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  • I like to think of life science as one big pyramid.

  • Let's call the pyramid, "biological organization".

  • Let's work our way from very small and specific concepts

  • to very large and complex topics.

  • So let's start at the tip of the pyramid,

  • with something so small, it can't be seen by the human eye,

  • a single cell.

  • A cell by itself is the most basic component of life.

  • A single cell, which is capable of living on its own,

  • is called a unicellular organism,

  • organisms like bacteria or protists.

  • These organisms are everywhere you look,

  • you just can't see them.

  • But, when cells join together,

  • with more than one cell like itself

  • to perform a similar function,

  • it's no longer a unicellular organism.

  • It's then called a tissue.

  • No, not that kind of tissue.

  • There are four types of tissues found in the human body:

  • connective,

  • muscle,

  • nervous,

  • and epithelial.

  • Bone tissue is a type of connective tissue

  • and it's not flimsy like a Kleenex at all.

  • Blood is also an example

  • of the same cells working together to perform the same job,

  • but it's a liquid,

  • again, not like a Kleenex at all.

  • No matter what the consistency is,

  • a tissue is a group of the same cells,

  • working together to perform a similar function.

  • Any time there are different tissues working together,

  • we then call it an organ.

  • That's the next level of the pyramid.

  • Animals aren't the only ones with organs;

  • plants have organs too.

  • When we find multiple different organs

  • working together to perform the same job,

  • we then call it an organ system.

  • Take the digestive system, for example.

  • It's made up of a mouth,

  • esophagus,

  • stomach,

  • pancreas,

  • liver,

  • gall bladder,

  • small intestine,

  • and large intestine,

  • also known as your colon.

  • Although each individual organ in this organ system

  • does a very different job,

  • together, these organs work to achieve the one goal

  • of taking all the nutrients out of the food we eat

  • and getting rid of what we don't need.

  • An organ system, by definition,

  • can only do one job,

  • like get the nutrients from our food,

  • send and receive electrical signals,

  • or exchange oxygen for carbon dioxide.

  • Regardless of their individual function,

  • all organ systems rely on one another

  • to do the vital jobs which they can't do themselves.

  • If one organ system doesn't work,

  • the others will shut down, too.

  • An organism is a complicated, living thing,

  • which requires the proper functioning

  • of multiple organ systems to maintain stability.

  • This stability is called homeostasis.

  • When all organ systems are working together

  • and maintaining homeostasis,

  • then it results in a happy, living organism.

  • Organisms are incredibly diverse

  • and can be as simple as a bacteria

  • or as complex as you.

  • When a group of the same organisms,

  • also known as a species,

  • live together in the same environment,

  • we then call it a population.

  • Often there are several populations

  • all living in one environment.

  • That is what we call a community.

  • Each time you look out the window,

  • you're seeing a community.

  • When we look at multiple communities,

  • along with how all of the organisms

  • interact with the physical environment,

  • then we refer to it as an ecosystem.

  • When you look at all the ecosystems of Earth together,

  • you're looking at

  • the Earth.

  • The Earth is a big, round circle of life.

  • That's why we call it a biosphere -

  • bio, meaning life

  • and sphere, meaning circle.

  • And there you go!

  • When you break it down to each level,

  • a very complex concept and phrase

  • becomes easy to understand.

  • All life starts with a single cell.

  • When cells join together,

  • they are called a tissue.

  • A group of different tissues are called an organ,

  • and a group of different organs are an organ system.

  • A group of organ systems working together

  • make up an organism,

  • and a group of the same organisms are a population.

  • Combining several different populations together

  • give us a community.

  • And several different communities in a large area

  • is an ecosystem.

  • And every ecosystem together

  • makes up our biosphere.

  • And that, my friends, is biological organization,

  • the pyramid of life.

I like to think of life science as one big pyramid.

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B1 TED-Ed organ tissue pyramid organism group

【TED-Ed】Making sense of how life fits together - Bobbi Seleski

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    VoiceTube posted on 2013/11/30
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