Cell Theory

Cells are basic unit of life

Cells are produced from other cells

Cells maintain homeostasis

Homeostasis of tissues, and higher results from the coordinated effort of many cells

The cell membrane/plasma membrane

Physical isolation

Regulates exchange

Sensitivity

Structural Support

Membrane Structure

Phospholipid bilayer Hydrophillic heads at the membrane surface Hydrophobic tails on the inside

Membrane Proteins

Receptor proteins- recognize certain molecules Ex. Glucose can be recognized, and stimulates

absorption of glucose

Carrier Proteins- transport solutes across the membrane

Channels- allows water and small soluted through the membrane

Membrane Permeability

Detemines which substances can enter and exit the cell

Selective permeability- permits free passage of some materials, and restricts others

Passive passage- requires no energy

Active passage- requires energy

Transport processes

Diffusion- movement of molecules from a high concentration to a low concentration Osmosis- refers to the movement of water

specifically

Isotonic- no flow of water into or out of the cellHypotonic- water flows into cellHypertonic- water flows out of cell

Filtration

Hydrostatic pressure forces water and solute molecules through the membrane Ex. In capillaries this pressure pushed water

and nutrients into the tissues of your body

Carrier Mediated Transport

Proteins carry substance across the cell membrane

Facilitated diffusion- Insoluble nutrients like glucose are transported by passively proteins

Facilitated Diffusion

Active Transport

Ions or molecules are moved across the membrane using ATP

Ion pumps- protein that transport ions through the membrane Ex. K+, Na+, etc.

Vesicular Transport

Materials move into or out of the cell through vesicles (small sacs)

Endocytosis- packaging of material outside of the cell and then dumping them into the cell

Vesicle Transport (cont.)

Pinocytosis- “cell drinking” sac fills with extracellular fluid, depression forms in membrane, and gets deeper until it pinches off

Phagocytosis- “cell eating” membrane surrounds solid objects outside of the cell and pinches off inside of the cell

Exocytosis

Vesicle created inside the cell fused with the membrane, and discharges its contents outside the cell

Opposite process of endocytosis