Which of the following is TRUE about the structure of...

Which of the following is TRUE about the structure of capillaries, arteries, and veins? a. Capillary walls are comprised of a single layer of endothelial cells. b. Veins contain two layers of tissue surrounding the endothelium: smooth muscle and connective tissue. c. Of the three types of vessels, arteries have the thickest walls, which help them to function at high blood pressure. d. All of the above. e. A and C only.

Transcript

00:02 Hi there.

00:03 For this question, i would like to discuss the flow of blood through arteries and veins from and to the heart.

00:14 So rather than trying to draw a four chamber heart, i am just going to write the word for that.

00:23 And blood can flow away from the heart.

00:28 It does that in arteries.

00:31 And blood can flow to the heart in veins.

00:43 So we typically think about arteries carrying oxygen -rich blood, whereas veins typically carry oxygen depleted blood.

01:07 But notice i said the word depleted.

01:10 That just means reduced.

01:13 It doesn't mean that this is completely void of oxygen.

01:20 In fact, oxygen depleted blood blood only has a reduction of about 25 % of the oxygenation.

01:31 That's a ballpark figure.

01:37 So only about 25 % less oxygen.

01:42 So the blood cells are still oxygenated.

01:44 They are just not nearly at the point of the oxygen -rich blood that goes to the arteries.

01:50 Another thing to keep in mind, i'm going to put the lungs here in my little flow chart.

01:59 The lungs will also use the pulmonary vein.

02:13 This is still considered a vein because it is pumping blood to the heart, but this has already been oxygenated in the lungs.

02:23 So it is fully oxygenated.

02:31 So we have cases here where, of course, arteries are carrying oxygen -rich blood, but we have pulmonary vein also carrying oxygenate.

02:42 Oxygen -rich blood and all of the other veins of the body carrying blood that has been oxygen depleted, but it really means it's only been reduced by about 25 % of the oxygen content.

02:54 So we have veins carrying oxygenated blood, just like arteries are.

03:00 It's just that the artery's blood is far more oxygenated...

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