Welcome biologists. In this session we're going to take a look at the bits underlined there, so the structural and functional differences between skeletal involuntary and cardiac muscle. So here are the three different types of muscle. You need to know similarities and differences between all three but also how to identify them from a microscope image. So there's some terminology involved here that we need to know first of all. Multinucleate means I've got several nuclei within the cell. Unicucleate means I've got one cell. striated means that I've got like a stripy appearance like in this image here and non-striated means that it's got it doesn't have that stripy appearance we have three different types of cells here so we've got a branch cell which as it implies the cell branches off we've got a cylindrical in shape and we've also got spindle in shapes which you'll see in the images in a minute we also need to know their function and the contraction length so is it going to be slow is it intermediate or is it a fast contraction So first of all, let's look at voluntary or skeletal muscles. So this is responsible for movement of conscious control. So for example, the movement of your arm or whatever. And what it has here is, as you can see in this particular image, this one is striated. It's multinucleate, so it has several nuclei within a cell and it's striated because of the bands of actin and myosin. The cells are cylindrical, so they're kind of like a cylindrical shape. and as I mentioned before it is involved with moving the skeleton or the bones or joints or limbs and this one has a very short contraction length it's very rapid cardiac muscle and so this is makes up the cardiac muscle that causes the heart to contract it is myogenic which means it contracts on its own without the nervous stimulation of the nervous system it's found only in the heart and this is striated but it's not as stronger stripy appearance as we just saw there within the skeletal muscle this one contains branch cells so as you can see here in this image the cells kind of like link up if you like they are separate but they are classed as branched cells and they have interlocking junctions which is what you can see here on this image. Now they are unit nucleates so although they kind of have if you like these bridges these interlocking junctions between them they are separate cells alright so each cell has one nuclei which is why it's called a unit nucleate. This one has an intermediate contraction length and speed. And the last one we need to be aware of is smooth muscle. Now this is involuntary control. So for example, the smooth muscle that lines the trachea in your airways. You don't need to think about how this is contracting or why it might contract. Smooth muscle, this is involuntary. Now this is non-steroided, as you can see here in this image, it doesn't appear as much of a stripy appearance as the other two. It is uninucleate, so it has one nuclei within each cell. and as you can see here they have a more of a spindle shaped cell for this one now these ones are involved for example with peristalsis controlling the diameter of the bronchi and the trachea and also the pupil size arteries and arterioles and there is no regular arrangement for these ones So what I advise that you do is pause the video, try and draw out this Venn diagram and fill in the blanks. So this will help you to determine the similarities and differences between all three of these which you do really need to be aware of. So pause it, have a go and then the answers are coming up now. So I'm not going to read through it all because you can see that in front of you but that is what we should be getting to know the differences and the similarities between all three of those types of muscle cells. Now the one thing that we haven't done is look at the images taken from a microscope image. OK, so here are three images of the different types of muscle under a microscope. And you do need to be able to identify these in an exam. It hasn't been on for a while, so it may come up soon. But these are the different types. If you want to pause it and have a go at trying to identify each one, that might be a good idea. So the first one is cardiac muscle. You can kind of see the interlocking junctions on those. Voluntary or skeletal muscle there for number two, which you can see really obvious stripy pattern in that striation of the muscle fibers. And then the last one there is a smooth muscle, which you can kind of see those spindle shaped cells within it. So there are clues within those images to give away which one is which muscle. So there we have it, that's a bit in red that we've looked at. We'll cover the rest of Spec Point L in another couple of videos because there's a lot of content here. Guys, good luck with your exams. Don't forget, don't use the word it, they, amount and size. Use good scientific terminology to make sure you get all of the marking points and good luck with your studies.