Lecture 15 Flashcards
right heart pumps blood to the _______
left heart pumps blood to the _______
lung back to left atrium
the body
Measurement of how much blood is pumped from the heart per min
cardiac output (CO)
formula for cardiac output
Function of stroke volume (SV) X heart rate (HR)
_____ is the amount (mL) of blood leaving heart with each beat
Determined by: _________________
_____ mL**
_____ is the number of beats per minute
70 mL X 80 bpm = 5600 mL = 5.6 L
(SV)
1) preload, 2) afterload and 3) myocardial contractility
70
(HR)
heart rate primarily determines by __________
nerves and hormones
stroke volume from _____________
blood volume
vascular resistance
cardiac output ______ with age.
CO is ____ proportional to overall metabolic demand and overall oxygen demand
CO also controlled by _________
at rest?
with exercise?
declines
directly
local tissue flow
- 4 mL/min/100 g muscle
- 200 mL/min/100 g muscle
Calculate the CO
A 60 year old male has a resting heart rate of 75 beats/min, arterial pressure 130/85 mm Hg, body temperature was normal. Using the pressure volume diagram below.
What is the stroke volume? CO in L/min?
135-65= 70 mL for SV
70 x 75 = 5,250 mL = 5.25 L/min
Cardiac Index
- Output increases in proportion to _________
- Index refers to CO per _________
- Preferred expression of CO
- Calculated by ______________
Normal hemodynamic measures ________ L/min/m2
Average cardiac index _____ L/min/m 2
Minimally accepted level _____ L/min/m2
body surface area
square meter
dividing the CO by the body surface area in meters squared
2.8 to 4.2 L/min/m2
3 L/min/m 2
2 L/min/m2
volume of blood in the ventricles at the end of diastole
preload
resistance left ventricle must overcome to circulate blood
afterload
preload is increased in ________-
hypervolemia
regurgitation of cardiac valves
heart failure
Afterload is increased in __________
hypertension
vasoconstriction
more afterload=more cardiac workload
Mechanisms to compensate for defects which could make the heart’s pumping action ineffective
cardiac reserve
Include hypertrophy, enlargement, increase in heart rate, increase in stroke volume
- A normal heart can pump up to _____ which is about _____ normal venous return
- Normal heart can increase rate to _______ bpm and contractility _____normal strength
13L/min
2.5X
180 to 200
2X
Factors Effecting CO
- Vascular (intrinsic)
- Heart muscle itself (intrinsic)
- Autonomic Nervous System (extrinsic)
- Endocrine-hormones, electrolytes (extrinsic)
- Intrathoracic Pressures: increased intrathoracic pressure reduces venous return (extrinsic)
Hearts ability to adapt (stretch) to an increased volume of blood flow (in a normal heart)
- An increase in venous return to the heart results in an increased ____ stretch
- As the heart muscle stretches, increasing chamber volume, the cardiac output __________
frank-starling law of the heart
diastolic
increases proportionately
Preload (volume)
- Venous return
- Stretches the cardiac fibers before ______
- Vascular system role is to ensure that the pressure does not = ______
- Dynamic exercise, posture change, aortic regurg increase preload
contraction
0 (0 return)
Afterload – aortic pressure _____ mm Hg
Static exercise, HBP, aortic stenosis can increase afterload
(____ mm Hg is needed to significantly reduce stroke volume, however)
120/80
160
Critical regulator of cardiovascular performance
Defined as the tension developed in the ventricular wall during ejection
afterload
after load determined by…
- _______ of the ventricular cavity
- ______ pressure
- Increases in afterload reduce _____________
- Increases in arterial pressure from vasoconstriction oppose myocardial fiber shortening, the ventricle dilates resulting in a ______________
Volume and thickness
Aortic
myocardial contractility
reduced stroke volume
the percentage of the blood in the ventricles that filled them during systole (from the atria), that is then pumped out is _______
This implies that not all of the blood in a normal heart is pumped out of the ventricles.
A normal is about _______
Ejection fraction (EF)
0.6 (60%)
If not enough of the blood pumped in gets pumped out (regardless of whether that’s at rest or during exercise), perfusion of body tissues will _______, and Heart Failure. This is sometimes the result of myocardial infarct, which causes death of the heart muscle and poor pumping strength. The first sign of this is the most common symptom presented in Primary Care Clinics: _______.
decrease
Fatigue and shortness of breath (SOB)
Extrinsic and Intrinsic Factors that affect Ejection Fraction:
- __________ ability (muscle strength) of the heart
- Peripheral factors, venous capacitance (______________-) make up venous return
Pumping
volume & vascular tone
preload venous return includes _______ and _______
systematic filling pressure
right atrial pressure
Systemic filling pressure reflects the pressure in the _______ circulation that forces the blood toward the _______
Right atrial pressure reflects the pressure in the ______ resisting the flow of blood from the ______
systemic
heart
RA
SVC/IVC
Total Body Effects During Exercise
_________ CO
_________ HR
_________ stroke volume
Redistribution of ___________
_____________ alveolar ventilation
_____________ oxygen demand
_____________ metabolic waste products
Heat elimination (_______)
Increased
Increased
Increased
organ blood flow
Increased
Increased
vasodilation
Heart rate increases
Maximal HR in healthy adults = ______________
208 - 0.7 x age (in years)
Stroke volume increases due to:
Increased __________
Increase (10%) in __________________
______ filling is enhanced due to capacity of venoconstriction
Greater negative ___________ pressures
___________ action of exercising limbs
contractility
left ventricular ejection fraction (LVEF)
LV
intrathoracic
Pumping
Left ventricular end-diastolic volume (LVEDV) increase by ________
LV end-diastolic pressure can increase by ______________
Diastolic filling is limited by the physical constraints of the _________
Exercise-induced elevations in left sided filling pressures can unmask heart failure
20 - 40 %
20 mmHg (N =7 mm Hg)
pericardium
In a healthy individual, EF goes from around ____ at rest to around ____during exercise.
In an individual with Coronary Artery Disease or after ST segment changes on EKG (STEMI or NSTEMI), Ejection fraction either _______ during exercise, or ________ in more severe CAD/STEMI/NSTEMI.
It may be that EF during exercise increases because the filling is limited by the ________, but need is still increased in exercise.
60%
72%
stays at baseline
decreases
pericardium
Voluntarycontractionandrelaxationofskeletalmuscles without changing themusclelengthor movingtheassociatedpartofthebody
Static exercise
static exercise results in…
massive increase in _____________
Results in a ______ CO
peripheral vascular resistance
lowered
Continuousandsustainedmovementofthearmsand legs;isotonicexercisesbeneficialtothecardiorespiratorysystems(running and bicycling
Dynamic exercise
Dynamic exercise results in…
Rise in __________
Lowered ____________ due to byproducts of tissue hypoxia such as:
Adenosine, potassium, lactic acid, carbon dioxide, prostaglandins, nitric oxide
_____afterload and _____ CO
cardiac output
peripheral resistance
lowered
higher
Redistribution of flow resulting in greater perfusion to muscles
Except ________________
Venous constriction - _______ venous return (preload) resulting in a________in EDV
coronary and cerebrovascular vessels
increases
increase
