Heller Ch. 10 Flashcards
What are the three ways of INCREASING stroke volume?
Increase preload
Increase contractility
Decrease afterload
What is proportional to preload?
Central blood volume
What are six ways of INCREASING central blood volume? (Thus increasing preload, thus increasing SV)
Increase total blood volume Increase peripheral venous tone Increase skeletal muscle pump Increase respiratory pump Decrease standing Decrease cardiac output
What increases contractility? (Thus increasing SV)
Increased sympathetic activity (NE–>beta receptors)
What increases venous tone? (Thus increasing central blood volume, thus increasing preload, thus increasing SV)
Increased sympathetic activity (NE–>alpha receptors)
What is proportional to afterload?
TPR (arterial tone)
What are two ways to DECREASE TPR? (Thus decrease preload, thus increase SV)
Decrease sympathetic activity (NE–>alpha receptor)
Increase local metabolites (increase local metabolic rate)
How does the “respiratory pump” (deep and rapid breathing) promote venous return? (Thus increase central blood volume, thus increase preload, thus increase SV)
Inspiration decreases thoracic pressure
What is one possible concern with a respirator?
A respirator increases thoracic pressure…may have CV implications
What happens when lung mechanoreceptors are stretched?
Vagal activity is INHIBITED–>increased HR
What response do cardiopulmonary baroreceptors have after inspiration?
Increase parasympathetic activity in the heart
What is the net effect of inspiration on blood pressure?
Blood pressure is increased (increased SV and HR)
What is the arterial baroreceptor response to the increased blood pressure?
Inhibit sympathetic activity
Increase parasympathetic activity
What is the valsalva maneuver? What are some examples?
Forced expiration against a closed glottis
Taking a big ol’ dukie
Heavy lifting
What are the consequences of the valsalva maneuver?
Increased arterial pressure (particularly on aorta)–> Fall in venous return and BP–>
Compensatory reflex increase in HR and TPR
What happens upon cessation of the valsalva maneuver?
Abrupt fall in BP (reduced intrathoracic pressure)
Increased peripheral return–> increased CVP–>
Increased SV, CO, MAP–>
Bradycardia
What combo/series of blood pressures can lead to a stroke?
High venous pressure… Followed by
High arterial and pulse pressure
What effect does standing have on venous transmural pressure in the lower extremities?
Transmural pressure is increased…decreases central venous return
What happens as a result of increased transmural pressure in the lower extremities?
Distends the compliant peripheral veins
Increases venous volume
What happens to transcapillary filtration rate upon standing?
Increased filtration rate…due to increased arterial pressure
What causes weight loss and hypovolemia upon long-term bed rest?
The kidney
What is the concern about standing after long-term bed rest?
Shifting an already low blood volume from central to periphery–>dizziness
What effect does exercise have on skeletal muscle vascular resistance–>TPR?
Exercise decreases the resistance
What is the effective of decreased TPR?
Decreased arterial pressure (MAP=COxTPR)
What is the end result of exercise on pressure regulation?
Decreased parasympathetic activity
Increased sympathetic activity
What causes the decreased parasympathetic/increased sympathetic activity during exercise?
Increased set point from the cerebral cortex and increased skeletal muscle chemo/mechano receptor activity
Decreased arterial baroreceptor firing
What are CV responses to dynamic exercise?
Skeletal muscle pump
Respiratory pump
Increased cardiac reserve
What is a major difference between dynamic and static exercise?
Dynamic has a significantly larger fall in TPR
What are the CV responses to static exercise?
Less of an increase in HR and CO
More increase in diastolic/systolic/mean pressures
What is the biggest advantage (from a CV perspective) of exercise?
Increased blood volume
Other than increased blood volume, what are some other CV benefits of exercising?
Decreased HR
Increased SV
Decreased resting MAP
What is the effect of the placenta on TPR?
The placenta decreases TPR by 40%
What is the percent increase in blood volume of pregos?
50%
What adjustment do arterioles go through after birth?
From thick-walled and small-diameter to thin-walled and large-diameter
What cardiac changes are age-dependent?
Decrease in resting and maximum cardiac index
Decrease in maximum HR
Increase in contraction and relaxation time
Increase in myocardial stiffness during diastole
Decrease in number of functioning myocytes
Accumulation of pigment in the myocardial cells
What vascular changes are age-dependent?
Decrease in capillary density in some tissues
Decrease in arterial and venous compliance
Increase in TPR
What is the effect of age-related increase in TPR?
Increase in pulse pressure
Increase in MAP–>increased afterload–> decreased cardiac index
What does estrogen directly do for the CV?
Lowers arterial BP
Greater aortic compliance
Improved ability to induce vasodilatory mechanisms
What is the result of the changes estrogen has on the CV?
Lower cardiac afterload–>lower LV mass:body mass index
What are other cardiac differences are there between men and women?
Women:
Have lower HR
Longer QT (greater risk of long-QT syndrome and Torsades)
Twice as likely to have AV nodal re-entry tachycardias
