Biomechanics Final Multiple Choice Questions (BIOE 3200)
Multiple synchronized motion capture camera images of reflective markers are used to mathematically determine the
3D locations of the markers relative to the lab coordinate system
The minimum number of markers to be embedded in a specimen to quantify the strain in 3D is
4
When a cylindrical specimen is subjected to a torsional load, the maximum tensile stress is generated in the direction that is ______ degrees ti the long axis
45
In 3D, there are 9 components of stress relative to the prescribed coordinate system. Of which, how many components are independent?
6
In Hooke's Law, how many independent parameters (E,G, etc.) are needed to completely describe orthotropic behavior (normal and shear) under isothermal conditions?
9
The modern concept of stress defined in the 19th century states that stress is a measure of a force acting over an oriented area. Thus, mathematically stress is a _______
Tensor
A condition characterized by hardening and narrowing of the artery from plaque build up is known as
athersclerosis
The gait event that marks the end of the stance phase and beginning of swing phase is called what?
foot off
Strain gauges allow strain measurements based on voltage outputs because as the material of interest experiences deformation and the wires inside the strain gauge are stretched, the electrical resistance _____
increase
How is hamstring spasticity in late swing phase of gait thought too affect knee flexion/extension at the point of second initial contact?
increases the knee flexion angle at second initial contact
In studying gait, what kind of analysis requires force plate data?
kinetics
Most soft biological tissues exhibit _____ and should be analyzed using _____
large deformation, exact measures of strain
If you were to rank the amount of hysteresis exhibited by soft tissues which of the following would be most likely?
ligament<tendon<intenstine
The integrity of the hip is enhanced by the strong ___ crossing the joint
ligaments
If the same material above was subjected to stretching at a slower rate, the stress-strain plot would shift to the right and the material would appear _______
more compliant
As discussed in class, extra challenges in subject calibration arise because of which of the following?
obesity
A "ghost marker"
refers to a motion data processing artifact
Give one example of bone fracture fixation technique/approach
splint
In biomechanics problems when there are not a sufficient number of equations for the number of unknowns, such cases are called
statically indeterminant
The amount of ____ a muscle group can generate at a _____ is used to measure muscular strength
torque, joint
Name one other component of bone matrix besides hydroxyapatite (calcium and phosphate) minerals or cells
water
BMI is calculated by
weight divided by the square of the height
When normal stress is at the maximum, the shear stress at the same point (under the same coordinate system) is
zero
Describe 2 limitations of using AFM to approximate the local mechanical properties of a single cell
1- We assume the cells are LEHI, but in reality most are not. 2- Tip geometry can affect how the cell responds mechanically
Which of the following numbers may be considered hypertension?
140/90 mmHg
How many different types of collagen are currently identified (as discussed in class)?
28
In 2D, the exact measure of Green strain has ____ independent components
3
Motion capture cameras acquire images of reflective markers placed on the test subject. What is the minimum number of markers required for each body segment for the observer to measure 3D movement of that segment?
3
Typically treatments for occlusive coronary artery disease include:
A, B and C (balloon angioplasty, bypass surgery, and endovascular stents)
In cell-matrix adhesion, vinculin proteins in focal adhesions link the extracellular matrix to ____ within cells
Actin Filaments
Endothelial cells located at the site of a partially clogged artery experience which of the following distributed forces
All of the above yo
If you were tasked with investigating the effect of membrane tension on the activation of ion channels located in the cell membrane, which experimental approaches might you utilize?
All of the above yo
What can cause a foot to "point" inward during gait?
All of the above yo
Why is the concept of processive motors important in the explanation of dynein and kinesin motor proteins
All of the above yo
When subjected to planar, equi-biaxial, tensile forces (same magnitude in two orthogonal directions) a heart valve leaflet tissue with dominant collagen fiber orientation in one direction will exhibit greater extension in cross-fiber direction. This is a manifestation of _______
Anisotropic behavior
In order to calculate stresses in a circular shaft subjected to torsion, one must know:
Applied torque, radius of the shaft, geometry of cross-section to calculate second polar moment of area
T/F: With quantitative clinical gait analysis, conventional video recording is not important because of the captured motion data
False
Shear strain is a measure of
Average change in the angle of distortion on xy-plane
A material is said to exhibit viscoelastic behavior when it exhibits
Changes in length under a constant load
overweight and obese individuals are at increased risk for which of the following?
Coronary Heart disease, type 2 diabetes, and hypertension
In an image showing the anterior view of the right forearm in pronation (palm is hidden from the view), the radius and ulna are _______
Crossed with each other and radius on top
When a 2D static equillibrium problem to find joint and muscle forces, like the examples discussed in class, ends up with more unknowns than the number of equations (sum of forces and moments), what can you do?
Decrease the number of unknowns by grouping or ignoring muscles or increase the number of equations by estimating force distribution in muscles
In a generic form of constitutive equation, stress can be determined as:
Derivative of strain energy with respect to strain
How is rectus femoris spasticity in early swing phase of gait thought to affect knee motion in early swing phase?
Disrupts the knee flexing motion that normally occurs in early swing
Give one example of a pathophysiological condition caused by degradation of elastin?
Emphysema
A lot of words so going to summarize---talking about residual stress in arteries and asking what will happen if one side is cut open (going from O shape to C shape)
Ends will pull away from each other
The earlier concept of stress was defined in the 18th century by _____
Euler
The problem associated with modeling of material viscoelastic behavior using Maxwell elements alone is that the material would seem to
Exhibit infinite creep in response to a step stress input AND exhibit complete stress relaxation to zero in response to a step strain input
The problem associated with modeling of material viscoelastic behavior using Kelvin-Voigt elements alone is that the material would seem to
Exhibit no stress relaxation in response to a step strain input
"Clearance" in gait refers to what quantity/parameter?
Foot height during swing phase
If the specimen was a hollow cylinder like the shaft of a long bone, with the same outer diameter and loading as the example in this problem. Will the value of the maximum shear stress be great, smaller, or the same?
Greater
Hypertension significantly increases the risk of
Heart attack and kidney disease
In typical or normal gait, knee flexion in swing is facilitated by:
Hip flexor muslces and ankle plantar flexor
The authors of the required textbook for BIO3200 are
Humphrey and O-Rourke
Give one example of an experimental (or physical) condition (not material composition) that influences the constitutive behavior of a material
Hydration
According to Fung's observation most soft tissues exhibit:
Hysteresis and Strain-rate insensitivity
Surgical intervention called muscle lengthening involves which of the following?
Incision of fascia followed by stretching of muscle
In performing push ups, holding the plank pose requires _____ contraction of muscles
Isometric
Which of the following statement(s) is/are true about collagens?
It accounts for 25-30% of the total protein in the body AND triple helical structure
When a soft tissue specimen is cyclically loaded and unloaded for 3-10 cycles the material tends to exhibit repeatable pseudoelastic response. This experimental process is called ______
Pre-conditioning
Mechanical stability of bone fracture fixation may be affect by (give one example)
Location of bone fracture
In the hierarchical structure of tendon, which of the following is the smallest?
Micro-fibril
If a force acting on an area is parallel to the outward normal vector (of the area), then the force is called
Normal force
Specialized bone cells that are entrapped in bone tissue are called what?
Osteocytes
In an image showing the posterior view of the left forearm in supination (palm is hidden from view) the radius and ulna are ______
Parallel with each other and radius on left
disruption of typical or normal ankle motion during gait can result in:
Possibly all of the above yo
What is muscle spasticity
Reflexive muscle contraction due to a quick stretch
The type of wrist injury that involves fracture in the radius bone is called what?
Smith's fracture (colle's)
A subject calibration trial provides the relationship between reflective markers placed on the surface of the skin and the underlying anatomy. Data are collected for this calibration trial while the subject is?
Standing still
Fung's idea to demonstrate the exponential form of constitutive relations of soft tissues was to plot
Stiffness vs stress
The term ____ refers to a condition when the implanted device is too rigid and carriers too much of the stress, which can result in weakening of bone
Stress Shielding
As a cantilevered beam, with a rectangular cross-sectional area decreases in length L, what has to happen to the thickness of the cantilever , if the base b remains the same, in order for the effective stiffness k to remain constant
The thickness needs to decrease
When a soft tissue is loaded under tension, straightening of crimp structure (without damage) in collagen fibrils results in which region of the stress-strain curve?
Toe region
Muscle's tension generating capacity is dependent on:
Training state of the muscle, and cross sectional area of the muscle fibers
The World Congress of Biomechanics 2014 took place in
USA
Mechanical behaviors of collagenous soft tissues (e.g. tendon) are governed mainly by change in entropy because:
Untangling of chain-like molecules
A condition characterized by enlargement of the diameter due to weakening of the aortic wall tissue is known as
anuerysm
____ muscles stabilize the pelvis during the support phase of walking and running and when you stand on one leg
abductor
Only two motion capture cameras are required to determine the location of a reflective marker. And yet, most clinical motion labs have 8-12 motion capture cameras. Why?
all of the above yo
In the stance phase of the gait cycle, what muscle group produces an ankle moment to control the forward movement of the tibia over the plantigrade foot (when the plantar surface of the foot is entirely on ground)
ankle plantar flexor muscles (calf muscles)
In Hooke's Law, the parameter that relates strain to change in temperature is called what?
coefficient of thermal expansion
List two applications where motion capture technology is used
dancing and virtual training
If you stretch elastic fibers that contain coiled molecules, the entropy in the material will _____ and heat flow will ____
decrease, out
According to cauchy's definition, strains are a combination of
displacement gradients
The space between loading and unloading curves in the plot above is known as hysteresis which results _____
dissipation of energy
Shear strain is a measure
distortion angle
