Intracellular compartment 67% of total body H2O

Extracellular compartment 33% of total body H2O   (20% blood plasma, 80% interstial fluid)

67% of the body is water and it is mostly in the interstitial space.

If they use a carrier or not

carrier =facilitated diffusion and active transport

and noncarrier =diffusion and osmosis

and by their energy requirements =Passive transport and active transport

nonpolar  molecules like O2

Lipid soluble  molecules like steroids

Small polar covalent bonds like CO2

H2O that has small size and lacks charge

Large polar molecules  (glucose)

Charged inorganic ions (Na+)

Must be a difference in solute on 2 sides of the membrane

membrane must be impermeable to the solute

the amount of solute dissolved in a specific amount of solvent. 

glucose disolved in H2O forms 1 mole and has a concentration of 1 Osm.

NaCl ionized in H2O and form 1 mle of Na+ and 1 mole of Cl- theus has a concentration of 2 Osm.

RBC lyses in a hypotonic solution

because the solute outside the cell is less than what is in the cell. 

Water goes into the cell, overfilling it and it burst or lyses.

RBC placed in high salt concentration.

RBC placed in hypertonic solution.

Water pulled out of the cell and cell shrinks or crenates

Osmoreceptors stimulate the hypothalamus.   The hypothalmus stimulates ADH to be released to resorb H2O

and thirst increases.

negative feed back loop

What happens when a person becomes dehydrated?

What happens when osmolity is increased?

Facilitated Diffusion

Active Transport

Primary Active Transport

Na + / K +     Pump

Secondary active Transport

Transport carriers for glucose are GLUT

It occurs in the muscles, liver and fat cells.

A carrier protein with a central channel. 

The molecule binds to carrier which changes shape and moves molecule down concentration gradient into the cell and released.  Movement of molecules will only happen if it is facilitated by protein carrier in the membrane.

Carrier proteins can be in cytoplasm in their unstimulated state.   In response to stimulation like insulin or exercise, the vesicle fuses with the plasma membrane and carriers are thereby inserted into the membrane. 

the molecule binds to recognition site on a carrier protein. 

Binding stimulates phosphorylation (breakdown of ATP) of a carrier protein.  Hydrolysis of ATP is directly required for the function of the carrier. 

It goes against the concentration gradient.

The carrier protein changes shape ...and a hinge - like motion releases the transported molecule to the opposite side of the membrane.  Hinge like.

Na+ / K+ pump

Type of primary active transport  or pump.

Carrier protein is also and ATP enzyme the converts ATP to ADP and P

It excludes 3 Na+  and transports 2 K+ inward against the concentration gradient.

the steep gradient serves 4 purposes.   see next card

1. Provides energy for coupled transport of other molecules

so it indirectly hydrolyzes ATP >ADP + P

2. It Regulates resting calorie expenditure and BMR

3. Involvement in electrochemical impulses

4. Promotes osmotic flow

Active transport =shape changes in trans-membrane protein

3 sodium ions bind to cytoplasmic side of the protein  changing its conformation. Molecule becomes phosphorylated spends a molecule of ATP.  At that it induces a second shape change that translocates the 3 sodium ions across the membrane. 

where it releases 3 Na to the extracellular area.

In the shape after Na is release it has a high affinity for K+  and 2 K+ molecules bind to the extracellular side of the protein.  The P dissociates and the protein goes to it's original shape and the two K+ diffuse into the interior of the cell.

secondary active transport is unlike this primary active transport. See next card

secondary active transport description

Na+/K pump

coupled transport

Na+ enters the cell and goes down its concentation gradient

it powers an ion against the gradient

Energy needed for the uphill movement is obtained from the downhil transport of Na+

Hydrolysis of ATP by the Na/K pump reqired indirectly to maintain the Na+ gradient

The other molecule goes along for the ride.

If it moves in the same directin as Na+ it is cotransport (symport)

If it moves in opposite direction to Na+ it is countertransport (antiport)

glucose is transported 3 ways:

Cotransport (a secondary active transport)

Primary active transport

Facilitated diffusion

Is is needed for cell respiration

How are molecules transported across the epithelial membranes?   

A molecule moves from the external environment into the blood by way of epithelial membrane...

How does it do it?

absorption

reabsorption

transcellular transport

 paracellulr transport

transport of digestion products across the intestinal epithelium into the blood    happens only in the intestines

a method to move molecules into the blood

Transportation of molecules out of the urinary filtrate back into the blood. 

blood - kidney - blood.

moves material through the cytoplasm of the epithelial cells  

from one spot in cell to another

Diffusion and Osmosis

through the tiny spaces between epithelial cells

one cell to the next

Movement of many

large molecules (that cannot be transported by carriers)

all at the same time.

Exocytosis = fusion of the membrane-bound vesicles that contain cellular products with the plasma membrane\

Polypeptides and proteins too large

hormones and neurotransmitts secreted by exocytosis

Endocytosis = specific molecules can be taken in because of the interaction of the molecule and the protein receptor.

cholesterol can be taken in because of the interactin between the cholesterol transport protein and a protein receptor on the plasm membrans.   Cholesteral is removed from the blood by the liver and by te walls of blood vesels though endocytosis

phagocyosis

pinocytosis

recepton-mediated endocytosis

phagocytosis

pinocytosis

receptor-mediated endocytosis

low-density lipoproteins LDL

these molecules bind to a specific receptor in the membrane.

the receptor protein are concentrated in an indented pit coated by the protein clathrin

when sufficient molecules accumulate in the coated pit the pit deepens, seal, and is incorporated into the cell as a coated vesicle.

The extent to which each ion contributes to the potential difference across the plasma membrane

Difference in charge acoss the membrane

cellular proten and phosphate groups are negatively charged  

These anions attract catons from the extracellular fluid that can diffuse through the membrane pores

The membrane is more permeable to K+ than it is to Na+

concentration gradients for Na+ and K+

K+ accumulates in the cell also due to electrical attraction

and there is the Na+ / K+ ATPase tht pumps 3 Na+ out and 2 K+ in

the unequal distribution of charges causes each cell to act as a tiny battery.

allows theoretical membrane potential to be calculated for a particular ion

membrane potential that would exactly balance the diffusion gradient and prevent the net movement of a particular ion

Value depends on the ration of ions on the 2 sides of the membrane

equilibrium potential for K+ = -90mV

a membrane potential of 90 mV, inside the cell being negative, is needed to prevent K+ from leaving the cell

K+ =  - 90 mV

Na+ = +66 mV

Cl- =

Ca+ = -71mV

signal can directly trvel from 1 cell to the next

through fused membrane channels  

cardiac cells