ME C178 Exam Style Questions terms/def's swapped

Living-cell therapy = BioTech; surgical robot = MedTech; at-home consumer health test = HealthTech.

L2 — A biomedical company develops a therapy by manipulating living cells. Another company sells a surgical robot to hospitals, and a third sells an at-home health test directly to consumers. Classify each as BioTech, MedTech, or HealthTech.

Sagittal divides left/right; coronal (frontal) divides front/back; transverse divides upper/lower.

L2 — Name the three primary anatomical planes and briefly state how each divides the body.

Medial and proximal.

L2 — A structure is closer to the body's midline and closer to the trunk than another structure. Which directional terms describe it?

Example: flexion decreases a joint angle while extension increases it; abduction moves away from the midline while adduction moves toward it.

L2 — Give two paired anatomical motions and describe the difference within each pair.

Human subjects: realistic anatomy and living response, but injury-level testing is unethical/unsafe. Cadavers: realistic anatomy, but only passive movement and no living biological response. ATDs: repeatable and instrumented for force/displacement measurements, but represent only selected standardized body types and do not fully reproduce human biology.

L3 — Compare human subjects, human cadavers, and ATDs as crash-test models. Give one major advantage and one major limitation of each.

ATDs contain sensors that measure quantities such as force and displacement/strain. These measurements help establish injury limits, safety criteria, and design standards.

L3 — What does an anthropometric test device (ATD) measure, and how is that information used in safety design?

False. Standard ATDs represent selected percentile body types, such as a 5th-percentile female and 50th-percentile male, so population variability is not fully represented.

L3 — True or False: NHTSA crash testing historically used ATDs that adequately represented the full range of human body sizes and shapes. Explain.

Because real users vary in body size, shape, posture, age, and other characteristics. A design optimized for an average can perform poorly for people far from that average.

L3 — Why can designing around an 'average' person produce a safety problem even if the average model is accurate?

Automotive ≈ 700; aviation/FAA ≈ 1000.

L3 — State the approximate HIC thresholds emphasized for automotive and aviation applications.

The longer-duration impact, because HIC depends on both head acceleration and the time interval over which the acceleration acts.

L3 — A crash produces the same peak head acceleration in two cases, but one impact lasts longer. Which case would generally produce the larger HIC, and why?

Observe & Notice → Frame & Reframe → Imagine & Design → Experiment & Test.

L4 — List the four quadrants of the design cycle in a logical sequence.

Observe/Notice the discomfort and appearance concern; Frame/Reframe the problem around comfort and adoption; Imagine/Design a revised form/socket; Experiment/Test the new design; use results to iterate.

L4 — A prosthetic user reports discomfort and poor appearance. Show how that observation could move through all four quadrants of the design cycle.

False. Design is iterative; testing creates new observations that lead to reframing and redesign.

L4 — True or False: A successful device design is typically the result of one pass through the design cycle. Explain.

False. Form is the external shape/appearance; function is what the device does or its purpose.

L4 — True or False: 'Form' refers to the purpose of a design, while 'function' refers to its appearance. Correct the statement.

Possible reasons include poor appearance/form, discomfort, identity concerns, cost, poor fit, or mismatch with user needs.

L4 — A prosthesis performs its mechanical task well but users still reject it. Give two lecture-consistent reasons this could happen.

SHAP evaluates grip/manipulation of objects of different sizes/shapes; Box and Block evaluates manual dexterity by moving blocks.

L5 — Name the two laboratory tests used to assess upper-limb function and state what each primarily evaluates.

False. It is normally closed at rest; the user applies body-powered motion/tension to open it.

L5 — True or False: In a voluntary-opening body-powered prosthesis, the terminal device is open at rest. Explain.

False. They are controlled by body motion and do not specifically require the opposite hand.

L5 — True or False: Body-powered upper-limb prostheses require the user's opposite hand for operation. Explain.

Natural-limb-like function increases complexity; mass production and cost reduction are difficult; users still need patient-specific fitting/customization.

L5 — Identify three barriers to creating a low-cost mass-produced prosthetic limb that still works well for many users.

The older adult is an active participant in need finding, interviews/observation, feedback, and iteration. The process focuses on understanding needs before proposing solutions and incorporates user/stakeholder feedback into design changes.

L5 — You are co-designing a grip-assist device with an older adult. What would make the process 'co-design' rather than simply designing for them?

The more compliant design generally favors deformation, shock absorption, and energy return/mobility; the stiffer design generally favors rigidity/support/stability.

L6 — Two prosthetic feet have the same overall geometry, but one is much more compliant than the other. Which design would generally favor energy return/mobility, and which would favor rigidity/stability?

Carbon fiber: lower stiffness, more deformation, lighter; stainless steel: much stiffer and heavier.

L6 — Compare carbon fiber and stainless steel for prosthetic applications using stiffness, deformation, and weight.

The natural knee is mechanically complex, so the prosthesis must balance stability, mobility/range of motion, load bearing, and load absorption.

L6 — Why is designing a purely mechanical prosthetic knee difficult?

More constraint/rigidity generally increases stability but can reduce mobility; more freedom/compliance can increase mobility but reduce inherent stability.

L6 — Explain the stability-mobility tradeoff in prosthetic knee or foot design.

To shape the knee's motion and help balance range of motion with stability.

L6 — What is the design purpose of a 4-bar linkage in a prosthetic knee?

Wear at moving joints/linkages and fatigue or degradation of repeatedly loaded compliant components such as springs, polymers, and foot structures.

L6 — A lower-limb prosthesis is repeatedly loaded through thousands of gait cycles. What types of damage would you reasonably expect from the lecture's design discussion?

About 60% stance and 40% swing.

L7 — In normal walking, approximately what fraction of the gait cycle is stance and what fraction is swing?

Examples: motion-capture markers/cameras track body or joint motion; force plates measure external forces; IMUs measure inertial motion; Kinects/BTS MOCAP capture movement; instrumented crutches can measure loading.

L7 — Name four types of equipment that could be used in a laboratory gait analysis and state what at least two of them measure.

Occlusion/blocked views, users moving outside camera range, and wearable or complex equipment interfering with normal activity.

L7 — Give three reasons a gait-analysis system that works well in a laboratory may perform poorly in the field.

They provide position/motion trajectories over time; velocity and acceleration can be derived from those trajectories.

L7 — What do reflective/visual markers directly provide in a gait lab, and what additional kinematic quantities can be derived from them?

An Inertial Measurement Unit; it can provide motion information such as acceleration and orientation/position-related data using sensors such as gyroscopes/accelerometers.

L7 — What is an IMU, and what types of gait-related information can it provide?

They are spending more time with both feet on the ground, suggesting greater need for stability and reduced single-leg support. It can be associated with reduced balance/stability and age-related changes, and may also reflect reduced strength or neurological/coordination changes.

L7 — An older adult's Double Support Time has steadily increased over a year. What does that suggest about gait, and what possible health-related changes could be associated with it?

Brace: external support for an injured body part. Orthosis: external device used to correct/support disorders of limbs or spine. Exoskeleton: wearable structure that augments, assists, or restores movement.

L8 — Distinguish a brace, an orthosis, and an exoskeleton.

Active designs use powered actuators/motors; passive designs use mechanical elements such as springs/linkages without powered actuation.

L8 — What is the key difference between an active and a passive exoskeleton?

Full-body systems can assist more joints/tasks but are heavier, more complex, and harder to control/fit. Single-joint systems are more targeted and simpler but only assist a limited motion/task.

L8 — Compare a full-body exoskeleton with a single-joint exoskeleton in terms of capability and design complexity.

Pneumatic, hydraulic, and electric/motorized.

L8 — Name the three actuator types discussed for active exoskeletons.

EMG → muscle activity; potentiometer → joint angle; pressure sensor → ground-reaction force/pressure; gyroscope/accelerometer → body/torso motion and orientation.

L8 — Match each exoskeleton sensor to its measurement: EMG, potentiometer, pressure sensor, gyroscope/accelerometer.

True. The goal was to augment strength, endurance, and load-carrying capacity.

L8 — True or False: Early exoskeleton development in the lecture was linked to military/DOD goals. What was the intended benefit?

Military, workplace ergonomics, medical mobility/rehabilitation, and spaceflight.

L8 — Give four application areas for exoskeleton technology discussed in lecture.

It can apply loads to the body to help counter bone loss and soft-tissue/muscle degradation caused by microgravity.

L8 — Why would an exoskeleton-like exercise system be useful in microgravity?

They can provide repeatable mobility/rehab assistance that complements PT work and may expand access for more patients, including rural or low-income populations.

L8 — How could rehabilitation exoskeletons help address a shortage of physical therapists?

Inconsistent state rules, adulterated products, misleading claims, growing ability to detect fraud/impurity, and public demand for safer food and drugs.

L9 — What problems in the late 1800s/early 1900s motivated stronger federal regulation of foods and drugs?

Controlled human feeding experiments led by Harvey Wiley to study the effects of food additives/chemicals and help determine acceptable exposure levels.

L9 — What was the 'Poison Squad,' and what question was it trying to answer?

Safety = no unacceptable risk/harm when used as intended; efficacy = the device performs its intended function.

L9 — The FDA evaluates devices for safety and efficacy. Define both terms in the context of a medical device.

False. 510(k) clearance can rely on substantial equivalence and laboratory evidence rather than long-term clinical outcomes.

L9 — True or False: FDA clearance always requires long-term clinical outcome data. Explain using the 510(k) pathway.

Class I = low risk/general controls; Class II = medium risk/additional standards and post-market surveillance; Class III = high risk and subject to premarket approval.

L9 — Classify the three FDA device classes by risk and regulatory burden.

False. Device/drug complications are part of the regulatory reporting system; manufacturers are specifically required to report complications to the FDA.

L9 — True or False: Problems with a medical device are handled only within the medical community and are not part of the FDA system.

510(k) and PMA.

L9 — Name the two device-market pathways emphasized in lecture.

Substantially equivalent device → 510(k). Novel, high-risk Class III device → PMA.

L9 — A company develops a device that is substantially equivalent to an existing device. Which pathway is more likely? What if the device is novel and high-risk?

Class III high-risk devices, including novel life-sustaining devices or devices with potential for serious injury.

L9 — What types of devices generally require PMA?

Voluntary consent without coercion; participants can stop and scientists must be prepared to terminate; experiment design should be based on prior evidence/testing.

L10 — State the three Nuremberg Code principles emphasized in lecture.

It reviews proposed studies involving living humans and determines whether human-subject testing can proceed, including whether benefits outweigh risks.

L10 — What is the role of an Institutional Review Board (IRB)?

Three phases before approval: I, II, III. Phase IV occurs after approval.

L10 — How many clinical trial phases occur before FDA approval, and which phase occurs after approval?

Post-market evaluation of longer-term effects/performance in a larger real-world population.

L10 — What is the purpose of Phase IV clinical testing?

Cell → sub-tissue → tissue → joint → body.

L11 — Put Yousuf's biomechanics length scales in order from smallest to largest.

Physical specimen testing = experimental; finite-element prediction = computational.

L11 — A researcher physically loads a tissue specimen and records stress-relaxation behavior. Another researcher uses a finite-element model to predict 3D tissue mechanics. Which is experimental and which is computational?

PSF uses stiff rods/fusion to rigidly correct and hold the spine. VBT uses a flexible tether to modulate growth while preserving more motion.

L11 — Compare posterior spinal fusion (PSF) and vertebral body tethering (VBT) for adolescent idiopathic scoliosis.

Cartilage handles compression through its water/proteoglycan-rich structure while collagen provides tensile/shear strength, analogous to concrete being reinforced to better resist tension.

L11 — Why was cartilage compared conceptually to reinforced concrete?

Osteoarthritis involves progressive cartilage wear/damage with chronic inflammation/pain. Cartilage has low self-regenerative capacity because it is avascular, nutrient-limited, and contains sparse chondrocytes within abundant extracellular matrix.

L11 — What is osteoarthritis, and why is articular cartilage poor at self-repair?

Cell biology: single-cell RNA sequencing; matrix: collagen and glycosaminoglycan; tissue mechanics: uniaxial unconfined compression/stress-relaxation testing.

L11 — Name Pete's three validation scales and one measurement at each scale.

It produces unloading/microgravity-related musculoskeletal degradation, making it useful for studying accelerated degeneration.

L11 — Why is spaceflight useful as a model in Jo's research?

The cartilage endplate (CEP).

L11 — What spinal structure is the main focus of Jo's research?

True. Flight endplate density was about 10% lower.

L11 — True or False: Jo's flight group showed lower endplate density than the ground group.

Mice (C57 mice in the RR10 cohort).

L11 — What experimental population was sent to space in Jo's study?

False. Arteries generally carry blood away from the heart to body tissues; veins generally return blood to the heart.

L12 — True or False: Veins are the vessels that generally carry oxygen-rich blood from the heart to body tissues. Correct the statement.

False. The heart is cardiac muscle and contracts involuntarily.

L12 — True or False: The heart is skeletal muscle that contracts involuntarily. Correct the statement.

An LED shines light into tissue; a photodetector measures changes in reflected/transmitted light caused by pulsatile blood-volume changes. Repeating peaks correspond to heartbeats.

L12 — Explain how a PPG heart-rate sensor converts a heartbeat into an electrical/optical signal that can be counted.

Oxygenated and deoxygenated hemoglobin absorb red and infrared light differently, so comparing two wavelengths allows estimation of oxygen saturation (SpO2).

L12 — Why does a pulse oximeter use two wavelengths of light rather than one?

Electrical depolarization activates cardiac muscle contraction; ventricular contraction creates pressure that drives blood through the circulation.

L12 — Connect the heart's electrical signal to mechanical blood flow.

Examples: skin tone/melanin, skin thickness, sensor location, sensor tightness/contact, movement/optical interference, and weak local perfusion.

L12 — Give four factors that can bias or reduce the accuracy of a PPG reading.

Green provides more reliable/consistent PPG data; red is more efficient. Blood absorbs green more strongly and reflects more red.

L12 — Compare green and red LEDs for PPG heart-rate sensing as described in lecture.

The vessel becomes constricted and downstream blood flow is reduced/restricted; severe blockage can cut off supply.

L12 — What happens hemodynamically when plaque narrows an artery?

PPG depends on detecting pulsatile changes in local blood volume; weaker perfusion produces a weaker optical pulse signal.

L12 — Why can poor peripheral blood flow make PPG heart-rate measurements less reliable?

Skin tone, skin thickness, sensor location, sensor contact/tightness, movement, and local blood perfusion.

L12 — A PPG sensor works poorly on one person but well on another. Give several variables you would investigate before blaming the sensor itself.

Cardiac muscle.

L12 — What muscle type makes up the heart?

Any lecture-consistent example: compare different sensor locations, exercise states, sensor tightness, movement levels, skin-related conditions, or compare PPG against a reference method.

L12 — Propose one follow-up experiment from the Heart Rate Lab that would test a variable affecting PPG accuracy.

Changes in ventricular electrical activity or conduction can alter QRS amplitude, duration, or shape; arrhythmias or heart damage can therefore affect the waveform.

L12 — What kinds of changes could alter the QRS waveform?