Cardiac output - circulation, Biology

Assignment Help:

Cardiac Output - Circulation

The cardiac output can be determined in a number of ways. The most common method is the Fick's principle. A. Fick a German physiologist in 1870 described a simple method of calculating cardiac output from measurement of oxygen consumption (or carbon dioxide production) and the difference between oxygen (or carbon dioxide) contents of blood entering and leaving the heart.

1961_Cardiac Output - Circulation 1.png

The volume of blood ejected by each beat of the heart is the stroke volume. The mean stroke volume is determined by dividing cardiac output by heart rate. In other words, cardiac output can be calculated if we know the values of heart rate and stroke volume. Therefore, cardiac output can be increased by increasing either the heart frequency or the stroke volume or both. However, in mammals there may be little change in stroke volume if cardiac output is to be altered, major adjustments are made in the heart rate. The distribution of blood to the various organs of the human body is given in Table You can see from the Table that kidneys, liver, heart and brain make up only 5% of the total body weight but receive more than half of the total cardiac output. Stroke volume can also be defined as the difference in volume of blood before and after contraction. Two factors influence stroke volume, one is the hormone adrenaline (epinephrine) which increases contractions thus forcing a larger volume of - blood out of the ventricles in a single stroke. The other is the amount of blood present in the ventricles before contraction.

1444_Cardiac Output - Circulation 2.png

If the returning venous blood to the heart is increased, then ventricles will be filled with more blood and following contraction more blood will be ejected out. This relationship between cardiac output and increased venous volume was discovered by the English physiologist Ernest H. Starling. This relationship will be further discussed when we talk of blood flow during exercise.


Related Discussions:- Cardiac output - circulation

Endoplasmic reticulum, ENDOPLASMIC RETICULUM (ER) Eucaryotic celIs have t...

ENDOPLASMIC RETICULUM (ER) Eucaryotic celIs have two major compartments- nucleus and cytoplasm. Cytoplasm was known to have no structure until the discovery of electron micrsscop

What is ammensalim, What is ammensalim? Ammensalism is the ecological i...

What is ammensalim? Ammensalism is the ecological interaction in which an individual harms another without obtaining advanatage. Ammensalism is an inharmonious (negative) ecolo

Explain the techniques of operation in post myocardial, Explain the Techniq...

Explain the Techniques of Operation used in post myocardial infarction ventricular septal defect? Normal 0 false false false EN-IN X-NONE X-NONE

Which substance does not contain hormones , Hormones are composed from seve...

Hormones are composed from several classes of molecules. As far as our present knowledge extends, hormones are not found in which of the subsequent categories of substances: a)

What are the benefits of cardiac rehabilitation, What are the benefits of c...

What are the benefits of cardiac rehabilitation ? The most substantial benefits include: 1 Improvement in exercise tolerance. 2 Improvement in symptoms. 3 Improvement in blood

What is meant by substrates of enzymatic reactions, Substrates are reagent ...

Substrates are reagent molecules upon which enzymes act. The enzyme has spatial binding sites for the attachment of its substrate. These sites are known as activation centers of

State the term - rCBF, State the term - rCBF In rCBF, the participant i...

State the term - rCBF In rCBF, the participant inhales a small amount of a radioactive gas such as xenon, which is absorbed into the bloodstream and thus transported around the

Define a ''rag doll'' seed tester, A 'rag doll' seed tester Fold a squa...

A 'rag doll' seed tester Fold a square metre of muslin twice in the similar direction. Near one end mark out eight or ten squares about 5 cm by 5cm with a pencil. Number the sq

Transferring the patient form icu to ward, Transferring the Patient form IC...

Transferring the Patient form ICU to Ward The patient is made to ambulate in ICU before shifting to ward . vitals are stabilized. The ward nurse is explained the pa

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd