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Biology library
Course: Biology library > Unit 36
Lesson 1: Crash Course: Biology- Why carbon is everywhere
- Water - Liquid awesome
- Biological molecules - You are what you eat
- Eukaryopolis - The city of animal cells
- In da club - Membranes & transport
- Plant cells
- ATP & respiration
- Photosynthesis
- Heredity
- DNA, hot pockets, & the longest word ever
- Mitosis: Splitting up is complicated
- Meiosis: Where the sex starts
- Natural Selection
- Speciation: Of ligers & men
- Animal development: We're just tubes
- Evolutionary development: Chicken teeth
- Population genetics: When Darwin met Mendel
- Taxonomy: Life's filing system
- Evolution: It's a Thing
- Comparative anatomy: What makes us animals
- Simple animals: Sponges, jellies, & octopuses
- Complex animals: Annelids & arthropods
- Chordates
- Animal behavior
- The nervous system
- Circulatory & respiratory systems
- The digestive system
- The excretory system: From your heart to the toilet
- The skeletal system: It's ALIVE!
- Big Guns: The Muscular System
- Your immune system: Natural born killer
- Great glands - Your endocrine system
- The reproductive system: How gonads go
- Old & Odd: Archaea, Bacteria & Protists
- The sex lives of nonvascular plants
- Vascular plants = Winning!
- The plants & the bees: Plant reproduction
- Fungi: Death Becomes Them
- Ecology - Rules for living on earth
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Circulatory & respiratory systems
Hank takes us on a trip around the body - we follow the circulatory and respiratory systems as they deliver oxygen and remove carbon dioxide from cells, and help make it possible for our bodies to function. Created by EcoGeek.
Want to join the conversation?
- So the Diaphragm causes a vacuum? forcing air into our lungs.(8 votes)
- The diaphragm doesn't lead to the creation of a perfect vacuum, but does lead to lower pressure. Air at a higher pressure thus moves into the lungs to decrease pressure differentials.(9 votes)
- Could you explain pressure and cavities of the lungs - concentrating on pressure changes through breathing?
e.g. intrapleural pressure & elastic pressure the point they balance and what happens when volume of lungs decrease and increase. P1 V1 = P2 V2
how time in video5:00(8 votes) - What happens if we don't have a heart? Can we survive? Can the blood just flow in our body by the principle of how veins work?(4 votes)
- We could not survive without a heart. The heart is what forces blood through the veins and arteries, so just having veins and arteries alone would not allow blood to flow. It would pool in our legs and not circulate up to our heads!(7 votes)
- what will happen when circulatory & respiratory will not able to perform their rules?(3 votes)
- If your heart stopped beating, or otherwise failed, then you would immediately drop to the ground. Your muscles need oxygenated blood to function. You would not have the muscle power to continue standing. Everything above your heart would completely fail, because it needs the pumping action of the heart to receive oxygenated blood. Your brain would quit, causing you to pass out, and die.
If you stopped breathing, or your lungs otherwise failed, the body would divert most of the oxygenated blood to the brain and heart (the most important organs), but that would only last a while, and eventually the brain would force the diaphragm to move, and you to breathe. This is why it is impossible to die from voluntarily holding your breath. If you breathe in something other than air, like water, your brain would not get the oxygen it needs, and you would pass out, and probably die.(5 votes)
- what happens if at, you didn't have the valves? what would happen to you blood 8:15(4 votes)
- If you didn't have the valves, your blood might flow backwards. Your blood might not get the oxygen it needs from the respiratory system. Also, the muscles in your body might not receive the oxygen it needs to expand and contract if the oxygenated blood is flowing backwards and away from the muscle tissue that needs oxygen to move. This will also cause the pressure in the circulatory system to be unstable. Hank talks about this at. 8:16(3 votes)
- Why do you yawn?(3 votes)
- TL;DR - It's hard to say for certain, as most people don't agree on exactly why.
Sometimes it seems to be linked to tiredness, boredom or stress, sometimes people seem yawn out of empathy (seeing and/or hearing someone else yawn, or sometimes just thinking about yawning).
Some people think yawning helps cool the brain (I think it's supposed be by widening the ear canals slightly, letting in more air to cool down the brain).
Sometimes animals will yawn just before (or when they've just begun) strenuous exercise (i.e. running from a lion). (I'm not sure if humans ever do this)
All of these potential causes are contested by many people, but fully believed by others.
Please note that I am not an expert and this is all second hand information, written as well as I can remember it right now. Sorry for the wall of text. Congratulations on making it to the bottom though!
I hope this helps (-:(2 votes)
- what stops blood in the arteries from flowing backwards, do they have valves 2?(2 votes)
- Arteries mostly go downward aided by the pull of gravity. Not only that, but the heart pumping also forces the blood to go in the right direction. Since veins mostly go upward and are not as close to the heart, they rely on valves which let the blood in one direction but don't let them go backward. Once sufficient pressure of blood is reached, more blood will go through. For this reason, you hear of 'arterial spray' but never 'venal spray'. Because arteries have so much more pressure than veins do.(2 votes)
- why do people actually yawn. I know that it is a silly question but it is quite interesting. So why do people yawn?(2 votes)
- I heard somewhere its because in that way we give more oxygen to our blood. One of the theory says, that this is the way to cool our brain and improve blood circulation.(3 votes)
- Do veins carry oxygenated or deoxygenated blood ?(2 votes)
- They do carry, but the reverse of what was previously stated. They carry deoxygenated blood away from the body and oxygenated blood from the lungs.
Veins go toward the heart. Arteries go away from the heart.(3 votes)
- If there were only oxygen in the air, regardless of how, then would we only have to breath in, or would we still have to breath out?(2 votes)
- We would still have to breath out because we need to rid our body of CO2 which is a by-product of cellular respiration. Exhaling the CO2 is the most efficient way of doing so. Also, after contracting our diaphragm to make us inhale, we need to relax the diaphragm by exhaling. It's like using any other muscle. If you do a push up, you're going to have to relax your pectorals and triceps to lower yourself.(3 votes)
Video transcript
- All members of the Kingdom Animalia need oxygen to make energy. Oxygen is compulsory. Without oxygen, we die. But as you know, the
byproduct of the process that keeps us all alive, cellular respiration, is carbon dioxide or CO2 and it doesn't do
our bodies a bit of good. So not only do we need
to take in the oxygen, we also got to get rid of the CO2, and that's why we have the respiratory and circulatory systems to bring in oxygen from
the air with our lungs, circulate it to all of
our cells with our heart and arteries and collect the CO2 that we don't need with our veins and dispose of it with
the lungs when we exhale. (upbeat music) Now, when you think of
the respiratory system, the first thing that you
probably think of is the lungs, but some animals can take
in oxygen without lungs by a process called simple diffusion, which allows gases to move into and pass through wet membranes. For instance, arthropods have little pores all over their bodies that just sort of let oxygen wander into their body where it's absorbed by special
respiratory structures. Amphibians can take in
oxygen through their skin, although they also have either lungs or gills to help them respire, because getting all your oxygen by way of diffusion takes freaking forever. So why do we have to have
these stupid lung things instead of just using simple diffusion? Well, a couple of reasons. For starter, the bigger the animal, the more oxygen it needs and a lot of mammals are pretty big, so we have to actively
force air into our lungs in order to get enough
oxygen to run our bodies. Also, mammals and birds are warm-blooded, which means that they have to regulate their body temperatures and that takes many many calories and burning those calories
requires lots of oxygen. Finally, in order for oxygen
to pass through a membrane, the membrane has to be wet, so for a newt to take
oxygen in through its skin, the skin has to be moist all the time, which, for a newt isn't a big
deal but I don't particularly want to be constantly moist, do you? Fish need oxygen too of course, but they absorb oxygen
that's already dissolved in the water through their gills. If you've ever seen a fish gill, you'll remember that they're just sort of a bunch of filaments of tissue layered together, as gill tissue extracts dissolved oxygen and
excretes the carbon dioxide. Still, there are some fish
that have lungs like lungfish, which we call lungfish
'cause they have lungs, and that's actually where
lungs first appeared in the animal kingdom. All animals from reptiles on upwards respire with
lungs deep in their bodies, basically right behind the heart. So a lot of us more complex
animals can't use diffusion to get oxygen directly. Our lungs can. Lungs are chock-full of
oxygen-dissolving membranes that are kept moist with mucus, moist with mucus, another great band name. The key to these bad boys is that lungs have a ton of surface area, so they can absorb a
lot of oxygen at once. You wouldn't know from looking at them, but human lungs contain
about 75 square meters of oxygen-dissolving membrane. That's bigger than the roof of my house. And the simple diffusion that your lungs use is
pretty freaking simple. You and I breathe oxygen in
through our nose and mouth. It passes down a pipe called your larynx, which then splits off from your esophagus and turns into your trachea, which then branches to form two bronchi, one of which goes into each long. These bronchi branch off again, forming narrower and narrower
tubes called bronchioles. These bronchioles eventually end in tiny sacks called alveoli. Each alveolus is about 1/5
of a millimeter in diameter, but each of us has about
300 million of them, and this, friends, is
where the magic happens. Alveoli are little bags
of thin moist membranes and they're totally covered in tiny narrow blood-carrying capillaries. Oxygen dissolves through the membrane and is absorbed by the
blood in these capillaries, which then goes off through
the circulatory system to make cells all over your
body happy and healthy. But while the alveoli are
handing over the oxygen, the capillaries are switching
it out for carbon dioxide that the circulatory system just picked up from all over the body. So the alveoli and capillaries basically just swap one gas for another. From there, the alveoli takes that CO2 and squeezes it out
through the bronchioles, the bronchi, the trachea, finally out of your nose and/or mouth. So inhale for me once, congratulations, oxygen is now in your bloodstream. Now, exhale, wonderful, the CO2 has now left the building and you don't even have to think about it, so if you could think about
something more important like how many Cheetos
you could realistically fit into your mouth at the same time. So now, you're all yeah, that's great, Hank, but how
do lungs actually like work, like how do they do the thing where they do where they get moved to come in and out and stuff? Well, eloquent question and well-asked. Lungs work like a pump, but they don't actually
have any muscles in them that cause them to contract and expand. For that, we have this
big flat layer of muscles that sits right underneath the lungs called the thoracic diaphragm. Now, at the end of an exhalation, your diaphragm is relaxed, so picture an arc pushing up
on the bottom of your lungs and crowding them out, so that they don't have very much volume. But when you breathe in, the diaphragm contracts and flattens out, allowing the lungs to open up, and as we know from physics, as the volume of a container grows larger, the pressure inside it goes down, and the fluids, including air, always flow down their pressure
gradient from high pressure to lower pressure, so as the pressure in our lungs goes down,
air flows into them. When the diaphragm relaxes, the pressure inside the
lungs becomes higher than the air outside, and the
deoxygenated air rushes out. And that is breathing. Now, it just so happens that
the circulatory system works on a pumping mechanism just
like the respiratory system, except instead of moving air
into and out of the lungs, it moves blood into and out of the lungs. The circulatory system
moves oxygenated blood out of the lungs to the places
in your body that needs it, and then brings the deoxygenated
blood back to your lungs, and maybe, you are thinking,
well, what about the heart? Isn't the heart the whole point
of the circulatory system? Well, settle down. I'm going to explain. We used to talk about the
heart as the head honcho of the circulatory system, and yeah, you would be in serious trouble if you didn't have a heart, but the heart's job is to basically power the circulatory system, move the blood all around your body and get it back to the lungs, so that it can pick up more
oxygen and get rid of the CO2. As a result, the circulatory system of mammals essentially
makes a figure eight. Oxygenated blood is pumped
from the heart to the rest of the body and then when
it makes its way back to the heart again, it's then
pumped on a shorter circuit to the lungs to pick up more oxygen and unload CO2 before it
goes back to the heart and starts the whole cycle over again. So even though the heart does all the heavy lifting in
the circulatory system, the lungs are the home base
for the red blood cells, the postal workers that
carry the oxygen and the CO2. Now, the way that your
circulatory system moves the blood around is pretty nifty. Remember when I was
talking about air moving from high pressure to low pressure? Well, so does blood. A four chambered heart, which is just one big hulking
beast of muscle is set up so that one chamber, the left ventricle, has a very high pressure. In fact, the reason it seems like the heart is situated
a little bit to the left of center is because the left ventricle is so freaking enormous and muscly. It has to be that way in order to keep the pressure high enough that the oxygenated blood
will get out of there. From the left ventricle, the blood moves through the aorta, a giant tube, and then
through the arteries and blood vessels that carry
the blood away from the heart to the rest of the body. Arteries are muscular and thick walled to maintain high pressure
as the blood travels along. As arteries branch off to
go to different places, they form smaller arterials, and finally, very little capillary beds, which, through their huge
surface area facilitate the delivery of oxygen to all of the cells in the body that need it. Now, the capillary beds are also where the blood picks up CO2. So from there, the blood keeps moving down the pressure gradient
through a series of veins. These do the opposite of
what the arteries did. Instead of splitting off from
each other to become smaller and smaller, little ones
flow together to make bigger and bigger veins to carry the deoxygenated back to the heart. The big difference between most veins and most arteries is that
instead of being thick walled and squeezy, veins have thinner walls and have valves that keep the blood from flowing backwards,
which would be bad. This is necessary because the pressure in the circulatory system
keeps dropping lower and lower until the blood
flows into two major veins. The first is the inferior vena cava, which one's pretty much
down the center of the body and handles blood coming from
the lower part of your body, and the second is the superior vena cava, which sits on top of the heart and collects the blood
from the upper body. Together, they run into the
right atrium of the heart, which is the point of the lowest pressure in the circulatory system. So all this deoxygenated blood
is now back in the heart, and it needs to sop up some more oxygen. So, it flows into the right ventricle and then into the pulmonary artery. Now, arteries, remember, flow away from the heart, even though in this case, it contains deoxygenated blood, and pulmonary means of the lungs. So you know that this is
the path to the lungs. After the blood makes
its way to the alveoli and picks up some fresh oxygen, it flows to the pulmonary vein, remember it's a vein 'cause
it's flowing to the heart, even though it contains oxygenated blood, and from there, it enters the heart again where it flows into the left atrium, and then into the left ventricle where it does the whole body circuit again and again and again and again. And that is the way that we work. Our hearts are really efficient and awesome and they have to be, because we are endotherms, or warm-blooded, meaning that we maintain a steady
internal temperature. Having an endothermic
metabolism is really great, because you're less vulnerable to fluctuations in external
temperature than ectotherms or cold-blooded animals. Also, the enzymes that do all the work in our bodies operate over a very narrow range of temperatures. In humans, that ranges between 36 and 37 degree Celsius. So the trade-off is that endotherms need to eat constantly to maintain our high metabolisms and also create heat. And for that, we need a lot of oxygen, hence the amazing efficient
four chambered heart and our gigantic fracking lungs. Ectotherms, on the other hand, have slow metabolisms and don't need as much in the way of food. A snake is totally pumped if
it gets a meal once a month. So since ectotherms aren't
doing much in the way of metabolizing, they don't
need much in the way of oxygen. So their circulatory systems
can be a little bit janky and inefficient and still cool. Remember back when we were tracking the development of chordates? One of the signs of
complexity was the number of chambers in an animal's heart. Fish only have two chambers,
one ventricle and one atrium. The blood gets oxygenated as
it moves through the gills and then carries oxygen through the rest of the body back to the heart where it's moved through the gills again. But reptiles and amphibians
have three chambered hearts. They've got two atria
but only one ventricle. And what that means is that not all of the blood gets
oxygenated every time it makes a full pass around the body. So oxygenated blood gets
pumped through the body and mixed up with a
little deoxygenated blood, not super efficient, but again,
doesn't really have to be. So there you have it, the how and why behind how oxygen gets to all the places it needs to be. The question is, what
powers the diaphragm, what powers the heart? Where does that energy come from? Well, it comes from the digestive system, and that's what we're gonna
be talking about next time.