Transcription
Hello. That's a low English. I'm back. So, let's talk about the requirements for life. Let me make this bigger. Come on. There we go. All right. M requirements for life. Maintaining boundaries. That doesn't mean keeping people away and social distancing. It means having an inside and an outside of a cell. Uh being able to move even most I don't want to say simplest organisms cuz life is not simple at all. Even most organisms can move toward good stimuli and away from bad stimuli. We can respond to those stimuli in our environment. We have to break down our food digestion. We have a metabolism that means using energy to maintain that organization and we get that energy production. Metabolism causes the production of waste products that we have to get rid of. And of course, reproduction is also a um basic attribute of life. And then growth. Start out small, grow bigger, reproduce again.
So let's go through each one of these. Maintaining boundaries. Separation between the internal and external environments must exist. And the analogy I'll use when we get to cells is your home. I hope we all have a home. And uh what the homes have is walls and doors and a roof and a floor. And that separates the inside environment inside the home from the outside of the home. And cells have something called a plasma membrane or cell membrane. Sometimes it's called. Cell membrane is an older term. Plasma membrane is a bit newer. And that separates the inside of the cell from the outside of the cell and allows the cell to have some control over its internal environment. On an organismal level, our skin separates us from the outside environment. In most places, the skin is open in some areas. eyes, ears, nose, mouth and throat, urinary tract, digestive system.
Um, movement. We must move. Locomotion is movement. Our muscular system allows movement. We have three types of muscles. We have uh the smooth muscle I've already discussed in the last video. We have cardiac muscle which makes up the muscle part of the heart. And then we have skeletal or voluntary muscle. Sometimes it's called striated. That's an older term because it appears striped when you when you look at it in the microscope. Uh and the skeletal muscles attached to mostly bones to allow our movement. Contractility, that's movement at the cellular level. That's a cell that can get shorter. Uh that when a cell contracts, it gets shorter. And the muscles are the only cells that that can really do that.
Um, yes, responsiveness. The ability to sense and respond to stimuli. Okay, stimuli. Let's talk about words. You're going to also find that as obs obsessed as I am with food, I'm also obsessed with words. You know that because I just gave you that horrific assignment, uh, your word list that I hope you're working on. Please work on it. Um, because words are important. They give you power. or the power to understand, the power to communicate. And we use medical terminology in anatomy and physiology and scientific uh terminology and uh the metric system to communicate with each other. And so it's important, very important. So make sure you listen to this. It's important that we use our words properly. If we don't use our words properly, then we don't come across as smart as we really are. So, um, stimulus is singular. Stimulus is singular. Stimuli is plural. So, I like to when I define these, use them in a sentence. Sometimes it has something to do with biology and sometimes it doesn't. Uh, maybe a lot of people got a stimulus check. a couple of months ago. One, but many people would like to have multiple stimuli. They want more checks. I don't know where the government's going to get the money, but if they want to send it to me, I'll take it. Uh, so stimulus is plural. Stimuli, I mean, stimulus, stimuli is plural. Uh, we can respond uh with a withdrawal reflex, an injury, like you grab on something hot and you pull your hand right away before you even know it. Control a breathing rate. So, uh, if you're at rest like you probably are right now, uh, listening to this and watching this, you're probably at a nice calm resting respiration rate. But if you get up and get some exercise, which I encourage you to do, I did go get some exercise yesterday just like I told you I would. Uh your breathing rate will go up. You might even break a sweat uh to respond to the heat production by your working muscles.
Digestion, that's breaking down ingested food stuffs followed by absorption of simple molecules into the blood. So, let's say h how does this work for let's say I don't know some random piece of food like uh oh a taco. You take the taco and just like the woman eating the carrot, you break it down into smaller pieces. You bite off a chunk and then you chew it into smaller and smaller pieces called mechanical digestion. And then you swallow it and goes to your stomach by means of the esophagus. And in the stomach the mechanical digest continues and then we start the chemical digestion. We break the big molecules into smaller molecules and we get them into the smallest possible molecules that we can and then the digestive tract mostly the small intestine. We absorb those molecules into the blood and they flow around in the blood and we use them wherever we need them.
Metabolism all the chemical reactions that occur inside cells. Uh there's two general categories of metabolic reactions. There's a couple ways that you can classify uh chemical reactions. One way is uh here. Do we build big molecules or do we break down big molecules into smaller molecules? Catab is the branch of metabolic reactions where we take big molecules and break them down. Catabolic reactions happen in the digestive system like I just described, breaking down big molecules into their smaller parts. Then we absorb those smaller molecules in the blood and they flow around the body until they get to where they're needed and then we might put them back together. Like I mentioned in the other slideshow that my tacos tonight are going to contain beef steak, which is beef. That's what's for dinner. And so beef is primary a source of protein. It's got other stuff in it too, but let's talk about focus on the protein in my beef steak tacos. So protein is a big molecule that it's small made up of a bunch of smaller molecules known as amino acids. And we'll talk about about that how they're built and what the what what is an amino acid kind of thing uh a bit later. So, but what happens in the body with the proteins that that I eat? So, I need a source of protein, right? For whatever purposes, maybe it's to make new red blood cells. Maybe it's to make new muscle cells since been sitting around getting out of shape during this pandemic. And then now I'm trying to get back into shape and building new muscles. And my muscles are made protein. But beastake is made from a cow. And although I might resemble a cow, I am not a cow. I need people protein. But cow protein and people protein are made of the same amino acid building blocks. So, what'll happen is once I chew up my my taco, which is my favorite part of the process, by the way, I'll swallow it and it'll get broken down and the amino acids will be absorbed by my uh small intestine and then they'll be distributed through the body. And then when they get to where they're going, where wherever a place is that I need proteins, then I can assemble them into the proteins that I need, whether that be part of skeletal muscle, maybe it's uh the hemoglobin molecule because I need new blood cells. So the breaking down of molecules in the digestive system is an example of a catabolic reaction. And the build of new proteins from amino acid building blocks is a part of anabolic or an anabolism or anabolic process. Now you've heard that term anabolic before. You know what that means and we'll revisit that in the metabolism section.
Uh excrete excretion. All this activity produces waste products. As we break down proteins and and and chop them up into their individual pieces, we get nitrogenous waste, nitrogen bearing waste, nitrogenous to to contain nitrogen. And we get rid of that. The urinary system gets rid of that for us in the form of ura, which is concentrated by the kidneys into urine. Carbon dioxide is also a waste product that diffuses into the blood, goes to the lungs, and we get rid of it. Uh feces undigested materials you know about that.
Reproduction at the cellular level reproduction involves a division of cells for growth or repair. So that's a necessary life function uh for a multisellular organism. It's actually the very first thing we did. Each one of us, each one of us start when an egg from our mom was fertilized by a sperm from our dad. And the very first thing that that fertilized egg or zygote did was make a copy of its genetic material and divide in two. It made a copy of its genetic material, we did, and divided into two. And that is uh something that can do that is a definition of life. And so a zygote, a fertilized egg fits the biological description of life. So I'm just going to tell you that. So remember that in the one of my goals in the syllabus is give you information to make decisions for yourself and families. So a fertilized egg is a living thing. living human thing. Now, what do we do with that egg? Well, that's not an egg anymore. It's a fertilized egg. It's a zygote. So, what do we do with that? Is it um okay to do this, that, or the other thing with it? I don't know. That's a moral question. I don't have the answer to that. You have to you have to put that through your own moral filter and figure out what comes out on the other end of that. But I can tell you when it makes when a fertilized egg makes a copy of it genetic material and divides into two, it is a living thing. All right, enough of that.
At the organismal level, reproduction is the production of offspring. So, uh the process there's a process that uh results in the formation of gameamtes. Gametes are sperm or egg and those are obviously involved in reproduction.
Growth increase in size of a body part or maybe even a cell gets bigger and then will eventually divide. Humans are multisellular. So to function individuals must be kept alive. Individual cells must be kept alive. multisellular. We're made up of more than one one cell. And uh we have to deliver whatever the cells need to every cell in the body, everyone, not just one or two. So um that's what the organ systems are designed to do. Um, are adapted to service the needs of the cells. There are 11 sis organ systems work that work together to maintain life. Here's a little interaction of these. So the respiratory system uh takes in oxygen. It diffuses into the blood. It circulates around. It delivers oxygen to all the cells of the body that need it. Um food goes in the mouth over here. food into the stomach and then absorbed into the blood and it circulates everywhere we need. We got some waste product get rid of carbon dioxide is exhaled and the kidneys will there's that word nitrogenous will um eliminate the ura and some other functions. The urinary system is actually quite fascinating. Urine comes out of that end. There's a waste product uh feces coming out of that end of the digestive system. This kind of illustrates uh something about the digestive system. I'll have this up is that the digestive system is really a tube inside the body that has openings on either end. In one end goes the food and the other end comes out unabsorbed waste products. It's technically not considered to have entered the body even though it's inside the body unless it crosses over a membrane. So the material in the in the stomach or in part of the other parts of the digestive system is uh those parts are still considered outside the body because we haven't crossed a barrier to get inside. More on that later. All right.
So, let's turn this presentation off and come back at you with a survey of these 11 systems.