y 發問於 科學及數學生物學 · 1 十年前

primary sexual characteristics

成日講secondary sexual characteristics?咁乜係primary sexual characteristics?

2 個解答

  • Schan
    Lv 6
    1 十年前

    Hope this helps you:

    Secondary Sexual Characteristics:

    ==In humans==

    [[Sexual differentiation]] begins during [[gestation]], when the [[gonads]] form. General habitus and shape of body and face, as well as sex hormone levels, are similar in prepubertal boys and girls. As [[puberty]] progresses and sex hormone levels rise, obvious differences appear.

    Male levels of [[testosterone]] directly induce growth of the [[penis]], and indirectly (via [[Dihydrotestosterone|Dihydrotestosterone (DHT)]]) the [[prostate]]. [[Estradiol]] and other hormones cause [[breast]]s to develop in females. However, fetal or neonatal [[androgen]]s may modulate later breast development by reducing the capacity of breast tissue to respond to later estrogen.

    In males, testosterone directly increases size and mass of muscles, vocal cords, and bones, enhancing strength, deepening the voice, and changing the shape of the face and skeleton. Converted into DHT in the skin, it accelerates growth of androgen-responsive facial and body hair. Taller stature is largely a result of later puberty and slower epiphyseal fusion.

    In females, breasts are the most obvious manifestation of higher levels of [[estrogen]], but estrogen also widens the pelvis and increases the amount of body fat in hips, thighs, buttocks, and breasts. Estrogen also induces growth of the [[uterus]], proliferation of the [[endometrium]], and [[menstrual cycle|menses]].

    In humans, secondary sex characteristics include:

    * [[Male]]

    ** [[abdominal hair|abdominal]] and [[chest hair]]

    ** more hair on other parts of body

    ** more [[facial hair]]

    ** on average, larger hands and feet than women

    ** broader shoulders and chest

    ** heavier skull and bone structure

    ** greater [[muscle]] mass and physical strength

    ** a prominent [[Adam's apple]] and deep [[human voice|voice]]

    ** [[fat]] deposits mainly around the [[human abdomen|abdomen]] and [[waist]] (apple shape)

    ** coarser skin texture

    * [[Female]]

    ** enlarged [[breast]]s

    ** on average, lower height than men

    ** wider in [[hip (anatomy)|hip]]s than in [[shoulder]]s

    ** less [[facial hair]]

    ** functional [[mammary gland]]s

    ** more [[subcutaneous fat]]

    ** fat deposits mainly around the [[buttocks]], [[thigh]]s and [[hip (anatomy)|hip]]s (pear shape)

    ** smoother skin texture


    Primary Sexual Characteristics:

    A sex organ, or primary sexual characteristic, narrowly defined, is any of those anatomical parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in a complex organism; namely:

    Male: penis (notably the glans penis), prepuce, testicles, scrotum, prostate, seminal vesicles, epididymis, Cowper's glands

    Female: vulva (notably the clitoris and labia), vagina, cervix, uterus, Fallopian tube, ovaries, Skene's gland, Bartholin's glands.

    The Latin term genitalia, sometimes anglicized as genitals, is used to describe the sex organs, and in the English language this term and genital area are most often used to describe the externally visible sex organs, known as primary genitalia or external genitalia: in males the penis and scrotum, in females the vulva.

  • 1 十年前

    Secondary sex characteristics are traits that distinguish the two sexes of a species, but that are not directly part of the reproductive system. Some have argued that in general they evolved to give an individual an advantage over its rivals in courtship. They are opposed to the primary sexual characteristics: the sex organs.