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 method for radiographic evaluation of the outcome, Method for Radiog...

Method for Radiographic evaluation of the outcome or RCT Ørstavik and associates suggest the use of the periapical index (PAI) for radiographic evaluation of the outcome of roo

Explain the predator-prey relationships, Explain the Predator-Prey Relation...

Explain the Predator-Prey Relationships ? The feeding by a population of one species upon members of another species is referred to as predation. Many scientists also consider

Explain free water - water found in food, Explain Free Water - Water Found ...

Explain Free Water - Water Found in Food? Water which is bound by such minute forces, that its vapour pressure is equal to the vapour pressure of pure water. It can be found as

Define the swab or agar - food microbiology, Define the Swab or Agar - Food...

Define the Swab or Agar - Food Microbiology? Slant Method The method involves sampling with cotton swabs that are transferred directly to slants. Other methods include use of u

Define pseudo-yeasts, Q. What are the Pseudo-yeasts? These are like tru...

Q. What are the Pseudo-yeasts? These are like true yeasts but do not form spores. All the members of this group are particularly unsuitable for fermentation purposes as they p

Pup, hey what is puperty

hey what is puperty

Define function of the iron uptake by cells, Define Function of the Iron Up...

Define Function of the Iron Uptake by Cells? Iron has several vital functions in the body. It serves as a carrier of oxygen to the tissues from the lungs by red blood cell haem

In which organ red blood cells are stored, Surplus red blood cells, require...

Surplus red blood cells, required to meet an emergency, are generally stored in what organ of the human body? Is it the: a) Liver b) Spleen c) pancreas d) Kidneys

What are the three periods into which interphase, Q What are the three peri...

Q What are the three periods into which interphase are divided? Interphase is the preceding phase to the mitotic division. It is divided into three periods, G1, S and G2 the le

Health impacts of water pollution, Health Impacts of Water Pollution I...

Health Impacts of Water Pollution It is well known that clean water is absolutely essential for healthy living. Although adequate supply of fresh and clean drinking water is a

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