C. What types of channels are found along an axon and along most of the sarcolemma? D. How do you activate/open these channels? E. What types of channels are found at an axon terminal that allows for vesicle fusion? F. How do these channels become activated? G. What neurotransmitter is released from the vesicles of the axon terminal? H. What specific type of channel does this neurotransmitter activate? I. Where are these channels located (what are the invaginations called)? J. What happens upon activation of these channels? uscle fiber activation/contraction
Added by Celia P.
Step 1
What types of channels are found along an axon and along most of the sarcolemma? Show more…
Show all steps
Your feedback will help us improve your experience
Adi S and 69 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
1. What is the initial stimulus for muscle contraction? 2. Which neurotransmitter is released at the neuromuscular junction after the action potential arrives? 3. When receptors open at the neuromuscular junction, does sodium travel in or out of the muscle fiber? 4. The action potential continues to travel down the muscle fiber on which structures? Which ion is released from the sarcoplasmic reticulum as this happens?
Adi S.
Acetylcholine-gated cation channels at the neuromuscular junction open in response to acetylcholine released by the nerve terminal and allow Na' ions to enter the muscle cell, which causes membrane depolarization and ultimately leads to muscle contraction. A. Patch-clamp measurements show that young rat muscles have cation channels that respond to acetylcholine (Figure $Q 11-4$ ). How many kinds of channel are there? How can you tell? B. For each kind of channel, calculate the number of ions that enter in one millisecond. (One ampere is a current of one coulomb per second; one pA equals $10^{-12}$ ampere. An ion with a single charge such as $\mathrm{Na}^{+}$ carries a charge of $1.6 \times 10^{-19}$ coulomb.
The force of contraction in a skeletal muscle is normally graded by ________. a. The amount of calcium released from the sarcoplasmic reticulum (SR) by an action potential. b. Activation of fast, glycolytic motor units instead of slow, oxidative motor units. c. Summation of action potentials to prolong motor nerve depolarization. d. Motor unit recruitment. e. Alteration in myosin ATPase activity. 2. Gap junctions ________. a. Are absent in cardiac muscles. b. Are present but of little functional importance in cardiac muscle. c. Are present and provide the pathway for rapid spread of excitation from one cardiac muscle cell to another. d. Are absent in visceral smooth muscles. e. Connect the sarcotubular (SR) system to individual skeletal muscle cells. 3. Acetylcholine receptors are ________. a. Skeletal muscle contractile proteins. b. Non-specific, small ion channels. c. Ligand-binding hormone receptors (membrane proteins). d. Calcium binding. 4. The action of curare, which can produce paralysis of skeletal muscles, is to ________. a. Block the release of ACh from the nerve terminal. b. Cause an explosive release of ACh at the neuromuscular junction. c. Bind reversibly to the ACh receptors. d. Bind irreversibly to the ACh receptors. e. Inhibit acetylcholine esterase. 5. Acetylcholinesterase, the enzyme which hydrolyzes ACh, is ________. a. Released from the presynaptic nerve terminal. b. Blocked by antibodies in Myasthenia gravis. c. Located in the junctional folds of the muscle cell membrane. d. Required for membrane depolarization. e. Dependent on increased intracellular calcium concentrations. 6. Endplate potentials, which are depolarizing due to the simultaneous movement of both sodium and potassium, are recorded at the ________. a. Presynaptic nerve terminal. b. Motor axon. c. T-tubule. d. Skeletal muscle. e. Sarcoplasmic reticulum.
Sri K.
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
18,000,000+
Students on Numerade
Trusted by students at 8,000+ universities
Watch the video solution with this free unlock.
EMAIL
PASSWORD