Injecting potassium into the blood stream stops the heart.  In this case, cardiac muscle cells would be stuck in the  Select one: a. Absolute refractory period b. Resting state c. Relative refractory period

If the resistance of the neuronal membrane goes from 250 Mᘯ to 500 Mᘯ, which of the following is most likely to occur?   Current will doble   Current will quadruple   Current will decrease by half   Current will increase by 1/4th

The walls of blood vessels in the brain are formed by cells that are very tightly packed. This arrangement of cells provides which of the following properties of most brain vasculature?     a. efficient removal of waste products by blood systems     b. rigidity and likelihood of stroke     c. most large and charged molecules cannot move from the blood to the brain     d. easy access to required blood chemicals such as glucose, oxygen, and various hormones   What does it mean to say that acetylcholine exerts ionotropic effects?     a. It opens ion channels.     b. It increases the concentration of ions within the vesicles.     c. It alters the permeability of the presynaptic neuron.     d. It changes the electrical charge of sodium ions from positive to negative.

Cardiac muscle cells have a longer refractory period than skeletal muscle cells.  This ensures that the heart is able to relax between contractions.  What would happen if the heart were not able to relax between contractions? The heart would no longer pump blood – because without relaxation, the heart cannot fill with blood. No change in heart function – contractions are the important part. The heart would pump more blood out with each heartbeat.

During the refractory period a second action potential______.   A cannot occur because voltage-gated Na+ channels are inactivated   B cannot occur because the heart muscle cell has already returned to resting potential   C can be initiated more easily because the threshold potential is reduced   D can be initiated more easily because the calcium level in the sarcoplasm is increased

What statement is NOT true about the length constant? is the distance along the dendrite from the site of current input to the site where Vm has decayed by 37% the decay of current by 37% over a specific segment along an axon the decay of membrane potential as a function of membrane and axial resistances the passive decay of current over distance

Describe what would happen to the action potential if we blocked the Calcium channels in caridac myocytes, and the effect it would have on the heart.

Only one is correct Contraction of cardiac muscle is initiated during which phase of the fast action potential? What ion mediates this effect?  A. Phase 0 due to Ca++ entry B. Phase 1 due to Na+ entry and K+ exit C. Phase 2 due to Ca++ entry D. Phase 4 due to K+ exit Group of answer choices Phase 2 due to Ca++ entry Phase 1 due to Na+ entry and K+ exit Phase 0 due to Ca++ entry Phase 4 due to K+ exit

Draw and discuss an AP (action potential). Below this graph draw and discuss the conductance of the important ions moving across this membrane that makes the action potential work. a. Cardiac fiber (non automatic cells) b. SA (self excitable cells)

An intravenous injection of potassium can cause death within a minute. From what you have learned about the resting membrane potential and action potential in chapter 7, how do you think it interferes with cellular function to cause death so fast?