Venous Return Flashcards
______ = EDV (end-diastolic volume) - ESV (end-systolic volume)
SV
______ = SV X HR
CO
______ = SV/EDV
EF
CO is controlled by _____ and effected by ______.
venous return, peripheral circulation
Cardiac Index _____ with age.
declines
Stretch of the atria ____ HR. This is called the _____ reflex.
increases, brainbridge
In normal function the heart can increase CO 2.5X above resting CO. If more is needed, what happens?
- SNS
- Catecholamine response
What causes the heart to become hypereffective?
- increase in SNS
- mycardial hypertrophy (exercise or hypertension)
What causes the heart to become hypoeffective?
- decreased ability to pump: MI from CAD, decreased SNS activation, congenital heart disease, hypertension, and myocarditis
What happens during exercise?
Increased SNS and catecholamine activity:
- aterial vasoconstriction to increase BP
- venous vasoconstriciton to increase preload
- incerased HR and strength of contraction
Increased skeletal muscle metabolism
- local arteriole dilation to support demand
What three factors effect CO?
- myocardial function
- peripheral factors that effect venous return
- tissue needs
What factors decrease preload?
- dehydration
- hemorrhage
- venous pooling (orthostasis)
- large vein obstruction (tumor, thrombosis)
- decreased muscle mass
- metabolic demand
What factors increase preload?
- hydration
- exercise
- anemia
- hyperthyroidism
What are 4 external forces that affect filling of chamber?
- inspiration
- positive pressure mechanical ventilation
- open thoracic cage
- cardiac tamponade
What 3 factors effect venous return
- Right atrial pressure (RAP)
- Mean Systemic Filling Pressure (Psf)
- Venous resistance (VR)
