Final answer:
a. Alpha receptors include subtypes α1 and α2, which are involved in smooth muscle motility and vasoconstriction.
b. Ejaculation is the expulsion of semen from the p*nis, facilitated by testosterone.
c. Erection is the process of blood engorging the erectile tissues in genitalia during sexual arousal.
Step-by-step explanation:
Alpha receptors, primarily of the α1 and α2 subtypes, are part of the adrenergic receptor family that bind to epinephrine and norepinephrine. They play various roles in the autonomic nervous system, such as causing vasoconstriction and affecting smooth muscle motility.
Ejaculation, or emission, is the process by which semen is expelled from the body during sexual climax. It involves the peristaltic movement of semen through the vas deferens and ejaculatory ducts from the urethra in the p*nis. Leydig cells secret testosterone, which is necessary for maintained fertility and regular ejaculatory functions.
Erection, or vasodilation, occurs when blood engorges the erectile tissues during sexual arousal, leading to an enlarged and rigid state of the p*nis in males, and engorged cl*toris and labia in females. Vasodilation in the erectile tissues facilitates sexual intercourse.