Unit 1 Day 1 Flashcards
Function of CV System
- provide cells with nutrients and to exchange oxygen
- to maintain homeostasis
Series Arrangement Circulatory
-blood flow in L and R heart is arranged in series, and therefore must be closely matched
Parallel Arrangement Circulatory
- systemic circulation is primarily in parallel
- changes in metabolic demand or blood flow to one organ does not affect other organs
4 Chambers of Heart R to L
- right atrium
- right ventricle
- left atrium
- left ventricle
4 Vessels of Heart R to L
- superior/inferior vena cava
- pulmonary artery
- pulmonary vein
- aorta
4 Valves of Heart R to L
- tricuspid
- pulmonary
- mitral (bicuspid)
- aortic
MIcrocirculation Arrangement
- arterioles to capillaries to venules
- blood flow determined by pressure and regulated by arterioles and precapillary sphincters
Function of Lymphatic System
- carries fluid from interstitial space to blood supply
- filters interstitial fluid in lymph nodes
Flow Equation
Q = deltP/R
- Q is flow (vol/time)
- deltP is pressure difference
- R is resistance
Poiseuille’s Equation
Q = deltP [(pi r^4)/(8nl)]
- Q is flow
- r is radius
- l is length of vessel
- deltP is pressure difference
- n is viscosity of blood
Pulsatile Flow
- heart beat produces pulsatile flow
- pulse pressure is dampened in arterial system
- flow is continuous in capillaries
Vascular Compliance
C = deltV/deltP
- C is compliance
- deltv is change in volume
- deltP is change in pressure
- compliance represents the elastic properties of vessels
LaPlace’s Law
T = (deltP x r)/u
- T is tension (or wall thickness)
- deltP is transmural pressure
- r is radius
- u is wall thickness
Fick’s Principle
Xused = Xi - Xo
- Xused is amount used
- Xi is initial amount
- Xo is final amount
- can be used to determine transcapillary efflux
- needs more info
Starling’s Equation
Flux = k[(Pc - Pi) - (PIc - PIi)]
- flux is net movement across capillary wall
- k is constant
- Pc is capillary hydrostatic pressure
- Pi is interstitial hydrostatic pressure
- PIc is capillary oncotic pressure
- PIi is interstitial oncotic pressure
- net hydrostatic pressure tends to be outward (filtration)
- net oncotic pressure tends to be inward (reabsorption)
- balance between hydrostatic and oncotic pressure in capillary bed determines the direction of transcapillary transport
Unique Cellular Properties of Cardiac Muscle
- 2-3 billion cardiac muscle cells
- striated (like skeletal muscle)
- not under direct neural control
- shorter, narrower, and richer in mitochondria than skeletal muscle cells
- ATPase activity of cardiac muscle is slower than skeletal muscle but faster than smooth muscle
- Ca2+ binding to troponin regulates actomyosin interaction
Cross-Bridge Cycle
- rest state- no Ca2+, weakly bound, non-force generating
- transition state-Ca2+ bound, XB weakly bound, non-force generating
- active state-Ca2+ bound, XB strongly bound, force generating
- active state- no Ca2+, XB strongly bound, force generating
Length-Tension Relationship (Frank-Starling) of Cardiac Muscle
- intrinsic mechanism by which the heart adapts to changes in preload
- violation of Starling’s Law corresponds to heart failure
- the effect of increasing preload on increasing force of contraction
- length-tension relationship: inc. volume in ventricle and cells stretch
- greater preload = greater force generated
Mechanisms Behind L-T Relationship
- extent of overlap
- change in sensitivity of myofilament to calcium
- inc. calcium release
- cardiac titin isoform is very stiff, resists stretch
Sarcomeric changes associated with heart failure
- contractile function is depressed in heart failure
- needs update
Cardiac Output
- volume of blood pumped per min by L ventricle
- CO = heart rate x stroke volume = 5 L/min
- stroke vol = vol blood pumped per beat
4 Phases of Cardiac Cycle
- diastole
- isovolumetric contraction phase
- ejection phase
- isovolumetric relaxation phase
End Diastolic Pressure-Volume Relationship Phase (EDPVR)
- pressure-volume relationship during filling of heart BEFORE contraction
- represents the PRELOAD on the heart
Preload
- length to which a muscle is stretched before shortening
- for L ventricle, preload ~ end diastolic volume
- inc. in preload = inc. in stroke volume
Afterload
- the load against which a muscle contracts
- for L ventricle, afterlaod ~ aortic pressure
- inc. in afterload = dec. in stroke volume
Systolic Pressure-Volume Relationship (SPVR)
- afterload
- pressure-volume relationship at peak of isomeric contraction
PV Loop Diagram
- diagram of pressure and volume during cardiac cycle
- see an example
Stroke Volume
-volume of blood pumped per beat
Stroke Work
- energy per beat in Joules
- corresponds to area inside PV loop diagram
- NOT same for L and R sides of heart- L heart does more work
Pulse Pressure
-difference between systolic and diastolic pressure points
Contractility
- inotropy
- length-independent mechanism
- most obviously regulated via sympathetic nervous system stimulation
- inc. in contractility = inc. in stroke volume
