Chapter 4 Flashcards
Membrane Transport Significance
Nutrition and Respiration ;
Waste Removal
Export of Products
Signaling
Membrane Transport Problems
The non-polar barrier. Things that are polar cannot get in.
Passive Membrane Transport
No additional energy required. Require two things; Kinetic Energy and Concentration Gradient
Diffusion
Flux: A singe Particle; the random movement of a specific particle.
Net Flux Definition
The combination of every particles movement and the average of where they’re going. Will balance out.
Net Flux Information
Move from a higher concentration to a lower one. Reach equilibrium if given enough time.
Effect of Concentration
Will determine the direction of net flux. The stronger the concentration, the higher the rate.
Factors that affect Permeability
Membrane solubility of solute
Size of solute
Presence of membrane channels/carriers
Membrane Thickness
Factors that affect Permeability (Membrane solubility of solute)
Polarity. Non polars always are soluble to that plasma membrane
Factors that affect Permeability (Size Of Solute)
Smaller the solute, the better chance it has to get across. Non polar doesnt need help in terms of size
Factors that affect Permeability (Presence of membrane channels/carrierS)
Carrier has to be involved. More of these mean the membrane is more permable
Factors that affect Permeability (“Membrane Thickness”)
Whats around that membrane, can slow down the diffusion. Pneumonia, Water around aveoli when exchanging oxygen.
Effects of Surface Area (Passive Membrane TransporT)
More surface area means we have a better chance in terms of rate of diffusion
Electrical Driving Force (Passive Membrane Transport)
Only applies to charged particles
Opposites attract, likes repel. Sodium will be pulled in do to negative charge.
Electrical Driving Force (Passive Membrane Transport) (Increase of Concentration)
Increase of concentration on the outside causes electrical driving force to accelerate that.
Mechanisms of Passive Transport (Simple Diffusion)
The passive movement of particles across the membrane unassisted. No polar molecules and small polar molecules (slowly)
Mechanisms of Passive Transport (Diffusion Through Channels) Ungated Channels
Pores open all the time. Can go in any direction, only a tunnel. Allows diffusion to occur and most common things going through are H2O and K+
Mechanisms of Passive Transport (Diffusion Through Channels) Gated Channels
These have to have a specific sequence to open them
Mechanisms of Passive Transport (Gated Channels) Ligand Gated
Ligand, but acts like a messenger
Mechanisms of Passive Transport (Gated Channels) Ionotropic
Receptor for ligand and channel for ion are made of the same protein. Have a direct relationship
Mechanisms of Passive Transport (Gated Channels) Metabotropic
Peripheral, attached to the membrane. Receptor and channel are different proteins. Steps occur before it opens and can trigger further actions in cell
Mechanisms of Passive Transport (Gated Channels) Voltage Gated
Change in voltage to membrane. Certain ions are outside and cause a change to the membrane
Mechanisms of Passive Transport (Gated Channels) Mechanically-Gated
Are opened physically, something is physically making this channel open.
Mechanisms of Passive Transport (Gated Channels) Mechanically-Gated Examples
Stretch receptors, Stretching rubber bands and seeing the pores
Mechanisms of Passive Transport (Gated Channels) Temperature Gated
Temperature triggers this. We have hot and cold receptors. Changes in temp means ion channels opening and closing.
Mechanisms of Passive Transport (Facilitated Diffusion)
Transport protein. Physically assists particle from one side to the other. Diffusion through carrier protein. Binding causes morphological change.
Mechanisms of Passive Transport (Facilitated Diffusion) Powered by what?
Powered by KE. It’s bi-directional. Can go against concentration gradient.
Clinical Application : Insulin Dependent Glucose Transporters
Insulin binds to receptor on the outside. Binds and starts a cascade of things . Gets embedded within the membrane inside the cell. This then lets glucose get into the cell.
Type I Diabetes
Insulin is not produced
Type II Diabetes
Insensitive to Insulin
What happens to the process to a person with untreated diabetes mellitus
If GLUT 4 not inserted in membrane, glucose will stay in the blood. Cells will starve. Glucose acts like solute and draws water toward blood stream. High BP, Urination, Water will want to dilute excess glucose.
Mechanisms of Passive Transport (Movement of Water) Two reasons why
The presence of a solute concentration gradient
The presence of an hydro static pressure gradient
Mechanisms of Passive Transport (Movement of Water) Presence of a solute
Diffusion goes toward a solute. H2O tries to create a solute concentration gradient
Osmolarity
Refers to the concentraation of solute within a solution
What is the normal osmolarity of plasma?
275-300 mOsm/L
Isotonic
Two solutions having the same concentration
Hypotonic
Decrease of concentration means a decrease in osmolarty. (Tap water) (0)
Hypertonic
Increase concentration means increase osmolarity (400)
How will water respond to the hypertonic solution if it (and only it) is able to cross the membrane?
Water will cross and attempt to create an isotonic solution
If normal cell is put in hypotonic solution?
Water will move toward more concentrated area
What kind of solution do you think intravenous flluids have?
If dehydrated, don’t give tap because it will rush to cell. Around 300 mOsm, because then you’re close to where you want it to be. If Hypo, it will rush to and kill cell. If hyper, will put water from dehyrdated cells.
Mechanisms of Passive Transport (Movement of Water) Presence of an hydrostatic pressure gradient
H20 pushing against a membrane, Strong sourse is blood pressure
Active Membrane Transport
Additional energy is required (ATP). ATP used directly or indirectly. Active transport moves material against its concentration gradient. Forced from low to high conc.
Primary Active Transport
Uses ATP directly.
Primary Active Transport Step 1
Specific ion links to the binding site (Pump)
Primary Active Transport Step 2
Binding causes ATP to release energy
Primary Active Transport Step 3
Carrier changes shape to move ions (“upstream”)
Primary Active Transport Example (Sodium-Potassium Pump)
2 K+ into cell and 3 Na out of cell. This pump is why Na exists in excess outside.
Primary Active Transport Example (Calcium Pump)
Stores calcium in muscle. Gets pulled and stored until we need to pull this muscle
Primary Active Transport Example (Hydrogen-Potassium Pump (Proton Pump))
Pushes hydrogen ios into the stomach. Uses ATP and role is to create concentration gradient.
Secondary Active Transport
Primary has to happen first, it’s going against concentration gradient that was created. Uses ATP indirectly
Secondary Active Transport Step 1
P.A.T moves x “upstream” (Provides Avenue)
Secondary Active Transport Step 2
X wants to diffuse “Downstream”
Secondary Active Transport Step 3
The KE of X is used to “pull” “S” upstream.S goes from a low to high concentration while x goes from a high to low
Secondary Active Transport; Co-Transport
(Symport) We assume that both are going in the same direction
Secondary Active Transpor; Counter-Transport or Exchange (Antiport)
These go in different directions
Functional Example; Glucose-Sodium Cotransporter (SGLT1) Step 1
P.A.T moves Na “upstream”
Functional Example; Glucose-Sodium Cotransporter (SGLT1) Step 2
Na+ wants to diffuse downstream
Functional Example; Glucose-Sodium Cotransporter (SGLT1) Step 3
KE of Na+ is used to “pull” glucose “upstream” face
Carrier-Mediated Transport Limitations; Specificity
Some are very specific. Some catalyze one while others catalyse multiple
Carrier-Mediated Transport Limitations; Competition
Those with less specificty and can carry more, competition increases that results in transport rate decrease, resources are being used up
Carrier-Mediated Transport Limitations; Saturation
When number of reactants exceeded the number of enzymes. Satuation completely saturated and the reaction rate is stabilized.
Multi-Transporter Clinical Application ; Normal Way
- Active chloride channel, used ATP
- Charge inbalance, sodium follows
- Water will passively follow water. Moves as result of osmonic hchange. Will thin out mucus layer
Multi-Transporter Clinical Application; Cystic Fibrosis
- Polypeptide Chain doesnt form fully, no channel.
- If the water doesnt move, the mucus gets thicker. Starts to block airways and becomes obstructive. Chloride is blocked from crossing.
Cytosis
Bulk transport into or out of the cell
Exocytosis
Large volume of molecules out of cells. Vesicles absorbed into membrane and released in cell environments
Andocytosis
Large volume of water goes into the cell
Pinocytosis
Water Drinking. Moves water in large volume into the cell
Phoyocytosis
Pulls large organisms into their cell to destroy them
Epithelial Transport
We are now trying to cross group of cells. Trying to cross sorts of cells. Named this since we have to cross the epithelium. “TRansport across a cell”
