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

Biological conservation, what are the significance of zoological parks in c...

what are the significance of zoological parks in conversation

Define recommended dietary allowance for riboflavin (rda), Define Recommend...

Define Recommended Dietary Allowance for riboflavin (RDA)? Several nutritional and physiological factors govern riboflavin requirements. Negative nitrogen balance reduces rib

Agro industrial-early embryonic mortality, Early embryonic mortality E...

Early embryonic mortality Embryo mortality is a serious problem for farmers, practitioners and researchers. The establishment and maintenance of pregnancy is a highly complica

Excretion, How many kidney in man?

How many kidney in man?

Define the effect of scfa on sodium absorption, Define the effect of SCFA o...

Define the effect of SCFA on Sodium Absorption? SCFAs (short chain fatty acids) have a stimulatory effect on sodium absorption from colonic lumen. The unionized SCFA crosses th

Cyclins and cyclin-dependent kinases, Rhythmic fluctuations in the abundanc...

Rhythmic fluctuations in the abundance and activity of cell-cycle control molecules pace the events of the cell cycle. • Kinase - a protein which activates or deactivates another

What is the role of platelet plug formation in hemostasis, What is the role...

What is the role of platelet plug formation in hemostasis? What events occur during platelet plug formation? Describe the circumstances that may induce inappropriate platelet plug

Explain the repair mechanisms of brain, Explain the repair mechanisms of br...

Explain the repair mechanisms of brain Scientists are just beginning to understand how these innate repair mechanisms might be harnessed to treat disease. On leading edge of th

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