Flashcards in Chapter 2.1 The study of cells Deck (33):
The structural and functional unit of all organisms, including humans
An adult human body contains about how many cells?
75 trillion cells
Most cells are composed of characteristic parts that work together to allow them to
Perform specific body functions
How many different type of cells are there in the human body
Approximately 200 different types of cells in the human body
Even though there are hundreds of different types of cells they all share certain common characteristics
*General "housekeeping functions"
*Must obtain nutrients and other materials essential for survival from its surrounding fluids
*Dispose of wastes they produce
*Shape and integrity is maintained by its internal contents and its surrounding membrane
*Most are capable of undergoing division to make more cells of the same type
The total of all the chemical reactions that occur in cells is called
If a cell didn't remove its wastes products what would happen?
The waste would build up in the cell and ultimately lead to the cells death
The study of cells is called
What is the greatest obstacle in obtaining the nature of a cell
Their small size
Cells were discovered after what was invented?
What are required to see the smallest human body cell?
What is often used to measure cell size?
The dimensional unit, the micrometer (um)
One micrometer is equal to how many centimeters?
1/10,000 of a centimeter
A red blood cell has a diameter of about
One of the largest human cells, the oocyte, has a diameter of about
The use of the microscope is called
This has become a valuable asset in anatomic investigations
What are the most commonly used microscopes
1) Light microscope (LM)
2) Transmission electron microscope (TEM)
3) Scanning electron microscope (SEM)
Because specimen samples have no inherent contrast, they cannot be seen clearly under the microscope unless
Contrast is added
Colored-dye stains are used in what type of microscope
Heavy metal stain preparations are used in
Electron microscopy, which includes both TEM and SEM
This type of microscope produces a two-dimensional image for study by passing visible light through the specimen. Glass lenses focus and magnify the image as it is projected toward the eye.
The Light microscopy (LM)
Uses a beam of electrons to "illuminate" the specimen. Easily exceed the magnification obtained by light microscopy, they improve the resolution by more than a thousandfold. Directs an electron beam through a thin-cut section of the specimen. The resultant two-dimensional image is focused onto a screen for viewing or onto photogenic film to record the image. Can show a close up
Transmission electron microscope (TEM)
Detailed three-dimensional study of the surface of the specimen. The electron beam is moved across the surface of the specimen, and reflected electrons generate a surface-topography image captured on a television screen
Scanning electron microscope (SEM)
In what ways do cells vary?
Size and shape
What are the different cell shapes?
Flat, cylindrical, oval, or quite irregular
Often cells functions are reflected on what?
Their size or shape
What are the general function of cells?
Describe how cells are used for covering
Epithelial cells form a sheet to cover surfaces. For example, skin cells cover the external body surface
Describe how cells are used for lining
Epithelial cells line the internal surfaces of our organs, such as the small intestine
Describe how cells are used for storage
Some body cells, such as hepatocytes (liver cells) and adipocytes (fat cells), store nutrients or energy reserves for the body
Describe how cells are used for movement
Muscle cells are composed of contractile proteins that cause the muscle to shorten (contract), thereby allowing movement to occur. Skeletal muscle cells attach to the skeleton so that when these cells contract, they move the skeleton. In contrast, when the muscle cells in the heart wall contract, they are able to pump blood throughout the body