Module 2: How Is The Body Supported? Flashcards
Prefix: intra
Give meaning and example
Between
E.g. Intracellular fluid
Prefix: meso
Meaning and definition
Middle
E.g. Mesentary
Prefix: Os
Meaning and example
Bone
E.g. Osteon
Prefix: osteo
Meaning and example
Bone
E.g. Osteoporosis
Prefix: peri
Meaning and example
Around
e.g. Periosteum–> membrane that goes around bone
Suffix: -blast
Meaning and example
To create/ form
E.g. Osteoblasts–> bone forming cell
chondroblast–> cartilage forming cell
Suffix: -clast
Meaning and example
Break down/ broken
E.g. Chondroclast- cartilage breaking cell
E.g. Osteoclast- bone breaking cell
Suffix: -cyte
Meaning and example
A cell
E.g. Chondrocyte- cartilage cell
E.g. Osteocyte- bone cell
What are the skeletal system components classified as?
And what does the skeletal system helps us with?
The skeletal system components are classified as connective tissue.
It helps us with our growth and posture.
How many total bones do humans have?
Between 206 and 228
What is connective tissue?
3 points
Connective tissue is a tissue that:
1) is abundant
2) makes up every organ in the body
3) consists of cells separated from each other by an abundant extracellular matrix
What are the connective tissue types associated with the skeletal system?
(4 types)
1) bone
2) cartilage
3) tendons
4) ligaments
Explain five functions of the CT associated with the skeletal system
1) connection: tendons connect muscles to bone and ligaments connect bone to bone
2) support moving body parts: bone provides rigid support, cartilage provides semi-rigid support
3) protection: bone protects the underlying tissue from damage and also play a role in producing the cells of the immune system
4) storage of compounds: bones store minerals such as calcium & phosphate, whereas adipose tissue stores triglycerides
5) enclosing and separating tissue: Sheets of connective tissue around organs such as the periosteum
Explain two functions of CT that are not associated with the skeletal system
1) transportation: blood, hormones, enzymes and immune cells
2) cushioning and insulation: such as adipose tissue under the skin
What are the six major functions of the skeletal system?
1) support
2) protection
3) assistance with movement
4) RBC production (bone marrow)
5) mineral homeostasis (calcium)
6) triglyceride storage (energy storage)
What is cartilage made up of?
Cartilage is made up of a matrix and fluid produced my chondroblasts which form a shapeless background substance
What is matrix?
Matrix is an acellular substance consisting of nonfibrous proteins and other molecules such as proteoglycans (proteins joined together with complex sugars)
Within the acellular matrix are:
2 points
1) a dense network collagen and elastic fibres that give the mechanical properties of this tissue
2) chondrocytes within little spaces called lacunae
Describe cartilage metabolically
Metabolically cartilage is fairly inactive, it has no blood or nerve supply (avascular and not innervated) and it has a very slow duplication time. Thus damage to cartilage takes a long time to repair.
What are the three key features of cartilage?
1) cartilage is avascular so cellular needs must diffuse through
2) cartilage not innervated (no nerve supply)
3) cartilage cells are formed from cells in the perichondrium & these cells produce the cartilage matrix
What are the two types of cartilage growth?
1) appositional growth: outside growth, new cartilage is added to the outside of existing cartilage.
2) interstitial growth: inner growth, chondrocytes within the matrix divide and add more matrix between chondrocytes
What are the three types of cartilage associated with bones and joints?
1) Hyaline cartilage
2) fibrocartilage
3) elastic cartilage
Describe hyaline cartilage and where it is found. Give specific example of its location.
- Gelatinous, glossy cartilage, with evenly distributed collagen fibres.
- Found where ever strong support and some flexibility is needed, these are generally areas where slight changes in the structure’s shape can occur.
- E.g. Rib cage and bronchi.
Describe fibrocartilage and where it is found. Give specific examples of its location.
- has more collagen fibre bundles than hyaline cartilage.
- slightly compressible and very tough
- found where ever there is a lot of mechanical pressure and stress
- E.g. The knee, in the jaw and the intervertebral discs between the vertebrae.
Describe elastic cartilage and where it is found. Give specific examples of its location.
- the matrix collagen is similar to hyaline cartilage except this has elastic fibres added
- somewhat flexible but is used when rigidity is needed
- E.g. External ear, epiglottis and auditory tubes
What does hyaline cartilage consist of?
6 points
1) chondroblasts: specialised cells that produce the matrix
2) chondrocytes: when chondroblasts become surrounded by matrix they are referred to as chondrocytes
3) lacunae: small spaces in which chondrocytes are located.
4) matrix: fundamental substance produced by the chondroblasts
5) perichondrium: surrounds the cartilage
6) the articular cartilage itself
Name the three bone cells
Osteoblast, osteoclast, osteocyte
Describe the function and origin of osteoblast.
- function: bone forming cells; produce the chemicals and structures that make up the matrix
- origin: periosteum
Describe the function and origin of osteoclasts.
- function: bone destroying cells; breakdown the matrix. Specialised for reabsorption and mobilise Ca2+
- origin: large multinucleated cells that originated in the red bone marrow
Describe the function and origin of osteocytes
- function: matrix maintaining cells.
- origin: located in specialised structures called lacunae
How much of the bone matrix is composed of organic tissue and how much is composed of inorganic tissue?
35% bone matrix is composed of organic tissue
65% of the bone matrix is composed of inorganic tissue
Name the organic components of bone matrix.
2 points
Collagen fibres and proteoglycans
Name the organic raw materials of bone matrix.
Carbon, hydrogen, nitrogen and oxygen atoms
Name the sources of organic raw materials of bone matrix.
Which cells make the bone matrix and which cells maintain them?
Made by osteoblasts from carbohydrates, proteins and lipid components and maintained by osteocytes.
Name the inorganic component of bone matrix.
Hydroxyapatite (CaPO4 crystals)
Name the raw materials of the inorganic component of bone matrix.
Calcium and phosphate ions (mineral part of bone)
Name the sources of inorganic raw materials of bone matrix.
Which cells make the bone matrix and which cells maintain them?
Made by osteoblasts from inorganic phosphate and calcium ions that are absorbed from diet and maintained by osteocytes.
How does bone matrix form? Specifically the organic and inorganic parts.
(4 points)
- mainly produced by osteoblasts
- through a process called ossification/osteogenesis
- collagen (organic part) is produced by the E.R and Golgi and released by exocytosis.
- inorganic part is produced by precursors of hydroxyapatite stored in vesicles, and released by exocytosis
Name the organic part of bone tissue and explain what would happen if it was removed.
The organic part of bone is collagen and proteoglycans.
If they are removed the bone will be too brittle and it will break.
Name the inorganic part of bone tissue and explain what would happen if it was removed.
The inorganic part of the bone is hydroxyapatite and if it was removed the bone would be too bendable and won’t be rigid.
Name the two types of bone growth.
Woven and lamellar.
A) When is woven bone growth formed?
B) How are its collagen fibres arranged?
A) Woven bone growth is formed during foetal development and during the initial repair of a fracture.
B) its collagen fibres are arranged randomly
A) When is lamellar bone growth formed?
B) How are its collagen fibres arranged?
A) lamellar bone growth is formed when woven bone is broken down by osteoclasts and reformed into thin sheets called lamellae
B) its collagen fibres are arranged parallel to each other in ea lamellae but in different lamellae the collagen fibres have different orientations
Where are the following bones found?: A) long bones B) short bones C) flat bones D) irregular bones
A) long bones: upper and lower limbs
B) short bones: tarsals (feet) and carpals (wrists)
C) flat bones: rib cage, sternum, skull and scapulae
D) irregular bones: vertebrae and facial
Complete the following sentence:
During foetal development bone formation starts in…
During foetal development bone formation starts in two different places, and is named by the type of tissue that is replaced. No matter where it formed, the type of bone eventually formed is woven bone.
Name the two types bone ‘development’
1) intramembranous ossification
2) endochondral ossification
Where does intramembranous ossification occur? Give an example.
It takes place within the membrane of connective tissues. It starts directly from precursors organising membranes.
E.g. Many skull bones
Where does endocondral ossification occur? Give an example.
Takes places in a cartilage template.
E.g. Bones on the base of the skull, part of the mandible, epiphyses of the clavicles and most of the remaining bones.
What is the embryonic precursor cell and tissue for bone?
Embryonic precursor cell: mesenchymal cell
Embryonic precursor tissue: mesenchymal tissue & mesoderm
What is mesoderm and mesenchyme?
At ~13-14 days of development the foetus forms an embryonic disc. Which has three layers:
- Ectoderm- outside layer, forms the epidermis of the skin
- Mesoderm- middle layer, forms bone except for facial bones. The tissue is called mesenchymal tissue
- Endoderm- inner layer, forms the lining of the digestive system
What is the embryonic precursor of tissues and cells forming intramembranous ossification?
(4 steps of intramembranous ossification)
- Occurs in mesenchymal cells within connective tissue e.g. The tissue surrounding the developing brain
- Mesenchymal cells differentiate into osteoprogenitor cells
- Osteoprogenitor cells differentiate into osteoblasts
- osteoblasts form woven bone matrix and eventually either trabeculae or the outer layer of lamellar compact bone
What is the embryonic precursor of tissue and cells forming endochondral ossification?
(5 steps of endochondral ossification)
- Mesenchymal cells aggregate & become osteochondral progenitor cells at ~4 wks of development
- These cells differentiate to become chondroblasts that form a cartilage framework
- Blood vessels invade the framework & osteochondral cells in the perichondrium differentiate into osteoblasts
- The osteoblasts move into the calcified cartilage framework and deposit a new bone matrix. May start at about week 8.
- The osteoblasts/cytes produces woven bone that is then remodeled. May continue till about 18-20 years of age
What are the 7 steps involved in endochondral ossification of bone?
- Chondroblasts produce a cartilage model that is surrounded by perichondrium, except where joints will form
- The perichondrium of the diaphysis becomes the periosteum, and a bone collar is produced. Internally, the chondrocytes hypertrophy and calcified cartilage forms.
- A primary ossification centre forms as blood vessels and osteoblasts lay down bone matrix, forming spongy bone.
- The process of bone collar formation, cartilage calcification and spongy bone production continues. Calcified cartilage begins to form in the centre of the diaphysis.
- Secondary ossification centres form in the epiphyses of long bones
- The original cartilage model is almost completely ossified. Unossified cartilage becomes the epiphyseal plate and the articular cartilage.
- In a mature bone, the epiphyseal plate has become the epiphyseal line, and all the cartilage in the epiphysis, except the articular cartilage has become bone.
What are the two ways of bone growth (as distinct from ossification) of long bones? And what does each kind do to the long bone?
1) interstitial growth: inter= between
- makes bone longer in length
2) appositional growth: appo= on top of/ growth added to the outside
- makes bone thicker and wider
How is bone classified?
Bone is classified by the amount of matrix it contains.
SPONGY BONE:
A) what are its alternative names?
B) describe its appearance and where it is located on the bone and then its location in the body.
A) cancellous bone, trabecular bone
B) • Appears porous. Contains columns of bone called Trabeculae.
• Generally surrounded by a sleeve of compact bone.
• Weight bearing. Found in spine and all articulating joints, especially ends of long bones
COMPACT BONE:
A) what is its alternative name?
B) what is its basic unit?
A) Cortical bone (cortex= outside)
B) Basic unit of structure of compact bone is the osteon or Haversian system- strong part.
What are the three main structures that make up the compact bone?
- Central (or Haversian) canals
- Lamellae all around the osteons:
a) Circumferential lamellae- more external
b) Interstitial lamellae-more internal - Perforating (or Volkmann’s) canal: makes vessels going through different central canals to different osteons
A) What is the location of the central canal or haversian system?
B) how does it receive its blood?
- Runs parallel to the main axis
* Receives blood from blood vessels in the perforating canals (these are horizontal)
In terms of their location, Lamellae can be…
3 points
- Concentric (around central canal)
- interstitial (between osteons, remnants of previous osteons)
- Circumferential (extend around the outside of the bone)
How does compact bone get its blood circulation?
2 points
- Perforating canals allow blood vessels from periosteum to penetrate the compact bone
- Vessels of the central canal
In a compact bone, how do Nutrients and wastes travel to and from osteocytes?
(2 points)
• Nutrients and wastes travel to and from osteocytes via:
- Interstitial fluid of lacunae and canaliculi
- From osteocyte to osteocyte by gap junctions
Describe the 5 steps involved in blood supply to the bones:
- 1 or 2 nutrient arteries pass through the periosteum into medulla (bone marrow)
- Medullary artery branches into ascending and descending branches
- Blood then passes in capillaries via perforating canals
- then to the Central canal of an osteon
- Then path reverses into venous system
Classify bones according to their shape and give examples of each classification type.
(4 types)
- Long: found in upper and lower limbs e.g. femur, tibia
- Short: found in carpals and tarsals
- Flat: found in ribs, sternum, skull, scapulae
- Irregular: found in vertebrae, facial
What are the key features of flat bones?
- No diaphysis & epiphyses. Sandwich of spongy between compact bone
- Some flat and irregular bones of the skull have sinuses lined by mucous membranes.
What are the key features of short and irregular bones?
They have a Compact bone that surrounds spongy bone center; similar to structure of epiphyses of long bones.
-No diaphysis and not elongated
Name the five key structures of a long bone
Diaphysis Epiphysis Epiphyseal plate Epiphyseal line Medullary cavity
Describe diaphysis
Shaft, largely compact bone
Describe epiphysis
Enlarged end of the bone, largely spongy bone
Describe Epiphyseal plate
Located between diaphysis and epiphysis, also known as the growth plate it is made of hyaline cartilage; present until growth stops
Describe epiphyseal line
Location is same as for epiphyseal plate. This is where Cartilage is replaced by bone and the bone stops growing in length.
Describe the medullary cavity
In children the medullary cavity contains red marrow, gradually this changes to yellow in limb bones and the skull (except for epiphyses of long bones). Rest of skeleton contains red marrow
Name three other (non-key) structures of long bone
1) periosteum
2) sharpey’s fibres
3) endosteum
Describe periosteum
- Two layers, outer is fibrous, inner is a single layer of bone cells including osteoblasts, osteoclasts and osteochondral progenitor cells
- Fibers of tendons become continuous with fibers of the periosteum
Describe Sharpey’s fibers
- These are periosteal fibers that penetrate through the periosteum and into the bone
- Strengthen attachment of tendons to bone
Describe endosteum
- Similar to the periosteum, but more cellular
- Lines all internal spaces including spaces in spongy bone.
