Biomechanics and Continuum Mechanics (Biomechanics II) Flashcards
Continuum Mechanics is concerned with:
- The mechanical behavior of solids and fluids
-On a scale in which their physical properties (mass, momentum, energy, etc) can be defined by - Continuous or piecewise continuous functions
- The scale of interest is “LARGE” compared with the characteristic dimension of the discrete constituents (e.g. cells in tissue, proteins in cells)
- In a material continuum, the densities of mass, momentum and energy can be defined at a point
What else is Continuum Mechanics involved with?
- Geometry and structure
- Boundary conditions
- Conservation laws such as mass, energy, and momentum
- Constitutive equations
What is involved with Physiology?
- Anatomy and morphology
- Environmental influences
- Biological principles such as mass transport, growth, and metabolism
- Motion, flow, equilibrium
- Structure-function relations
What are the different types of Conservation Laws
- Conservation of Mass
- Lagrangian (nodes)
- Eulerian (mesh) - Conservation of Momentum
- Linear
- Angular - Conservation of Energy
Describe the Heart (NOT FUNCTIONS)
- First organ developed
- Pumps over 7k liters of blood along 1 million miles of vessels daily
- Contracts over 3 billion times over the lifespan
- Cardiomyocytes occupy about 80% of the heart volume
- Embryonic cardiomyocytes can contract and divide simultaneously
What are the 3 Functions of the Heart
- Generating blood pressure
- Required for blood flow through the blood vessels - Routing blood
- Two pumps, moving blood through the pulmonary and systemic circulations - Regulating blood supply
- Adjusts blood flow by changing the rate and force of heart contractions as needed
Describe the Starling’s Law of the Heart
- Compares Stroke Work to Preload (EDV or EDP)
- When the heart fills with more blood, the cardiac muscle stretches
- The stretched muscle contracts with more force
- The heart pumps out more blood during systole
- This increases cardiac output
What formula is associated with Stroke Volume?
SV=EDV-ESV
What formula is associated with Ejection Fraction?
EF=SV/EDV
Explain ECMO (Extracorporeal membrane oxygenation)
- Provides cardiac and respiratory support oxygen to patients
- Veno-Atrial (VA) and Veno-Venus (VV) formats
Principles of Sphygmomanometry
- Cuff inflated until brachial artery compresses and blood flow stops >120 mmHg and no sound is heard
- Slowly release pressure until you hear sound
- Should be between 120 mmHg for systole and 80 mmHg for diastole
Not sure if we need serum reports, but that is found here
LOOK AT SLIDES!
What are Glucose measurements used for?
Used in the diagnosis and treatment of carbohydrate metabolism disorders including diabetes mellitus, neonatal hypoglycemia, idiopathic hypoglycemia, and pancreatic islet cell carcinoma
How can we relate Oxygen with Blood Glucose?
Oxygen is consumed at the same rate as glucose reacts to form gluconic acid
What are the 3 types of Lipoproteins?
- VLDL and Chylomicrons: Worst! Potentially pro-inflammatory and >30 nm
- LDL: Medium, Potentially pro-inflammatory and 2–22 nm
- HDL: Best! Potentially anti-inflammatory and 9-15 nm
Look at slides for the Role of Lipoproteins in Atherogenesis
- Look at slides!
- Note:
- HDL prevent oxidative modification of LDL which prevents its continuation to advanced fibrocalcific lesion
- HDL causes LDL and VLDL to go to the liver which causes cholesterol to be excreted
How are Cholesterol esters hydrolyzed?
Cholesterol esters are hydrolyzed by cholesterol esterase to cholesterol and fatty acids
What are the desirable, borderline, and high reference ranges for cholesterol
- Desirable: <200 mg/dL
- Borderline: 200-230 mg/dL
- High: >240 mg/dL
Compare the different types of fat plus the effects on Cholesterol levels
- Monounsaturated: Best fat! Lowers LDL and Raises HDL
- Polyunsaturated: Lowers LDL and Raises HDL
- Saturated: Raises both LDL and HDL
- Trans: WORST FAT! Raises LDL
What are some main sources of the types of fats
- Monounsaturated: Olives, olive oil, canola oil, and peanut oil
- Polyunsaturated: Corn, soybean, fish, and safflower
- Saturated: Whole milk, butter, cheese, ice cream, red meat, coconut, egg yolk, and chicken skin
- Trans: Most margarines, vegetable shortening, deep-fried chips, fast food, and commercial baked goods
Compare a Fasting Lipid Panel from a Non-fasting Lipid Panel
- Non-fasting Lipid Panel: Measures HDL and total cholesterol
- Fasting Lipid Panel:
- Measures HDL, total cholesterol, and triglycerides
- LDL cholesterol is calculated by saying LDL cholesterol = total cholesterol - (HDL + triglycerides/5)
What are the Goals/Optimals for Lipids in terms of LDL, Total Cholesterol, HDL, and Serum Triglycerides
- LDL: <100 is optimal
- Total Cholesterol: <200 is desirable
- HDL: <40 is Low and >60 is High
- Serum Triglycerides: <150 is normal
In human blood plasma, the reference range of uric acid is what in males and females
Male: 4-6 mg/dL
Female: 3-5 mg/dL
Note:
- Uric acid concentrations in blood plasma above normal (>6mg/dL) is known as hyperuricemia
- Uric acid below normal (<3mg/dL) it is known as hypouricemia
What are the 2 main reasons of hyperuricemia?
- About 10% of cases produce too much uric acid
- About 90% of cases are unable to excrete enough uric acid into the urine
Uric Acid and Gout. Do mean get gout more or women?
- Excess serum accumulation of uric acid can lead to a type of arthritis known as gout
- This is needle-like crystals of uric acid precipitating in joints and capillaries
- Gout occurs when serum uric acid levels are as low as 6 mg/dL
- Men get gout MORE than women due to men having more metabolic activity
Purposes of Oxygen
- Essential for human function
- Necessary for proper cellular metabolism (without oxygen, lactic acid builds from anaerobic metabolism)
- Oxygen transport ( About 2% of oxygen gets dissolved in plasma and oxygen is bound to hemoglobin in blood (98%) )
NOTE: Hemoglobin can carry 4 oxygen molecules
What is the Beer-Lambert Law?
- Beer’s Law: The absorption of light is proportional to the concentration of a sample
- Lambert’s Law: Absorption is proportional to the thickness of a sample
What are the Principles of Pulse Oximetry
- Based on differential absorption of light by oxyhemoglobin and deoxyhemoglobin
- Oxygenated hemoglobin allows red light (660nm) to transmit through and absorb more infrared light while the deoxygenated hemoglobin allows infrared (940nm) to transmit through and absorbs more red light.
- HbO2 higher at infrared
- Hb higher at red
After the Photodetector in Pulse Oximetry, what ratio is calculated and what do the ratios correspond to?
- The Red/Infrared ratio
- Ratio corresponds to SpO2
- 0.5 is approx. 100%
- 1 is approx. 85%
- 2 is approx. 0%
What does Pulse Oximetry measure?
- Measures oxygen saturation of hemoglobin
- Infrared and Red light emitted into tissue
- Sensor then reads amount returned to photo detector
- Hemoglobin reflects light differently when oxygenated vs. not oxygenated
- Saturation is measured with each pulse as blood passes
What are Readings of Pulse Oximetry + what is reasonable?
- Readings are measured in SpO2
- Average reading is 95-99%
- Acceptable range is 93-100%
- Oximetry also gives a pulse reading
What are 5 Complications with Oximetry?
- Hypoperfusion (Not enough blood in capillary bed to obtain accurate reading)
- Site is too cold
- Patient movement can alter effectiveness
- Nail Polish (especially metallic particles)
- Carbon monoxide poisoning (Hemoglobin gets saturated with compounds other than Oxygen)
How do Infrared Thermometers work?
- Anything above o Kelvin emit electromagnetic waves associated with its surface temperature
- These sensors work based on the infrared emissions from the object being measured
- No contact needed
Ideally, an IR Thermometer consist of a sensor and a detector. Describe what they do
- Sensor: Monitors the temperature of a detector
- Detector: Gets the radiative heat transfer of the object’s surface
Maybe Question: What is the Operating principle of Infrared Thermometers?
Stefan-Boltzmann law (LOOK AT SLIDES!!!)
What wavelength can humans see?
400 nm - 700 nm
What are the limitations of IR Thermometers?
- Limited variety of lenses a filter can be chosen to build IR Emission Thermometers
- IR refractive materials have high absorption of light. Thus, there is a limitation with lenses since they need to be relatively thick
