<< Chapter < Page Chapter >> Page >

When the myocardium of the ventricle contracts, pressure within the ventricular chamber rises. Blood, like any fluid, flows from higher pressure to lower pressure areas, in this case, toward the pulmonary trunk and the atrium. To prevent any potential backflow, the papillary muscles also contract, generating tension on the chordae tendineae. This prevents the flaps of the valves from being forced into the atria and regurgitation of the blood back into the atria during ventricular contraction. [link] shows papillary muscles and chordae tendineae attached to the tricuspid valve.

Chordae tendineae and papillary muscles

This photo shows the inside of the heart with the main muscles labeled.
In this frontal section, you can see papillary muscles attached to the tricuspid valve on the right as well as the mitral valve on the left via chordae tendineae. (credit: modification of work by “PV KS”/flickr.com)

When the right ventricle contracts, it ejects blood into the pulmonary trunk, which branches into the left and right pulmonary arteries that carry it to each lung. The superior surface of the right ventricle begins to taper as it approaches the pulmonary trunk. At the base of the pulmonary trunk is the pulmonary semilunar valve that prevents backflow from the pulmonary trunk.

Left atrium

After exchange of gases in the pulmonary capillaries, blood returns to the left atrium high in oxygen via one of the four pulmonary veins. Blood flows nearly continuously from the pulmonary veins back into the atrium, which acts as the receiving chamber, and from here through an opening into the left ventricle. Most blood flows passively into the heart while both the atria and ventricles are relaxed, but toward the end of the ventricular relaxation period, the left atrium will contract, pumping blood into the ventricle. This atrial contraction accounts for approximately 20 percent of ventricular filling. The opening between the left atrium and ventricle is guarded by the mitral valve.

Left ventricle

Recall that, although both sides of the heart will pump the same amount of blood, the muscular layer is much thicker in the left ventricle compared to the right (see [link] ). The mitral valve is connected to papillary muscles via chordae tendineae.

The left ventricle is the major pumping chamber for the systemic circuit; it ejects blood into the aorta through the aortic semilunar valve.

Heart valve structure and function

A transverse section through the heart slightly above the level of the atrioventricular septum reveals all four heart valves along the same plane ( [link] ). The valves ensure unidirectional blood flow through the heart. Between the right atrium and the right ventricle is the right atrioventricular valve    , or tricuspid valve    . It typically consists of three flaps, or leaflets, made of endocardium reinforced with additional connective tissue. The flaps are connected by chordae tendineae to the papillary muscles, which control the opening and closing of the valves.

Heart valves

This diagram shows the anterior view of the heart with the different heart valves labeled.
With the atria and major vessels removed, all four valves are clearly visible, although it is difficult to distinguish the three separate cusps of the tricuspid valve.

Questions & Answers

1-chemical level 2-cellular level 3-organ system level 4-tissue level 5-organism level 6-molecules
Dennis Reply
when cell are dead in any part of the body what happen to that place
Dennis Reply
describe the Krebs cycle
Lian Reply
the sequence of reactions by which most living cells generate energy during the process of aerobic respiration. It takes place in the mitochondria, consuming oxygen, producing carbon dioxide and water as waste products, and converting ADP to energy
shea
thanks
Lian
Andy is 1.0 m tall and weighs 45kg Bmi= weight / Height (squared) what's his bmi? Is it high or low?
zafirah Reply
where did our atmosphere came from
Thomas Reply
Our atmospher came from outer space.
R0se
Do mitotic and mitosis mean same?
Abhishek Reply
yes
momo
what are some mechanisms for regulating electrolytes and fluid in the body?
Anita
how do it move
Jaheim Reply
what is biology fall under
Twayne Reply
what is life?
Suliman Reply
define unit membran model?
Suliman
define unit membran model?
Suliman
different between human being and animals
Habeeb Reply
what is fat soluble drugs
Acho Reply
drugs that dissolve mostly in fatty tissues
shea
what is cell
Sesay Reply
cell is the basic unit of life.
ibtisam
how many double bond present in arachidonic acid?
Rekha
what is the source of the homologous chromosomes and the importance of its event?
Tani Reply
what is biology
Habeeb
bio mean life. logy mean study. so study of life. life is the diffrent between living and non living such as digestion ,respiration, reproduction,movment etc
Suliman
chemical, cellular, tissue, organ, organ system, organisms
Saleema Reply
chemical, tissue, cellular, organ, organism, organ system
Saleema
yes, both parts are apart of the reproductive and endocrine system because they function in both
Saleema
du antigen
gambo
what is antigenic
gambo
how many bones are there in a human
Tih Reply
206
Shivani
206 when they fused together
gambo
206 bones
Kate
206bones
R0se
206
Mahmmad
define ornithology
Aniowo
ornithology is the study of birds in every aspect.
Hemamalene

Get the best Human biology course in your pocket!





Source:  OpenStax, Human biology. OpenStax CNX. Dec 01, 2015 Download for free at http://legacy.cnx.org/content/col11903/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Human biology' conversation and receive update notifications?

Ask