Membrane Physio Flashcards
Extracellular fluid components
Large amount of:
Sodium
Chloride ions
Small amount of:
Potassium
Intracellular fluid components
Phosphates
Proteins
Parts of lipid bilayer
- Phospholipids
- Lipid soluble substances
- Water soluble substances
Imbedded in the lipid bilayer through hydrophobic interactions
Integral membrane proteins
Loosely attached to the cell membrane through electrostatic interactions
Peripheral proteins
2 main types of membrane proteins
- Integral membrane proteins
- Peripheral proteins
Protein molecules (2)
Channel proteins = have watery spaces all the way through the molecule and allow free movement of water as well as selected ions or molecules.
Carrier proteins = bind with molecules or ions that are to be transported
2 types of intercellular junctions
- Tight junctions (Zonula occludens)
May be “tight” (impermeable), as in renal distal tubule, or “leaky” (permeable), as in
renal proximal tubule and gallbladder. - Gap junstions
Are the attachments
between cells that permit
intercellular communication.
Parts of a gap junction
- Connexon =comprised of 6 Connexin. 2 Connexon form 1 gap junction.
- Connexin = subunits of Connexon
4 functional classification of cell junctions:
- Anchoring junctions
- Occluding junctions
- Channel-forming junctions
- Signal-relaying junctions
Factors that affect the rate of diffusion
- Concentration gradient
- Surface area of the membrane
- Solubility in the membrane
- Thickness of the membrane
- Molecular weight
molecules of each species diffuse independently
inspired nitrogen in room air is replaced by helium, rate of
oxygen and carbon dioxide diffusion will be unaffected
2 types of diffusion
- Simple diffusion
= • Is the only form of transport that is not carrier-
mediated
• occurs down an electrochemical gradient (downhill)
• Does not require metabolic energy and therefore is
passive - Facilitated diffusion
= • similar to simple diffusion
= • carrier-mediated - exhibits stereospecificity,
saturation, and competition
Types of proteins for facilitated diffusion
- Ion channels
- Porins
- Permease
Channels in ion channels (3)
- Ligand-gated channels
- Voltage-gated channels
- Mechano-gated channels
Permease acts like an enzyme instead of a pore
is the transport rate when the carriers are
saturated
Transport maximum
What is chemical specificity
only the natural isomer will be transported
Characteristics Common to All Protein-Mediated Transport
- Rate of diffusion
- Saturation kinetics
- Chemical specificity
- Competition for carrier
Types of protein transport
- Facilitated transport
= Net movement is always down a concentration gradient.
= inhibited by sugar such as galactose - Active transport
= Net movement is against a concentration gradient
Type 1 diabetes vs. Type 2 diabetes
T1 = No insulin
T2 = Cells do not respond to insulin