biofluids & dynamics
DESCRIPTION
Biofluids & Dynamics. Studies the way that fluids move in the human body. Gastric acid/Juice. Pericardial fluid. Amniotic fluid. BLOOD. Urine. Mucus. Synovial fluid. Pus. Saliva. Blood Flow. Understanding the relationship between blood and its containing vessels. - PowerPoint PPT PresentationTRANSCRIPT
Biofluids & Dynamics
Studies the way that fluids move in the human body
BLOOD
Amniotic fluid
Gastric acid/Juice Pericardial
fluid
Mucus
PusSaliva
Synovial fluid
Urine
Blood Flow
• Obstructions in blood passageways • Smallest transport lines for blood/some
point allows individual RBC’s
Understanding the relationship between
blood and its containing vessels
• Research on small blood passages in cancer cells Treatment of Cancer
Biofluid mechanics
Biofluids Mechanics Biomechanics
Study of Fluid Movement in the
BodyAnalysis of any
Dynamic System
Mechanics applied to
Biological entity
Biofluid Mechanics
Newton’s Laws
First Law: An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.
Second Law:When a force is applied to an object, it accelerates.
The acceleration takes place in the direction of the applied force, and is proportional to the magnitude of the force. It is also inversely proportional to the mass of the object.F = ma Where F is the force (N), m is the mass in kg, and a is the acceleration in metres per second squared. F and a are vectors.
Third Law: To every action there exists an equal and opposite reaction
Stress
Stress = Load applied / Sectional Area
Normal Stress: Force acting perpendicular to the plane
Shear Stress: Force acting tangential to the plane
Strain = Change in length / Original length
E = Stress / Strain
Hook’s Law
Strain
Hook’s Law: The ratio of stress to strain is a constant
Hook’s Law does not depend on time
Elasticity
Physical property of materials which return to its original shape after they are deformed
Stress-Strain Curve
Hook’s Law
Materials E (GPa)
Mild Steel 200
Oil Paint 1.66
Rubber 0.01-0.1
Collagen 6
Which one is Elastic??
Collagen
Triple Helix
Madras Model
Linear Elasticity Pseudo Elasticity
Study of how solid objects deform and become internally stressed due to loading conditions
Elastic response to an applied stress, caused by phase transformation (austenite and martensite) of a crystal
Elasticity exhibit in Fluids
Fluid is a substance which deforms continuously when subjected to shear forces
• Newtonian Fluids• Non- Newtonian
Fluids
Newtonian Fluids : Fluids which obey Newton’s law of Viscosity
• Water
• Air
Non-Newtonian Fluids : Fluids which do not obey Newton’s law of Viscosity
• Pastes• Gels• Polymer
solutions
Various Non-Newtonian behaviors:
Time Independent
• Bingham –plastic
• Pseudo plastic• Dilatant fluids
Resist small shear stress but flow easily under large shear stress. Eg: tooth paste, jellies
Viscosity decreases with increase in velocity gradient (Shear Thinning Fluids). Eg:
Polymer solutions, Blood
Viscosity increases with increase in velocity gradient (Shear Thickening Fluids).
Time dependent
• Thixotropic fluids
• Rheopectic fluids
• Viscoelastic fluids
Viscosity decreases as the duration of stress increases
Eg: Honey
Viscosity increases as the duration of stress increasesEg: Gypsum suspension in
water
Fluids which exhibits both elastic and viscous
characteristics Eg: biopolymers
Newton’s Law of Viscosity
States that “Shear stress between adjacent fluid layers is proportional to the negative value of the velocity gradient between the two layers”
ViscosityMeasure of resistance of a fluid which is being deformed either by shear stress or tensile stress
“Thickness or internal friction”
Water
Honey
Viscoelastic materials
Materials for those the relationship between stress and strain depends on time
Materials that exhibit both viscous and elastic characteristics when undergoing deformation
Properties : • Hysteresis is seen in the stress-strain curve• Stress relaxation occurs: constant strain
causes decreasing stress• Creep occurs : constant stress causes
increasing strain
Hysteresis: If a body is subjected to a cyclic loading, the stress-strain relationship in the loading process usually different from the unloading process and this phenomenon is called hysteresis
Stress Relaxation: When a body is suddenly strained and then the strain is maintained constant afterward, the corresponding stresses induced in the body decrease with time
Creep: If the body is suddenly stressed and then the stress is maintained constant afterward, the body continue to deform and the phenomenon is called Creep
Elastic Vs Viscoelastic materials
a) Elastic materialb) Viscoelastic material
Elastic Viscoelastic
Elastic component Elastic and viscous components
Do not dissipate energy Losses energy
No hysteresis Hysteresis
Types of Viscoelasticity
• Linear Viscoelasticity• Non-linear
Viscoelasticity
Function is separable in both creep response and loadApplicable only for small
deformations
Function is not separable. Applicable for large
deformations
Models : Linear Viscoelasticity
Viscoelastic Materials can be modeled to determine the stress or strain interactions and their temporal dependencies
Modeled
Models :
• Maxwell model• Kelvin-Voigt model• Standard Linear Solid model
“To predict a materials response under different loading conditions”
Viscoelastic material
Elastic Viscous
Springs Dashpots
“Electrical circuits”
Elements and their electrical equivalence
Elements Electrical
Stress Voltage
Derivative of strain Current
Elastic modulus of spring (E) Capacitance
Viscosity resistance
Elastic component Springs
Viscous component Dashpots
σ - stress, η - viscosity of the material, and dε/dt - time derivative of strain
σ - stress, E - elastic modulus of the material, and ε - strain that occurs under the given stress
Maxwell Model
Viscous Elastic
“Viscous damper and elastic spring connected in series”
“It predict that stress decays exponentially with time, accurate for most polymers”
Limitation: “It does not predict creep accurately”
Kelvin-Voigt Model
“Viscous damper and elastic spring connected in parallel”
“Extremely good in modeling creep in materials but less accurate in modeling relaxation”
Applications: Organic polymers, rubber, wood when load is not high
Standard Linear Solid Model (Kelvin model)
“Combines Maxwell model and Spring in parallel”
“Accurate in predicting material responses compared to Maxwell and Voigt’s model but the results for strain under specific loading conditions are inaccurate”
Biological tissues: Cartilage, bone, skeletal muscle, cardiovascular tissue, tendon and ligament
Use of Viscoelastic models
“Biomechanics” – Biological tissues have Viscoelastic properties
Vascular Tree
Blood Flow, Blood Pressure and Resistance
Blood Flow: Volume of blood flowing through a vessel, organ or entire circulation in a given period (ml/min)Blood flow of entire circulation is equal to cardiac output
Blood Pressure: Force per unit area exerted by blood against a vessel wall (mm Hg)
Resistance: It is a measure of the friction between blood and the vessel wall
a) Blood Viscosityb) Blood Vessel Lengthc) Blood Vessel Diameter Radius increases: resistance drops
exponentially
Total Peripheral Resistance: Resistance throughout the entire systemic circulation
Relationship between Flow, Pressure and Resistance
Blood flow
Q = A x V A – area, V - velocity
P1 V1
P2 V2 P1 – 5 barV1 – 2 m/sP2 - ?V2 – 3 m/s
P1-P2 = 0.5 x (V22 – V1
2)
P2 = 2.5 bar
Bio-Viscoelastic FluidsBiological fluids that exhibits both viscous and elastic characteristics
Biological Viscoelastic Fluids: Saliva, mucus and synovial fluid
Saliva
Function:a) Protect hard and soft oral tissues from wear, dehydration,
demineralization, chemical insult and microbial imbalanceb) Lubricative function
Mucins Proline
• High & low molecular
weight, secreted from sub
mandibular – sublingual
salivary glands
• Secreted from parotid
glands
Saliva is a dilute Viscoelastic polymer solution with very low shear modulus
Synovial Fluid
• Pale, yellow viscous fluid, non-Newtonian • Lubrication and
Nutrition of joint tissues • Hyaluronic acid
High-molecular weight polysaccharide
Volume of normal synovial fluid in the Knee joint is estimated around 0.5 to 2 ml
Viscosity depends on rate of shear
Thixotropic (time dependent)
Synovial resembles to egg albumin
MucusSlippery secretion
covered by mucus membrane
Viscous colloid containing antiseptic enzymes (lysozyme), immunoglobulins, inorganic salts, proteins (lactoferrin) and
glycoproteins (mucins)
Serve to protect epithelial cells in the respiratory, gastrointestinal, urogenital, visual and auditory
systems
Mucus from the respiratory tract
Aid in the protection of the lungs by trapping foreign particles
“Phlegm”
Nasal mucus is produced by nasal mucosa
Small particles, such as dust, particulate pollutants, allergens and infectious agents such as bacteria
The body’s natural reaction is to increase mucus production
Aids in moisturizing the inhaled air and prevents tissue (nasal and airway epithelia) drying out
Increased mucus production in the respiratory track is a symptom of many common illnesses. i.e common cold and influenza
Hyper secretion in case of inflammatory respiratory diseases i.e allergic reaction, asthma and chronic bronchitis
Mucus in the Digestive system
Mucus acts as lubricant for
materials that must pass over
membranes
A layer of mucus along the inner wall of stomach is vital to protect the cell linings of that organ from the highly acidic environment
within it
Protoplasm
Living content of a cell surrounded by plasma membrane
Cytoplasm
Composed of mixture of small molecules such as
ions, amino acids, monosaccharides, water
and macromolecules such as nucleic acid, proteins,
lipids and polysaccharides
1) Significant features of non-Newtonian fluids?
2) How mucus play an important role in controlling antigen present in the system?
3) What is meant by Pseudo-elasticity?
4) Short notes on i) Hookes law, ii) Newtonian and non-Newtonian fluids, iii) Resistance against flow
5) What is bioviscoelastic fluid? Explain its biological functions with example
Previous year Q
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