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Temple A&P > Lecture: Reproduction & Development > Flashcards

Lecture: Reproduction & Development Flashcards

1
Q

Define: gametes.

A

sex cells;

males: spermatozoon (sperm);
females: ovum (egg)

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2
Q

Explain chromosomal sex determination.

A 
23 pairs of chromosomes:
-22 autosomes
-1 pair of sex chromosomes;
ovum contains X;
half of sperm contain X, half contain Y
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3
Q

Does sexual differentiation end with fertilization? Explain.

A

No: requires an interaction between genetics and hormones;

fetus is “non-committed” until 5-6 weeks

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4
Q

Name the 2 ducts adjacent to gonadal ridges which interact with prenatal hormones to undergo sexual differentiation.

A

2 pairs of ducts along each mesonephros, or primitive kidney:

1) mesonephric (wolffian) ducts:
2) paramesonephric (mullerian) ducts:

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5
Q

Explain how the mesophrenic (wolffian) ducts interact with prenatal hormones to undergo sexual differentiation.

A

Y chromosome has a gene called SRY (sex-determining region of the Y) that codes for a protein called testis-determining factor (TDF);
rudimentary testes form in 8-9 weeks and secrete:
-testosterone: causes development of male reproductive tract
-mullerian-inhibiting factor (MIF): causes atrophy of paramesonephric ducts

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6
Q

Explain how the paramesonephric (mullerian) ducts interact with prenatal hormones to undergo sexual differentiation.

A

absence of testosterone and MIF causes development of female reproductive tract

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7
Q

Define: homologous.

A

male and female organs that develop from the same embryonic structure

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8
Q

In the embryo, the genitals begin developing from identifical structures in both sexes. Name these 3 structures (present at 6 weeks) and name what they develop into.

A

1) genital tubercle: penis/clitoris
2) urogenital folds: urethra/labia minora
3) labiosacral folds: scrotum/labia majora

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9
Q

Describe the process of the descent of the testes.

A

begins around embryonic week 6;
though inguinal canal to scrotum (~7 months);
descent guided by testosterone, but not well understood

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10
Q

Define: inguinal canal.

A

path of low resistance through the groin that serves as a path for testicular descent

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11
Q

Define: cryptorchidism.

A

condition present in 3% of boys in which they are born with undescended testes

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12
Q

Name the major structures and functions of the male reproductive system.

A

scrotum and testes: spermatogenesis;
spermatic ducts and accessory glands: transport;
penis: emission

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13
Q

Describe the contents of the scrotum.

A 
testes;
spermatic cord:
-ductus deferens (sperm duct)
-blood/lymph vessels
-nerves
mechanisms for temp regulation
-cremaster muscle: contracts when cold
-dartos muscle: contracts when cold
-pampiniform plexus: network of veins that cools warm arterial blood that would inhibit sperm production
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14
Q

Describe the microanatomy of the testes.

A

tunica albuginea: outer white fibrous capsule;
250-300 lobules: each contains 1-3 seminiferous tubules, which produce sperm;
3 cell types:
interstitial (Leydig) cells: produce testosterone;
germ cells: in process of becoming sperm;
sustenacular (Sertoli): protect germ cells and promote their development; secrete nutrients and inhibin

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15
Q

Describe the 3 special cell types present in the testes.

A

1) interstitial (Leydig) cells: produce testosterone;
2) germ cells of germinal epithelium: in process of becoming sperm;
3) sustenacular (Sertoli): protect germ cells and promote their development;
secrete nutrients and inhibin;
form blood-testis barrier (BTB)

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16
Q

Define: inhibin.

A

hormone secreted by sustenacular (Sertoli) cells which regulates the rate of sperm production;
helps to produce a protein called ABP (androgen-binding protein)

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17
Q

Define: blood-testis barrier (BTB).

A

barrier formed by sustenacular (Sertoli) cells which protects sperm from attack by immune system

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18
Q

Describe the 3 spermatic ducts.

A

1) efferent ductule carries sperm from posterior testes to epididymis
2) ductus (vas) deferens propels sperm from epididymis to urethra
3) ejaculatory duct: where ductus deferens and seminal vesicle meet;
passes through prostate and empties into urethra

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19
Q

Define: epididymis.

A

site of sperm maturation and storage

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20
Q

Name the 3 accessory glands associate with the male reproductive system.

A

1) seminal vesicle
2) prostate gland
3) bulbourethral gland

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21
Q

Explain the role of the seminal vesicle.

A

mucus-like secretions make up 60% of semen volume;
provides nutrients for sperm;
secretions contain proseminogelin;

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22
Q

Explain the role of prostate gland.

A

alkaline secretions protect sperm from acidity of vagina;
calcium, citrate, phosphate;
serine protease: liquefies semen;
clotting enzyme activates proseminogelin to seminogelin, which gives sperm its stickiness

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23
Q

Explain the role of bulbourethral gland.

A

secrete alkaline fluid, which neutralizes the urethra, when sexual arousal first occurs;
lubricates penis

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24
Q

Explain composition and function of the penis.

A

3 divisions:

  • root
  • shaft: 2 bodies of erectile tissue (corpus spongiosum & corpus cavernosum)
  • glans
    function: delivery of semen
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25
Q

Explain endocrine control of puberty.

A

at puberty, hypothalamus begins releasing gonadotropin-releasing hormone (GnRH);
GnRH stimulates anterior pituitary to release FSH and LH

26
Q

Explain follicle-stimulating hormone’s (FSH) role in puberty.

A 
stimulates sustenacular (Sertoli) cells to secrete androgen-binding protein (ABP);
without FSH and ABP, testosterone would have no effect on the testes
27
Q

Explain luteinizing hormone’s (FSH) role in puberty.

A

stimulates interstitial (Leydig) cells to release androgens, especially testosterone

28
Q

What is the role of androgen-binding protein (ABP)?

A

raises testosterone levels in the seminiferous tubules and epididymis;
without FSH and ABP, testosterone would have no effect on the testes

29
Q

Name the 7 effects of testosterone.

A

1) spermatogenesis
2) secondary sex characteristics
3) enlargement of reproductive structures
4) inhibits GnRH, FSH, and LH secretion
5) body growth
6) accelerates erythropoiesis
7) awakens libido

30
Q

Give an overview of the process of sperm production.

A

Division of germ cells;
meiosis I:
-parent cell is diploid (2n) (46 chromosomes);
-2 daughter cells are haploid (n) (23 chromosomes);
meiosis II:
-more like mitosis;
-ends with 4 haploid cells (n) (23 chromosomes);
each spermatid undergoes spermatogenesis

31
Q

Explain spermatogenesis.

A

primordial germ cells: first stem cells destined to become sperm; after they migrate to the gonadal ridges, they change into spermatagonia, which lie upon the basement membranes of the seminiferous tubules outside of the BTB;
spermatagonia:
-Type A: always remain at basement membrane outside of BTB
-Type B: migrate toward the lumen of the seminiferous tubule and become…
primary spermatocytes, which move through the BTB and undergo meiosis I to become…
-2 haploid secondary spermatocytes, which each undergo meiosis II to become…
-2 spermatids (4 total)

32
Q

Explain spermiogenesis.

A

spermatid undergoes spermiogenesis, in which it differentiates into a spermatozoon (sperm):
-sprouts tail (flagellum)
-discards cytoplasm
-takes 74 days
sperm production: 300,000/min, 400million/day

33
Q

Describe the structure of spermatozoa.

A 
head:
-nucleus with tip covered by acrosome, which contain enzymes to penetrate the egg
tail:
-midpiece, contains mitochondria
-principal piece
-end piece
34
Q

Describe the composition and functions of semen.

A

10% sperm
30% prostatic fluid
60% seminal vesicle fluid
function: nourishment, protection, & activation of sperm

35
Q

Compare and contrast normal and infertile sperm count.

A

normal: 50-120 mill/mL
infertile: 20-25 mill/mL

36
Q

Name the 4 stages of male sexual arousal.

A

1) excitement
2) plateau
3) orgasm
4) resolution

37
Q

Describe the excitement stage of male sexual arousal.

A

vasocongestion;
myotonia: muscle tension;
parasympathetic fibers release nitric oxide, which leads to a relaxation of the deep arteries so that they fill with blood

38
Q

Describe the plateau stage of male sexual arousal.

A

effects of excitement stage are maintained

39
Q

Describe the orgasm stage of male sexual arousal.

A

ejaculation:
-emission: SNS stimulates peristalsis in the smooth muscle of the ductus deferens;
path of sperm: tail of epididymis, ductus deferens, ampulla, prostatic urethra, urethra;
-expulsion: SNS stimulates expulsion of semen and constricts the urethral bladder

40
Q

Describe the resolution stage of male sexual arousal.

A

SNS reduces blow flow;
detumescence: penis becomes soft and flaccid again;
refractory period: 10 mins to hours; no erection possible

41
Q

Name the female reproductive organs.

A 
gonads: ovaries;
genitalia:
internal
-uterine tubes
-uterus
-vagina
external:
-labia majora
-labia minora
-clitoris
-vestibular glands
42
Q

Describe the function and structure of ovaries.

A 
functions: produce gametes and sex hormones
structure:
-capsule: tunica albuginea (like testes)
-cortex: contains follicles
-medulla: contains blood vessels
43
Q

Describe the composition of the uterine tubes.

A 
a.k.a. oviducts or fallopian tubes;
infundibulum with fimbriae;
tissue layers:
-middle: smooth muscle
-mucosa: cilia and secretory cells
held by ligaments
44
Q

Describe the function and structure of the uterus.

A

function: nourishment of zygote;
regions: fundus, body, cervix;
cervix contains cervical glands which secretes mucus;
layers: perimetrium, myometrium, endometrium

45
Q

Describe the functions and structure of the vagina.

A

functions:
-discharge of menstrual fluid
-intercourse
-childbirth
structures:
-vaginal orifice
-hymen
-dendritic cells: antigen-presenting cells, a route by which HIV from infected semen invades the female body

46
Q

Describe the female external genitalia.

A

mons pubis: area where pubic hair grows above pubic symphysis;
labia majora;
labia minora;
vestibule: area enclosed by labia minora
-clitoris: erectile tissue
-vestibular glands: lubrication
-paraurethral glands: similar to prostate

47
Q

Describe the composition of the mammary glands.

A

breasts composed of lobes of glandular tissue;

lobes converge to form lactiferous duct, which dilate to form a lactiferous sinus opening into the nipple

48
Q

Describe the cascade of hormones which cause female puberty.

A

hypothalamus secretes GnRH, which stimulates anterior pituitary to release FSH and LH:
-FSH stimulates development of ovarian follices, which in turn stimulates secretion of ovarian hormones

49
Q

What are the 3 noticeable effects of female puberty?

A

1) thelarche: onset of breast development
2) pubarche: appearance of pubic and axillary hair
3) menarche: first menstrual period

50
Q

Define: climacteric.

A

midlife change in hormone secretion, accompanied by menopause, the cessation of menstration

51
Q

Give an overview of the female reproduction.

A 
oogenesis: egg production;
sexual cycle:
-ovarian cycle: events in ovaries
-menstrual cycle: events in uterus
reproductive cycle: events from fertilization to birth
52
Q

Describe the process of oogenesis.

A

haploid gametes produced by meiosis;
cyclic event that releases one egg/month;
germ cells arise from the embryonic yolk sac and differentiate into oogonia;
6-7 million present shortly prefer birth;
oogonia transform into primary oocytes;
however, atresia (degeneration) occurs:
only about 400,000 primary oocytes remain by puberty

53
Q

Name the 4 stages of female sexual arousal.

A

1) excitement
2) plateau
3) orgasm
4) resolution

54
Q

Describe the excitement stage of female sexual arousal.

A 
vasocongestion:
-clitoris
-labia majora & minora
-vaginal transduate: serous fluid that lubricates canal
myotonia
55
Q

Describe the plateau stage of female sexual arousal.

A

effects of excitement stage are maintained;

tenting effect: uterus stands vertical instead of tilting forward toward the urinary bladder

56
Q

Describe the orgasm stage of female sexual arousal.

A

clitoris: sensory nerve endings
paraurethral glands (homologous to male prostate): “female ejaculation”;
uterus exhibits peristaltic contractions which may help to draw semen from the vagina

57
Q

Describe the resolution stage of female sexual arousal.

A

unlike men, no refractory period, so women may experience multiple orgasms ;)

58
Q

Describe the 4 hormones that play a role in pregnancy.

A

1) human chorionic gonadotropin (HCG)
- secreted by placenta
- detected by home pregnancy tests
2) estrogen
- stimulates tissue growth
3) progesterone
- secreted by placenta and corpus luteum
- prevents follicle development & menstruation
4) human chorionic somatommotropin (HCS)
- not understood, thought to contribute to growth and development of

59
Q

Give a brief overview of the key elements of childbirth.

A 
childbirth = parturition;
Braxton Hicks contractions = weak contractions that occur throughout gestation;
labor induced by positive feedback:
-cervical stretching >>> oxytocin secretion >>> uterine contraction >>> cervical stretching
3 stages:
-dilation
-expulsion
-placental
60
Q

Explain lactation.

A

synthesis and ejection of milk;
estrogen, progesterone, prolactin, and GH cause development of mammary glands during pregnancy;
in late pregnancy, colostrum secretion begins;
prolactin governs milk synthesis; its levels cycle between infant feedings;
milk synthesis also requires GH, cortisol, insulin, and PTH;
milk ejection: mechanical stimulation (suckling) stimulates oxytocin

Temple A&P (15 decks)

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