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
