Introduction To Blood - Video Tutorials & Practice Problems
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Functions of Blood
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In this video, we're going to talk about blood and the functions of blood. And so we already know from some of our past life experiences of getting injured. And from some of our previous lesson videos that blood is a red viscous or thick specialized liquid connective tissue of the cardiovascular system, which recall includes the heart, the blood itself and the blood vessels that project throughout the body. In fact, technically, blood is the only liquid tissue in the body, which is pretty interesting to note. And again, we know that blood is a reddish color, but the shading of red can actually vary depending on the oxygen content of the blood. And so blood tends to be a bright red color with high oxygen content and it tends to be a darker red color with lower oxygen content. And again, blood is quite viscous or thick. And so it tends to be more dense than water and also stickier than water as well. Now, blood is also slightly alkaline or slightly basic in terms of its PH. And so it has a PH that is slightly above seven and more specifically, the PH tends to be in this specific range of 7.35 to 7.45. And it's critical for the blood to be able to maintain this specific PH range for all of its components to be able to function properly. Now, there is quite a lot of blood in the typical human body. In fact, adults tend to have somewhere between 4 to 6 L of blood in the body, which is equivalent to about 1 to 1.5 gallons of blood. And that makes up about 8% of the total body mass. And so again, that's a pretty significant amount of blood in the human body. And once again, we already know that blood is crucial in supporting life. We know this from a young age, losing blood is not something that's good. And this is because blood actually carries out many different functions, including these three functions that are essential that we have listed down below in our table, which are transport regulation and protection. So in terms of transport, the blood can actually serve as a vehicle to help deliver oxygen gas or 02 nutrients such as glucose, for example, and several different types of hormones to the body cells. And so notice in this image, we've got a picture of the lungs which allows us to inhale oxygen gas. And again, the blood can help to serve as a vehicle to deliver that oxygen gas to tissues and cells throughout the body. Blood can also help to transport waste products as well such as for example, carbon dioxide gas and it will transport those waste products to elimination sites. And so again, the tissues and cells throughout our body will produce carbon dioxide gas as a waste. And the blood can transport that waste to the elimination site, which in this case is the lungs and that allows us to exhale the carbon dioxide gas into the environment. Now, the next function that we have here is regulation and the blood can help regulate the body in several different ways. It can help to maintain body temperature since the blood is a source of heat. And recall from our previous lesson, videos on the integumentary system that the blood vessels near the surface of the skin can actually vasoconstrict or narrow down when it's really cold outside and when it does that, it reduces blood flow toward the surface of the skin and that helps our bodies maintain heat during cold conditions since it is going to prevent heat loss from the blood to the environment. And then in the opposite conditions, when it's really hot outside, the blood vessels near the surface of the skin dilate and that increases blood flow to the surface of the skin. And so that is going to help facilitate heat loss from the blood to the environment and that helps cool us down under hot conditions. Now, the blood also has buffers in it that help maintain the optimal PH range which recall blood is slightly alkaline with a PH range of about 7.35 to 7.45. And it's critical that the blood is able to maintain that specific range. And it again, it uses buffers in order to do that. And then last but not least here, the blood has proteins that allows it to maintain fluid volume in the cardiovascular system. And so this helps to ensure that not too many uh not too much fluid is lost from the blood into the surrounding tissues. Now, the final function that we have here is protection. The blood can help protect our bodies by helping to prevent blood loss after an injury. Since blood has proteins in it, that allows it to form blood clots that and reduce blood loss after an injury. And so notice here in this image, you can see that there's a cut in this person's hand, but notice that shortly after the cut is made that there is a blood clot that forms and that reduces blood loss and ultimately helps to protect our body. Also, the blood can help to prevent infection since it has immune cells that help defend against invaders and pathogens. And so this year concludes our brief lesson on blood and the functions of blood. And as we move forward in our course, we'll be able to learn a lot more. So I'll see you all in our next video.
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example
Introduction to Blood Example 1
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2m
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So here we have an example problem that asks which of the following functions is not primarily associated with blood. And we've got these four potential answer options down below. Now, option A says transport of hormones from endocrine glands to tar organs. And of course, recall from our previous lesson, videos that endocrine glands will secrete their products which are hormones into the bloodstream. And we know that the bloodstream essentially serves as a highway that reaches to almost every part of our body. And so we know that the blood is able to transport these h hormones to their specific target organs. And so again, option A is a function associated with blood. So for that reason, we can cross it off because again, we're looking for the function that is not primarily associated with blood. Now, option B says regulation of PH balance by buffering acidic and alkaline substances. And so recall from our last lesson video that the PH of blood is maintained at a slightly basic range of 7.35 to 7.45. And so, in order to maintain that very specific Ph range, it does utilize buffers. And so it does regulate ph through the use of buffers and it is able to buffer acidic and alkaline substances. So option B again is a function associated with blood. We can cross it off because we're looking for the function that is not associated with blood. Now, option C says production of digestive enzymes for breaking down food in the stomach. Now this is something that we have not talked about in our previous lesson, videos being associated with blood. In fact, this is not a function of blood and it is more the function of epithelial cells that are lining the stomach. And so for that reason, we can indicate that c here is the function that is not primarily associated with blood. So see here is the correct answer to this problem. Now, just to be short, let's check option D which says removal of metabolic waste products such as carbon dioxide and urea. And again, we know that the blood is able to uh transport these metabolic wastes and transport them to their elimination sites. So carbon dioxide elimination site would be our lungs in urea, the elimination site would be the kidneys. Yeah, through the urine. And so uh option D again is associated with blood and so we can cross it off and again. Option C is the correct answer. So that concludes this problem and I'll see you all in our next video.
3
concept
Composition of Blood
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7m
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In this video, we're going to talk about the composition of blood. So blood can actually be separated out into three components that we have numbered down below in the text 12 and three. Now, before we cover each of these three components of blood, let's first recall from our previous lesson videos that blood is a type of specialized liquid connective tissue and like all tissues. It's going to consist of living cells and a nonliving extracellular matrix. And so notice this is exactly what we're indicating on the right side that these three com components of blood are either considered living cells or cell fragments that we call formed elements or they're considered part of the nonliving extracellular matrix. So let's take a look at the very first component of blood listed in our lesson, the erythrocytes which are commonly known as red blood cells and can be abbreviated as RB CS. And so these erythrocytes or red blood cells are actually the most numerous type of cell in the blood. And so they are the main cell type in the blood. And as their name implies, their components give them a reddish color. And so because they are the most numerous cell type in the blood. Really, this is what gives our blood that reddish color. Now, functionally, these erythrocytes or red blood cells are adapted for gas transport, specifically oxygen or 02 gas and CO2 or carbon dioxide gas transport. So as we move forward in our course, we'll get to talk more details about the structure and function of these erythrocytes or red blood cells. Now, the term hematocrit is highly linked to erythrocytes or red blood cells. The hematocrit represents the percentage of the total blood volume that is composed of red blood cells. And so the hematocrit is an important value because it can give medical professionals insight into the overall health of their patients. If the value of the hematocrit falls outside of the normal range, that could indicate that there's a problem with the patient. And so the normal range for the hematocrit is somewhere between 36 and 50. And it's important to note that males tend to have a higher hematocrit than females. And so let's say that the hematocrit value for a specific patient is somewhere in between these values, let's say about 45 what that means is that 45% of the total blood volume is made up of red blood cells or erythrocytes. Now, the second component of blood is the Buffy coat, which is actually named after its color since it has this light buff type of color. Now, the Buffy coat actually consists of white blood cells, which are also known as leukocytes, which are important for providing immunity. And the Buffy coat also consists of platelets which are also known as thrombocytes. And these are cell fragments that are important for the blood clotting process, which helps to reduce blood loss during an injury. And so as we move forward in our course, we'll get to talk more details about these white blood cells and more details about the platelets as well. But what you should notice here is that together again, the erythrocytes or red blood cells and the Buffy coat make up the living cells or the formed elements, which is why we have them bracketed here as you see here. Now, last but not least is the third and final component of the blood, which is the plasma and the plasma is actually the nonliving extracellular matrix. And so this plasma is actually a liquid extracellular matrix because it is actually 90% water. And it has dissolved within that water electrolytes such as sodium ions, chloride ions and more. And it also has various proteins dissolved in it as well, such as for example, albumin globulins and fibrinogen, which are plasma proteins that we'll talk more about later in our course. So let's take a look at our image down below and notice on the left hand side, we have this vial or this test tube that's filled with a patient's blood. And notice that initially, the blood is pretty homogeneous, meaning that the components of the blood are pretty evenly distributed throughout the two. And so what this means is that we can't initially visually distinguish those three components of the blood. However, if we take this vial of the patient's blood and insert it into an instrument or a device known as a centrifuge which spins the sample really, really fast. It can actually separate out the components of the blood based on their densities where the more dense components end up closer toward the bottom of the, the vial or the tube. And so notice that's exactly what we have over here. We can now visually distinguish those three separate components of the blood. And so notice that toward the bottom we have in red, the erythrocytes, which recall are also known as red blood cells and can be abbreviated as RB seeds. And again, the hematocrit represents the percentage of the total blood volume that's made up of red blood cells. And notice here in this image that the hematocrit is being indicated as 45% about 45%. Which means that for this particular patient, the uh 45% of the total blood volume is made up of red blood cells or erythrocytes. Now, the next component of the blood is right here and notice that it is quite thin and this represents the Buffy coat. In fact, the Buffy coat actually makes up less than 1% of the total blood volume in most people. And so that's why it's such a small layer here in the vial. And again, the Buffy coat is going to consist of those white blood cells or leukocytes and the platelets or thrombocytes. And collectively the Buffy coat and the erythrocytes make up the living components of the blood and they are referred to as formed elements. And that's exactly what these brackets here are indicating. Now, last but not least is the final component of the blood, which we can see here in this yellow color. And this represents the plasma, which is the nonliving extracellular matrix. Again, it is a liquid extracellular matrix since it is 90% water with some electrolytes and various proteins dissolved in it. And what you'll notice is that the plasma actually makes up the largest percentage of the total blood vol, it can make up about 55% of the total blood volley. And so, uh again, it is going to be the matrix, the extracellular matrix. Now moving forward in our course, we'll get to talk a lot more details about the structure and function of blood and these components of the blood. But for now, this year concludes our brief lesson on the composition of blood and I'll see you all in our next video.
4
example
Introduction to Blood Example 2
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1m
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So here we have a pretty straightforward example problem that says label the pie chart representing the components of blood. And so notice down below, we've got this pie chart and we've got these three interactive blanks that we need to fill in. Now, we are going to start with this red portion over here. And of course, we know from our last lesson video that this must represent the red blood cells or the erythrocytes. And so here in this blink, you can fill in either erythrocytes, red blood cells or you could put RB CS as the abbreviation for red blood cells. Now, the red blood cells can make up anywhere between about 36 to about 50% of the total blood volume under normal circumstances. And so notice over here, we're indicating that it's taking up about 45% of the total blood volume or 45% of the pie chart and recall that this percentage of the total blood volume made up specifically by red blood cells is referred to as the hematocrit. Now, the next region that we're going to look at is this tiny sliver that you can see here and this is going to be the Buffy coat and recall that the Buffy coat is going to consist of white blood cells or leukocytes and platelets as well. And then last but not least we have this yellow region over here. This is going to represent the blood plasma, which recall is the liquid extracellular matrix. It's made up of 90% water with dissolved electrolytes and dissolved proteins and the plasma can make up the vast majority of the total blood volume. Here, we're indicating that it's making up about 55% of the total blood volume. And you can see those ions, those electrolytes dissolved here in the plasma. And so this here concludes our example problem and I'll see you all in our next video.
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Problem
Problem
Plasma accounts for _____% of all blood, and water accounts for _____% of plasma.
A
55;90
B
90;55
C
45;55
D
55;45
6
Problem
Problem
The most numerous formed element in blood are the ____________, and their function is ____________.
A
Platelets; to prevent bleeding from open wounds.
B
White blood cells; to carry oxygen.
C
White blood cells; to fight infection.
D
Erythrocytes; to carry oxygen and CO₂
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