The Reproductive System Flashcards

1
Q

What are the primary functions of the reproductive system?

A
  • reproduction: to ensure the survival of the species of an animal
  • rather than to maintain the homeostasis of the body, unlike all other systems
  • not essential to the life of an animal
  • completion of the full function requires a second opposite sex animal
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2
Q

What is included in the reproductive system?

A

gonads (testes and ovaries)
- produce gametes (spermatozoa and oocyte) and hormones

ducts: receive and transport the gametes

accessory glands: secrete fluids into the ducts

perineal structures: collectively known as external genetalia

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3
Q

What are the principal structures of the reproductive organs of a male?

A
  • testes
  • epididymis
  • ductus deferens (vas deferens)
  • ejaculatory duct
  • urethra
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4
Q

What are the accessory glands of the reproductive organs of a male?

A
  • seminal vesicles
  • prostate glands
  • bulbourethral glands
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5
Q

What are the external genitalia of the male reproductive organs?

A
  • scrotum
  • penis
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6
Q

What are the functions of the testes?

A

spermatogenesis: produce the male gametes (spermatozoa or sperm), half billion/day

male sex hormone production: androgen (principally testosterone)
- develop male secondary sex characteristics and male sex drive
- stimulate bone and muscle growth

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7
Q

What is the structures of the testes?

A

tunica vaginalis
- two layers of serous membrane: parietal (scrotal) and visceral (testicular)

septa subdivide testes into lobules

lobules contain about 800 slender and tightly-coiled seminiferous tubules
- 15-20 large efferent ductules connect the rete testis to the epididymis

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8
Q

What are the seminiferous tubules?

A

wall formed by specialized epithelium = sertoli cells (sustentacular cells)

cells at different stages of spermatogensis

leydig cells: outside of the wall

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9
Q

What are sertoli cells?

A
  • support, nourish spermatogenesis
  • move developing sperm cells to lumen of seminiferous tubules
  • reduce motility of sperm cells to maintain viability
  • mediate hormonal effects
  • form blood-testis barrier
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10
Q

What is the relevance of sertoli cell tumor in intact male dogs?

A
  • sertoli cell tumors can produce estrogen and a condition called hyperestrogenism
  • hyperestrogenism can cause signs of feminization
  • this includes enlarged mammary glands and nipples, a pendulous prepuce, hair loss, and hyperpigmentation (darkening) of the skin
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11
Q

What do interstitial cells (leydig cells) do?

A

produce androgens (testosterone)

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12
Q

What is spermatogenesis?

A
  • is the process of sperm production
  • begins at outermost cell layer in seminiferous tubules
  • proceeds toward lumen
  • meiosis produces gametes: that contain 1/2 of chromosomes in somatic cells
  • for each cell entering meiosis: tests produce 4 spermatozoa (ovaries produce 1 ovum and 3 polar bodies)
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13
Q

What happens to the spermatozoa during sperm maturation?

A

detach from sustentacular cells (sertoli cells)

are free in lumen of seminiferous tubule

are functionally immature

are moved by cilia lining efferent ductules:
- into the epididymis
- facilitates functional maturation

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14
Q

Describe the regulation of testis functions by gonadotropin:

A
  • FSH and testosterone, BOTH, are required for initiation of spermatogenesis during sexual maturation
  • FSH and testosterone maintain the gametogenic function
  • FSH - stimulates the proliferation and secretory activities of sertoli cells
  • LH stimulates production of testosterone by Leydig cells
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15
Q

What are the functions of testosterone?

A
  • higher libido
  • increases muscle mass
  • strengthens bone
  • sperm production
  • penis development
  • development of phenotypic characterstics
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16
Q

What are the principal reproductive organs of the female?

A
  • ovaries
  • oviduct (uterine tubes)
  • uterus
  • vagina
17
Q

What are the accessory glands of the reproductive organs of the female?

A
  • paraurethral glands
  • greater vestibular glands
18
Q

What are the functions of the ovaries?

A

production of immature female gametes (oocytes)
- release one per month in human
- depends on species

secretion of female sex hormones:
- estrogens
- progestins (mainly progesterone)

19
Q

What produces estrogen?

A

follicle cells

20
Q

what produces progesterone?

A

corpus luteum

21
Q

What is oogenesis?

A
  • also called ovum production
  • begins after birth
  • accelerates at puberty
  • ends at menopause
22
Q

What is the process of oogensis?

A

primary oocytes remain in suspended development until puberty

at puberty:
- rising FSH triggers start of ovarian cycle

each month thereafter (in human):
- some primary oocytes are stimulated to develop futher

23
Q

How does oogenesis work?

A
  1. cytoplasm of primary oocyte divides unevenly:
    - producing 1 ovum (with original cytoplasm)
    - and 2 or 3 polar bodies (that disintegrate)
  2. ovary releases secondary oocyte (not mature ovum)
    - suspended in metaphase of meiosis II
    - meiosis is completed upon fertilization
24
Q

What are the steps of the ovarian cycle?

A
  1. formation of primary follicles
  2. formation of secondary follicles
  3. formation of a tertiary follicle
  4. ovulation: tertiary follicle releases secondary oocyte (cat and rabbit are induced ovulators)
  5. formation of corpus luteum
  6. if fertilization does not occur, corpus luteum degenerates about 12 days after ovulation
25
Q

What is the ovarian cylce divided into?

A

follicular phase (preovulatory phase)
luteal phase (postovulatory phase)

26
Q

Describe hormonal regulation of the female reproductive cycle:

A

when estrogen level exceed threshold value for about 36 hours
- resulting in massive release of LH from anterior pituitary gland
- high LH triggers ovulation

27
Q

What is the estrus cycle?

A

the time from the beginning of one heat period to the beginning of the next

28
Q

What is proestrus?

A

the period of follicular development

29
Q

What is estrus?

A

the heat period, or the period of sexual receptivity (ovulation)

30
Q

What is metestrus?

A

the period after ovulation when the corpus luteum develops

31
Q

What is diestrus?

A

the active luteal stage when the corpus luteum has reached maximum sizwe

32
Q

What is anestrous?

A

a period of temporary ovarian inactivity

33
Q

Describe the uterine control of luteolysis:

A
  • luteolysis is the process by which the corpus luteum loses its capacity to synthesize and secrete progesterone
  • PGF2a is secreted from the endometrium and enters ovary and induces luteolysis
34
Q

What is the sequence of events for diestrus and proestrus?

A

diestrus:
- high P4 from CL
- negative feedback on GnRH release –> uterine PGF2alpha –> luteolysis

proestrus:
- P4 declines
- FSH and LH increase
- E2 begins to rise