Transcript How things get in and out of a Cell HOMEOSTASIS

How things get in and out of a Cell
HOMEOSTASIS Maintaining a constant internal environment
• the human body maintains homeostasis through
body temperature, blood pressure, heart rate,
oxygen balance and water balance, and waste disposal.
THESE ARE ALL EXAMPLES OF HOMEOSTASIS.
• EVERY organism MUST maintain homeostasis.
• Each INDIVIDUAL CELL must maintain homeostasis.
- Cells do this by controlling what enters it and what goes out of it.
Which cell structure aids the cell in maintaining homeostasis ?
THE PLASMA MEMBRANE !
PASSIVE TRANSPORT Allowing substances in or out of the cell WITHOUT
requiring energy.
Types of Passive Transport
1. DIFFUSION -
Movement of stuff from an area
of higher concentration to an area
of lower concentration
- diffusion will occur until a DYNAMIC EQUILIBRIUM
(concentration of particles are equally spread out)
is reached.
Rate of Diffusion is affected by :
temperature
concentration
pressure
Diffusion is occurring.
(the particles of sugar are spreading
from high concentration to lower
concentration)
An equilibrium has been reached.
(the particles of sugar are evenly spread out.)
Another type of PASSIVE TRANSPORT is …
OSMOSIS - Diffusion of water
* Osmotic Pressure = the pressure that is exerted by
H2O on the cell.
* PLANTS have TURGOR PRESSURE
(pressure exerted by stuff in the cell on the cell wall)
* PLASMOLYSIS -
The loss of turgor pressure
(when this happens, the plant wilts)
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ACTIVE TRANSPORT
allowing substances in and out of cell USING energy
- usually moves stuff in or out AGAINST the diffusion gradient
(a.k.a. - the concentration gradient).
* The diffusion gradient refers to the different
levels of concentration inside and outside
of the cell
When a cell uses ACTIVE TRANSPORT,
things CAN move from low to high concentrations.
Types of Active Transport
1.
ENDOCYTOSIS
movement of stuff INTO the cell
using energy
- cell use endocytosis to take in more food,
minerals, and ions that diffusion allows
them to.
2.
EXOCYTOSIS
movement of stuff OUT OF the cell
using energy
- lipids, wastes, hormones, and enzymes
leave the cell by exocytosis.