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

Define key concepts and facts of polysaccharides, Define Key Concepts and F...

Define Key Concepts and Facts of Polysaccharides? 1. All polysaccharides contain several monosaccharide units. 2. All monosaccharide units are joined to each other by glycosidi

Phlum protoza, what are the some examples of phlum protoza?

what are the some examples of phlum protoza?

Show the circulatory system present in arthropods, Q. What is the kind of c...

Q. What is the kind of circulatory system present in arthropods? Do these animals have respiratory pigments and heart? In arthropods the respiratory system is open (lacunar). B

Define discovery of other essential nutrients, Define Discovery of other Es...

Define Discovery of other Essential Nutrients? Following the identification of the food factors involved in beriberi, pellagra and scurvy, the search was on for other water-sol

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

Explain the sources of microorganisms, Explain the Sources of Microorganism...

Explain the Sources of Microorganisms? Microorganisms are virtually present everywhere in nature including air, water and soil. The microbial flora is also associated with the

Zoology, two larva forms of sponge

two larva forms of sponge

Disease has a high morbidity and low mortality, The disease has a high morb...

The disease has a high morbidity and low mortality Genital disease: Affected cow develop fever, depression and stand apart, with tail held away from vulva, urination is freq

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