Physiology 1: Cell Physiology Chp1

Front 1

Peripheral Proteins

Back 1

-assoc w/ mem lipids or integral proteins at inner or outer surface
- connect neighboring cells
- immuno properties of cell

Front 2

Cell membrane structure

Back 2

-phospholipids, sphingolipids, cholest
- polar head
- chol stabilizes

Front 3

Membrane permeability

Back 3

- permeable to small neutral molecules
- water corrects osmotic pressure difference in less than 1 min
- tight to most ions and large molecules

Front 4

Membrane spontaneous repair

Back 4

-amphiphatic molecules attracted, not chemically bound in membrane
- can change location up to 10 million x/ sec
-mem liquid, repaired/ closed easily

Front 5

Selective permeability

Back 5

neutral molec > charged
- small molecules ( eg oxygen) >
large molecules ( eg globulin)

Front 6

Passive transport general

Back 6

-"diffusion": difference in chemical (concentration) or electrical gradient
- (-) attracts (+) ions and vice versa
- rarely, transp against a gradient
when chem and elect gradient oppose each other then stronger gradient forces transport against the direction of the weaker

Front 7

Simple diffusion general

Back 7

- small neutral particles
- small ions ( electrolytes) occur at very low rate
- PT
- NOT saturable

Front 8

Facilitated diffusion general

Back 8

- integral protein binds ion at one side, passes it though and releases it on the other side
- does not require energy (=PT)
-saturable

Front 9

Active transport general

Back 9

- E to gen or maint gradient
- transporter is an ATPase or pump
that uses ATP
- integral mem pro bind to one or more ions, transport across membrane, and release
- transp is saturable ( no further inc beyond Vmax)
-pump binds to ATP and changes to ADP and P, while the E released is used for transport

Front 10

Primary active transport general

Back 10

- transporter uses E directly to transport substrate itself

Front 11

Secondary Active Transport General

Back 11

1. carrier binds S and dissolves through mem channel (like facil diff)
2. carrier and S dissociate
3. carrier returned by E requiring pump

Front 12

Simple diffusion rate

Back 12

-Fick's: rate dep on area, diff coefficient, and mem thickness
-not perfect: all small molec and ions pass by diffusion but at very slow rate b/c of their low diffusion coefficient

Front 13

Facilitated/ carrier-mediated diffusion

Back 13

-mainly ions
- S binds carrier (integral) protein which passes it through the membrane and releases it on the other side
- driving force is the electro-chemical gradient of S: no E
- depends on [S], so saturable
-carriers are selective= transport only one kind of substrate
-

Front 14

total driving force of ionic diffusion

Back 14

F= Fel +Fchem
Fel= electrical gradient
Fchem= chemical gradient

Front 15

Diffusion of K+

Back 15

-high intra and low extracellular [], the chemical gradient supports diffusion out of the cell
- extra side of membrane + and intra side -, therefore the electrical gradient supports diffusion into cell
- net flow determined by the total of the forces and ceases when they are equal

Front 16

Membrane channels

Back 16

- allow controlled diffusion through selective (for ion) pores
-driven by electro-chemical gradient
- diffusion is saturable because of number and capacity of channels
- gated (Na, K, Ca) or open (Cl)
- 1 gate (K) or 2 gates (Na)

Front 17

Single-gated membrane channel

Back 17

-eg K
-stimulus (eg depolarization) opens the gate and allows the ions to pass through the membrane along their electro-chemical gradient
-when stimulus disappears (eg repolarization) the gate closes

Front 18

Na/K pump

Back 18

-primary active transport
- moves 3 Na out of the cell and 2K into the cell, thus generating a high [Na] extracellularly and high [K] intracellularly
-exchanges 3 Na for 2K thus generating differences in their concentration b/w ICF and ECF

Front 19

Secondary active transport

Back 19

-step 1: carrier binds S and transport happens through diffusion from high to low concentration= no E
-step 2: to maintain the chem gradient of the carrier, the carrier must be returned to source using E (active transport)

Front 20

antiport or counter-transport

Back 20

-type of secondary active transport
- carrier and substrate are transported in opposite directions

Front 21

symport or co-transport

Back 21

- type of secondary active transport
- both carrier and substrate are transported in the same direction

Front 22

electro-neutral ion transport

Back 22

-has no effect on membrane potential
- symport: same number of (+) and (-) charges in the same direction
- antiport: same number of charges of the the same polarity in opposite directions

Front 23

electrogenic ion transport

Back 23

-changes membrane potential
- symport: different # of charges in the same direction
- antiport: different # of charges in opposite direction

Front 24

electrogenic antiport example

Back 24

-1 Ca exchanged for 1 Na
- results in a net transport of one positive charge across the cell membrane

Front 25

electrogenic symport example

Back 25

- 1 Na and 1 glucose transported in same direction
- results in a net one positive charge across the membrane

Front 26

Bulk flow

Back 26

volume flow of water carries dissolved substances
-eg blood

Front 27

solvent drag

Back 27

paracellular water flow drags dissolved substances

Front 28

phagocytosis

Back 28

-cells take in large particles (bacteria, dust) by surrounding the particle with projections of its cell membrane (=pseudopods)
- the completely covered particle is then incorporated as a vesicle and broken down (digested) by lysosomes

Front 29

pinocytosis

Back 29

tiny droplets of extracellular fluid are surrounded by pseudopods and incorporated as vesicles

Front 30

exocystosis

Back 30

incorporated vesicles (by phagocytosis or pincytosis) fuse with the cell membrane and release their contents into the extracellular fluid