Neuromuscular Junction: Structure and Function

What is the result of the local depolarization wave continuing to spread?

The fiber becomes refractory.
The permeability of the sarcolemma changes. (correct)
The axon terminal releases ACh.
The permeability of the sarcolemma decreases.

What happens to the Na+ channels during repolarization?

They close. (correct)
They remain open.
They become voltage-gated.
They open further.

What is the function of the Na+K+ pump?

To restore the resting polarity of the fiber. (correct)
To release ACh from the axon terminal.
To increase the permeability of the sarcolemma.
To generate an action potential.

What is the state of the fiber during the refractory period?

It cannot be stimulated. (D) Signup and view all the answers

What occurs during local depolarization?

The end plate potential is generated on the sarcolemma. (C) Signup and view all the answers

What is the result of K+ efflux during repolarization?

The resting polarity of the fiber is restored. (A) Signup and view all the answers

At which stage do Na+ channels close and K+ channels open?

During repolarization (B) Signup and view all the answers

What occurs during the latent period?

Events of excitation-contraction coupling (C) Signup and view all the answers

What is the number of polypeptide chains in a hemoglobin molecule?

4 (A) Signup and view all the answers

What type of channels are open during the generation of the end plate potential?

Only Na+ channels (B) Signup and view all the answers

What is the sequence of events that leads to muscle contraction?

Transmission of an action potential, generation of the end plate potential, and excitation-contraction coupling (C) Signup and view all the answers

What is the function of the heme group in hemoglobin?

To bind with oxygen (A) Signup and view all the answers

What is the role of ACh in the sequence of events?

To bind to nicotinic receptors on the sarcolemma (B) Signup and view all the answers

What is the name of the process by which blood cells are formed?

Hematopoiesis (D) Signup and view all the answers

Where does hematopoiesis occur in the body?

Red bone marrow of axial skeleton (B) Signup and view all the answers

What is the overall effect of the sequence of events?

Muscle contraction (A) Signup and view all the answers

What is the name of the cells that give rise to all formed elements in the blood?

Hemocytoblasts (C) Signup and view all the answers

What is the space between the axon terminal and the muscle fiber called?

Synaptic cleft (D) Signup and view all the answers

What percentage of CO2 is carried in the blood by carbaminohemoglobin?

20% (D) Signup and view all the answers

What is the role of voltage-gated Ca2+ channels in the neuromuscular junction?

To open and allow Ca2+ to enter the axon terminal (A) Signup and view all the answers

What is the function of acetylcholinesterase in the neuromuscular junction?

To break down acetylcholine in the synaptic cleft (C) Signup and view all the answers

What is the type of channel that allows simultaneous passage of Na+ into the muscle fiber and K+ out of the muscle fiber?

Na+ K+ channel (C) Signup and view all the answers

What is the purpose of the action potential arriving at the axon terminal?

To release acetylcholine from the synaptic vesicles (D) Signup and view all the answers

What is the location of the ACh receptors in the neuromuscular junction?

In the junctional folds of the sarcolemma (B) Signup and view all the answers

What is the normal stimulus for the homeostatic response to increase oxygen-carrying ability in the blood?

Hypoxia (A) Signup and view all the answers

What is the role of the kidney in the homeostatic response to hypoxia?

To release erythropoietin (C) Signup and view all the answers

What is the average lifespan of a red blood cell?

100-120 days (D) Signup and view all the answers

What happens to the heme part of hemoglobin when it is degraded?

It is converted into bilirubin (D) Signup and view all the answers

What is the final destination of the broken-down bilirubin in the body?

The feces (A) Signup and view all the answers

What is the fate of the globin part of hemoglobin when it is degraded?

It is broken down into amino acids (C) Signup and view all the answers