Welcome to our lesson on tissues. When cells that do a similar job come together, they form tissues that then can create organs.
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- To build organs that make us up, cells with similar functions need to aggregate together and form tissues. Epithelial tissue makes up structures that cover us, such as our skin, as well as linings of tubes like the gut or blood vessels for example. What is muscular tissue’s main job? What about nervous tissue?
- When we bump into something, our skin protects us. When we eat something, our gut absorbs nutrients we then use to get energy from. What other functions does epithelial tissue have?
- The reason why we don’t bleed when our skin hits an object is because it’s top layers are dead cells that simply slough off. There are no blood vessels present. Cells in epithelial tissue continually regenerate. There is also no blood supply within it. Nourishment comes from the underlying connective tissue. List some other characteristics of epithelial tissue.
- Considering epithelial tissue’s different tasks helps us understand its different cell shapes. Thin, flat cells let substances easily penetrate as is necessary for example when oxygen moves from the atmosphere into the blood stream. What are cuboidal (cube shaped) cells good for?
- The cells can be single layered (simple), which is good for material to pass through them. is a stratified arrangement (multiple layers) useful for?
- Gut cells job for example is to absorb nutrients. Their top surface has finger-like projections that increase the surface area; the larger the surface, the more nutrients can be absorbed. What are those extensions called?
- The skin is a good example to understand connections that form between cells. Skin is pretty tough. You can pull on it and it will not rip! That is because strong, anchoring connections form between cells. What are those connections called?
- Some epithelial cells task is to make substances that they export; sweat for example. Sweat actually carries heat away from the body to cool it off, it exits the body; we call cell clusters that do that exocrine glands. Other substances, such as hormones for example are secreted into the blood stream. What do we call those kind of glands?
- Epithelial tissue cells also function as the gateway for a brain to experience the surrounding world. The nervous system works on electricity. Nerves are essentially cables with a lot of individual wires in them that have a start and finish point. If you get poked for example, the physical pressure on the skin is translated into an electrical signal (by epithelial cells) that sends the message ‘poked’ to the brain. What other types of stimuli can you think of?
- When I think of the 4 tissue types making up all of our body, muscle and nerve tissue have very specific functions; contracting and dealing with electricity and information. Epithelial tissue can be understood by it’s functions and characteristics; it is lining and coverings mostly. Connective tissue is the most diverse, it’s all over the body and has many functions. It’s recognizable by it’s common fundamental components: cells as well as a matrix (organized material). What is the extra-cellular matrix composed of?
- Connective tissues organization is largely done by different types of fiber. We know of 3 main types. Collagen is most commonly found; a thread that cannot be pulled apart, it is non-distensible. What are the other 2 types called and what are their qualities?
- Cartilage is made of rubbery material. We find it where bones come together making joints, a place of pressure and friction; think of a knee. Besides in the skeleton, where else is cartilage useful?
- If you think of a knee, cartilage at the ends of the leg bones get compressed and squeezed every time we take a step. There is no way blood vessels can survive, so there aren’t any. Since blood brings nutrients to the cells of a tissue, how do we assure that cartilage cells get fed?
- Cartilage comes in 3 main different types with each having unique qualities that make it suited for tasks. Name the 3 types and where they are found.
- Bones are absolutely cool. They hold us up, protect delicate organs, and give muscles ‘sticks’ to attach to and pull on so that we move. What other 2 unrelated functions can make us grateful to have bones?
- Compare to cartilage, bone has excellent blood supply, which make it heal quite well. What other feature helps the healing process?
- Bone seems like dead material, because we know it from dried out skeletons. They are actually constantly changing organs. For example, a hip becomes stronger the more it is trained; that is, the bone physically changes its composition to withstand a greater force: collagen fibers are laid down along stress lines and calcium salts are deposited. On the other hand, when our blood needs more calcium ions, bone becomes an incredible reservoir to pull from. All that ‘building up’ and ‘breaking down’ work is done by three main cell types. List them and indicate their function.
- Consider your own bones, they come in many different shapes; the leg, arm, and also finger/toe bones are longer than wide, so they call them long bones. Others are more cube shaped, flat, or have things sticking out. List the different shape classifications.
- Long bones have to heavily grow in length as we grow. They do that towards both ends. That growth area separates a long bone into 3 main sections. Can you list them?
- When we see a bone from the outside, it’s surface is smooth. One type of bone material is compactly built, hard and very strong. It also makes it very heavy. Therefore, on the inside, we find a softer, lighter bone, built of pillars that are arranged along stress/force lines. What is that type called?
- The smallest, study-able bone subunits are called osteons. They are tiny, round pillars built to withstand compression, so that an organism can raise itself up against gravity; sort of small, tiny, little 4x4 beams stemming up the roof of a house. A channel going up and down on the inside carries nutrient vessels. It is surrounded by sheets of collagen fibers with calcium salts deposited between them. Osteocytes are the keepers and maintain these structures. What are the ‘little houses’ called that they live in?
- Bone is created in two main ways. Flat bones start out as 2 membranes. Bone ‘sprouts’ fill in the spaces in between. Most other bones start as a cartilage model that then is replaced by bone. What is the second type of ossification?
Please email me the answers prior to the class meeting to DocMuli@hotmail.com. Thank you.
This first talk is about tissues in the lab and how they can aid us.
This talk I do enjoy so much that I have gotten his app and subscribed to it.
Our minds are so incredibly busy all the time making us incredibly distracted. It's almost like we are keeping our brain bombarded with input from TV, Facebook, magazines, advertisement, anxiety about the future, grief over the past, and the list goes on. Bringing some awareness about our own mind into our lives has been proven to be extremely beneficial on how we experience it. Watch Andy explain it, he is much better at it.