Jump to navigation
Jump to search
Heart performance during ventricular diastole: early diastole is a suction mechanism that draws blood ‘down’ from the left atrium (pink) and right atrium (blue) into each of the two ventricles. Then, in late ventricular diastole, the two atrial chambers begin to contract (atrial systole), forcing additional blood flow into the ventricles.
Diastole // is the part of the cardiac cycle during which the heart refills with blood after the emptying done during systole (contraction). Ventricular diastole is the period during which the two ventricles are relaxing from the contortions of contraction, then dilating and filling; atrial diastole is the period during which the two atria likewise are relaxing, dilating, and filling. The term diastole originates from the Greek word διαστολή, meaning dilation. 
- 1 Role in cardiac cycle
- 1.1 Early ventricular diastole
- 1.2 Late ventricular diastole
- 1.3 Atrial diastole
- 2 Diastolic pressure
- 3 Clinical notation
- 4 Diagnostic value
- 5 Effects of impaired diastolic function
- 6 See also
- 7 References
- 8 External links
Role in cardiac cycle[ edit ]
A Wiggers diagram , showing various events during diastole. During early ventricular diastole—see vertical bar marked “Isovolumetric relaxation”—pressure in each ventricle (light-blue trace) begins to drop quickly from the wave height reached during systole. When ventricular pressures fall below those in the atrial chambers the atrioventricular (mitral and tricuspid) valves open, causing blood volume (red trace) in the atria to flow into the ventricles. + In late ventricular diastole, the two atrial chambers begin to contract ( atrial systole ), causing blood pressure in both atria to increase and forcing additional blood volume into the ventricles. This beginning of the atrial systole is known as the atrial kick—see “Ventricular volume” trace (red) directly above the P-wave in the electrocardiogram trace (dark-blue).
For a healthy human heart the entire cardiac cycle typically runs less than one second. That is, for a typical heart rate of 75 beats per minute (bpm), the cycle requires 0.3 sec in ventricular systole (contraction)—pumping blood to all body systems from the two ventricles; and 0.5 sec in diastole (dilation), re-filling the four chambers of the heart, for a total time of 0.8 sec to complete the entire cycle. 
Early ventricular diastole[ edit ]
During early ventricular diastole, pressure in the two ventricles begins to drop from the peak reached during systole. When pressure in the left ventricle falls below that in the left atrium the mitral valve opens due to a negative pressure differential (suction) between the two chambers, causing blood in the atrium (accumulated during atrial diastole) to flow into the ventricle (see graphic at top). Likewise, the same phenomenon runs simultaneously in the right ventricle and right atrium through the tricuspid valve .
The ventricular filling flow (or flow from the atria into the ventricles) has an early (E) diastolic component caused by ventricular suction, and then a late one created by atrial systole (A). The E/A ratio is used as a diagnostic measure as its diminishment indicates probable diastolic dysfunction . 
Late ventricular diastole[ edit ]
Early diastole is a suction mechanism between the atrial and ventricular chambers.  Then, in late ventricular diastole, the two atrial chambers contract (atrial systole), causing blood pressure in both atria to increase and forcing additional blood flow into the ventricles. This beginning of the atrial systole is known as the atrial kick—see Wiggers diagram. The atrial kick does not supply the larger amount of flow (during the cardiac cycle) as about 80 per cent of the collected blood volume flows into the ventricles during the active suction period. 
Atrial diastole[ edit ]
At the beginning of the cardiac cycle, all four chambers of the heart—two atria and two ventricles—are in relaxation and dilation, or diastole. The atria are filling with separate blood volumes returning to the right atrium (from the vena cavae ) and to the left atrium (from the lungs). After chamber and back pressures equalize, the mitral and tricuspid valves open, and the ‘return’ blood flows are passed through the atria into the ventricles. When the ventricles have completed most of their filling, the atria begin to contract (atrial systole), forcing blood under pressure into the ventricles. Now the ventricles start to contract, and as pressures within the ventricles rise, the mitral and tricuspid valves are closed.
As pressures within the ventricles continue to rise, they exceed the ‘back pressures’ in the aorta trunk and the pulmonary arteries trunk, and the aortic and pulmonary valves open—and now blood is ejected from the heart. Ejection causes pressure within the ventricles to fall, and, simultaneously, the atria begin to refill (atrial diastole). Finally, pressures within the ventricles fall below the back pressures in the trunks of the aorta and the pulmonary arteries, and the aortic and pulmonary valves close. The ventricles start to relax, the mitral and tricuspid valves begin to open, and the cycle begins again. 
In summary, when the ventricles are in systole and contracting, the atria are relaxed and collecting blood as ‘return’ flows. When, in late diastole, the ventricles become fully dilated, the atria begin to contract, pumping blood to the ventricles. The atria feed a steady supply of blood to the ventricles, thereby serving as a reservoir to the ventricles and ensuring that these pumps never run dry.  This coordination ensures that blood is pumped and circulated efficiently throughout the body. 
Diastolic pressure[ edit ]
Here the adjective “diastolic” refers to the function (the ” diastolic function “) of filling the heart with blood between muscle contractions ; it describes that portion of the cardiac cycle opposite to contraction. The term is more commonly known as one of the two main components for measuring blood pressure —namely, ” diastolic pressure ” refers to the lowest pressure in the arterial bloodstream occurring during each heartbeat. (The other component is “systolic pressure” , which is the highest arterial pressure during each heartbeat.)
Clinical notation[ edit ]
When blood pressure is stated for medical purposes, it is usually written with the systolic and diastolic pressures separated by a slash , for example, 120/80 mmHg . This clinical notation is not a mathematical figure for a fraction or ratio, nor a display of a numerator over a denominator. Rather it is a medical notation showing the two clinically significant pressures involved (i.e., systolic-slash-diastolic, or 120/80). It is often shown followed by a third number, the value of the heart rate (in beats per minute), which typically is measured jointly with blood pressure readings.
Diagnostic value[ edit ]
Examining diastolic function during a cardiac stress test is a good way to test for heart failure with preserved ejection fraction . 
Classification of Blood Pressure in Adults 
|Blood Pressure Classification||Systolic BP (mmHg)||Diastolic BP (mmHg)|
|Stage 1 Hypertension||140–159||or 90–99|
|Stage 2 Hypertension||≥160||or ≥100|
Effects of impaired diastolic function[ edit ]
Brain natriuretic peptide (BNP) is a cardiac neurohormone secreted from ventricular myocytes (ventricular muscle cells) at the end of diastole—this in response to the normal, or sub-normal (as the case may be), stretching of cardiomyocytes (heart muscle cells) during systole. Elevated levels of BNP indicate excessive natriuresis (excretion of sodium to the urine) and decline of ventricular function, especially during diastole. Increased BNP concentrations have been found in patients who experience diastolic heart failure . 
Impaired diastolic function can result from the decreased compliance of ventricular myocytes, and thus the ventricles, which means the heart muscle does not stretch as much as needed during filling.  This will result in a reduced end diastolic volume (EDV) and, according to the Frank-Starling mechanism , a reduced EDV will lead to a reduced stroke volume , thus a reduced cardiac output . Over time, decreased cardiac output will diminish the ability of the heart to circulate blood efficiently throughout the body.
See also[ edit ]
- Systole (medicine)
- Blood pressure
- Wiggers diagram
References[ edit ]
- ^ Diastole . Merriam-Webster Online Dictionary. 24 August 2008.
- ^ a b Widmaier, Eric P. (2014). Vander’s Human Physiology: The Mechanisms of Body Function, 13/e. McGraw Hill Education. p. 378.
- ^ Mohamed, A. L.; Yong, J; Masiyati, J; Lim, L; Tee, S. C. (2004). “The prevalence of diastolic dysfunction in patients with hypertension referred for echocardiographic assessment of left ventricular function” . The Malaysian Journal of Medical Sciences. 11 (1): 66–74. PMC 3438153 . PMID 22977362 .
- ^ Sabbah, H. N.; Stein, P. D. (1981). “Pressure-diameter relations during early diastole in dogs. Incompatibility with the concept of passive left ventricular filling”. Circulation Research. 48 (3): 357–65. doi : 10.1161/01.RES.48.3.357 . PMID 7460209 .
- ^ Williams, Gareth. Advanced Biology for You.[ page needed ][ full citation needed ]
- ^ Hall, John (2011). Guyton and Hall textbook of medical physiology (12th ed.). Philadelphia, Pa.: Saunders/Elsevier. ISBN 978-1-4160-4574-8 .
- ^ Topol, Eric J (2000). Cleveland Clinic Heart Book. New York: Hyperion. pp. 4–5. ISBN 0-7868-6495-8 .
- ^ Betts, J. Gordon (2013). Anatomy & physiology. pp. 787–846. ISBN 1-938168-13-5 .
- ^ Erdei T, Aakhus S, Marino P, Paulus WJ, Smiseth OA, Fraser AG (2015). “Pathophysiological rationale and diagnostic targets for diastolic stress testing”. Heart . 101 (17): 1355–60. doi : 10.1136/heartjnl-2014-307040 . PMID 26001845 .
- ^ “The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure” (PDF).
- ^ Eroglu, Serpil; Bozbas, Huseyin; Muderrisoglu, Haldun. “Diagnostic value of BNP in diastolic heart failure” . Biochemia Medica: 183–92. doi : 10.11613/bm.2008.018 .
External links[ edit ]
|Look up diastole in Wiktionary, the free dictionary.|
- Blood pressure
- Wikipedia articles needing page number citations from May 2015
- Articles with incomplete citations from May 2015
- All articles with incomplete citations
- This page was last edited on 4 September 2018, at 21:42 (UTC).
- Text is available under the Creative Commons Attribution-ShareAlike License ;
- About Wikipedia
- Contact Wikipedia
- Cookie statement
- Mobile view
- Medical Centres
- Women’s Health
- Men’s Health
- Children’s Health
- Blood Centre
- Lungs and Breathing
- Mental Health
- Pregnancy Centre
- Sexual Health
- Weight Loss
- Latest Health News
- Clinical Trials
- Healthy Living
- Mental Health
- Occupational Health and Safety
- Pregnancy and Lifestyle
- Preventative Health
- Smoking and Alcohol
- Health Topics
- View all Health Topics
- Popular Health Topics
- Alcohol and Drinking
- Bed Wetting (Nocturnal Enuresis)
- Cancer: Overview
- Child Developmental Milestones
- Cold and Flu
- Erectile Dysfunction
- Nutrition: Overview
- Testosterone Deficiency
- Videos Tools
- Popular Videos
- Cardiovascular Disease Prevention
- Dr Joe: Anal Bleeding
- Dr Joe: Skin
- Dr Joe: Stress Management
- Prostate Cancer: Diagnosis and Treatment
- The Medical System – Bulk Billing Medicare
- Popular Videos
- Health Tools
- Directories Support
- Medical A to Z
- Medical Dictionary
- Supportive Care
- Useful Links
- Medical Professionals
- Editorial Advisory Board
- Case Studies
- Research and Trials
- Consult Magazine
- Newsletters for Health Professionals
- myVMC Competitions
- Previous Competition Winners
- About myVMC
- Contact Us
- Copyright Information
- Editorial Advisory Board
- Investor Information
- Our Partners
- User-Generated Content
- Editorial Advisory Board
- Advertise With Us
- Advertising Policy
- Sign up
- Why myVMC?
- Cardiovascular system (heart) anatomy
Cardiovascular system (heart) anatomy
- An Introduction to the Cardiovascular System
- Structure and Function of the Heart
- Function and Location of the Heart
- Structure of the Heart
- Chambers of the Heart
- Blood Vessels
- What is the Cardiovascular System?
- What is the Cardiac Cycle?
- Components of the Heartbeat
- The Electrocardiogram
- Effects of Aging on the Heart in Men and Women
An Introduction to the Cardiovascular System
The cardiovascular system can be thought of as the transport system of the body. This system has three main components: the heart , the blood vessel and the blood itself. The heart is the system’s pump and the blood vessels are like the delivery routes. Blood can be thought of as a fluid which contains the oxygen and nutrients the body needs and carries the wastes which need to be removed. The following information describes the structure and function of the heart and the cardiovascular system as a whole.
Information on re-publishing of our images
Structure and Function of the Heart
Function and Location of the Heart
The heart’s job is to pump blood around the body. The heart is located in between the two lungs. It lies left of the middle of the chest.
Structure of the Heart
The heart is a muscle about the size of a fist, and is roughly cone-shaped. It is about 12cm long, 9cm across the broadest point and about 6cm thick. The pericardium is a fibrous covering which wraps around the whole heart. It holds the heart in place but allows it to move as it beats. The wall of the heart itself is made up of a special type of muscle called cardiac muscle .
Chambers of the Heart
The heart has two sides, the right side and the left side. The heart has four chambers. The left and right side each have two chambers, a top chamber and a bottom chamber. The two top chambers are known as the left and right atria (singular: atrium). The atria receive blood from different sources. The left atrium receives blood from the lungs and the right atrium receives blood from the rest of the body. The bottom two chambers are known as the left and right ventricles. The ventricles pump blood out to different parts of the body. The right ventricle pumps blood to the lungs while the left ventricle pumps out blood to the rest of the body. The ventricles have much thicker walls than the atria which allows them to perform more work by pumping out blood to the whole body.
Blood Vessel are tubes which carry blood. Veins are blood vessels which carry blood from the body back to the heart. Arteries are blood vessels which carry blood from the heart to the body. There are also microscopic blood vessels which connect arteries and veins together called capillaries . There are a few main blood vessels which connect to different chambers of the heart. The aorta is the largest artery in our body. The left ventricle pumps blood into the aorta which then carries it to the rest of the body through smaller arteries. The pulmonary trunk is the large artery which the right ventricle pumps into. It splits into pulmonary arteries which take the blood to the lungs. The pulmonary veins take blood from the lungs to the left atrium. All the other veins in our body drain into the inferior vena cava (IVC) or the superior vena cava (SVC) . These two large veins then take the blood from the rest of the body into the right atrium.
Valves are fibrous flaps of tissue found between the heart chambers and in the blood vessels. They are rather like gates which prevent blood from flowing in the wrong direction. They are found in a number of places. Valves between the atria and ventricles are known as the right and left atrioventricular valves , otherwise known as the tricuspid and mitral valves respectively. Valves between the ventricles and the great arteries are known as the semilunar valves . The aortic valve is found at the base of the aorta, while the pulmonary valve is found the base of the pulmonary trunk. There are also many valves found in veins throughout the body. However, there are no valves found in any of the other arteries besides the aorta and pulmonary trunk.
What is the Cardiovascular System?
The cardiovascular system refers to the heart, blood vessels and the blood. Blood contains oxygen and other nutrients which your body needs to survive. The body takes these essential nutrients from the blood. At the same time, the body dumps waste products like carbon dioxide, back into the blood, so they can be removed. The main function of the cardiovascular system is therefore to maintain blood flow to all parts of the body, to allow it to survive. Veins deliver used blood from the body back to the heart. Blood in the veins is low in oxygen (as it has been taken out by the body) and high in carbon dioxide (as the body has unloaded it back into the blood). All the veins drain into the superior and inferior vena cava which then drain into the right atrium. The right atrium pumps blood into the right ventricle. Then the right ventricle pumps blood to the pulmonary trunk, through the pulmonary arteries and into the lungs. In the lungs the blood picks up oxygen that we breathe in and gets rid of carbon dioxide, which we breathe out. The blood is becomes rich in oxygen which the body can use. From the lungs, blood drains into the left atrium and is then pumped into the left ventricle. The left ventricle then pumps this oxygen-rich blood out into the aorta which then distributes it to the rest of the body through other arteries. The main arteries which branch off the aorta and take blood to specific parts of the body are:
- Carotid arteries , which take blood to the neck and head
- Coronary arteries , which provide blood supply to the heart itself
- Hepatic artery , which takes blood to the liver with branches going to the stomach
- Mesenteric artery , which takes blood to the intestines
- Renal arteries , which takes blood to the kidneys
- Femoral arteries , which take blood to the legs
The body is then able to use the oxygen in the blood to carry out its normal functions. This blood will again return back to the heart through the veins and the cycle continues.
Information on re-publishing of our images
What is the Cardiac Cycle?
The cardiac cycle is the sequence of events that occurs in one complete beat of the heart . The pumping phase of the cycle, also known as systole , occurs when heart muscle contracts. The filling phase, which is known as diastole , occurs when heart muscle relaxes. At the beginning of the cardiac cycle, both atria and ventricles are in diastole. During this time, all the chambers of the heart are relaxed and receive blood. The atrioventricular valves are open. Atrial systole follows this phase. During atrial systole, the left and right atria contract at the same time and push blood into the left and right ventricles, respectively. The next phase is ventricular systole . During ventricular systole, the left and right ventricles contract at the same time and pump blood into the aorta and pulmonary trunk, respectively. In ventricular systole, the atria are relaxed and receive blood. The atrioventricular valves close immediately after ventricular systole begins to stop blood going back into the atria. However, the semilunar valves are open during this phase to allow the blood to flow into the aorta and pulmonary trunk. Following this phase,Â the ventricles relax that is ventricular diastole occurs. The semilunar valves close to stop the blood from flowing back into the ventricles from the aorta and pulmonary trunk. The atria and ventricles once again are in diastole together and the cycle begins again.
Components of the Heartbeat
The adult heart beats around 70 to 80 times a minute at rest. When you listen to your heart with a stethoscope you can hear your heart beat. The sound is usually described as “lubb-dupp”. The “lubb” also known as the first heart sound, is caused by the closure of the atrioventricular valves. The “dupp” sound is due to the closure of the semilunar valves when the ventricles relax (at the beginning of ventricular diastole). Abnormal heart sounds are known as murmurs . Murmurs may indicate a problem with the heart valves, but many types of murmur are no cause for concern. (For more information see: (see Valvular Heart Disease )
The heart has an inbuilt rhythm of contraction and relaxation. A small group of heart muscle cells called the pacemaker help achieve this. The pacemaker generates an electrical impulse which spreads over the atria, making them contract. This impulse then spreads to the ventricles, causing them to contract. The electrical changes that spread through the heart can be detected at the surface of the body by an instrument called the electrocardiograph. Electrodes are placed in a number of positions over the chest and the electrical changes are recorded on moving graph paper as an electrocardiogram (ECG) .
Effects of Aging on the Heart in Men and Women
As a part of the normal aging process a number of changes occur to the cardiovascular system.
- Our heart rate slows down because the time between heartbeats increases as we age. This is one of the main reasons why the heart is unable to pump out more blood during exercise when we become old.
- The amount of blood the heart pumps each minute can change as we age. It decreases slightly in older women. However, it does not change in healthy older men who have no heart disease. The reason for the difference between the sexes is not fully understood.
- As we age, our blood pressure falls much more on standing from the sitting position compared to when we are younger. This phenomenon is known as postural hypotension. This explains why elderly people are more likely to feel dizzy or to fall when they stand up quickly from a resting position.
- Beers, M. (editor-in-chief) “Aging and the Cardiovascular System”[online], The Merck Manual of Geriatrics. Merck & Co. Inc. 2006. Available at URL: http://www.merck.com/mrkshared/mmg/search.jsp (last accessed: 30/6/06)
- Guyton, A and Hall, J. (editors) Textbook of medical physiology. Philadelphia, W. B. Saunders, 2000.
- Johnson, L. (editor) Essential medical physiology. Philadelphia, Lippincott-Raven, 1998.
- Saladin, K. Anatomy & physiology: the unity of form and function. Boston, McGraw-Hill, 2001.
- Talley, N and O’Connor, S. Clinical examination: a guide to physical diagnosis. Sydney, MacLennan & Petty, 2001.
Created by: myVMC
Virtual Medical Centre is Australia’s leading source for trustworthy medical information written by health professionals based on Australian guidelines. View more information about myVMC.
Please be aware that we do not give advice on your individual medical condition, if you want advice please see your treating physician.
Parenting information is available at Parenthub.com.au
Partners and Accreditations
- Copyright Information