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

Analyze the regional wall motions, Q. Analyze the Regional Wall Motions? ...

Q. Analyze the Regional Wall Motions? Ans. Various attempts have been made in the past to try and quantify the ischemic myocardium, however till date the best and most wid

State the uni-ocular movements, State the Uni-ocular Movements In each...

State the Uni-ocular Movements In each eye, for every movement there is an agonist, antagonist, and a synergist. An agonist is the main muscle that is active in carrying out t

What factor cause the measurement to change, During gym class Sally noticed...

During gym class Sally noticed that her friend Melissa always ran faster than her. Sally knew that they exercised equally, so she wondered what could cause Melissa to run so fast.

Tools and techniques - effects of plant growth regulators, Tools and Techni...

Tools and Techniques - Effects of Plant Growth Regulators We have discussed about the "effect of auxins". In this section we shall discuss the methodology being followed in h

The iodine test, why is it necessary to grind food before the testng?

why is it necessary to grind food before the testng?

Eczema, E c z e m a It is inflammatory reaction of epidermal cells...

E c z e m a It is inflammatory reaction of epidermal cells to the substances to which these cells are sensitized. Such substances may be present either in the external or

What is transgenic food, What is transgenic food? Transgenic beings are...

What is transgenic food? Transgenic beings are animals, microorganisms and plants that have recombinant DNA, i.e., genes from other plants, microorganisms or animals artificial

Seed germination - development of plant, Seed Germination - Development of ...

Seed Germination - Development of plant The environmental factors that influence the germination of seeds are: Water availability, Optimal light, Aeratio

What is a biome, What is a biome? A biome is the prevailing ecosystem c...

What is a biome? A biome is the prevailing ecosystem constituted by similar abiotic and biotic factors present in one or more regions of the planet.

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