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

Photosynthetically active radiation, Photosynthetically Active Radiation ...

Photosynthetically Active Radiation This is usually in direct proportion with the incident solar radiation, you know that tropic$ are probably the best illuminated part of the

Microorganisms on on basis of nutrient degradation capacity, Q. Microorgani...

Q. Microorganisms on On basis of nutrient degradation capacity? On basis of nutrient degradation capacity: - Proteolytic: Microorganisms, which are capable of protein degra

Explain the phase contrast microscope, Explain the Phase Contrast Microscop...

Explain the Phase Contrast Microscop? Unpigmented and unstained living cells can be easily observed by phase contrast microscope. It has a special objective and a condenser th

Explain a home-made wormery, A home-made wormery A wooden box 30 cm by ...

A home-made wormery A wooden box 30 cm by 30 cm by 15 cm fitted with a glass front is beneficial for studying the habits of earth-worms. Fill the box nearly to the top with

What is meant by terminal electron acceptor, What is meant by terminal elec...

What is meant by terminal electron acceptor? Give examples of e acceptors for aerobic and anaerobic respiration.

Describe st segment depression, Q. Describe ST Segment Depression? The ...

Q. Describe ST Segment Depression? The development of ST-segment depression with exercise is probably the most reliable sign if myocardial ischaemia and appears to be the most

What is the advantage of that innovation, What is the main evolutionary inn...

What is the main evolutionary innovation presented by nematodes? What is the advantage of that innovation? The short evolutionary innovation of nematodes is the complete digest

Hermaphroditism, Hermaphroditism You would have completely appreciated...

Hermaphroditism You would have completely appreciated now that sexual reproduction is definitely the more advanced type of reproduction. It gives for combination of genes from

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