Lungs: Anatomy (Nursing)

00:01 So now let's look a little bit closer at the anatomy of the lungs themselves.

00:07 So your lungs are mostly composed of the millions of alveoli.

00:13 The rest of the lungs are going to consist of stroma and elastic connective tissue.

00:19 Due to this composition, the lungs have a very elastic and spongy feel.

00:27 So in this image of the lungs, I want to highlight the different lobes of the lungs.

00:33 On the right lung you have three lobes the superior lobe, the middle lobe and the inferior lobe.

00:41 On the left lung, there are only two lobes.

00:44 The superior lobe and the inferior lobe.

00:48 Also pay attention to the space between the two lungs.

00:52 This space is known as the cardiac notch and this is where the heart is going to sit.

01:00 So how does blood get to the lungs? This process is known as perfusion or blood flow and it can occur by two routes.

01:12 The first route is pulmonary circulation.

01:15 In pulmonary circulation, the pulmonary arteries are going to deliver systemic venous blood that has left the heart gone through the body and return to the lungs for oxygenation.

01:30 These arteries are going to branch profusely in order to feed into the pulmonary capillary networks.

01:38 Pulmonary veins are then going to carry oxygenated blood from the respiratory zones back to the heart.

01:47 Now notice that pulmonary veins contain oxygenated blood and these are the only veins in the body that do contain oxygenated blood.

01:56 Most of the time veins are associated with deoxygenated blood.

02:02 Pulmonary circulation is going to be a low pressure high volume system.

02:09 And the lung capillary endothelium is going to also contain many enzymes that can act on different substances in the blood.

02:18 So for example, we have the angiotensin converting enzyme or A-C-E or ACE, and this is going to activate our blood pressure hormones in order to change the vasoconstriction and vasodilation of our blood.

02:35 The other route is going to be bronchial circulation.

02:39 And this case the bronchial arteries are going to bring oxygenated blood directly from the heart to the lung.

02:47 This blood comes from the aorta and enters the lung at the hilum.

02:53 Because this is a part of a systematic circulation.

02:57 This is a high pressure low volume system.

03:02 These bronchial arteries are going to supply all of the lungs tissue except for the alveoli and sometimes these two circulatory pathways, the pulmonary and the bronchial circulation can be connected when bronchial veins anastomose with pulmonary veins.

03:21 But in general, most of your pulmonary veins are going to carry most venous blood back to the heart.

03:30 So now that we discuss how blood gets to the lungs.

03:33 Let's talk about how the lungs are innervated.

03:36 The lungs are innervated by both parasympathetic and sympathetic motor fibers as well as some visceral sensory fibers.

03:46 The nerves are going to enter through the pulmonary plexus on the lung root and they're going to run along the bronchial tubes and the blood vessels of the lung.

03:56 Parasympathetic fibers in the lung are going to cause bronchoconstriction whereas sympathetic fibers of the lungs cause bronchodilation.

04:09 So now if we look at the entire thoracic cavity, we notice that there is a thin double layered serosa membrane known as the pleurae.

04:21 A this is going to divide the thoracic cavity into two plueral compartments as well as the mediastinum.

04:30 The pleura is made up of two layers.

04:33 The parietal pleura, which is the membrane that is connected to the thoracic wall, the superior face of the diaphragm around the heart and in between each lung.

04:46 Also, we have the visceral pleura, which is going to be the membrane that is associated with the surface of the lung.

04:57 Between the parietal and the visceral pleura.

05:00 We have pleural fluid.

05:02 In this fluid fills this very tiny cavity between those two pleurae.

05:09 The fluid is going to provide lubrication and as well surface tension that's going to help in assisting us with expansion and recoil of the lungs.

05:19 Will talk about this space a little bit later.