Cardiac output - circulation, Biology

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.

Posted Date: 1/16/2013 12:38:16 AM | Location : United States







Related Discussions:- Cardiac output - circulation, Assignment Help, Ask Question on Cardiac output - circulation, Get Answer, Expert's Help, Cardiac output - circulation Discussions

Write discussion on Cardiac output - circulation
Your posts are moderated
Related Questions
Q. Write the meaning of Hyperglycemia? Hyperglycemia is a Greek term: hyper -meaning excessive; glyc - meaning sweet; and emia- means "of the blood". It is a condition in whic

Q. How is heart contraction triggered? Heart contraction is independent from neuronal stimulus although it can be modulated by the autonomous nervous system in the heart there

Concerning the maintenance of body temperature how do beings of the class Reptilia classify? Like fishes and amphibians, beings of the class Reptilia are heterothermic animals

how much classification of protozoa

mode of nutrition in tapeworm

PROJECTS THAT HAVE TO BE DONE IN SCHOOL ABOT PICICULTURE

Q. How does digestion in beings of the phylum Annelida work and which type of digestive system do they have? Digestion in beings of the phylum Annelida is extracellular. These

Q. What is embryonic sac? Which are the cells that form the embryonic sac? What are their ploidies? The embryonic sac is female gametophyte of angiosperms. The embryonic sac

Q. Which are mineral salts? Where in living beings can found mineral salts? Mineral salts are simple inorganic substances made of metallic chemical elements, like sodium, iron,

Celia is a nurse in a geriatric ward.  She noticed that older persons in her care are having problems sleeping at night.  She decided to introduce non-pharmocologic ways of relaxat