Human Biology (Diffusion, Osmosis, Cell Transport) Flashcards
Homeostasis
Maintenance of a constant, optimal internal environment. The inside of the cell must be separated from the outside so that homeostasis can be maintained.
The human body has an optimal temperature of 37°C.
Intracellular Fluid
Fluid inside the cell – e.g. cytoplasm, nucleoplasm
Extracellular fluid
Fluid outside of the cell (between cells) e.g. blood plasma
Cell Membrane
Is the protective double layer that is responsible for allowing materials to enter and leave the cell. The structure is too small so ‘models’ are used to describe structure.
Fluid Mosaic Model
The accepted model for the structure of the cell membrane.
Fluid because the molecules constantly change position
Mosaic because it is like a lattice of many different molecules.
What is the Cell Membrane made of?
Composed of two layers of chemicals called ‘phospholipids’. Because there are two layers its structure is described as a phospholipid bilayer.
Compartments of phospholipids
A ‘head’ made of phosphate. They are hydrophilic (water loving/attracting)
A ‘tail’ made of fatty acids (lipids). They are hydrophobic (water hating/repelling)
Arrangement of the phospholipid bilayer
Hydrophilic heads are on the outside hydrophobic tails are on the inside.
Cholesterol Molecules
Embedded in the phospholipid bilayer, and aid in the stability of the membrane.
What do proteins do in the cell membrane?
Embedded in the membrane and may serve as hormone receptors, channel proteins for transport and cell-identity markers.
Selectively Permeable
Allows some materials to pass through it but not others, usually based on size.
Passive and Active (and some transports)
Passive processes are processes that do not require energy. They include – Diffusion, osmosis, facilitated diffusion
Active processes are processes that do require energy. They include – Active transport, Vesicular transport
Concentration Gradient
The difference in concentration between the two areas. The greater the difference in concentration, the greater the concentration gradient.
High to low concentration term
Follow the concentration gradient.
Low to high concentration term
Against the concentration gradient.