Flashcards in Vertebrates 4 - Cell properties Deck (23)
Cell membrane function
cell integrity, cell metabolism, cell to cell signalling
Osmolarity of mammalian blood
Total concentration of all solutes. 300 mOsm (mM). Cells often have to actively pump solutes in/out
Electrical properties of cells
All cells have different concentrations inside vs outside, creates resting membrane potential.
Affected by concentration and electrical field across membrane. Nernst equation for equilibrium of any ion. Eion = 58mv/Z) log([ion]out/[ion]in)
Passive electrical properties of membranes
membranes are like circuits - bilayer like capacitor (ions at both heads) and channels like resistors (few = big resistor - slows current flow). V = IR!
Molecules that Diffuse across membrane
Hydrophobic (steroids), small molecules (O2, CO2, NO)
Molecules that Diffuse through channels
Ions and polar molecules (glucose, amino acids) are repelled by bilayer, therefore need channels
Specific channels; Transport maximum (Tmax) is the max rate of transport across membrane. Can change with a change in number of channels
Also has Tmax. Pumps use ATP. Includes coupled transporter like H/Na antiport (NO ATP)
Reading: Julian Creek Dunnarts fall under which family(?) ?
The metatheria, or marsupials
Reading: What types of animals have cutaneous respiration
Occurs in all, but highest in amphibians. Skin of reptiles and mammals is too thick
Reading: What problems may marsupials encounter with respiration?
Young are born underdeveloped. Thought lungs were not developed enough, but most breathe well as newborns. Dunnarts are exception
Reading: Julian Creek Dunnarts respiration
Significant cutaneous respiration for first several days after birth, lungs are under developed because it is so small (grain of rice).
Reading: What do you need for a good gas exchange surface?
High SA/V, thin wall, blood vessels close to surface, moist surface.
Steps in exocytosis
Priming, docking, and fusion. Regulated by Ca influx
Compare types of endocytosis
working on it…
Tight: in epithelia, nothing get across; Intermediate: not as tight, but strong for stretching (cardiac muscle intercalated disks); gap: communication
Epithelial transport examples
Ex. fish gills, amphibian skin, intestine, kidney tubule.
Glass chamber in which you insert tissue to study what can move across it.
Very organized, lots of tight junctions. Studied with ussing chamber. Studied with radioactive Na, moved inwards but not out. Membrane is somehow asymmetrical
Describe epithelial tissue
Exterior, lumen or mucosal side, and interior or serosal side. Paracellular path not common (tight junctions). Transcellular path (diffusion or facilitated)
How does Na+ enter through epithelium?
First H+/Na+ antiport, then a Na/K pump