Lymphatic tissues that form a protective ring around the back of the nose and throat are called __________
Fill in the blank(s) with the appropriate word(s).
Ans: Tonsils
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Maturing spermatozoa are stored primarily in the
A) seminiferous tubules. B) straight tubules. C) lobules. D) interstitial areas. E) epididymis.
Which of these substances normally cannot pass through the filtration membrane?
A) hemoglobin B) water C) sodium ions D) bicarbonate ions E) glucose
A positive feedback loop occurs when the outcome of an event causes the event to continue occurring and amplifies its effects. Which of the following aspects of an action potential constitutes a positive feedback loop?
A. Opening of voltage-gated sodium channels causes voltage-gated potassium channels to open and release potassium to the extracellular environment, slowly counteracting sodium influx. B. The sodium-potassium pump exactly balances ion leaks by pumping three sodium and two potassium ions across the membrane. C. An initial flow of sodium ions into the neuron opens voltage-gated sodium channels, rapidly causing more sodium to enter. D. The threshold potential is around -55mV.
Place the following events in synaptic transmission at a cholinergic synapse in order: A - A postsynaptic potential is produced; B - Voltage gated calcium channels open and calcium enters the cell; C - ACh is released and diffuses across the axon terminal; D - A nerve signal arrives at an axon terminal; E - Ligand gated sodium channels open and sodium enters the cell.
A. D, B, E, A, C B. B, C, D, E, A C. D, B, C, E, A D. B, D, C, A, E