Kinesiology-quiz 3

What are the three ways you can observe viscoelasticity?

1. creep deformation 2. stress-relaxation 3. hysteresis

Describe the difference between a ductile and brittle material and give examples of both.

A ductile material is one that can undergo a lot of deformation before reaching the breakage point, such as a ligament. A brittle material is one that can not undergo a lot of deformation before breaking, such as bone.

For the Ligaments Stress-Strain Curve, what does it mean when it has a gradual slope?

A gradual slope means there is a low modulus of elasticity and the material is easily deformable.

What does the slope on a load-deformation curve tell you?

A steep slope represents a material that is stiff or resistant to elongation. A gradual slope represents a material that is easily deformed.

In cartilage, what contributes to resisting compression forces?

Aggregating PGs (therefore water) and intact collagen network.

What is an enthesis and describe its level of stress?

An enthesis is the site of attachment (insertion) of ligament, tendon to bone and it has the highest stress concentration.

What happens to the fluid in cartilage during compression?

An increase in pressure on the cartilage will create outward flow of fluid.

Cartilage has both fluid and solid and thus can be described as?

Biphasic

In what ways can bone be remodeled?

Bone can be remodeled in mechanical and non-mechanical factors facilitating remodeling. Mechanical factors are key for remodeling because remodeling occurs in response to forces. Application of forces stimulate osteoblast activity to increase bone mass. Non-mechanical factors refer to modulating bone density. Some examples of non-mechanical factors are diet, vitamins, sun, and thyroid. Non-mechanical factors are needed because the load itself may not be enough.

It is known that bone is dynamic, so what are two ways each that it can decrease or increase?

Bone can decrease with increased age and decreased activity, and it can increase through mechanical and non mechanical factors.

What is bone health in regards to Wolff's law?

Bone grows and remodels based on response to the forces that act upon it, thus bone adapts its mechanical properties according to the needed mechanical function.

Why does bone have a steeper elastic region in the stress-strain curve?

Bone has a steeper elastic region because it is less ductile. It can withstand a great amount of stress before deformation occurs. (less deformation before reaching failure point)

What can contribute to bone health?

Bone health can be influenced by mechanical factors (such as an increased amount of force applied to the bone) and modulating non mechanical factors (such as proper dieting and vitamins).

Do bone tend to be more brittle or more ductile? Do ligaments tend to be more brittle or more ductile?

Bone tend to be more brittle because they do not deformate a lot before breaking down. Ligaments tend to be more ductile because it deforms greatly before failure.

Which tissue will have a steeper slope in the elastic region of the load deformation curve: bone or cartilage?

Bone will have a steeper elastic region slope because it is able to withstand a greater amount of force before deformation occurs.

How are bursae named? Give 3 examples.

Bursae are named based on the area in which they are found. 1. subacromian bursae 2. subdeltoid bursae 3. subpatellar bursae

Which of the following is true? A. Cortical bone can withstand lesser magnitudes of stress with more deformation than cancellous bone. B. In general, ligaments can withstand more stress than bone. C. Cortical bone can withstand greater magnitudes of stress with less deformation than cancellous bone. D. Cancellous bone can withstand greater stress than cortical bone.

C. Cortical bone has the ability to withstand high stress with lesser deformation than cancellous bone can. Cancellous bone has the ability to withstand greater deformation (strain), but at lower stresses.

What type of bone reduces the load/impact and is found around joints and soft tissue?

Cancellous (trabecular) bone reduces the load/impact by distributing the load applied. This type of bone has a higher % of deformation.

Where are cancellous and compact bone located on long bones?

Cancellous bone is located at the loading surfaces, which are the ends or epiphyses of the bone. Compact bone is located around the cancellous bone on the ends and primarily along the diaphysis.

Where are cancellous bone and cortical bone found?

Cancellous bone, aka spongy bone, is found at the head and condyles of long bones. It can also be found in the middle of the vertebrae. The cortical bone is found around the cancellous bone and in the shaft of bones.

What property of cartilage allows it to absorb compression forces? What structure is primarily responsible for this?

Cartilage is Hydrodynamic. Proteoglycans are responsible for this as the negative charge from the keratin and chondrotin allow it to attract water back in to the cartilage, after the compression forces it out.

How does cartilage make movement easier?

Cartilage is smooth so it reduces the friction that occurs in joints during movement, making movement easier

Why is cartilage said to have biphasic behavior?

Cartilage maintains solid structure but also a fluid structure that has the ability to flow in and out depending on the load.

What do the load deformation curves of trabecular bone and compact bone tell you about the properties of these tissues?

Compact bone is stiff. It can withstand a lot of force but can only deform a small amount. It can absorb a lot of load but does not deform greatly. It withstands more stress than strain. Trabecular bone can withstand a smaller amount of stress but has a large the ability to deform. It withstands more strain than stress.

Describe the differences between cortical and cancellous bone in terms of load/stress and deformation/strain.

Cortical bone can withstand a high level of stress (load per unit area) but cannot withstand a lot of strain (percentage of deformation). Cancellous bone can withstand a lot of strain but cannot absorb a high level of stress.

What is the role that cortical and trabecular bone play?

Cortical bone gives the skeleton strength because it absorbs a lot of load and deforms very little. Trabecular bone is located at loading surfaces.

In which of these curves is stress (load) held constant to measure deformation over time?

Creep-Deformation

How do the Crystals of Hydroxyapatite affect the bone function?

Crystals of Hydroxyapatite are made of calcium and phosphate. These minerals aid in the bones structural rigidity as well as allow the bones to serve as a calcium and phosphate ion reserve.

What are five things that could decrease bone health?

Disuse, inactivity, weightlessness, age and nutrition.

Why is cartilage said to be hydrodynamic in nature?

Due to alternating patterns in compressive forces, there will be a movement of water in and out of the cells to accommodate for the changes in pressure; thus, making the cartilage hydrodynamic.

What is the ligament/tendon to bone insertion called?

Enthesis

True or False: Bone exhibits only plastic properties.

False-Bone exhibits both plastic and elastic properties

What are the three types of cartilage?

Fibrocartilage (disc/plates), elastic cartilage (ear/epiglottis), hyaline cartilage (synovial joints)

What types of collagen is found in fibrocartilage?

Fibrocartilage consists of type I and type II collagen. It allows the fibrocartilage to withstand both tensile and compressive forces.

What are bursae and what is their function?

Flat sacs of synovial membrane that reduce friction and facilitate movement

What is on the x and y axes for the creep and stress-relaxation curves?

For both the creep and stress-relaxation curve, time is measured on the x axis. Creep measures deformation on the y axis and stress-relaxation measures stress on the y axis.

What is the main difference between creep and stress relaxation?

For creep, there is a fixed amount of load overtime which can result in permanent deformation if left for a long period of time. However, for stress relaxation, there is a fixed amount of deformation which overtime will result in less force needed to attain that same amount of deformation.

What is Utah's paradigm explaining regarding bone health?

He is saying it is important to have mechanical loads for bone health but additionally you need non-mechanical factors, such as die and or calcium to MODULATE (not replace) the mechanical factors.

What is Wolf's Law regarding bone health?

He refers to mechanical load/forces. It is essential to have forces in order to stimulate osteoblast, which will increase bone health. Now with a reduction of forces osteoCLAST activity will dominate and bone mass will decrease.

What type of material produces which type of behavior?

Heterogeneous material exhibit anisotropic behavior and Homogeneous material exhibit isotropic behavior.

Question: What differences can you see in the curves of ligaments and bones?

In bones, the modulus of elasticity is steeper than that of ligaments. Also, once in the plastic zone, the slope of the bone plateaus. Lastly, there is a toe region in ligaments.

What are 3 factors that can cause a decrease in bone density?

Inactivity, Weightlessness, Poor Nutrition, Age

What is the attachment of muscle to bone? What is the attachment that connects bone to bone?

Muscle to bone: tendon Bone to bone: ligament

What is fibrocartilage composed of?

On the cellular side its compose of fibroblasts, fibrocytes, and fibrochondrocytes. In regards to the ECM it is ground substance filled with water and proteoglycans, and the fibrillar components include collagen type 1 and 2.

What are the bone's effector cells?

Osteoblasts and osteoclasts work to maintain "bone homeostasis".

Compare osteoblasts and osteoclasts.

Osteoblasts are bone-making cells, while osteoclasts degrade bone. Both have a function in the repair and remodeling of bone.

During times of immobilization, which of the following would be true about the femur?

Osteoclast activity exceeds osteoblast activity, resulting in a decrease in bone mass.

What is the condition called when there is more osteoclast activity then osteoblast?

Osteoporosis

Why does osteoporosis cause weakness in bones?

Osteoporosis is caused by the unbalanced ratio of osteoblasts and osteoclasts in the bone. In osteoporosis, osteoclast cells predominate over osteoblasts and a greater degradation of the bone will occur. A degredation of bone cells will decrease the amount of force the bone is able to withstand, making it weaker.

Describe the difference between passive or static stabilizers versus active or dynamic stabilizers.

Passive or static stabilizers are not able to create movement themselves and include structures such as capsules, ligaments and tendons. Active or dynamic stabilizers are able to create movement themselves by contracting their fibers and include structures such as muscles.

What are primary functions of Bursae?

Reduce friction and facilitate movement

What are two functions of bursae?

Reduce friction and facilitate movement

What does isotropic behavior mean?

Regardless of where the force is applied, the behavior is the same. This is exhibited by homogenous materials.

What is the best way to nourish cartilage?

Since cartilage is avascular, the best way to nourish cartilage is to stimulate fluid flow by movement such as exercise.

What do steep and gradual slopes for Young's Modulus of Elasticity indicate?

Steep slope means there is a high modulus and the material is stiff, while a gradual slope means there is a low modulus and the material is easily deformed.

When talking about strain, what are we talking about?

Strain is the percentage of deformation, not just the fact that it is deformed.

What is the difference between tendon and ligament vascularization?

Tendons have better vascularization and receive blood supply from muscle (perimysium), bone (periosteum insertion), and the surrounding tissues through vessels. This increases their healing process. Ligaments are hypovascular, meaning that they have a lower vascularization (excluding the MCL). This decreases their ability to heal.

What does a steeper slope of the elastic zone indicate to you?

That the tissue can withstand a lot of stress but cannot withstand much deformation before failure.

What creates the Toe Region in the Stress-Strain curve?

The Toe region on the stress-strain curve is a visual representation of the structural components that ligaments have; stress and strain remain the same for a period of time before deforming because the ligament resists change due to it's alignment of "wavy"

what is viscoelasticity?

The biomechanical properties of tissue that respond to load/deformation in a time and rate dependent behavior

Is bone more brittle or ductile?

The bone is more brittle because it tends to fail before it reaches the deformation point.

What is the difference between trabecular bone and cortical bone when considering a stress and strain curve?

The cortical bone withstand greater stress with much lower strain whereas the trabecular bone experiences much greater strain with lower stress. This shows that the cortical bone is much more stiff and strong whereas the trabecular bones has to deform more and does not handle as much stress.

What is the creep phenomenon?

The creep phenomenon describes how when a load is applied to a viscoelastic material, there is a sharp increase in deformation in the beginning. Over time, deformation will reach an equilibrium, and when the load is removed, the material will go back to its original shape if the load was not applied for too long. However, if the load was applied for too long, there will be some remaining deformation.

Compare and contrast the load-deformation curves of normal bone and osteoporotic bone.

The curves of both bones will not have a toe region like ligaments and will have a steeper elastic region than ligaments. This is because they can withstand a lot of stress even though they do not deformate as much as ligaments. However, normal bones can withstand more load and deformation than osteoporotic bones. This is because osteoporotic bones are more brittle and more prone to breakage than normal bones. Thus, the slope of the curve of the normal bone will be steeper than that of the curve of the osteoporotic bone.

What is one difference between cartilage and tendons/ ligaments?

The difference is that the cartilage can withstand compression forces and the tendons/ ligaments withstand tensile forces.

What are the two main purposes of the endotenon?

The endotenon, that is a thin film of loose CT that wraps around a fascicle, facilitates the sliding movement between fascicles(1) and creates a conduit for blood vessels (2).

What are the differences between ligaments and bones in the load deformation curve?

The first difference would be that ligaments have a toe-region, where because of their wavy structure they can deform before entering the elastic region. The bone does not have this region because it is more brittle. When ligaments reach the yield point, they have micro-failures that eventually lead to the breakpoint. Ligaments may not reach the breakpoint. However, when bones hit the yield point, they break much faster because they are more brittle.

What extra-cellular component(s) of hyaline cartilage allows the cartilage to withstand compressive forces?

The ground substance (interfibrillar matrix), which is made up of proteoglycans and glycoproteins.

What is in the interfibrillar matrix (Ground substance)

The interfribillar matrix are composed of proteoglycans and glycoproteins. They are made up of Hyauronan molecules (GAG's) That are connected to link proteins and expand the structure to have "brush like components" The "brush like" components are made up of keratin (small brush) and Chondroitin (big brush). Keratin and Chondroitin make up the aggreccan in addition to the core protein at the opposite end of the link protein. The glycosaminoglycans are located at the tips of the brushes and they are negatively charged which attracts water because water are positively charged. Therefore opposites attract.

What are the layers of the tendon?

The layers are the endotenon and peritenon, which is divided into epitenon and paratenon.

What allows aggrecans to keep their structure?

The negative charges of the GAGs prevents them from attracting each other and allows aggrecans to keep their shape while also allowing for the attraction of water towards the proteoglycans.

When cartilage experiences a compressive force, what happens to the pressure inside and where does the water inside of the cartilage go?

The pressure within the cartilage increases, which forces the water inside the ground substance to move outside. When the compressive force is removed, the pressure within the cartilage decreases, which pulls water back inside so cartilage can return to the original shape.

A 17 year old baseball player complains of shin pain, and gets an X-ray. The findings show that during his last game, he fractured the his tibia five inches above his ankle. What type of bone is present in this region of the tibia, and what is the best plan of action for healing?

The region of the tibia that is fractured is cortical bone. Since cortical bone is highly vascularized the fracture will heal on its own, but the baseball player should not put excessive pressure on it during the healing process.

Why is it important for glycoaminoglycans to have negative charges?

The repulsive forces between GAGs helps maintain structure and stiffness. The attraction of GAGs to oppositely charged water molecules gives tissues the cushion properties in their ability to withstand compressive forces. Overall, the charges lead to electroneutrality of tissues.

What region of the Stress-Strain curve is specific to ligaments and what does it represent?

The toe region represents the "stretching out" of the crimped collagen fibrils.

What is the ultimate stress? What is the ultimate strain?

The ultimate stress is the amount of stress at the point of failure. Stress is load/area. The ultimate strain is the amount of strain at the point of failure. Strain is percentage of deformation

Within the plastic zone of ligament stress-strain curve, there is what?

There are microfailures, which make the ligament more susceptible to breaking at the breaking point.

What occurs in the plastic zone of the ligament stress-strain curve that precedes the breaking point?

There is progressive failure created by microfailures which causes the ligament to go past the breaking point of failure on the curve.

What is a key identifier for the bone load-deformation curve and why does that occur?

There will be a higher modulus of elasticity within the curve. This occurs because bone is capable of withstanding a greater amount of stress with only a small amount of deformation, which results in a steeper curve.

What kind of force can proteoglycans (PGs) withstand?

They can withstand compressive forces.

What region in a load-deformation curve is specific to just ligaments?

Toe region (wavy pattern)

Name the four regions of a Stress-Strain Curve for a ligament.

Toe region, Elastic region, Plastic region, Failure region

With regard to strength and stiffness, how is cortical bone different from trabecular bone?

Trabecular bone is much more porous, spongy, and vascularized than cortical bone. It reduces load and is often found at the ends of long bones, around joints and soft tissue. Trabecular bone withstands compression forces. Cortical bone is stiffer and stronger, giving the skeleton the strength to withstand load and tensile forces.

What is the movement of water during swelling behavior in cartilage?

Water moves out of the cartilage when there is load and compressive forces being applied because pressure becomes greater inside, then moves back into the cartilage when these forces are removed because pressure is now less inside.

What happens when a load is applied to cartilage?

When a load is applied, the pressure inside the cartilage increases, moving the water from the area of high pressure to low pressure or outside. When the pressure is balanced, the flow stops. Once the load is removed, the pressure inside decreases so the pressure will move back in because the pressure outside is higher than inside resulting in inward movement. Water is attracted back into the cartilage because of the PGs.

Explain the swelling behavior in cartilage.

When a load is placed on the cartilage, the pressure will increase inside and since pressure moves from high pressure to low pressure, water will exit. The water will stop exiting when balance is achieved. When the load is removed, pressure inside will decrease, and water moves back inside because PGs attract it back in.

In the creep method, what happens with the deformation over time?

When the load is first applied there is a great deformation, after a certain amount of time the deformation plateaus. If this occurs for a long period of time, when the load is removed there will be permanent deformation.

What is creep deformation? What happens at equilibrium?

When there is a constant load over a long period of time, the tissue deforms very quickly until it reaches equilibrium. Once equilibrium is reached, it will stay at this point until the load is removed (continued deformation).

What are the key words for Wolf's Law and Utah's paradigm?

Wolf's law is mechanical, while Utah's is modulate. This is important because the bones need stress and strain (mechanical forces) to maintain remodeling. These non-mechanical factors could be things like diet or vitamins.

What are the key points of Wolfe's Law and Utah's Law?

Wolfe's Law describes how bone mass increases with the application of mechanical forces (by stimulating osteoblasts to create more ECM) and bone mass decreases when less mechanical forces are applied (because osteoclasts are breaking down bone). Utah's law describes how non-mechanical, biological factors can modulate the mechanical forces that facilitate bone health.

What is the relation between Wolff's Law and Utah's Paradigm?

Wolff's Law explains that bones respond and adapt to external and internal mechanical forces being exerted on them. The more forces exerted will result in growth and strengthening of the bone, while inactivity will degrade the bone. Utah's Paradigm goes further to explain that there are factors that could modulate the effects of the forces explained in Wolff's Law. For example, proper nutrition could aid in bone remodeling due to increased forces, where as a poor diet could limit the remodeling effect expected from those increased forces

What is wolfs law and what is an example of it?

Wolfs law is when a load is applied to the boan, the mechanoreceptors will respond to the load and will activate osteoclast and osteoblast to increase the bone mass. If forces are not applied to the bone, the osteoclast is going to dominate over the osteoblast. Bone growth and remodeling is dependent on the mechanical forces. Therefore an increase in the stimulus will lead to more bone formation (vice versa).

Which of the cartilaginous zones has the least vascularity?

Zone 1

How does cartilage rely on its nutrient supply?

cartilage relies on diffusion for its nutrient supply. This diffusion is facilitated by applying a load to the cartilage.

True or false, heterogenous materials exhibit isotropic behavior?

false

In what direction does the fibers of the collagen in a tendon go?

parallel to muscle fiber direction

In Swelling Behavior, what protein attracts water back into cartilage after the load on the cartilage is removed?

proteogylcans

What is the difference between cortical bone and spongy bone in regards to the load deformation curve?

spongy bone can deform more than cortical bone while cortical bone can withstand a higher level of stress

On the load deformation curve what is another way to describe the x axis other then deformation?

strain or change in length

Ligaments transmit ________ loads in comparison to bone which transmits ________ loading.

tensile, complex