Download Homeostasis and Cell Transport

Homeostasis and
Cell Transport
Homeostasis

“biological balance between a cell or
organism and it’s external environment”

Maintained by the cell controlling what
enters and exits (plasma cell membrane)

Good Stuff
a. CHO
b. Lipids
c. Proteins
d. Nucleic Acid
e. Water
f. Various chemicals

Bad Stuff
a. Waste
b. Extra Water

Ways a cell maintain homeostasis
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
4. Gated Channels
5. Active Transport
6. Endocytosis
7. Exocytosis
Diffusion

“movement of molecules from area of
HIGH concentration to LOW
concentration”

Concentration Gradient – difference in
concentration

Equilibrium – point where the
concentration of a substance
is equal throughout the
solution
Types of Diffusion

Facilitated Diffusion
“diffusion of molecules across the cell
membrane with the help of a carrier
protein”
Osmosis

Osmosis – the process by which WATER
MOLECULES diffuse across
a selectively permeable
membrane

Direction of Osmosis
1. Hypotonic Solution
a. solute is less on the outside of cell
compared to the inside
b. water is greater on the outside
compared to the inside
CELL SWELLS
2. Hypertonic Solution
a. solute is more on the outside than the
inside
b. water is less on the outside than the
inside
CELL SHRINKS
3. Isotonic Solution
a. everything is equal
b. homeostasis
Examples

Hypotonic Solution
* Jellyfish in Lake Norman
 Cell swells, fish dies

Hypertonic Solution
* freshwater plant in a salt water solution
 Plant shrinks/shrivels and dies

Isotonic Solution
* Jellyfish in the Atlantic Ocean
Equilibrium/Homeostasis!!!
Roles of Osmosis

Kidneys use it to maintain water levels in
the blood

Turgor Pressure
 water pressure in plant cells
 hypotonic environment
Plasmolysis
 hypertonic environment
 cell shrinks due to water leaving


Cytolysis
 hypotonic environment
 cell bursts due to water rushing into
the cell
Active Transport

“movement of molecules from areas of
LOW concentration to areas of HIGH
concentration”

Uses ATP to power it
ATP
“source of energy”
 Adenosine triphosphate
 ATP-ADP Cycle


Gated Channels
a. protein that can be opened or closed to
allow molecules to enter or leave the cell
b. specific to certain ions crossing the cell
membrane
c. diagram

Endocytosis
a. process where large molecules are
taken into the cell
b. Two types
1. Phagocytosis
2. Pinocytosis
c. diagram

Exocytosis
a. getting rid of large molecules
b. diagram

Sodium-Potassium Pump
a. used to carry nerve signals
b. diagram