Cells: The Building Blocks of Life Review

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Cells: The Building Blocks of Life Review

  • There are four major types of tissues found in the human body: epithelial, connective, muscle, and nervous.Cells are considered the building blocks of life. Humans are multi-cellular organisms with differentiated, eukaryotic cells. It is estimated that there are over 37 trillion cells in the human body. The cell theory states all living things are made of cells, cells are the basic unit of structure and functions, and the cell comes from pre-existing cells.
  • Inside the eukaryotic cell are small structures that help a cell to function called organelles. Be sure to go back and review organelles in the Structure and Function of a Eukaryotic Cell learning object.
  • Cells are constantly functioning and maturing. Therefore, a constant demand exists for cellular reproduction. Cellular reproduction occurs through a process called mitosis in all somatic cells.
  • The many chemical reactions occurring inside the cell membrane are described as metabolic processes. Human cells have a continuous need for water and various nutrients, to fuel these processes as well as for cellular growth and repair. Cellular respiration within the mitochondria produces ATP from food energy that powers cellular processes.
  • A cell needs to be able to transport needed materials into a cell and transport wastes out of a cell. This is done through two different processes. Passive transport moves materials down a concentration gradient and does not require ATP. Diffusion and osmosis are examples of passive transport. Active transport moves materials up a concentration gradient and does require ATP.  A sodium-potassium pump is an example of active transport.
  • Tissues are the next level of organization in the human body is tissues. Tissues are composed of layers of similar cells with a common function.   There are four major types of tissues found in the human body: epithelial, connective, muscle, and nervous.
  • Every condition that affects the human organism originates in the cell. Cellular injury and death can impede the normal function of the human body. This includes factors such as defects in the cellular division process. As humans age, cells become larger and production slows significantly.

 

 

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