Midterm 2 Flashcards
Define passive transport.
Does not require ATP to move molecules across membrane - uses potential energy stored in concentration (Facilitated diffusion)
Define active transport.
Requires cellular ATP to move molecules across the cell membrane against the concentration gradient.
What is the osmotic concentration blood plasma (ECF)?
~ (about) 300mOsM (million Osmolar)
Define simple diffusion. Make a list of the important molecules that move by simple diffusion.
Diffusion directly across the phospholipid bilayer of a membrane. (O2, CO2, lipid steroid testosterone)
What about simple diffusion could be considered an advantage to a cell? Disadvantage?
Advantage - Molecules pass through quickly - fast
Disadvantage - Not good control
Make a list of important molecules that cross cell membrane by diffusion through channel proteins.
Na+, K+, Cl-
Explain how protein-carriers are different from channel proteins.
Channel proteins require a protein to open the channel whereas protein-carriers change the shape of the channel (protein) in order for it to open.
What about facilitated diffusion (as a process) could be considered advantageous to a cell?
- Uses no ATP
2. Provides cell with control
The means by which large molecules are transported out of cells is what?
exocytosis
How would solutes in an aqueous solution move from an area of low concentration to high concentration?
only active transport
A cell that is permeable to Solute X is place into solution containing a higher concentration of X. Net diffusion occurs until equilibrium is attained. At this time…
A) there is no movement at all of Solute X across the membrane, B) there is no further change in concentration of Solute X, C)Both of the statements are correct, D) Neither are correct
B. no further change in concentration
How does glucose enter most body cells?
via facilitated diffusion
List the factors that influence the rate at which molecules diffuse. Explain how changes in each will affect the rate of diffusion.
- The higher the gradient, the faster the diffusion rate
- Diffusion is faster over short distances
- The higher the temperature, the faster the rate of diffusion
- Smaller molecules diffuse more quickly
Define facilitated diffusion. List the important molecules that are moved by facilitated diffusion.
Transport that is passive and moves molecules down their concentration gradient stopping when concentrations are equal on both sides of the membrane.
Glucose, sodium, chloride (GLUT4)
Describe in detail the activity of calcium pumps found in the sarcoplasmic reticulum of skeletal muscle cells.
ATP is used to power the pump which moves Ca+ out of the cell.
Describe in detail the activity of the Sodium/Potassium pump. In which body cells are these proteins found?
Found in all body cells.
The Na+/K+ pump maintains the gradients for sodium and potassium in a living cell by pumping in K+ and pumping out Na+. The ECF is almost all Na+ and the ICF is almost all K+. 30-60% of BMR goes to powering this pump. It cost 1 ATP to move 3 Na+ ions out and 2 K+ in.
What generates the gradients for Na+ and K+ in a living cell.
Sodium Potassium pump
A sensory neuron can communicate information about the strength stimulus when its action potentials become…
more frequent only
What is spatial summation?
When AP’s occur at multiple synapses
What is temporal summation?
When a second AP arrives at a single synapse before the effects of the first have disappeared (timing - high frequency)
What affect does the parasympathetic NS have on secretion in gastric glands?
increases
What affect does the parasympathetic NS have on the volume of sweat secreted?
none
What affect does the Sympathetic NS have on smooth muscle contraction of the ileocecal valve?
increases
What affect does the parasympathetic NS have on the rate the SA node depolarizes?
decreases
What affect does the parasympathetic NS have on secretions by the adrenal medulla?
none
What affect does the Sympathetic NS have on the diameter of smooth muscle in bronchioles?
increases
