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Cells, Tissues, Organs, and Systems

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Sci Files segment describing the building blocks of the body.

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Hi, Dr. D. Hi, kids. 00:00:00
We need to learn more about cells and how they operate. 00:00:04
Can you help us? 00:00:07
Sure. 00:00:08
A cell is a basic building block of the body, and your body has about 10 trillion cells. 00:00:09
10 trillion? 00:00:14
That's a one followed by 13 zeros. 00:00:15
That's a lot. 00:00:18
Here are some examples of cells you might find in your body. 00:00:19
This nerve cell is long and has a lot of branches. 00:00:21
It's very different from this white blood cell. 00:00:25
What do they both have in common? 00:00:28
Well, it looks like they all have that thing in the middle. 00:00:29
That thing in the middle is called the nucleus. 00:00:31
They also have a membrane which holds the cells together. 00:00:33
And this semi-fluid region inside of each cell is called the cytoplasm. 00:00:37
That's cool. 00:00:41
Over there you have what looks like a lot of cells together. 00:00:42
What's that called? 00:00:46
Cells of the same structure and function that are grouped together are called tissue, like 00:00:47
this muscle tissue or like this tissue, which is the outer layer of the skin. 00:00:51
This skin model looks like shingles on a roof. 00:00:55
Very good. 00:00:57
It's designed to keep moisture in and microbes out. 00:00:59
Now when you combine various tissues together, you get an organ. 00:01:01
You mean like a heart or the lung? 00:01:04
Exactly. 00:01:07
Now here's a model of the largest organ in the body. 00:01:08
It looks like skin. 00:01:10
It is. 00:01:11
Now, when you combine two or more organs that have a common task, they're called an organ 00:01:12
system. 00:01:16
Dr. Texboat mentioned something about body systems. 00:01:17
Let's look at this human torso as an example. 00:01:20
This is the digestive system. 00:01:23
It starts with the teeth, the tongue and salivary glands, then the esophagus, then the stomach 00:01:25
and the intestines. 00:01:32
They all work together to digest food. 00:01:33
The body is very complex. 00:01:35
Yes, it is. 00:01:37
It's amazing how the systems work together for the good of the body. 00:01:38
The body works really hard to keep itself in homeostasis. 00:01:41
Wait a minute, Dr. D. That's a big word. 00:01:43
Okay. 00:01:47
Homeostasis means keeping the body's internal environment, like its temperature, fairly 00:01:48
constant. 00:01:52
The body has what are called feedback controls that act to reverse any changes. 00:01:53
It's like a thermostat. 00:01:57
Let me show you how a thermostat works. 00:01:58
When I heat up this bimetal strip, it bends upward. 00:02:01
When it touches this rod, it makes an electrical connection, which turns on this fan and cools 00:02:04
things down. 00:02:10
Then when the metal becomes cooler, it straightens out and breaks the electrical connection and 00:02:11
turns off the fan. 00:02:15
That's pretty cool, but what does it have to do with the body? 00:02:18
When the body heats up, the feedback controls cause the body to perspire, and the blood 00:02:21
vessels near the skin dilate or get larger in diameter. 00:02:25
When the perspiration evaporates, it cools the body, and the increased blood flow to 00:02:28
the larger vessels also releases more heat. 00:02:33
So when these things cool the body down, the perspiration stops and the blood vessels return 00:02:36
to normal? 00:02:40
That's right. 00:02:41
So are different body systems affected differently? 00:02:42
Yes. 00:02:45
Some systems, like the digestive and the respiratory systems, are more susceptible to infection. 00:02:46
Do you know why? 00:02:50
I guess we all have to eat and breathe, and viruses and bacteria can get into the food 00:02:51
that we eat and the air that we breathe. 00:02:55
That's right. 00:02:57
Thanks, Dr. D, but we still need to learn more about how cells are infected. 00:02:58
I thought you might. 00:03:01
When you take your petri dishes to Mr. Frank at TCC this afternoon, you can also ask him 00:03:02
about infection. 00:03:07
Great. 00:03:08
Thanks, Dr. D. 00:03:09
You're welcome. 00:03:10
Let me know what you find out. 00:03:11
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Idioma/s:
en
Niveles educativos:
▼ Mostrar / ocultar niveles
      • Nivel Intermedio
Autor/es:
Office of Education
Subido por:
EducaMadrid
Licencia:
Reconocimiento - No comercial - Sin obra derivada
Visualizaciones:
1461
Fecha:
28 de mayo de 2007 - 15:32
Visibilidad:
Público
Enlace Relacionado:
NASAs center for distance learning
Duración:
03′ 13″
Relación de aspecto:
4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
Resolución:
480x360 píxeles
Tamaño:
19.36 MBytes

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