BMC L12 Flashcards
State the 3 types of adult human cartilage
- Elastic
- Hyaline
- Fibrocartilage
Describe the structure of hyaline cartilage
Amorphous matrix contains chondrin - gelatinous / rubbery substance
Chondrin contains condroitin sulphate
holds incompressible water -
negatively charged sulphates repel one=another to RESIST COMPRESSION, therefore, CUSHIONING
State where hyaline cartilage is found
Adults - Nose, respiratory tract, ribs, articular surface of bones
Fetus: in skeleton, before replaced by bone
Describe the structure of elastic cartilage
Amorphous matrix contains protein fibres
FIBRES: collagen, elastic fibre networks, therefore, this cartillage is more elastic than hyaline cartilahe
elastic fibres are ELASTIN
ELASTIN: elastic protein, provides flexibility + strength
FLEXIBLE BUT MAINTAINS SHAPE
YELLOW
Where is elastic cartilage found?
Externeal ear (pinna)
Walls of external auditory canal
Epiglottis
Larynx
Describe the structure of fibrocartilage
Amorphous matrix contains protein fibres
Fibres: collagen
COLLAGEN: resists tension / stretching
Why is fibrocartillage resistant to stretching?
Amorphous matrix conatins protein fibres
Protein fibres = collagen
Collagen arranged in bundles, all point in specific direction, therefore, resist stretching, compression, shearing (SLIDING / TEARING)
HIGH TENSILE STRENGTH
SHOCK ABSORBING
What is the most abundant type of cartillage?
Hyaline cartillage
State where fibrocartilage is found
Intervertebral disks
Menisci of knee
State the role of the perichondrium
Fibrous sheath surrounding cartilage except where cartilage merges
Contains blood vessels
BODY OF CARTILAGE IS AVASCULAR
Does fibrocartillage have a perichondrium layer? Explain your answer
No
Perichondrium is a sheath surrounding cartilage except from where it merges
Fibrocartilage merges into hyaline cartilage
What are the implications of cartilage being avascular?
Perichondrium contains blood vessels
Body of cartilage - avascular
NO BLOOD SUPPLY TO BODY OF CARTILAGE
AFFECTS FUNCTION, GROWTH, ABILITY TO HEAL
Limited ability to heal: NO DIRECT BLOOD SUPPLY, cells that repair cartilage, including chondrocytes, recieve nutrients and oxygen through diffusion from surrounding tissues rather than direct blood supply
Limited growth potential - lack of blood vessels = poor nutrient supply
Describe the blood supply of the cartilage
Supplied by blood vessels of:
- Perichondrium
- Synovial fluid
Describe the structure of fibrocartilage in the intervertabral disks
Annulus fibrosus - Layers of fibrocartilagein between the intervertebral disks in the spinal cord
Nuclues pulposus: Watery, (works like air in tire)
Intervertebral disks can resist lots of compression
Why can intervertebral disks resist a large amount of compression
-contain fibrocartilage
-in fibrocartilage, amorphous matrix conatins protein fibres
-fibres are collagen
-collagen provides tensile strength, resists tension / stretching - shock absorbing
-thereforee, resists compression
-the annulus fibrosus layer of fibrous cartilage in the intervertebrel disk
-nucleus pulposus - watery
State the 2 types of bones
- compact
-spongy
State the functions of bones
- Support
-Protection
-Leverage
-Storage of fats, minerals
-Synthesis of blood cells (RBC, WBC)
Bone anatomy
Diagram L12
Cartilage
Epiphyseal line
Spongy bone
Compact bone
Bone marrow
Nutrient foramen
Nutrient vessel
Endosteum
Periosteum
Medullary cavity
State the 5 divisions of bones
- Long bones - humerus, femur, radius
- Short bones - carpals, tarsals
- Flat bones - sternum, cranium, scapula
- Irregular bones - vertebra, facial
- Sesamoid bones
What is the difference between sesamoid bones and other divisions of bones
Sesamoid do not share joints with other bones - they “float”
Examples include:
patella
hyoid bone of larynx
Describe the structure of a bone
DIAGRAM L12
Epiphysis - END
-spongy bone, red marrow
-compact bone, articular cartilage
Diaphysis - Middle
compact bone
medullary cavity contains yellow marrow (fat)
lined with endosteum (squammus epithelium)
Periosteum
membrane of connective tissue - covers enter outer surface of bone except epiphysis
Endosteum
-COVERS INERNAL BONE SURFACE
-THIN LAYER OF CONNECTIVE TISSUE
-OSTEOGENIC: contains osteoprogenitor cells
How is the periosteum attached to the bone?
Periosteum is secured to the bone via Sharpey’s fibres
State the 2 sublayers of the periosteum
- Outer fibrous layer
- Inner cellular osteogenic layer on compact bone (contains osteoprogenitor cells)
Describe the structure of compact bone
- Osteocytes in spaces called lacunae, arranged in concentric circles - lamellae
- This suddounds central canal - complex is called Haversian system - THE OSTEON
- Canaliculi connect osteocytes to central canal + to each other
State the role of osteocytes
- Detect mechanical stress
- Regulate BONE REMODELLING - via communicating with osteoblasts and osteoclasts
What is the origin of osteocytes
Derived from OSTEOBLASTS during bone deposition
How are osteocytes connected to one another?
GAP JUNCTIONS
(electrically connected via gap junctions, can transmit electrical signals to one another + to osteoblasts)
State two differences between Osteoblasts and Osteoclasts
Osteoblast are uninucleate
Osteoclasts are multinucleate
Osteoblasts secrete bone matrix
Osteoclasts absorb bone matrix
Where is spongy bone most commonly found?
Epiphyses
Where is spongy bone only found? Why?
Epiphyses
Only found here because
-epiphyses subject to less mechanical stress than diaphysis
-epiphyses does not need same level of strength / support as diaphysis (shaft)
-helps to reduce weight of bone, making it easier for bone to move at the joint
State the function of spongy bone
shock absorber
State the stages involved in bone development
- Bone collar forms around hyaline cartilage model
- Cartilage in the centre of diaphysis calcifies and then develops cavities
- The periosteal bud invades the internal cavities and spongy bone begins to form
- The diaphysis elongates, medullary cavity forms as ossification continues.
Secondary ossifcation centres appear in the epiphyses in prepation for stage 5 - The epiphyses ossify. When completed, hyaline cartilage remains only in epiphyseal plates + articular cartilages
Explain the difference between development of bone in foetus and in children and young adults
In foetus - develops from hyaline cartilage
In children and young adults - Epiphyseal plate closure rate different by different locations
Can be used to estimate age
Bone reaches its peak density at around age 35
Diagram of epipgyseal growth plates in child and adults
DIAGRAM L12
CHILD: LEFT
ADULTS: RIGHT
State 3 types of joints
- Fibrous, surrounded by collagen fibres - NO MOVEMENT
- Sinovial, surrounded by sinovial fluid - LOTS OF MOVEMENT
- Cartilaginous, surrounded by cartikage - SOME MOVEMENT
State the 3 types of fibrous joints
- Sutures
FOUND ONLY IN SKULL - Syndesmosis
FOUND IN LIMBS - Gomphosis
HOLDS TOOTH IN SOCKET
What type of joint is the pubic symphysis?
Cartilganious Joint
State the location and functions of the pubic symphysis joint
4-5 mm gap Filled with FIBROCARTILAGE - strong connective tissue, flexible, allows small movement between two pubic bones
JOINS TWO PUBIC BONES AT FRONT OF PELVIS
Describe what can happen to the pubic symphysis during pregnancy
gap filled with fibrocartilage increases
allows movement, flexivility during childbirth allowing pelvis to expand to allow passage of baby
joint can dislocate during rapid birth
What is Pelvic Girlde Pain?
related to pubic symphysis
More common pregnant women
PAIN / DISCOMFORT in pelvic region
POST NATAL - AFTER BIRTH
State the synovial joints
Plane joint - Intercarpal - between fingers
Hinge joint - elbow joint
Pivot joint - lower arm
Condyloid joint
Saddle joint - thumb
Ball-and-socket - SHOULDER
Describe the composition of synovial fluid
Hyaluronic acid - hyaluronan
Lubricin- GLYCOPORTEIN
IT IS GOOPEY - VERY VISCOUS
Where is lubricin produced?
- Chondocytes
-Synovial membrane cells
Where is hyalaronic acid produced?
What type of fluid is synovial fluid?
A non-newtonian fluid
Dilitant - DILATES - undergoes shear thickening
Viscocity increases with stress
making it a good shock absorber
State the functions of Synovial fluid
- Lubrication
of synovial joints - Shock absorption
in synovial joints - aided by cartilage / spongy bone - Maintenane of cartilage
Carries nutrients to chondrocytes in avascular cartilages+ + removes waste
Why is synovial fluid a good shock absorber?
Non-newtonial fluid
Diltant - shear thickening with pressure
Viscocity increases with stress
State an example of a newtonian fluid
WateraIR
State causes of bone fractures
High force
High impact
High stress
Trivial injury as a result of certain medical conditions that weakens bones
Give examples of bone fractures
PATHOLOGIC FRACTURES:
- OSTEROPEROSIS
OSTEOGENSIS IMPERFECTA
Describe the process of bone remodelling
- Hemeatoma forms
- Fibrocartilaginous callus forms
- Bony callus forms
Newtonian Fluid Calculation
Stress in fluid = viscocity x strain in fluid
Stress - force per unit of area - SHEAR STRESS
Strain - Deformation of fluid - SHEAR STRAIN
Describe the characteristics of a newtonian fluid
As shear stress increases, shear strain also increases
As shear strain increases, viscocity stayes the same
Viscocity = constant at all strains / stresses
What are the two types of non-newtonian fluids?
- Shear thinning
- Shear thickening
Describe the characteristics of shear thinning non-newtonian fluids
- Stran increases non-linearly with stress
- Viscocity decreases with increasing strain / stress
BLOOD
PAINT
Describe the characteristics of shear thickening Non-Newtonian Fluid
- Strain increases non-linearly with stress
- Viscocity increases with increasing strain / stress
SYNOVIAL FLUID (and other dilitants)
