Lecture 27 - Tissue Intro Flashcards
What are the 4 classes of connective tissue
1) Blood
2) Bone
3) Cartilage
4) Connective tissue proper
Connective tissue of all types is characterized by
1) Extracellular matrix
2) Cellular Component
T or F: Extracellular matrix and the cellular component determine the properties of tissue, but mainly the extracellular matrix
T
Extracellular Matrix is made of what 2 components
- Fibrillar component
- Interfibrillar component
What 2 things makes up the fibrillar component of the extracellular matrix
- Collagen
- Elastin
What 2 things makes up the interfibrillar component of the extracellular matrix
- Proteoglycans
- Glycoproteins
What cells make up the cellular component
Resident cells
What are 4 types of resident cells
1) Fibroblasts
2) Osteoblasts
3) Chondroblasts
4) Tenoblasts
Fibroblasts make
collagen
Osteoblasts make
Bone
Chondroblasts make
cartilage
Tenoblasts make
tendon
What are 4 characteristics of collagen
1) Provides functional integrity to connective tissue structures
2) Non-elastic
3) Most abundant protein in body
4) White fibrous tissue
Crimping
Orientation of collagen that allows elongation of the fibers before tensile stresses are experienced
What are the 3 types of collagen
1) Type I
2) Type II
3) Type III
Type I Collagen
Found in all connective tissue (most common) that resists tensile forces
Type II Collagen
Found in hyaline cartilage and intervertebral discs that resist compressive and shear forces
Type III Collagen
Found in skin, joint capsules, muscles, and tendon sheath that are used for healing/repair
3 characteristics of elastin
1) Yellow fibrous tissue
2) Elastic
3) Resist tensile forces, but have more give when elongated
Proteoglycans
Found mainly in connective tissue that affect hydration of the tissue
Describe the stress strain curve
What is viscoelasticity
Combined properties of viscosity and elasticity
Elasticity
Ability to return to original length/shape after removal of load
What does elasticity of a tissue depend on
elastin and collagen content and organization
Viscosity
Resistance to flow
What does viscosity depend on
proteoglycan and water composition of tissue
What 2 types of loading cause viscoelastic materials to undergo deformation
1) Tensile
2) Compressive
What are 4 viscoelastic characteristics
- Creep
- Stress-relaxation
3) Hysteresis
4) Strain-rate sensitivity
Creep
Phenomenon in which tissue will deform over time under constant load
Stress-Relaxation
Tissue stretched to constant length
Hysteresis
When a tissue is repeatedly loaded and unloaded, some energy is dissipated through tissue elongation and energy loss
Strain-Rate Sensitivity
Mechanical behavior is different depending if structure loaded rapidly or slowly
What happens if a force is applied quickly (Strain-Rate Sensitivity)
Tissue becomes stiffer and experiences greater stress
What happens if a force is applied slowly (Strain-Rate Sensitivity)
Tissue is more compliant and experiences less stress
T or F: It is important to teach speed of doing exercises for normal tissue and for healing tissue with properties that are below normal
T, go slow
T or F: Muscle and connective tissue are not dynamic
F, they are
What are 4 important modifiers of tissue properties
1) Age
2) Loading/Unloading (immobility/disuse, exercise)
3) Medication
4) Injury
What are 6 changes that occur to aging connective tissue
1) Decreased flexibility of joint capsule
2) Decreased quality and quantity of synovial fluid
3) Decreased information from joint receptors
4) Increased ligament stiffness
5) Decreased cartilage thickness
6) Decreased water content
What is Wolff’s law in regards to mechanical loading and unloading
Bone in a healthy person/animal will adapt to loads under which it is placed
Wolff’s Law if loading on bone increases
The bone will remodel itself over time to become stronger to resist that sort of loading
Wolff’s Law if loading on the bone decreases
The bone will remodel itself over time to become weaker
What happens to astronauts in space in regards to bone loss
With decreased gravity they have increased bone resorption that is 10x greater than osteoporosis. They need to exercise 2.5 hrs a day and it takes 2-3 years to recover the bone loss upon arriving back on earth
What were the effects Dallas Bedrest Study and its implications
Effects: 20% loss of strength in 1 week, 1% loss bone mineral density in per week and loss of ROM and shortening of connective tissue around joints (5-7 days post-bedrest)
Implications: Doing exercise in bed or sitting is not sufficient to offset effects of bedrest
Summary charts of effects of loading on different types of connective tissue (tendons/ligaments, meniscus, bone, joint capsule)
What are corticosteroids
Powerful antiinflammatories
Where are natural corticosteroids produced in our body
adrenal glands
What are 2 side effects of corticosteroids due to prolonged use
1) Weaken non-contractile tissues
2) Interferes with normal turnover of collagen fibers
T or F: Its safe to receive corticosteroid injections 3 x a year
T
Ehlers-Danlos Syndrome
Genetic disorder that affects synthesis of collage (Types I, III, V) affecting skin, ligaments, joints and vasculature
Rheumatoid Arthritis
Inflammatory disease that cause joint destruction at the cartilage (destroys synovium), bone (bone resorption), and ligaments (become lax)
What is the contractile unit of the muscle
Sarcomere
What are the 5 structures of the muscle (contractile elements)
1) Muscle
2) Fascicle
3) Muscle Fiber
4) Myofibril
5) Sarcomere
What are the 3 muscle connective sheaths of skeletal muscle
1) Epimysium
2) Endomysium
3) Perimysium
T or F: When muscle lengthens or shortens the connective tissue components will do the opposite
F, they will do the same
What are the 3 components of muscle connective tissue
- Connective tissue with surrounding muscle
2) Titin (within sarcomere)
3) Tendon (origin and insertion)
Passive Insufficiency
Muscles cannot stretch enough to allow full ROM in both joints at the same time (eg. finger extensors/flexors with wrist movement)
Active Insufficency
Muscles cannot contract maximally through full available ROM at both joints at the same time
eg. finger flexion with wrist flexion
Name 4 electrolytes found in the muscle
1) Calcium
2) Magnesium
3) Potassium
4) Sodium
Describe the 2 effects of calcium electrolyte on muscle
1) Hypocalcemia: Muscle cramps, tetany
2) Hypercalcemia: Muscle weakness
Describe the 2 effects of magnesium electrolyte on muscle
1) Hypomagnesemia: Muscle cramps and weakness
2) Hypermagnesemia: Muscle weakness
Describe the 2 effects of potassium electrolyte on muscle
1) Hypokalemia: Muscle weakness, fatigue, and muscle cramps
2) Hyperkalemia: Cardiac abnormalities
Describe the 2 effects of sodium electrolyte on muscle
1) Chronic Hyponatremia: Muscle cramps, fatigue, gait disturbances
2) Hypernatremia: Lethargy, weakness
4 effects of immobilization on the muscle in a shortened position
1) Decrease the number of sarcomeres
2) Increase the amount of perimysium
3) Thickened endomysium
4) Weight loss and atrophy of muscle (Increase ratio of connective tissue:muscle tissue)
What are 3 functional consequences of immobilization of a muscle in a shortened position
1) Loss of ROM
2) Decrease maximal tension capacity
3) Increased stiffness to passive stretch
** IF some movement extent of changes will be limited vs with no movement marked changes will occur
What are 2 effects of immobilization in a lengthened position for a muscle
1) Increased number of sarcomeres
2) Increased endomyseal and perimyseal connective tissue
What are 2 functional consequences of immobilization in a lengthened position for a muscle
1) Max tension is generated at longer length
2) No change in passive tension
What are the 2 most common injuries in sport
1) Contusion
2) Strain
Contusion
Heavy, extrinsic compressive force (eg. direct blow to muscle)
Strain
Myofibers exposed to excessive intrinsic tensile forces leading to rupture of muscle fibers, connective tissue and blood vessels
What are 3 classifications of muscle injuries
1) Grade 1 or Mild
2) Grade 2 or Moderate
3) Grade 3 or Severe
What are 3 characteristics of a Grade 1/Mild muscle injury
1) Tear of only a few muscle fibers
2) No loss of function or strength
3) Low grade inflammatory response
What are 2 characteristics of Grade 2/Moderate Muscle Injury
1) Greater damage to muscle tissue
2) Clear loss of function but some remains
What are 2 characteristics of Grade 3/Severe muscle injury
1) Tear across entire cross-section of muscle
2) Complete loss of function
What are the 4 phases of healing for the injury to a muscle
1) Hematoma phase
2) Inflammatory phase
3) Proliferation
4) Remodeling
What 3 factors happen during hematoma and inflammation phase for a muscle
1) Rupture of muscle fibers leads to bleeding
2) Necrosis of muscle fibers
3) Inflammation occurs by tearing of blood vessels
What 2 simultaneous processes occur during repair and remodeling
1) Regeneration of disrupted myofibers
2) Formation of scar tissue
What are the 5 stages of healing for muscle(repair and remodelling)
1) Type III collagen and proteoglycans of ECM provide wound tissue with initial strength to withstand contractile forces
2) Type 1 collagen produce mature scar
3) Regeneration of myofibers to extend toward connective tissue scar
4) New muscle fibers mature where new muscle attaches to scar tissue
5) Small zone of connective tissue interposed between myofibres to cause permanent change within muscle tissue
4 early mobilization benefits during the healing process for muscle
- Rapid capillary regrowth
2) Better regeneration of muscle fibers
3) Parallel orientation of regenerating myofibers
4) Better biomechanical strength recovery
What are 3 cons to early mobilization for muscle repair
1) Larger connective tissue scar
2) Penetration of muscle fibers through scar tissue reduced
3) Re-rupture at injury site
3 early immobilization benefits for muscle injury
1) Reduce excessive scar tissue formation
2) Reduce risk of re-rupture at injury site
3) Allow scar tissue to mature enough to withstand contraction forces
3 early immobilization cons of muscle injury
1) Atrophy of healthy muscle fibers
2) Excessive deposition of connective tissue with the muscle
3) Delayed recovery of strength
a 42yr old male fractured his left ankle playing soccer, underwent surgery and then 6 weeks in a below knee cast non-weight-bearing on left leg. what changes would we expect to the stress strain curve for a ligament of the ankle after 6 weeks of non-weight-baring?
- max force will be dropped significantly due to reduction in strength,
- expect a more gradual slope in the elastic region.
- B and C will both be shifted left
