Editing File
Cardiac Cycle I&II
Physiology Team 439
Black: in male / female slides
Red : important
Pink: in female slides only
Blue: in male slides only
Green: notes
Gray: extra information
Helpful video
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Reduced Ejection. (0.15 sec). Ventricular Systole (0.3 sec). Ventricular Diastole (0.5 sec). *IVC: IsoVolumetric Contraction. IVR*. (0.06 s). Rapid Filling.
Typology: Study notes
2022/2023
1 / 31
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Cardiac Cycle I&II and more Study notes Physiology in PDF only on Docsity!
Editing File
Cardiac Cycle I&II
Physiology Team 439
Black: in male / female slides
Red : important
Pink: in female slides only
Blue: in male slides only
Green: notes
Gray: extra information
Helpful video
Objectives
1.Enumerate the phases of cardiac cycle
2.Explain the effect of heart rate on duration of systole and diastole
3.Recognize the pressure, electrical, sound and volume changes during cardiac
cycle
4.Correlate different phases of cardiac cycle with various changes in events
5.Compare and contrast left and right ventricular pressures and volumes during
the normal cardiac cycle
6.Describe atrial pressure waves & their relationship to cardiac cycle
7.Describe the use of the pressure-volume loop in describing the phases of the
cardiac cycle
Atrioventricular valves: Semilunar valves:
Valves of The Hearts
1. Tricuspid valve: between right atrium & right ventricle.
2. Mitral valve: between left atrium & left ventricle.
1. Pulmonary valve: between right ventricle & pulmonary artery.
2. Aortic valve: between left ventricle & aorta.
Functions of The Valves
❖ Valves allow blood to flow in only ONE direction.
❖ Opening & closure of valves occur as a result of pressure gradient across the valve.
(high pressure against the valve = opening of valve)
❖ When A-V valves open, semilunar valves close and vice versa. (They can never open at the same
time, but can close at the same time like in Isovolumetric phases , This is to prevent backflow of blood
from aorta or pulmonary artery to their perspective Ventricle)
❖ A-V cusps are held by chordae tendineae to muscular projections called “papillary muscles”.
This is to limit movements and eversions of the valves during ventricular systole. i.e. To hold it in
place/prevent inversion prolapse during systole (ﺛﺎﻧﯾﺔ ﺟﮭﺔ ﻣن ﺗﻔﺗﺢ ﻣﺎ ﺗﺳﻛر ﻟﻣﺎ ﯾﻌﻧﻲ). Have no role in opening
or closing the valves.
Definitions
Volume of blood in each ventricles at the end of diastole = 110-130 mL.
End-Diastolic volume (EDV):
Amount of blood left in each ventricles at the end of systole = 40-60 mL.
End-Systolic Volume (ESV):
Amount of blood ejected from ventricles during systole = 70 mL/beat.
It is Volume Of Blood Pumped out by each ventricle per beat.
SV = EDV – ESV
So when SV decreases the ESV increases, because there will be more blood left in the ventricle.
Stroke Volume (SV):
Ejection Fraction (EF):
The percentage of EDV which is ejected with each stroke. It is a good index of ventricular function.
Normal ejection fraction is about 60 – 65 %.
SV or EDV-ESV
EDV
EF= X 100
EF = (75 /120*100=62.5%)
❖ Considered ‘8’ phases if including 1st phase of diastole
-reduced filling has the longest duration.
The Cardiac cycle
❖ Cardiac cycle: the sequence of events that take place in the heart in each beat (from the
beginning of one heart beat to beginning of the next one).
❖ Each cycle is initiated by depolarization of S-A node, followed by contraction of the atria.
❖ The signal is transmitted to ventricles through A-V node & A-V bundle to cause ventricular
contraction.
❖ Events of the Cardiac Cycle
➢ Mechanical Events:
1. Pressure changes during cardiac cycle
2. Volume changes during cardiac cycle
3. Heart sounds
➢ Electrical Events:
Electrocardiogram (ECG)
IVC*
(0.05 s)
Rapid/Maximum Ejection (0.10 sec)
Reduced Ejection
(0.15 sec)
Ventricular Systole (0.3 sec) Ventricular Diastole (0.5 sec)
*IVC: IsoVolumetric Contraction
IVR*
(0.06 s)
Rapid Filling
(0.11 sec)
Reduced Filling
(0.22 sec)
*IVR: IsoVolumetric Relaxation
Atrial Diastole
(0.7 sec)
Atrial Systole
(0.11 sec)
The 7 Phases of the Cardiac cycle
Diastole of whole heart (0.4 sec)
Phases ﻧﺎﺣﯾﺔ ﻣن ﻋﻠﯾﮫ ﯾﻧﺳﺣب ﻋﻠﯾﮫ ﺳﺣﺑت ECG ﺣﺗﻰ ﻣرﺣﻠﺗﯾن آﺧر وﻗت ﻧﻔس ﻓﻲ ﯾﺻﯾر ﻷﻧﮫ
!"#$%$&'()+", ,$-+.,"$- .-/ +)&. 0 ."$- 1 .%)
- 1 ) # 1 $+)# /'+.*"$- 2
Cardiac Cycle Duration
0.1 0.3 0.5 0.
Atrial (0.8)
Ventricles (0.8)
Systole Diastole
Normally, diastole is longer > systole
atrial diastole : 0.
ventricle diastole : 0.
But diastole of whole heart is : 0.
atrial systole : 0.
ventricle systole: 0.3 :
Might help you memorize the values from previous slide
Heart Rate & Cardiac Cycle
❖ The higher the heart rate, the lesser is duration of Cardiac cycle. However, the duration of systole is much more fixed than that of diastole.
Physiologic and clinical implications of shortened diastole :
❖ The heart muscle rests during diastole. Coronary blood flows to the subendocardial portions of the left ventricle only during diastole. Furthermore, most of the ventricular filling occurs in diastole.
❖ Up to about 180/min, filling is adequate as long as there is enough venous return, and cardiac output per minute is increased by an increase in rate. However, at very high heart rates, filling may be compromised to such a degree that cardiac output per minute falls.
At rest, atrial contraction adds little extra blood to the ventricles. When the heart rate is high, ventricle filling time is reduced. During exercise, atrial contraction adds a larger amount of blood to the ventricles.
Male slide only
Effect of Atrial Contraction on Ventricular Filling
1-Atrial Systole (0.11 sec)
Mechanical Events
It occurs at the end of ventricular diastole (last ⅓ of diastole) 25 % of blood passes to the ventricles. Atria act as primer pumps & increase the ventricular pumping effectiveness as much as 20-25% ﺑﯾﻧﺗﻘل؟ اﻟرﺑﻊ ﺑس ﻟﯾﮫ Because of the ventricles suction which responsible for 75% of blood movement. Valves: AV valves still open ( semilunar valves still closed ) AV valves opened during rapid filling phase of ventricles blood goes from atria to ventricles.
Ventricular Volume Changes
↑ due to blood passage into ventricle. It reaches EDV 130 ml (remember the ventricle already filled with 75% passively during the ventricle diastole)
Pressure Changes
Atrial: First ↑ due to systole of atria. Then ↓ due to blood passage into ventricles As the atrial pressures fall, the AV valves close and left ventricular volume is now maximum → EDV (120 ml in LV) Ventricular : First slightly ↑ due to entry of blood from atria. Then ↓ due to dilatation of ventricles (for accommodation) In both cases, it is less than atrial pressure (because once it’s higher, AV valve will close)
Heart Sounds (^) 4th heart sound heard due to 1-atrial contraction 2-Blood rush from atria to ventricles.
Before you study this part, check the boxes on the right side.
ﯾﻣرض ﻟﻣﺎ ﻟذﻟك Atrium ﻧﻌﺗﺑره ﻣﺎ اﻧﻘﺑﺎﺿﮫ وﺗﺄﺛر ﻛﺎن ٍﺳﺑب ﻷي Life threatening ﺣﺎﺟﺗﮭﺎ ﻣن ٧٥٪ ﺑﺗﺄﺧذ اﻟﻔﻧﺗرﯾﻛﻠز ﻷن ﻋﺎدي اﻧﻘﺑﺎﺿﮫ ﺑدون
Left Atrial Pressure + Left Ventricular Pressure First ↑ due to systole of atria. Then ↓ due to blood passage into ventricles.
(LVP) Left Ventricular Pressure
(LAP) Left Atrial Pressure
(LVEDV) Left Ventricular End Diastolic Volume
Increased Left Ventricular End Diastolic Volume due to blood passage into ventricle. It reaches the EDV 130 ml.
Ventricular systole (3 phases)
Second one: 3- Maximum (Rapid) Ejection Phase (0.10 sec)
[Duration 1/3] (2/3 or 70% blood is ejected)
Mechanical Events
when LV exceeds 80mmHg (which is the aortic pressure) And RV > 8mmHg. (AV valves still closed) Semilunar valves open at beginning of this phase اﻻﺗ﷼ ﻣن أﻋﻠﻰ وﺻل اﻟﻔﻧﺗرﻛﻠز ﻣﺎﻗﻠﻧﺎ ﻣﺛل ﻷن The ventricles contract isotonically (with shortening) pushing or emptying most of blood (70%-75% of ventricular blood ) into aorta & pulmonary artery passively.
Ventricular Volume Changes ↓^ sharply due to shortening of ventricular wall and ejection of blood.
Pressure Changes
Atrial pressure: ↓ because when ventricles contract, they pull fibrous AV ring with AV valves downward thus ↓ atrial P. اﻟﺿﻐط ﻓﺎﻧﺧﻔض اﻟﺣﯾن ﻧزل ﺷوي، ﻗﺑل ارﺗﻔﻊ ﻗﻠﻧﺎ اﻟﻠﻲ اﻟﺑﺎرﺷوت Ventricular pressure : reaches 120 mmHg in left Ventricle.
Heart Sounds No sound (Any sound occurs in ejection phases it will be pathological conditions)
ﻓﻲ ﺳواء داﺋﻣًﺎ Contraction ejection / relaxation filling ﻣﻘﻔل وﺻﻣﺎم ﻣﻔﺗوح ﺻﻣﺎم
Left ventricular pressure ( LVP) ↑ reaches 120 mmHg in left V (^) (LVP) Left Ventricular pressure
(LAP) Left Atrial Pressure
(LVEDV) ↓ sharply due to shortening of Left Ventricular end Diastolic volume ventricular wall and ejection of blood.
Left atrial pressure ( LAP ) First ↓ because when ventricles contract, they pull fibrous AV ring with AV valves downward thus
Team 436: -In this phase aortic (not atrial) pressure reaches its maximum value which is also 120 mmHg (like LV) after aortic valve opens. -IN THIS PHASE BLOOD GOING FROM LV TO AORTA > THAN BLOOD LEAVING AORTA TO TISSUES.
Ventricular systole (3 phases)
Third one: 4- Reduced (slow) Ejection Phase (0.15 sec)
[Duration 2/3] (1/3 or 30% blood is ejected)
Mechanical Events
The ventricles contract with less shortening than the previous phase and less blood is ejected (end of systole).
Almost ( 25% of ventricular blood ) is ejected, 25% of SV.
(Semilunar valves still opened
AV valves still closed)
Ventricular Volume Changes
Continue ↓ gradually till it reaches the end systolic volume (ESV=60 ml).
Pressure Changes
Atrial pressure:
Still ↑ gradually due to accumulation of venous blood.
Ventricular pressure:
↓ gradually (from 120 to 80 mmHg in LV), as volume of blood
leaving ventricles > the decrease in ventricular volume.
The pressure in the ventricle keeps decreasing until it becomes lower than that of the great vessels
Heart Sounds No sound
That means the ejection of Stroke volume is: 75% of it ejected during maximum ejection 25% of it ejected during reduced ejection
ﻣرﺣﻠﺔ ﯾﻘﺻد ھﻧﺎ ﺗرا atrial diastole ﻋﻠﯾﮭﺎ اﻧﺳﺣب ﻗﻠﻧﺎ اﻟﻠﻲ
Left ventricular pressure ↓ gradually, as volume of blood leaving ventricles > the decrease in ventricular volume (^) Left Ventricular pressure(LVP)
(LAP) Left Atrial Pressure
(LVEDV) Left Ventricular end Diastolic volume
Constant! Left Ventricular end Diastolic volume “Isovolumetric”
Left atrial pressure ( LAP ) Still ↑ gradually due to accumulation of venous blood.
ﯾﻌﻧﻲ ﺻﺢ وﻗﺗﮫ اطول ﺑس ﻛﻣﯾﺔ اﻟدم اﻟﻠﻲ ﯾﺿﺧﮭﺎ أﻗل
Ventricular relaxation/diastole (3 phases)
Second one: Maximum (Rapid) Filling Phase
Mechanical Events
Atrial pressure > ventricular pressure: AV valves open. (Semilunar valves still closed ) ≈ 60-70% of blood passes passively to the ventricles along pressure gradient.
Ventricular Volume Changes ↑^ because it is being filled with blood^ (remember AV valve opened!!)
Pressure Changes
Atrial pressure: First sudden ↓ due to rush of blood from atria to ventricles. Then gradually ↑ due to entry of venous blood
Ventricular pressure: Slightly ↑ but < atrial pressure (اﻟﻔﺎﻟف ﺗﻘﻔل راح اﻻﺗرﯾوم ﻣن اﻋﻠﻰ ﺻﺎر ﻟو)
Heart Sounds 3rd heart sound heard^ due to rush of blood into ventricles and vibration in ventricular wall.
ﻣﺎﺗﻧﻔﺗﺢ ﻗﺎﻋدة، ﺧذوھﺎ AV valves ﻋن اﻻﺗرﯾوم ﺿﻐط زاد إذا إﻻ وﻗﻔﻠﮭﺎ ﻓﺗﺣﮭﺎ ﺑﺈﺧﺗﺻﺎر ﯾﻌﻧﻲ اﻟﻔﻧﺗرﯾﻛﻠز اﻻﺗرﯾوم ﺿﻐط ﻓﯾﮭﺎ ﻣﺗﺣﻛم
ﻓﻲ ﻣﺎﻗﻠﻧﺎ ﻣﺛل Ejection or Filling ﻣﻘﻔل وواﺣد ﻣﻔﺗوح واﺣد : AV < Filling ﻓﻲ اﻟﻣﻔﺗوح ﻟﻠﻔﻧﺗرﻛﻠز ﻣﺗوﺟﮫ اﻟدم ﻷن Semilunar < Ejection ﻓﻲ اﻟﻣﻔﺗوح Aorta or pulmonary ﻟل ﻣﺗوﺟﮫ اﻟدم ﻷن Why passive? Because the Normal suction by ventricles, ٢٠٪ او اﻟدم ﺑرﺑﻊ اﻻﺗرﯾوم اﻧﻘﺑﺎض ﻋﻠﻰ ﻧﻌﺗﻣد ﻗﺑل ﻣﺎﻗﻠﻧﺎ ﻣﺛل ﯾﺟﻲ؟ ﻛﯾف اﻟﺑﺎﻗﻲ ﻓﺳروا ھﻧﺎ 60-70% : by maximum filling <5% : by reduced filling (next slide)
Left ventricular pressure Slightly ↑ but < atrial pressure (LVP) Left Ventricular pressure
(LAP) Left Atrial Pressure
(LVEDV) Left Ventricular end
↑ because it is being filled with Diastolic volume
blood
(LAP) Left Atrial Pressure First sudden ↓ due to rush of blood from atria to ventricles. Then gradually ↑ due to entry of venous blood
ﺗﺧﯾﻠو ﺑﻠوﻧﮫ ﻓﯾﮭﺎ ﻓﺗﺣﺗﯾن وﺣدة ﻛﺎﻧت ﻣﻘﻔﻠﺔ واﻟﺛﺎﻧﯾﺔ ﻓﺎﺗﺣﺔ وﻗﺎﻋده ﺗﻌﺑﯾﮭﺎ ﺑﻣﺎء ﻓﺎﻟﺿﻐط ﻋﺎﻟﻲ ﺟوا، اول ﻣﺎ ﺗﻔﺗﺢ اﻟﻔﺗﺣﺔ اﻟﺛﺎﻧﯾﺔ اﻟﻣﺎء ﺑﯾﺗدﻓق وﺑﯾطﻠﻊ ﻣﻧﮭﺎ ﻓﺎﻟﺿﻐط ﺑﯾﻘل ﺑﺎﻷول ﺑس ﺑﻣﺎ ان اﻟﻔﺗﺣﺔ اﻟﻠﻲ ﺗﻌﺑﯾﮭﺎ ﻣﺎء ﻟﺳﮫ ﻣﻔﺗوﺣﺔ ﺑﯾرﺟﻊ ﯾرﺗﻔﻊ
Ventricular relaxation/diastole (3 phases)
Third One: Reduced (slow) Filling Phase (Diastasis)
middle 1/3 of diastole
Mechanical
Events
Remaining atrial blood (≈ <5%) passes passively & slowly to the ventricle by pressure gradient. (A-V valves still open Semilunar valves: Still closed )
Ventricular Volume Changes Still ↑ due to entry of blood into ventricles.
Pressure Changes
Atrial pressure: Still ↑ gradually due to continuous venous return. Ventricular pressure: Slightly ↑ gradually because the increase in volume is less than the entering blood.
Heart Sounds -
Left ventricular pressure Slightly ↑ gradually because the increase in volume is less than the entering blood. (LVP) Left Ventricular pressure
(LAP) Left Atrial Pressure
(LVEDV) Left Ventricular end Diastolic volume
Constant! Left Ventricular end Diastolic volume “Isovolumetric”
(LAP) Left Atrial Pressure Still ↑ gradually due to continuous venous return.
Pressure changes in cardiac cycle
Location
Normal range
Systole Diastole
RT Atrium 2- 8 ,7 mmHg
LT Atrium 2-10 mmHg
Pulmonary Artery 25-30 mmHg
4-12 mmHg
10 mmHg
RT Ventricle 25-30 mmHg 2-8 mmHg
LT Ventricle 100-120 mmHg 3 or 2 -12 mmHg
Aorta 120 mmHg 80 mmHg
Aortic Pressure Changes (Curve)
Why is aortic pressure higher than ventricular pressure during diastole? Because during ventricular contraction, the aorta stores energy by stretching (pressure reservoir). During ventricular diastole, the aorta releases this pressure to maintain blood flow to the body.
Pulmonary artery pressure changes are similar to the aortic pressure changes [Magnitude 3-4 times Less]. Normal pulmonary artery pressure during the cardiac cycle ≈ 25-30/4-12 mmHg
A) Ascending or Anacrotic Limb
With the ‘rapid ejection phase’. Aortic pressure ↑ up to 120 mmHg (ھﺎﻟوﻗت ﻓﻲ ﻟﻠﺟﺳم ﯾﻧﺿﺦ اﻟﻠﻲ ﻣن اﻛﺛر ﺑﺳرﻋﺔ ﯾدﺧل ﻗﺎﻋد اﻟﻠﻲ اﻟدم ﻻن ﯾزﯾد راح)
B) Descending or Catacrotic Limb
Passes in 4 stages:
1. ↓Aortic Pressure With ‘reduced ejection phase.’ Amount of blood amount leaves aorta > enters 2. Dicrotic Notch (Incisura) Sudden drop in aortic pressure. Due to closure of aortic valve. This notch is seen in the aortic pressure curve at end of ventricular systole 3. Dicrotic Wave Slight ↑ in aortic pressure. Due to elastic recoil of the aorta. 4. Slow ↓ Aortic Pressure Down to 80 mmHg. Due to continued flow of blood from aorta into systemic circulation
Ascending /Anacrotic Limb
Descending / Catacrotic Limb
1
2
3
4