Garman CV3- Mechanical Flashcards
Range of normal systolic pressure PA?
15-30
Range of normal diastolic pressure PA?
3-12
Mean pressure PA?
14 mmHg
Range RA pressure? Mean RA pressure
0-8 mmHg, NO variation 4 Mean
Systolic range and mean for RV pressure?
Systole 15-28 mmHg, Mean 24 mmHg
End diastolic range of pressure RV?
0-8 MMhG Mean 4 mmHg
Aortic systolic range?
90-140mmHg
Aortic diastolic range?
60-90mmHg
Mean aortic pressure?
120
LA range pressure?
4-12mmHg (no systolic/diastolic range) Mean 8 mmhg
LV Systolic range? Mean?
90-140 Mean 130
LV End diastolic range? Mean?
7 mmHg
When does mitral valve close in cardiac cycle?
Beginning of isovolumetric contraction (Force of ventricular contraction causes blood to push back on AV valve, causing closure)
What happens when mitral valve closes?
S1 sound “lubb”
When does aortic valve open?
End of isovolumetric contraction.
What electrical event happens right before mitral valve closes?
R-wave. (Ventricular depolarization causing ventricular contraction and mitral valve to close)
When does aortic valve close?
Beggining of Isovolumetric relaxation Why? Pressure in ventricle begins to decrease during ventricular repolarization (after T wave). Pressure is less in ventricle than aorta, blood flows backward, closing aortic valve.
What happens when aortic valve closes?
S2 “dubb” closure of semilunar valves
How many valves are open in the heart during isovolumetric relaxation?
0 valves open. (i.e. isovolumetric)
What other time in cardiac cycle are all vavles close?
Isovolumetric contraction (no blood leaving heart= all valves closed)
When does mitral valve open?
At end of isovolumetric relaxation. Pressure is now lower in ventricle than atria, mitral valve is allowed to open and blood passively fills ventricle.
What happens after mitral valve opens?
Blood “rushes into” ventricle causing rapid ventricular filling (rapid passive filling)
What creates S3 sound?
Rapid ventricular filling AKA Diastolic filling (from blood sloshing against walls of heart) Can typically only hear in young children.
What happens at a-wave in left atrial pressure waveform?
Atrial contraction (after P wave on EKG)
What happens at c wave on left atrial pressure waveform?
Bulging back of mitral valve into atrium from ventricle d/t pressure from ventricular contraction
What happens at V wave on left atrial pressure?
Ventricular relaxation. Blood beings to flow into ventricle causing decrease in LA pressure
As the blood rushes back into ventricle during vectricular relaxation, does some blood go into LV from aorta?
Yes. Small amount causing slight negative deflection in aortic blood flow waveform
What causes S4 on heart sounds?
Atrial contraction. Always pathologic
What represents ventricular systole on ekg?
R-T
What causes a, c, v wave on venous pulse waveofrm?
a- atrial contraction c- mitral valve bulging back v- ventricular relaxation (filling) after atrial filling
What marks closure of AV valves?
S1 “lubb”
What marks closure of semilunar valves?
S2 “dubb”
What happens if S3 present?
Rapid passive filling of ventricle. Normally not heard in adults May be present in children and endurance athletes
What happens at S4?
Atrial systole ALWAYS pathological if heard
What is a murmur?
Gugling sound made as blood moves through a damaged valve
What is a buirt?
Abnormal sound as blood runs past obstruction in arteries
When is jugular venous pulse useful?
Diagnosis of heart disease
Why can you see jugular venous pulse?
No valve separating RA from central venous space. Seeing backpressure of blood flow
What does SV equal?
LVEDV- LVESV Amount of blood left at end of diastole (when ventricle filled)- amount of blood left at end of systole (when ventricle is emptied)
What is compliance defined to be?
change in V/change in P
The more ____ aorta is, the greater compliance
elastic
During diastole, the aorta ____
recoils
What helps maintain pressure during distole?
Diastolic recoil
Where does the stroke volume go during systole?
Into distention of the aorta, blood goes forward.
Aging generally results in a decrease in aortic _____ and _____
elasticity and compliance
Decrease in elasticity and compliance leads to increase in ____ _____
pulse pressure
What happens to PP with decreased HR?
Increase in PP and it is not a sign of stiff arteries. Heart just has more time to fill, so therefore high SV, higher PP
What does arterial wave form look like in aortic insufficiency
Blood is going back into ventricle during systole, therefore LV is becoming more filled each time. Heart ejecting more blood each time, therefore higher pressure generated. Systolic pressure also drops faster than normal since blood is able to go back into LV Diastolic pressure drops because of incompetent valve
What happens to arterial pressure waveofrm in arterosclerosis?
D/t hardening of arteries, when you eject, a higher systolic pressure is required. Also causes higher diastolic pressure. Makes heart work harder and harder for heart to oxygenate cardiomyocytes as well.
What influences SV?
Preload (EDV) Contractility Afterload (SBP)
Equation for CO?
HR(mL/beat) X (EDV-ESV) (beats/min)
What makes up autonomic nervous system?
Sympathetic innervation, parasympathetic innervation
What plays a role in sympathetic innervation
Norepinephrine/epinephrine Receptors- beta 1 response Positive chronotropic effect
What happens with parasympathetic innervation?
Acetylcholine Receptor: muscarinic ach M2 receptor Negative chronotropic effect
What is ejection fraction?
SV/EDV or (EDV-ESV)/EDV
What is normal EF of normal heart?
>0.5 (50%)
Force of contraction is a function of what?
Number of cross-bridges formed
What are 2 different mechanisms the heart can increase cross-bridge formation?
1) Frank-starling law of heart 2) Contractility
How does frank-starling law of heart influence cross bridge formation?
- Increasing functional overlap of myosin and actin Preload-greater filling stretches myocytes–> stronger contraction (until the myosin/actin is expanded too much)
How does hte heart increase contractility?
Increasing Ca++ in cardiomyocytes normally through SNS activation. E -Epinephrine increases Ca influx -Parasympathetic does not affect contracility. Either heart increases contractility or it contracts at normal strength.
Ventricular pressure above _____ doesn’t increase CO and results in slow decline in CO
12 mmHg
What is mean circulatory pressure when heart is stopped?
7 mmHg
What does vascular function curve show?
Inverse relationship between CO (independent variable) and CVP (dependent variable)
What is cardiac function curve
Direct relationship between CVP (independent) and CO (dependent) (frank-starling mechanism)
What is found by plotting both vascular function curve and cardiac function curve?
Resting equilibrium point
What is the x-intercept of volume function curve
Mean circulatory pressure
Which curve moves when the volume status is changes?
Vascular function curve
Which curve moves when contractility is changed?
Cardiac function curve
Why does preload decrease with higher CO?
Moving more blood, so less left in heart
What does increase resistance cause?
Accumulation blood on arterial side
What is equation for SVR?
MAP/CO
What does this cardiac pressure volume loop show a change in?
Green is decrease in preload
Grey is normal
Red is increase in preload
What does this cardiac pressure volume loop show?
Green is decrease inotropy
Red is increase inotropy
Grey is control
What does this cardiac pressure volume loop show?
Green= decrease afterload
Red= increase afterload
What effect does increase HR have on cardiovascular system?
Increase CO
Increase BP
Increased contractility has what effect on heart?
Increase contractility–> increase EF, Increase CO, Increase BP
What does increase SVR do to cardiovascular system?
Increase SVR (constrict artery)–> Decrease CO but Increase BP
What does incrase CVP do to cardiovascular system?
Increase CVP (constriction veins)–> Increase LVEDV, Increase SV, Increase CO, Increase BP
What factors influence venous return?
1) Skeletal muscle activity
2) Blood volume
3) Changes in peripheral circulation
What influences preload
1) Venous return
2) Filling time (limiting factor for HR)
What influences contractility
- Autonomic innervation
- Hormone
What influences End-Diastolic volume
Preload
What influences end-systolic volume?
- Contractility
- preload
- Afterload
What influences afterload?
Vasoconstriction and vasodilation
What influences HR
- Atrial reflex—> autonomic innervation
- Hormones
What are baroreceptors?
- Respond to changes in stretch
- Increased stretch–> increased firing of sensory nerves
- Decreased stretch–> decreased firing of sensory nerves
Where are baroreceptors located?
- Wall of aortic arch–> sensory nerve: vagus nerve
- Carotid sinues–> sensory nerve: Glossopharyngeal nerve
What is the Nucleus tractus solitarii
CV center of the brain in the medulla
What does the NTS do?
- Take information from baroreceptors
- If BP needs to lower, cardioinhibitory center is activator–> activate parasympathetic to decrease HR via SA node
- If BP needs to increase, vasomotor center is activated, activating sympathetic nervous–> increase HR, contractility, constrict arterioles and veins.
What is role of atrial natruretic peptide?
- ANP is released in response to atrial stretch from increased atrial pressure
- ANP dilates some vessels and has important effects on sodium and water balance, and long term regulation of blood pressure
What is the Renin-angiotensin-aldosterone system?
- RAAS
- Renal juxtaglomerular cells sense decrase in BP and release renin
- Renin activated angiotensinogen to angiotensin I
- Angiotensin I converted to angiotensin II via angiotensin-converting enzyme (ACE) in lung
- Angiotensin II promotes vasoconstriction and stimulates aldosterone secretion from adrenal cortex resulting in…
- Renal sodium and water retention and an increase in BP
What is MAP?
COx TPR (total peripheral resistance (or SVR))
What does renin activate?
Activates angiotensinogen from liver to angiotensin I
What is angiotensin I’s role in RAAS?
Concerted to angiotensin II via angiotensin-converting enzyme (ACE) in lung
What is angiotenin II’s role in RAAS?
Promotes vasoconstriction and stimulates aldosterone secretion from adrenal cortex.
What is aldosterone’s role in RAAS?
Promote renal sodium and water retenstion to cause incrase in BP
What are effector organs for angiotensin II?
- Blood vessels
- Heart
- Adrenal cortex
- Hypothalamus
What is effect of AngII on blood vessels?
vasoconstriction causing increase SVR
What is effect of Ang II on heart?
Increase CO
What is effect of Angi II on adrenal cortex
Aldosterone release increase Na reabsorption by kidney
What is effect of Angio II on hypotehalamus?
Minor increase in ADH release: increase water reabsorption by kidney
What are stimuli for renin relase?
- Decrease in BP (stretch receptors in kidney tubules “renal baroreceptors”
- Sympathetic activation (tubules innervated with sympathetic nerves)
- Decreased flow of sodium through kidney tubules
What are effects of ANP?
- Increased sodium excretion
- water excretion
- vascular smooth muscle relaxation (vasodilation)
- blocking ADH, aldosterone, NE
Increased blood in atria–> increased atrial stretch–> increased ANP release–> increased sodium and water excretion–> decrease blood volume
THIS IS ONLY BACKUP. Should not happen day-to-day
What are chemoreceptor reflexes?
- Specialized receptors in carotid sinus and aortic arch
- respond to pH levels in blood
- Eleveated co2= decrease in pH
- If high CO2 detected, increase cardioacceleratory centers stimulated, vasomotor centers stimulated and cardioinhibitory centers inhibited
- this causes increase in CO, BP and vasoconstirciton in order to decrease CO2
What is myocardium innervated by?
Sympathetic nerves
What are SA node and AV nodes innervated by?
Both sympathetic and parasympathetic nerves
Autonomic efferent activity is regulated by _____ reflux
baroreceptor
Arterial and venous vessels throughout body are innervated by ________
sympathetic nerves
Which systems are quicker in regulatin BP (short-term response)
Baroreceptors
Chemoreceptors
CNS ischemic response
What are all the systems activated in response to low blood volume?
- Increase thirst
- Increase ADH
- Increase sympathetic nerve activity–> increase renin–> RAAS system activation
- Increase aldosterone (Na retnetion)
What is response to increased blood volume?
- Decrease ADH
- Decrease sympathetic activity
- decrease renin and angiotensin II by kidney
- adrenals decrease aldosterone
- ANP release causes increase in NaCl and H2O excretion
