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Nursing > 231 L06 Reproduction > Flashcards

231 L06 Reproduction Flashcards

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1
Q

Define and describe erection in the male reproductive system.

A
  • Enlargement and stiffening of the penis, results from engorgement of the erectile bodies with blood. When sexual excitement triggers a parasympathetic reflex, NO relaxes smooth muscle in the penile blood vessel walls, dilating these arterioles, and the erectile bodies fill with blood.
  • Expansion of the corpora cavernosa of the penis compresses their drainage veins, stopping blood outflow and maintaining engorgement. Parasympathetic input also stimulates secretion from the bulbo-urethral glands.
  • Various sexual stimuli can initiate erection. The CNS responds by activating parasympathetic neurons that innervate the internal pudendal arteries serving the penis.
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2
Q

Define and describe ejaculation in the male reproductive system.

A

The propulsion of semen from the male duct system. When impulses provoking erection reach a critical level, a spinal reflex is initiated, and a massive discharge of nerve impulses occurs over the sympathetic nerves serving the genital organs. As a result:

  • The ductus deferens, prostate, and seminal glands contract, emptying their contents into the prostatic urethra. At the same time, the bladder internal sphincter muscle constricts, preventing expulsion of urine or reflux of semen into the bladder.
  • Semen in the urethra triggers a spinal reflex through somatic motor neurons. The bulbospongiosus muscles of the penis undergo a rapid series of contractions, propelling semen from the urethra.
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3
Q

Define mitosis.

A

Mitosis means the cells divide and the chromosomes replicate and you end up with 2 cells from one cell and they have both got 46 chromosomes.

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4
Q

What are the functions of the reproductive system?

A
  • produce gametes (both male and female)
  • create offspring (female)
  • produce hormones (female and male)
  • carry baby and maybe feed it (female)
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5
Q

Where does the process of spermatogenesis start?

A

In the testes

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6
Q

Where in the testes are sperm made?

A

Seminiferous tubules, then move onto other tubules to mature

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7
Q

What are 2 functions of meiosis?

A

1: It halves the chromosome number and 2: provides genetic variability

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8
Q

When a female is born at what stage of development are her eggs?

A

They have all undergone mitosis and just started the process of the first meiotic division

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9
Q

When will they complete the second meiotic division?

A

If penetrated by a sperm travelling down the fallopian tube just before fusion of egg and sperm nuclei

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10
Q

What is the function of the corpus luteum?

A

It produces estrogen and progesterone

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11
Q

What role does having high concentrations of both estrogen and progesterone (at the same time) have?

A

Negative feedback effect on FSH and LH

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12
Q

What is erection and which division of the ANS regulates it?

A

Erection is the stiffening of the penis that occurs when blood floods the cavernous tissue and is also prevented from leaving the penis. It is caused by the parasympathetic division of the autonomic nervous system.

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13
Q

Define spermatogenesis.

A

Is the process of forming male gametes. It occurs in the seminiferous tubules of the testes and is the hallmark of sexual maturity. Spermatogenesis begins at puberty, around the age of 14 years, and continues throughout life. Every day, a healthy adult male makes about 90 million sperm.

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14
Q

What are the two main cells involved in spermatogenesis in the seminiferous tubules?

A

sustenocytes and spermatogenic cells

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15
Q

Define sustenocyte.

A

Nourishes spermatogenic cells in the seminiferous tubules, gets rid of their waste, and moves them through the tubule wall. Are joined by tight junctions.

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16
Q

What do the tight junctions between the sustenocytes create?

A

The blood testis barrier. This ensures that as the sperm develop, you don’t trigger an immune reaction because the developing sperm have not been exposed to the immune system and it would not recognize those cells as belonging to the male. (they didn’t have them before puberty)

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17
Q

What happens to the type A daughter cell that is produced during spermatogenesis?

A

Remains at the basal lamina to maintain the pool of dividing germ cells.

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18
Q

What happens to the type B daughter cell that is produced during spermatogenesis?

A

The type B daughter cell gets pushed toward the lumen, where it becomes a primary spermatocyte destined to produce four sperm.

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19
Q

What happens to primary spermatocytes?

A

Undergoes meiosis I, forming two smaller haploid (23 chromosome) cells called secondary spermatocytes.

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20
Q

What happens to secondary spermatocytes?

A

The secondary spermatocytes continue on rapidly into meiosis II. Their daughter cells, called spermatids, are small round cells, with large spherical nuclei, seen closer to the lumen of the tubule.

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21
Q

What happens during spermiogenesis?

A

Each spermatid has the correct chromosomal number for fertilization (n), but is nonmotile. It still must undergo a streamlining process called spermiogenesis, during which it elongates, sheds its excess cytoplasmic baggage, and forms a tail.

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22
Q

What does the hypothalamus release relative to reproduction?

A

GnRH = gonadotropin-releasing hormone

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23
Q

What does GnRH cause relative to reproduction?

A

Causes anterior pituitary gonadotropic cells to release FSH = follicle-stimulating hormone and LH = luteinizing hormone.

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24
Q

What is FSH’s role in spermatogenesis?

A

Indirectly stimulates spermatogenesis by causing sustenocytes to release ABP, which keeps the local concentration of testosterone high.

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25
Q

What is LH’s role in spermatogenesis?

A

Stimulates interstitial endocrine cells to secrete testosterone, which is essential for spermatogenesis.

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26
Q

What are interstitial endocrine cells?

A
  • in connective tissue between seminiferous tubules

- secrete testosterone

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27
Q

What are the parts of a mature sperm?

A
  • head
  • midpiece
  • tail
28
Q

Define ovarian follicle

A

Ovarian structure consisting of a developing egg surrounded by one or more layers of follicle cells

29
Q

What are the two main things that the ovaries do?

A

The ovaries produce the female gametes and secrete female sex hormones (estrogens and progesterone).

30
Q

What are the phases of the ovarian cycle?

A
  • follicular phase
  • ovulation (day 14)
  • luteal phase
31
Q

What are the phases of the uterine cycle?

A
  • menstrual phase
  • proliferation phase
  • secretory phase
32
Q

Define oogenesis.

A

process of ovum (female gamete) formation.

33
Q

What is the dominant follicle?

A

The first phase is called the follicular phase because many large vesicular follicles are growing in the ovary during this phase. FSH is a survival factor for vesicular follicles, allowing them to continue to survive and grow. One of these growing vesicular follicles becomes more sensitive to FSH than the others. As FSH levels begin to drop in the middle of the follicular phase, that follicle outcompetes the other follicles for FSH, and so continues to escape from atresia and becomes the dominant follicle.

34
Q

What happens to the primary oocyte of the dominant follicle?

A

As one of the final events of follicle maturation, the primary oocyte of the dominant follicle completes meiosis I to form the secondary oocyte and first polar body. Once this has occurred, the stage is set for ovulation.

35
Q

Define ovulation.

A

Ejection of an egg from the ovary.

36
Q

What happens to the remaining granulosa cells after the follicle ruptures?

A

The remaining granulosa cells enlarge, and along with the internal theca cells they form a new, quite different endocrine structure, the corpus luteum. The corpus luteum supplies the high levels of progesterone and estrogens that characterize the luteal phase.

37
Q

What happens to the corpus luteum if pregnancy does not occur?

A

If pregnancy does not occur, the corpus luteum starts degenerating after about 10 days and its hormonal output ends.

38
Q

What happens to the corpus luteum if the oocyte is fertilized and pregnancy occurs?

A

If the oocyte is fertilized and pregnancy ensues, the corpus luteum persists until the placenta is ready to take over its hormone-producing duties in about three months.

39
Q

How do identical twins differ developmentally from fraternal twins?

A

Identical twins develop from separation of a very young embryo (the result of fertilization of a single oocyte by a single sperm) into two parts. Fraternal twins develop when different oocytes are fertilized by different sperm.

40
Q

What occurs in the luteal phase of the ovarian cycle?

A

In the luteal phase, the follicle from which an oocyte has been ovulated develops into a corpus luteum, which then secretes progesterone (and some estrogens).

41
Q

When does spermatogenesis begin?

A

at puberty

42
Q

Which cells in the seminiferous tubules secrete testosterone?

A

interstitial endocrine cells

43
Q

Describe the hormones involved in male reproduction.

A

FSH causes sustentocytes to produce androgen-binding protein (ABP). LH stimulates interstitial endocrine cells to release testosterone, which binds to ABP, stimulating spermatogenesis. Testosterone feeds back to inhibit the hypothalamus and anterior pituitary. Inhibin, released by sustentocytes, inhibits FSH release.

44
Q

Describe oogenesis.

A
  1. Oogenesis, the production of eggs, begins in the fetus. Oogonia, diploid stem cells that give rise to female gametes, are converted to primary oocytes before birth. The infant female’s ovaries contain about 2 million primary oocytes arrested in prophase of meiosis I.
  2. At puberty, meiosis resumes. Each month, one primary oocyte completes meiosis I, producing a large secondary oocyte and a tiny first polar body. Meiosis II of the secondary oocyte produces a functional ovum and a second polar body, but does not occur unless a sperm penetrates the secondary oocyte.
  3. The ovum contains most of the primary oocyte’s cytoplasm. The polar bodies are nonfunctional and degenerate.
45
Q

Describe the hormonal events of the ovarian cycle.

A

The hormonal events of each ovarian cycle are as follows: (1) GnRH stimulates the anterior pituitary to release FSH and LH, which stimulate follicle maturation and estrogen production. (2) When blood estrogens reach a certain level, positive feedback exerted on the hypothalamic-pituitary-gonadal axis causes a sudden release of LH that stimulates the primary oocyte to continue meiosis and triggers ovulation. LH then causes conversion of the ruptured follicle to a corpus luteum and stimulates its secretory activity. (3) Rising levels of progesterone and estrogens inhibit the hypothalamic-pituitary-gonadal (HPG) axis, the corpus luteum deteriorates, ovarian hormones drop to their lowest levels, and the cycle begins anew.

46
Q

Describe the uterine cycle phases.

A

During the menstrual phase of the uterine cycle (days 0–4), the functional layer sloughs off in menses. During the proliferative phase (days 5–14), rising estrogen levels stimulate its regeneration. Under the influence of both estrogens and progesterone during the secretory phase (days 15–28), the uterine glands secrete nutrients, and endometrial vascularity increases further. This makes the uterus receptive to implantation about one week after ovulation. Falling levels of ovarian hormones during the last few days of the ovarian cycle cause the spiral arteries to become spastic and cut off the blood supply of the functional layer. The uterine cycle begins again with menstruation.

47
Q

True or false. The mitosis phase in oogonium happen in females before birth.

A

True

48
Q

What hormone regulates the events of the ovarian cycle?

A

fluctuating levels of pituitary gonadotropins (FSH and LH)

49
Q

When a female is born at what stage of development are her eggs?

A

They have all undergone mitosis and just started the process of the first meiotic division

50
Q

When will a female’s egg complete the second meiotic division?

A

If penetrated by a sperm travelling down the fallopian tube just before fusion of egg and sperm nuclei

51
Q

Define atresis.

A

Programmed cell death of the follicles in the female reproductive system.

52
Q

Which part of the ovarian cycle is usually constant across females?

A

Luteal phase.

53
Q

In the female, once the FSH is produced by the anterior pituitary, where does it go?

A

To the ovary and then the follicle and stimulates cells that make up the granulosa. Increased granulosa cells means increased estrogen.

54
Q

In the female, once the LH is produced by the anterior pituitary, where does it go?

A

To the ovary and then a different part of the follicle than the FSH. Produce thecal cells. Thecal cells produce androgens, that move into granulosa cells, which convert androgens to estrogen).

55
Q

Define thecal cell.

A

In females, they are involved in the ovarian cycle. Stimulated by LH, they produce androgens that move into the granulosa cells, which convert androgens to estrogen.

56
Q

In the early days of the ovarian cycle, when estrogen is low, what kind of feedback loop is it?

A

Negative feedback loop. The estrogen and inhibin reduce release of GnRH and therefore FSH. Want this so we don’t end up with more than one viable eggs. Only the dominant follicle can survive the dip in FSH.

57
Q

In the late follicular and lutal phase, what effect does estrogen have?

A

It has a positive feedback loop. Positive feedback is exerted by the large increase is estrogen output in the maturing follicle. Leads to increase in GnRH and a LH surge.

58
Q

What does the surge of LH cause in females?

A

It weakens the wall of the wall of the ovary, and the egg can pop out and head down to Fallopian tube. It also rouses the primary oocyte in the follicle to complete its first meiotic division.

Also transforms the ruptures follicle into the corpus luteum and stimulates it to produce large amounts of progesterone and some estrogen.

59
Q

What day of the ovarian cycle does estrogen peak?

A

day 13

60
Q

What happens on day 14 of the ovarian cycle?

A

Estrogen drops like crazy, and LH and FSH go down. LH is still in high concentration on days 15 and 16.

61
Q

What is the purpose of the progesterone produced by the corpus luteum?

A

Helps maintain the functional layer of the endometrium and is essential for maintaining pregnancy should conception occur.

62
Q

What hormones does the corpus luteum produce?

A
  • progesterone
  • estrogen
  • inhibin
63
Q

During the luteal phase, what kind of feedback loop is there?

A

The rising estrogen and progesterone cause a negative feedback loop. The inhibin produced by the corpus luteum also enhances the inhibitory effect on the hypothalamus and anterior pituitary, reducing FSH and LH.

64
Q

What happens on day 26-28 of the ovarian cycle?

A

if there is not fertilized egg, corpus luteum will know and start to break down. This will cause blood estrogen and progesterone levels to drop, which ends the blockade on FSHand LH. Cycle can start anew.

65
Q

How does the corpus luteum know if we are pregnant or not?

A

hcG - this is only present if there is a fertilized egg

human chorionic gonadotropin

Nursing (29 decks)

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