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Pulmonary circulation

Recall that blood returning from the systemic circuit enters the right atrium ( [link] ) via the superior and inferior venae cavae and the coronary sinus, which drains the blood supply of the heart muscle. These vessels will be described more fully later in this section. This blood is relatively low in oxygen and relatively high in carbon dioxide, since much of the oxygen has been extracted for use by the tissues and the waste gas carbon dioxide was picked up to be transported to the lungs for elimination. From the right atrium, blood moves into the right ventricle, which pumps it to the lungs for gas exchange. This system of vessels is referred to as the pulmonary circuit    .

The single vessel exiting the right ventricle is the pulmonary trunk    . At the base of the pulmonary trunk is the pulmonary semilunar valve, which prevents backflow of blood into the right ventricle during ventricular diastole. As the pulmonary trunk reaches the superior surface of the heart, it curves posteriorly and rapidly bifurcates (divides) into two branches, a left and a right pulmonary artery    . To prevent confusion between these vessels, it is important to refer to the vessel exiting the heart as the pulmonary trunk, rather than also calling it a pulmonary artery. The pulmonary arteries in turn branch many times within the lung, forming a series of smaller arteries and arterioles that eventually lead to the pulmonary capillaries. The pulmonary capillaries surround lung structures known as alveoli that are the sites of oxygen and carbon dioxide exchange.

Once gas exchange is completed, oxygenated blood flows from the pulmonary capillaries into a series of pulmonary venules that eventually lead to a series of larger pulmonary veins    . Four pulmonary veins, two on the left and two on the right, return blood to the left atrium. At this point, the pulmonary circuit is complete. [link] defines the major arteries and veins of the pulmonary circuit discussed in the text.

Pulmonary circuit

This diagram shows the network of blood vessels in the lungs.
Blood exiting from the right ventricle flows into the pulmonary trunk, which bifurcates into the two pulmonary arteries. These vessels branch to supply blood to the pulmonary capillaries, where gas exchange occurs within the lung alveoli. Blood returns via the pulmonary veins to the left atrium.
Pulmonary Arteries and Veins
Vessel Description
Pulmonary trunk Single large vessel exiting the right ventricle that divides to form the right and left pulmonary arteries
Pulmonary arteries Left and right vessels that form from the pulmonary trunk and lead to smaller arterioles and eventually to the pulmonary capillaries
Pulmonary veins Two sets of paired vessels—one pair on each side—that are formed from the small venules, leading away from the pulmonary capillaries to flow into the left atrium

Overview of systemic arteries

Blood relatively high in oxygen concentration is returned from the pulmonary circuit to the left atrium via the four pulmonary veins. From the left atrium, blood moves into the left ventricle, which pumps blood into the aorta. The aorta and its branches—the systemic arteries—send blood to virtually every organ of the body ( [link] ).

Questions & Answers

why does the material not allow in mri
Simran Reply
what is the meaning of sutures
Ibrahim Reply
i do not know
immovable joints btn two bones.eg the skull bones
Really,it's true
Sutures are immovable junction between two bones e.g those of the skull
what should I do to get or to know what to do for me to be excellent in the course of anatomy and physiology
Sandra Reply
study harder
Between the heart and the Brain which one is more important to human being... discuss
Faith Reply
well the brain is important for motor skills, the heart is important for involuntary muscle movement supporting body functions. the body can survive without brain involvement, but the body cannot last without the heart
granted the heart is important, but the brain gives the body purpose
the brain is more important
Even though the brain helps the human being to behave normally and purposefully, I think the heart is much more important cos human being cannot live without the heart
change the question
hello guys
it is difficult to select which organ is more important, now you can replace the heart with a mechanical device and the body could still function, and with technology today brain activity can also be replicated. But life would not be the same
there's coordination btn the two..so without any of them no life
the heart
The brain is important to humans.
what is homeostasis
Rebecca Reply
what is the composition of saliva
Vijay Reply
ഫസ്റ്റ് ചാപ്റ്റർ ഇംപോർട്ടൻസ് പോസ്റ്റ്
Reshma Reply
nhi samjh aya
Nhi wt is this
I don't know
Okk wre frm u r
what is mean of? reshma
I don't know but would like to
D bone in d ankle joint re what ?
Ifunanya Reply
can one define a cell as a basic unit of a living organism
Michael Reply
cell is the structural and functional unit of living organisms
Which of the following hormones are responsible for the adolescent growth spurt? estrogen and testosterone, even in women?
Kepa Reply
estrogen hormone
yes estrogen hormone
What is sling give d characteristics of sling uses of sling
adamu Reply
a sling a rope used in hunting ie throwing of rocks
I went to learn anatomy of joints
Arman Reply
me 2
joint have 3 cartilaginous joint fibrous joint synovial joint U can reserch in Google can explain U well
define sling
To throw with a circular or arcing motion
pls hux I was given an assignment,, Between the heart and Brain which one is more important to human being... discuss
what is respiration
Osele Reply
what is respiration
Respiration is the process by which oxygen is taken in and carbon dioxide is given out.
Respiration is the combination of inhalation and exhalation.
inhalation is the taking in air from environment to lung and exhalation is taking out sir from the lung to environment ..
is the process by wich gases(oxygen and carbon(IV)oxide go through the nose, trachea and the lungs to the blood stream
what is holistic
Kibrom Reply
Holistic means encompassing the whole of a thing, and not just the part. Holistic medicine looks at the whole person for answers, not just at physical symptoms. You might have heard of holistic medicine, which tries to treat someone as mind and body, instead of treating only the part of the patient
I want to learn one by one system like skeleton system... muscular system
Mary Reply
i want to learn this
what is the difference between regional anatomy and system anatomy
system anatomy is when we study the system like digestive, circulatory, reproductive, but regional anatomy is studying the anatomy by regions of body like anatomy of neck, thorax, head etc. Regional anatomy may include system anatomy...

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