- Interstitial - enlarges from within so internal chondrocytes devide
- Appositional - growth at surface so cells in inner layer of perichondrium divider
- Cartilage has very poor recovery from damage
5
Q
Bone Histology
Bone (Osteo)
A
- Cells - osteocytes, located in lacunae interconnected by canaliculi
- Matrix - Collagen fibers (1/3) and calcium salts (2/3)
- Highly vascularized
- Periosteom - covers bone surfaces
6
Q
Bones
Bone growth and Repair
A
- Appositional - growth at surface
- cells in inner layer of periosteium divide
- Good recovery from damage
7
Q
Tissues
Osseous Tissue
A
- Matrix = crystals of hydroxyapatite - composed of calcium phosphate, calcium carbonate, and potassium, sodium, and magnesium
- Collagen - protein fiber framework
- By weight = 1/3 collagen and 2/3 calcium salts
8
Q
Cells
Cells in Bones
A
- osteoprogenitor cells (stem cells) - differentiatie into osteoblasts
- osteoblasts - synthesize new matrix - osteogenesis
- Osteocytes = mature bone cells - in lacunae connected by canaliculi
- Osteoclasts - disolve bone matrix - osteolysis also multinucleated
- Osteoprogenitror cells -> Osteoblasts -> Osteocytes
9
Q
Tissue
Bone (osseus tissue)
A
- Bones contain two forms of osseus material:
- Compact Bone - (dense)
- Spongy Bone - (Cancellous)
- Marrow cavaties in bone contain connective tissue:
- Yellow Marrow - Adipose connective tissue
- Red marrow - Fluid connective tissue - red and white blood cells and blood stem cells
10
Q
Bone Types
Compact Bone and Spongy Bone
A
- Basic unit of a copmpact bone is an osteon - Haversian system
- Osteocytes arranged around a central canal
- Perforating canals extend between adjacent osteons
- Spongy bone contains a trabeculae
11
Q
Bones and Stress
Bones and Stress
A
- Compact Bone - located where stresses are applied in a focoused drection along the bine axis
- Spongy Bone - located where stresses are weaker, multi-directional, or spread out over a larger cross-sectional aera
12
Q
Long Bones
What does a long bone typically include?
A
- Diaphysis - shaft or central part of a long bone
- Epiphyses - the end of a long Bone
- Metaphysis - the wide part of a long bone and where growth occurs
- Articular cartilage
- Marrow cavity - filled with red or yellow marrow
13
Q
Bones
Bone Development and Growth
A
- Cells invloved in development and growth, as well as remodeling and repair come from:
- periosteum - covers outter surface of bone made of a fibrous outter layer and inner layer of stem cells
- Endosteum - lines inner surfaces of bone made of a layer of stem cells, plus osteoblasts and osteoclasts
14
Q
Bone Development
Bone Development
A
- Ossification:
- Converting other tissues to bone
- Intramembranous ossification (calcification)
- Endochondral ossification (calcification)
- Calcification = depositing calcium salts whithin tissues
14
Q
Bone Development
Bone Development
A
- Ossification:
- Converting other tissues to bone
- Intramembranous ossification (calcification)
- Endochondral ossification (calcification)
- Calcification = depositing calcium salts whithin tissues
15
Q
Ossification
Intramembranous Ossification
A
- Bone develops within mesenchymal (embryonic) connective tissues
- Osteoblasts differentiate in embryonic tissue and create ossification centers
- Mesenchymal cells produce osteoblasts
- Forms flat bones (dermal bones) consiting of spongy bone with thin layer of compact bone
16
Q
Ossification
Endochondrial Ossification
A
- During embryogenesis, hyaline cartalige forms first= cartilaginous model
- Cartilage model gradually replaced by bone
- Cartilage remains in articular cartilage at ends of bones
- Cartilage remain in epiphyseal plate (growth plate)until epiphyseal closure
- Endochondrial ossification contiues until closure
17
Q
Elongation of long bones
Growth at Epiphyseal Plates
A
- Cartilage growth - eppiphysis side
- Ossification - diaphysis side
- Diaphysis gets longer, as epiphyses are pushed further apart
- Equal rate of cartilage groth and ossification matains epiphyseal plate
- Higher rate of ossification leads to closure of epiphyseal plate
- Achondroplasia - slow cartilage growth leading to epiphyseal plate closure at very early age
18
Q
Remodeling
Dynamic nature of bone - Remodeling
A
- Organic and mineral components continually recycled and renewed
- Aproximatley 20% or 1/5 of adult bone replaced per year
- Osteocytes - monitor and mantain surrounding bone matrix
- Osteoblasts - form new bone matrix
- Osteoclasts - Remove bone matrix
19
Q
Dynamiuc Nature of Bone
Dynamic nature of bone (effects of exercise)
A
- Bone is stronger and thicker in aeras that are stressed
- Stress may generate small electrical fields in crystal matrix,stimulating osteoblasts
- Bones not subject to normal stress become thinner and weakwer
20
Q
Bone growth and maintenance
Hormones Regulation of Bone Growth and Maintenance
A
20
Q
Bone growth and maintenance
Hormones Regulation of Bone Growth and Maintenance
A
21
Q
Development and Maintenance of Bone
Hormonal and Nutritional effects on development and maintenance of bone
A
- Dieatary intake of Ca and Phosphate salts
- Calcitriol (derived from cholecalciferol) - hormone synthesized in kidney needed for calcium and phosphate absorption from digestive tract
- Viatamin D (Cholecalciferol) - required for calcitriol synthesis and deficiency causes osteomalacia (rickets) due to insufficent minerelization of bone
- Vitamin Cneeded for collagen synthesis - defficency causes scurvy
22
Q
Homeostatis for calcium and phosphate
Homeostatic regulation of calcium and Phosphate in body fluids
A
- 99 percent of bodys calcium is in bone
- Blood calcium Ion concentration - must be maintained within a narrow range. Homeostatic mechanisms control bones, GI tract, and kidneys
- Parathyroid Hromone and Calcitriol - from the parathyroid gland and PTH increases blood calcium levels
- Calcitonin- from the thyroid gland decreases blood calcium levles
23
# **Blood Calcium levels**
**Blood Calcium level increase pathway**
1. low calcium ion level in blood (below 8.5mg/dL)
2. Low calcium level causes the parathyroid gland to secrete **PTH**
3. **Osteoclasts** are triggerd to release stored calcium ions. **Intestional absorption** of calcium increases. **Kidneys** absorb more calcium and send more calcitriol to the intestines.
4.**Calcetriol Aids in every step of the process**
24
# **Blood Calcium Levels**
**Decresing calcium ion concentration in blood**
1. High calcium ion level in blood (**above 11mg/dL**)
2. C cells in the tyroid gland secrete**calcitonin**
3. **Osteoclast** activity **decreases**. **Intestinal** absorption of calcium **decreases**. Kidneys **excrete calcium** ion and **less calcitriol** is sent to the intestiens.
25
# **Hormonal/Nutritional Effects**
**Hormonal and Nutritonal Effects**
* **Growth Hormone** - from putituitary gland. Stimulates protien synthesis and cell growth through out the body. disorders include: **Putuitary dwarfism, Gigantism, and Acromeglay **
* **Thyroxine**- from the thyroid gland. **Increases bone mas**s by stimulating osteoblast activity.
* **Sex Hormones (estrogens and androgens)** - **epiphyseal plate closure** due to increased osteoblast activity
26
# **Skeletal System**
**Functions of the Skeletal System**
1. **Support** - Framework for attachment of soft tissues, organs, muscles
2. **Storage of mineral and lipids**
* Mineral reserce for Ca and P, helping to maintain normal levels in blood
* Store lipids in yellow marrow
3.**Blood cell production** - red bone marrow
4. **Protection** - surrounds many soft tissues
5. **Leverage for movemen**t - muscles generate force
27
# **Aging**
**Effects of Aging on Skeletal System**
* **Osteopenia** - **osteoblast activity decline**s with declining levels of sex hormones resulting with a **reduction in bone mass**
* Vertebrae, maxillary and mandible, epiphyses of long bones
* more rapid in females than males
* **Osteoporosis** - Loss of bone mass sufficent to **compromise normal functions**
28
# **Bone Damage**
**Fracture Repair**
* **Fracture hematome** - blood clot
* **External Callus** - enlarged collar of bone and cartilage
* **Internal Callus** - forms within marrow cavity
* **Ossification occurs in callus cartilage** and broken edges become united by **spongy bone**
* **Osteoclasts and osteoblasts remodel bone** until nomral compact and/or spongy bone is in place
29
# **Arthritis**
**Arthritis**
* **Osteoarthritis** - normal wear and tear
* **Rheumatoid arthritis** - autoimmune disorder
* **Gouty arthritis** - uric acid crystals
30
# **Skeletal disorders**
**Skeletal Disorders affecting Bone Mass**
* **Excessive bone growth** - **Heterotopic (ectopic) bone formation** often resulting in bone spurs from excessive mechanical stress
* **Acromegaly (Hormonal) - GH post puberty**
* **Gigantism (Hormonal) - GH Prepuberty**
31
# **Skeletal Disorders**
**Skeletal disorders affecting bone mass**
* Bone mass may decrease due to:
* **Inactivity**
* **Osteopenia and osteoperosis** - hormonal
* **Osteomalacia (rickets)** - Vitamin D Deficency
* **Osteogenesis Imprerfectia** - Genetic gene mutation related to collagen formation
* **Achondroplasia** - genetic
* **Pituitary Dwarfism** - hormonal
32
**What is Spina Bifida linked to?**
**Low folic acid levels in the mother during the preganacy**
