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PT 670 Conn. Tissue
| Question | Answer |
|---|---|
| List the major connective tissue in the body | Tendons Ligaments Cartilage Bone Muscle |
| List the major components of connective tissue | Fibers Ground substance with associated tissue fluid cellular substances |
| What are the two types of fibers found in connective tissue? | Collagen Elastin |
| What cellular substances are found in connective tissue? | Fibroblasts (osteoblasts in bone, chondroblasts in cartilage Cells specific to each CT type |
| Type I collagen fiber is resistant to what? Makes up what? | Tension Ligaments, bone, dermis, fibrous cartilage, epimysium, perimysium, endomysium, fascia, joint capsule, meniscus, mature scar |
| Type II collagen fibers are resistant to what? | Intermittent Pressure |
| What are the characteristics of Type II collagen fibers? | Loosely packed, no fibers, very thin fibrils such as hyaline and elastic cartilage, menisci |
| What is the role of Type II collagen fibers? | Structured maintenance for organs |
| What are the characteristics of Type III collagen fibers? | Loosely packed, thin fibrils such as smooth muscle in CV and GI systems |
| What is the role of Type IV collagen fibers? | support and filtration |
| What is the characteristics of Type IV collagen fibers? | Thin amorphous such as basement membrane |
| Process of Extracellular formation of collagen is... | tropocollagen--> fibrils--> collagen fibers |
| What are the smallest collagen structure observable by electron microscope? | fibrils |
| What is the arrangement of collagen in tendons? | Closely packed and roughly parallel |
| What is the arrangement of collagen in ligamnets? | Not as parallel as a tendon but more organized than a capsule |
| What is the arrangement of collagen in joint capsules? | Loose weave of interlaced fibers |
| What is the clinical implication of how collagen aligns? | Collagen aligns in the direction of force or pressure, if no activity collagen does not align well. Early movement allows for better alignment and motion. |
| What precautions must be considered with early movement? | The more precarious the repair the more careful we must be. (eg. Rotator cuff repair 4-6 weeks) |
| Most injuries/ repairs can be moved early with what technique? | Passive Range of Motion (no stress on the area) |
| What are the functions of connective tissue? | Support Strength Repair Mechanical and chemical connector between cells |
| What are five major characteristics of connective tissue? | Abundant and diverse Provides tensile strength Weaker at tissue intersurface Vascularity is generally poor with the exception of bone Neural innervations are abundant (except in cartilage): muscle spindle, GTO |
| What does the tensile strength depend on? | Arrangement of the collagen intermolecular bonds relationship between the ground substance and the collagen |
| ________ is the only tensile resistant protein in ligaments, tendons, and joint capsules | Collagen |
| Connective tissue is strongest where? | middle |
| What property does elastin give connective tissue? | Provides elastic properties by their unique cross linking |
| Why is it important to understand the healing phases of CT? | too early disrupt collagen formation, too late, randomized collagen formation, alignment more and more unlikely |
| What are some factors that influence the healing process? | location, age, extent of the injury, patient compliance, nutrition, blood supply, |
| What is the first phase of recovery? how long does it last? rapid or slow response? | Inflammatory Phase (1-6 days) rapid response |
| What is the role of the inflammatory phase? | protective and generally beneifical |
| Prolonged inflammation is not good, what can be done to help change the course of the injury? (eg. tendinosis) | create an acute inflammatory response with deep friction massage |
| What are the four cardinal signs of inflammation? | Erythema- rubor Heat- calor Edema- dolar Pain- functiolaesa (leads to loss of function) |
| Name the steps of the inflammatory phase | Vasoconstriction Vasodilatation Clot Formation Phagocytosis |
| What is vasoconstrictions role in the inflammatory phase? Duration? | Helps minimize blood loss, very short time (minutes) |
| What is vasodilations role in the inflammatory phase? Duration? | Accompanied by increase in capillary permeability Duration: Up to 1 hour |
| What is involved in clot formation | Platelets: first responders, bind to the exposed collagen and release fibrin to stimulate clotting |
| What cells are responsible for phagocytosis? | monocytes convert to macrophages |
| What is the most important cell in the inflammatory phase? why is it essential? | macrophages, responsible for wound healing |
| What is the role of macrophages in phagocytosis? | they produce enzymes such as collagenase which facilitates the removal of necrotic tissue and bacteria |
| What are the systemic affects of acute inflammation? | Tachycardia Fever Hypermetabolic state Increase WBC in the circulating blood |
| What is the second phase of healing? Duration? | Proliferation phase, 3-20 days |
| What does the proliferation phase involve? | Involves connective tissue (strengthen the site) and also epithelial cells (cover the wound) |
| What do epithelial cells form in the proliferation phase? | Epithelial cells form the covering of mucous and serous membranes and the epidermis of the skin |
| What are four processes that take place during the proliferation phase? | Epithelialization Collagen Production Wound Contraction Neovascularization |
| When a wound is superficial when does epitheliazation occur? deep? | superficial: within hours deep: after collagen production and neovascularization |
| What is the purpose of epithelialization? | provides a barrier to prevent fluid and electrolyte loss and to decrease risk of infection |
| What is contact inhibition? what happens with the loss of contact inhibition? | Epithelial cells are normally in contact with one another and when interrupted (loss of contact inhibition), they begin to migrate |
| Clean, approximated wounds can be resurfaced in _________? larger can take several __________ | 48 hours, several weeks |
| Name the steps of collagen production. | Fibroblasts synthesize procollagen to tropocollagen to collagen fibrils to collagen filaments to collagen fibers |
| What is granulation tissue? | Tissue that contains newly formed capillaries and myofibroblasts |
| Granulation tissue is comprised of what collagen type? how much? and what is its tensile strength? | Type III, the most amount of collagen, low tensile strength |
| When does wound contraction begin? | approximately five days and peaks after 2 weeks |
| What are the primary cell for wound contraction? their function? | Myofibroblasts are the primary cells for wound contraction; they attach to the margins of intact skin and pull the entire epithelial layer inward |
| What happens if wound contraction is excessive? | formation of contractures (may result from adhesions, muscle shortening, tissue damage) |
| What is a primary union/ intention contraction? | Wounds that are rapidly closed (during the inflammation phase) with sutures heal without wound contraction |
| What is a secondary union/ intention contraction? | Secondary intention or indirect union: has the element of wound contraction |
| What happens during neovascularization? | Generation of a new vascular network Anastomosis to preexisting vessels Coupling of the vessels in the injured area New growth is marked by small bud outgrowths, thin and vulnerable in nature |
| What is the clinical impact of the proliferation phase? (scar) as well as newly formed structures | Scar: During the proliferation phase the scar is normally red, swollen, and fragile Newly formed structures: too much stress damages emerging structures, too little might cause excessive adhesions or wound contractures |
| What is the remodeling phase? Duration? | Orientation and cross linking of the collagen fibers; Maximize the strength of the healing tissue duration: 12-24 mos (majority w/in 3-4 mos) |
| What is the primary resistance against tensile loads? | collagen fibers |
| How do collagen fibers respond to tensile loads? | straightening from their resting postion |
| How does collagen respond during the elastic phase? | linear fashion (4 % elongation), will return to prior state (no change made) |
| What happens if the tensile force elongates tissue beyond 4%? | plastic changes begin, must be repeated or changes can be lost |
| What is the difference between a viscous or elastic material? | A viscous material is resistant to flow, and an elastic material returns to the original state following deformation and after the force is removed |
| What impacts a tissues viscoelasticity? | duration of the applied load and the rate at which the load is applied impact a tissue’s viscoelasticity |
| Define creep (type of tissue response) | When a load is applied for an extended period of time, the tissue elongates, resulting in permanent deformation. |
| What effects the amount of deformation ? | depends on the amount of force and the rate at which the force is applied. |
| Define relaxation (type of tissue response) | When a tissue is pulled to a fixed length a certain force is required. As the tissue is held at this length, the amount of force necessary to maintain that length decreases |
| How does creep and relaxation prevent damage? | Creep and relaxation allow connective tissue to adapt to and function in a variety of loading conditions without being damaged |
| Why are stretching exercises considered important for lengthening soft tissue? | Tissues pulled into tension lengthen and relax, which provides the rationale for stretching exercises to lengthen shortened soft tissue |
| Define stress | The resistance of the intermolecular bonds to physical deformation when external loads are applied |
| Define strain | The amount of displacement a material undergoes when a force is applied |
| What does the stress-strain curve illustrate? | Illustrates how as force is applied, connective tissue will deform, and in doing so will create an internal stress/tension |
| On the stress strain curve, what is the toe region? | toe region- the part where you are taking up the slack in the tissue |
| On the stress strain curve, what is the a-b region? | point a-b: tissue will resume its prior length (no change in length after the stretch) |
| On the stress strain curve, what is the b-c region? | point b-c: plastic region where changes in the length can occur |
| What is point c on the stress strain curve? | point c is ultimate failure where that tissue will fail and tear |
| How does the stiffness or extensibility of the material influence the stress strain curve? | stiffer- steeper extensible- horizontal |
| What do muscles, bone, and tendons look like on a stress strain curve? | Muscle- More horizontal Bone- More vertical Tendon- Depends on tendon; More vertical in nature |
| Describe the points on the stress strain curve of a ligament? (A, B, C, D) | A- fibers recruited B- all fibers tight C- fibers tightened 1st fail 1st D- progressive fiber failure |
| How does temperature influence connective tissue? | increase heat, increase elasticity |
| What might conditions of force magnitude,, time and direction influence the performance of connective tissue? | 1. Low force applied slowly may cause tissue deformation 2. High forces applied quickly may cause tissue failure 3. Moderate force applied in a repetitive manner may cause tissue failure |
| How does age influence CT? | 1. Increase in CT stiffness 2. Loss of water content altering the normal ground substance and an increase in interconnection between ground substance and collagen |
| How dould immobilization influence CT | 1. Influences remodeling collagen to lay down tissue is a random arrangement decreasing strength 2. Ground substance dehydration with increase viscosity and increased stiffness, and decreased elasticity |
| How does inflammation influence connective tissue? | If chronic may result in structural changes within the connective tissue and decreases its normal strength and extensibility |
| What strategies must be considered to prevent contractures and adhesions? | 1. Placing CT structures in a lengthen position during immobilization 2. Intro stress to immobilized limbs early 3. Intro stress by protected motion during the healing process 4. Controlling/reducing inflammation Example 5. Stretching 6. Positioning |
| How could you introduce stress to immobilized area early? | example: isometric contraction |
| How could you Intro stress by protected motion during the healing process? | Example- gravity minimized in protected range |
| What can be done to control/ reduce inflammation? | ranging the joint to help prevent adhesions and contractions |
| How will a slow stretch effect ground substance? | Slow stretch will allow ground substance to more easily deform (elongate) |
| What would need to be done to create strength in the CT? | If your goal is to have strong CT, then create forces in the direction you want collagen laid down during remodeling |
| What can be one to disrupt the CT? | 1. High forces applied quickly will result in tissue failure 2. Low forces applied over time will gradually elongate 3. Less force will be required to hold a given length over time, therefore increase force and change length |
| What position should CT be in during immobilization, if possible? | elongated |
| What influences viscoelasticty? | temperature, force and time |
| How does collagen align itself? | COLLAGEN ALLIGNS ITSELF IN THE DIRECTION OF THE FORCE APPLIED |
| Regular mobility of affected area has been know to help maintain what? | helps maintain the lubrication and critical fiber distance |
| How does immobilization effect connective tissue? | Immobilization is associated with increased deposition of connective tissue along with loss of water in the tissue (dehydration) and an increase in intermolecular cross linking, further restricting the extensibility of the tissue |
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