In the Absence of Extracellular Ca⁺⁺,an Action Potential in a Motor

question 9

Multiple Choice

In the absence of extracellular Ca⁺⁺,an action potential in a motor neuron fails to initiate contraction of the innervated skeletal muscle because of:

• A)Inhibition of Ca⁺⁺ influx into the innervated muscle.
• B)Inhibition of acetylcholine (ACh)binding to receptors on the muscle end plate.
• C)Stimulation of ACh degradation.
• D)Inhibition of ACh release from the motor neuron.
• E)Inhibition of Ca⁺⁺ binding to troponin C in the innervated muscle.

---

Definitions:

Penis

The male external genitalia that serves as both the organ of sexual intercourse and the passageway for urine to leave the body.

Testis

The male reproductive gland that produces sperm and testosterone, located in the scrotum.

Ductus Deferens

A tube that carries sperm from the testes to the urethra in male mammals.

Epididymis

A long, coiled tube attached to the back of each testicle where sperm matures and is stored.