Exam 1 Flashcards
Preload
End-diastolic volume
After load
Stress in the wall of left ventricle during ejection (SVR/TPR)
SVR
Systemic vascular resistance (afterload)
TPR
Total peripheral resistance
Contractility
Inotropy- innate ability of the heart muscle to contract and generate force
Treppe reflex
Increases in HR result in increases in contractile force
Frank-starling mechanism
Ability of heart to change its force of contraction and therefore stroke volume in response to changes in venous return
Cardiac output =
Heart rate x stroke volume
Blood pressure =
Cardiac output x total peripheral resistance
As BP decreases, the baroreceptor firing rate …….and sympathetic output….
Decreases (think foot off the brake)
, increases
Anrep reflex
With an abrupt increase in afterload, contractility increases to prevent dangerous decreases in SV
Bainbridge Reflex
Increase venous return-> stimulation of right atrium stretch reflex -> tachycardia
VO2 =
Cardiac output x (A-V) O2 difference
Q= (think pressure)
Change in pressure/resistance (r^4)
Q= (think velocity)
Velocity x Area
Heart layers from outside to inside
Epicardium, myocardium, endocardium
Myocardial Cells
Branching, one central nuclei, intercalated discs
Gap junctions
Form between myocardial cells allowing small molecules including ions to pass
Wigger’s diagram
Cardiac cyle
Pressure/volume diagram
A-mitral valve opens, B-mitral valve closes, C- aortic valve opens, D- aortic valve closes
SA Node Rate
60-100
AV Node Rate
40-60
Ventricular/Purkinje System Rate
20-40
Parasympathetic control on HR
SA and AV nodes concentrating in atria
Sympathetic node control
Supply SA/AV nodes and muscles of the ventricles
Chronotropy
Heart rate
Dromotropy
Conduction velocity
Inotropy
Contraction of myocardium
Lusitropy
Relaxation of myocardium
What does Epi/norepi effect on alpha 1 receptors?
Located on smooth muscle and causes vasoconstriction
What does Epi/norepi effect on beta-1 receptors?
Heart - increases HR, contractility, conduction velocity
What does Epi/norepi effect on beta-2 receptors?
Lungs- smooth muscle in coronary arteries and lungs causing vasodilation
When in cardiac cycle does the heart get its own blood?
Diastole
Functions of pericardium
Reduce friction with contraction, stabilizes/anchors heart in thorax, protection, promotes distribution of contractile forces
Cardiac Tamponade
Build up of fluid in the pericardium
Windkessel Effect
Arteries distend when blood pressure rises in systole and recoil when BP falls in diastole - keeps blood flow constant down stream
Function of small arteries and arterioles
Regulate BP, regulate blood distribution
Capillaries
Function to provide area of exchange for gases, nutrients and waste.
Single layer of endothelial cells
Associated with contractile pericytes
Venous system
Return blood to heart, serve as reservoir for blood (capacitance vessel)
Auto regulation
Attempts to maintain a constant blood flow of an organ despite changes in perfusion pressure
Mean Arterial Pressure (MAP)=
Diastolic BP + 1/3(SBP-DBP)
Represents organ perfusion pressure (NEEDS to be above 60mmHg)
Normal resting membrane potential
-70mV
Hyperkalemia
Too much potassium (membrane potential become more positive) - happens in kidney disease, diabetes, post-op
Can lead to spontaneous cell depolarization altering nerve, heart and muscle function
Potassium
Normal:3.5-5.3
Hyperkalemia: >5.3
Signs: fatigue, muscle weakness, flaccid paralysis
ECG: widening of QRS, tachycardia, cardiac arrest
Hypokalemia
Fatigue, paralysis, respiratory failure
ECG: st segment depression, PVC/PAC, v-fib
Cardiomyocyte action potential curve:
4: resting cell
0: sodium comes in
1: potassium comes out
2: calcium comes in, potassium comes out
3: potassium comes out
Exercise Stress Test
Progressively stress cardiovascular and pulmonary systems in a controlled manner
Exercise test
Speed/elevation/resistance
Goal: 8-12min
Large muscle groups and rhythmic in nature
Pharmacological Test
Used for those who cannot exercise
Dipyridamole(persantine) - vasodilator
Adenosine- vasodilator
Dobutamine- increases HR/contractility
Submaximal test
Test is terminated at predetermined end point- HR/specific workload/time point
Maximal test/graded exercise test
Peak- symptom limited
Max- specific conditions must be met
VO2 max criteria
HR:BP plateau even though workload increases
Within 5-15beats of predicted max HR
Blood lactate > 8-100mmol/L
Heart Failure (ventilation)
Increased ventilation at all workloads
Decreased maximal ventilation
Increased CO2 production at all workloads
Phase 1 cardiac rehabilitation
F: mobilization 2-4x daily
I: 3-5 METs , resting HR + 50bpm
T: progress to >150min light to mod
T: AROM, ADLs, light resistance
Phase 2 cardiac rehab
F: 3-5x per week
I: HR based or RPE
T: greater than 150min per week mod
T: aerobic and resistance exercise training
BP and exercise
Systolic: increases with intensity
Diastolic: stays relatively the same 10-15mmhg
Rate Pressure Product
Measure of the stress put on cardiac muscle
RPP= HR x systolic BP
Pharmacokinetics
How body acts on drug
Absorption
Distribution
Metabolism
Elimination
Pharmacodynamics
How drug acts on body
ADR
Adverse drug reaction
Portal Circulation (first pass metabolism)
The circulation of nutrient rich blood between the gut and liver. Portal venous blood contains all products of digestion absorbed from GO tract
Bioavailability
Amount of drug that reaches the systemic circulation
Volume of distribution
The total amount of drug in the body compared to the concentration in the bloodstream
Half Life
Time it takes for concentration of drug to be reduced by 50%
Steady state
When clearance rate and dose rate are equal - continuous infusion is 3-5 half lives
Long half life
Drug takes a long time to reach steady state - a loading dose is often given
Short half life
Drug reached steady state quicker
Higher potency
Similar effect at lower dose
Efficacy of drug
% response
