Block 3 Exam Flashcards
Implications of Poiseuille’s Law
Flow is directly proportional to axial pressure and fourth power of vessel radius
Flow is inversely proportional to length and viscosity
Assumptions of Poiseuille equation
Fluid must be incompressible
Tube must be straight, rigid, cylindrical, and unbranched, and have a constant radius
Velocity of thin fluid layer at wall must be zero
Flow must be laminar
Flow must be steady
Viscosity of fluid must be constant
What does mechanical impedance include
Compliant impedance
Viscous (or resistive) impedance
Inertial impedance
Compliant impedance
Opposes volume change
Viscous (or resistive) impedance
Opposes flow
R in dP = FR
Inertial impedance
Opposes change of flow
Four factors that generate pressure
Gravity
Compliance of the vessels
Viscous resistance
Inertia
Role of circulation
Homeostasis
Supply and Demand
What is hemodynamics and why study it?
Study of physical aspects of blood circulation
Control of flow and volume
Relationship to other systems
S1 Heart Sound
AV valves closing
S2 Heart Sound
Semilunar valves closing
S3 Heart Sound
Ventricular filling
When is S3 sound normal?
Young patients
When is S3 sound pathological?
Adults
S4 Heart Sound
Atrial kick
Caused by vibration of ventricular wall
Diastole
Filling of ventricle
~500ms
Systole
Ejection from the ventricle
~300 ms
Increase Preload
Increases EDV and SV
Increase afterload
Decreases SV
Increases ESV
Resistance in series
Greater than any individual resistance
What parts of circulation use resistance in series?
Renal portal system
Hepatic portal system
Hypophyseal portal system
Resistance in parallel
Far lower resistance than any individual resistance
What causes turbulent flow?
High velocity Pulsatile flow Changes in vessel diameter Larger vessel diameter Density of blood
What does turbulent flow help diagnosis?
Stenosis
Murmurs
Shunts
Valvular problems
Turbulent flow
Re is greater than 3000
Laminar flow
Re is less than 2000
What is transmural pressure affected by?
Physical tissue changes
Wall tension
Noninvasive and indirect measurement of cardiac parameters
Sphygmomanometry Dilution methods (urine)
Invasive and indirect measurement of cardiac parameters
Dilution methods (blood)
Noninvasive and direct measurement of cardiac parameters
Ultrasonic flow meters echocardiography & doppler
Invasive and direct measurement of cardiac parameters
Angiography cardiac catheterization
1st Korotkoff sound
Suprasystolic
No audible sounds
Artery is completely occluded
2nd Korotkoff sound
Systolic pressure
First sound
Initial blood slips through with help of ventricular contraction
3rd Korotkoff sound
Diastolic pressure Last sound (muffled) Blood flows into artery while heart rests
4th Korotkoff sound
True diastolic
Cessation of sound
Compliance
Total quantity of blood that can be stored in a given portion of the circulation for a given rise in pressure
Elastance
Opposite of compliance
Elastic tension exerted by artery when it is stretched by a volume
Average CO
5L/min
Average HR
60-100 bpm
Average stroke volume
70mL
Average SBP
120mmHg
Average DBP
80 mmHg
Average MAP
95 mmHg
What can lead to a decreased viscosity?
Low hematocrit
Anemia
Kidney failure
What can increase viscosity?
High hematocrit
High altitude
Polycythemia
Three pressures in circulation
Driving pressure
Transmural pressure
Hydrostatic pressure
Driving pressure
Difference in pressure along axis of vessel
Transmural pressure
Pressure difference across vessel wall
Hydrostatic pressure
Change in pressure due to gravity
Arteries
Distribution system
High pressure
Veins
Collection system
Low pressure
Microcirculation
Diffusion and filtration system
Arterioles + capillaries + venules
Aggregate flow
Conserved at each level of arborization
Aggregate cross-sectional area
Increases with arborization
Where does the steepest drop in pressure occur?
Across the arterioles
Vascular resistance
Depends on action of smooth muscle cells
What happens to Pc when Rpost increases?
Increases
What happens to Pc when Rpre increases?
Decreases
High Young’s modulus
High elastance
Low compliance
Low Young’s Modulus
High compliance
Low elastance
Blood pressure
Pressure exerted by the blood against the walls of the blood vessels
Systolic pressure
Pressure exerted in the arteries while blood is leaving the heart
Diastolic pressure
Pressure exerted in the arteries during the filling of the ventricle
Narrow pulse pressure
Commonly indicates decrease in stroke volume
Wide pulse pressure
Commonly indicates decrease in compliance of the aorta
Cardiac tamponade
Blood fills the pericardial sac surrounding the heart, which decreases the ability of the heart to expand, leading to a decrease in preload and stroke volume
Aortic valve stenosis
Narrowing of aortic valve, causing decrease in radius of aortic valve
What does increasing driving pressure lead to?
Increase transmural pressure Elastic wall distension Increase radius Decrease viscous resistance Increase conductance Pressure-flow curve steepens
High pressure system
Left ventricle in contracted state to systemic arterioles
Low pressure system
Systemic capillaries back to the right heart, through the pulmonary circuit, into the left heart in the relaxed state
Three groups of capillaries
Continuous
Fenestrated
Discontinuous (Sinusoidal)
Continuous capillary
Most common form
Interendothelial junctions
Fenestrated capilary
Perforated with fenestrations
Surround epithelia
Discontinuous capillary
Large gaps
Fenestrae
Found in sinusoids
AV valves
Inlet valves of ventricles
Tricuspid valve
Between right atrium and right ventricle
Mitral valve
Bicuspid valve
Between left atrium and left ventricle
Seminlunar valves
Outlet valves of ventricles
Pulmonary valve
Between right ventricle and pulmonary artery
Aortic valve
Between left ventricle and aorta
Cardiac cycle phases
Inflow phase
Isovolumetric contraction
Outflow phase
Isovolumetric relaxation
Inflow phase
Inlet valve is open
Outlet valve is closed
Isovolumetric contraction
Both valves are closed
Outflow phase
Outlet valve is open
Inlet valve is closed
Isovolumetric relaxation
Both valves are closed
Protodiastolic gallop
Ventricular gallop
S1-S2-S3
Presystolic gallop
Atrial gallop
S4-S1-S2
Maximize rate of O2 uptake
Increase HR
Increase SV
Increase Oxygen extraction
Microcirculation components
Terminal arteries Arterioles Metarterioles Precapillary sphincters True capillaries Venules
What components are innervated?
Terminal arteries
Arterioles
Venules
What components are not innervated?
Metarterioles
Precapillary sphincters
True capillaries
Parts of true capillaries
Basement membrane
Interendothelial junctions/tight junctions/claudins
Coated pits/caveolin-coated vesicles
Glycocalyx
Vasoconstriction
Increased resistance
Vasodilation
Decreased resistance
Vasomotion
Rhythmic oscillations superimposed on a tonic contraction
OR
Spontaneous contractions caused by rhythmic oscillations in Ca2+ and membrane potential
Partial pressure of O2 depends on:
Dissolved O2 in blood O2 content of RBC Capillary blood flow Radial diffusion coefficient of O2 Capillary radius O2 consumption by surrounding tissue cylinder Axial distance along length of capillary
Solute flux
Refers to movement of solute X per cm^2 of capillary wall
Solute flow for an entire organ
Addition or removal of solute X to/from the organ
Positive Jv
Filtration
Water leaving capillary
Negative Jv
Absorption
Water entering capillary
Jv
Volume flux
Lp
Hydraulic conductivity
Pc
Hydrostatic pressure in capillary
Pif
Hydrostatic pressure in interstitial fluid
Pi(c)
Colloid osmotic pressure in capillary
Pi(if)
Colloid osmotic pressure in interstitial fluid
Sigma
Average colloid osmotic reflection coefficient of capillary wall
What decreases pi(c)
Nephrotic syndrome
Pregnancy
Malnutrition
Starling force
Mechanical pressure difference
Starling hypothesis
Overall transendothelial gradients of starling forces, obtained from “bulk solution” measurements of P and pi
Endothelial cells of initial lymphatics
Oak leaf-shaped
Lack junctions at tip
Anchored on sides by discontinuous button-like junctions
Endothelial cells of collecting lymphatics
Conventional, continuous, zipper-like junctions also found in endothelial cells of blood vessels
Free edges
Sites of fluid transit
Three convective loops of extracellular water
Cardiovascular loop
Transvascular loop
Lymphatic loop
Distribution of vessels
Conductance vessels
Arteries
Diffusion/Filtration vessels
Capillaries
Resistance vessels
Arterioles
Venules
Collection vessels
Capacitance vessels
Veins
Pulse pressure
SBP - DBP
Perfusion Pressure
Pa - Pv
Artery makeup
Intima
Media
Adventitia
Adventitia makeup
Collagen
Fibroblasts
Vasa vasorum
Nerves
Normal endothelial cell function
Impermeable to large molecules Anti-inflammatory Resist leukocyte adhesion Promote vasodilation Resist thrombosis
Normal smooth muscle cell function
Normal contractile function
Maintain extracellular matrix
Contained in medial layer
Activated endothelial cell function
Increase permeability Increase inflammatory cytokines Increase leukocyte adhesion molecules Decrease vasodilatory molecules Decrease antithrombotic molecules
Activated smooth muscle cell function
Increase inflammatory cytokines
Increase extracellular matrix synthesis
Increase migration and proliferation into subintima
Regulation of vascular tone
Multi-organ system input
Extrinsic regulation of vascular tone
Constriction
Neural
Humoral
Intrinsic regulation of vascular tone
Dilation Tissue metabolites Local hormones Myogenic Endothelial factors
Nitric oxide
Vasodilator
EDHF
Vasodilator
ET-1
Vasoconstrictor
PGI2
Vasodilator
P-MLC/t-MLC ratio
Molecular signature of smooth muscle cell force production
Endothelial cell function
Respond to shear and other stimuli
Health of endothelium
Determines the net effect of signals to endothelial and smooth muscle cells
O2 consumption
Cardiac work
Coronary flow reserve
Exercise stress test
Chemical stress test
Adenosine infusion
Vascular disease
Endothelial dysfunction, early marker of vascular disease
Mechanism of vascular disease
Reduced bioactivity of NO
Oxidative stress: NO inactivation
Decreased NO synthase protein
Vascular disease featured in:
Diabetes
Hypertension
Atherosclerosis
Autoregulation
Intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure
High autoregulatory ability
Cerebral
Coronary
Renal
Low autoregulatory ability
skin
Formed elements of blod
RBCs
WBCs
Platelets
GM-CSF
Stimulates proliferation of a common myeloid progenitor
Promotes production of neutrophils, eosinophils, and monocytes
G-CSF and M-CSF
Guide ultimate development of granulocytes and monocytes-macrophages/dendritic cells
IL-5
Sustains terminal differentiation of eosinophilic precursors
EPO
Homologous to TPO
Supports erythropoiesis
Proerythroblasts
Lack hemoglobin
Major tasks of RBCs
Carrying O2 from lungs to systemic tissues
Carrying CO2 from tissues to lungs
Assisting in the buffering of acids and bases
Two functions of macrophages
Phagocytosis of pathogens or cellular debris
Presentation of antigens to lymphocytes
Wigger’s diagram phase 1
Filling
Inlet valve is open
Wigger’s diagram end of phase 1
Atria contraction
Atrial kick
Wigger’s diagram phase 2
Isovolumetric contraction
Wigger’s diagram phase 3
Outlet valve opens
Ejection
Wigger’s diagram phase 4
Isovolumetric relaxation
What do smooth muscle lack that both skeletal and cardiac have?
Troponin
VSMC contraction
Increased Ca2+
Decreased cAMP
Decreased cGMP
VSMC relaxation
Decreased Ca2+
Increased cAMP
Increased cGMP
Requirements of vasomotion
Endothelial cells VSMCs Cav channels Cl channels SR (SERCA + RYR) Gap junctions
What is not required for vasomotion
Neuronal input
Regulated contraction
Central
Local
Central control
Nervous system
Humoral agonists
Local control
Myogenic
Metabolic
Endothelial
Nervous system control
NE
Epi
ATP
Neuropeptide Y
Sympathetic vasoconstriction in blood vessels
Norepinephrine
Adrenal medulla mediated vasodilation of blood vessels
Epinephrine
Parasympathetic vasodilation of erectile tissue
Co-release of ACh, NO, VIP
Parasympathetic vasodilation of salivary gland
ACh
Sympathetic vasodilation of sweat gland
Cholinergic ACh
Sympathetic vasodilation of blood vessels of muscle
Cholinergic ACh
Humoral control
Angiotensin II
ADH
Serotonin
Neuropeptide Y
Endocrine/Paracrine vasoconstriction
Angiotensin II
ADH
Serotonin
Neuropeptide Y
Endocrine/Paracrine vasodilation
Histamine
VIP
ANP
Local control
Myogenic
Metabolic
Endothelial
Endothelin
Vasoconstrictor
Nitric oxide
Vasodilator
Autoregulation location
Coronary
Cerebral
Renal
Systemic capillaries
No capillary pulse
Pulmonary capillaries
Small pulsations