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DAT - Biology > Chapter 17 - Reproductive System > Flashcards

Chapter 17 - Reproductive System Flashcards

1
Q

What is reproduction?

A

Complex process involving formation and fertilization of gametes and regulation of these processes by both parents

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2
Q

What occurs after fertilization?

A

Once fertilization occurs, an embryo is formed and that embryo matures into a fetus through rapid division and differentiation

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3
Q

What is sexual reproduction? How does it occur?

A

Genetic material of two organisms combines and results in a genetically unique offspring
- Occurs via fusion of 2 gametes, specialized sex cells produced by each parent

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4
Q

What does sexual reproduction require?

A

1) Production of functional sex cells or gametes by adult organisms
2) Union of these cells (fertilization) to form a zygote
3) Development of the zygotes into another adult, completing the cycle

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5
Q

What are gonads? Where are the gonads produced in males vs. females? What about hermaphrodite species?

A

Gonads: Production of gametes within this specialized organ

Males: Testes; product sperm in tightly coiled seminiferous tubules

Females: Ovaries; produce oocytes

Hermaphrodite: Possess both functional male/female gonads
- Ex. Earthworm and hydra

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6
Q

What is gametogenesis?

- Males vs. females?

A

The production of functional sex cells

  • Males: Spermatogenesis; occurs in the seminiferous tubules of the testes
  • Females: Oogensis; occurs in the ovaries
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7
Q

What is fertilization?

A

The union of the egg and the sperm nuclei to form a zygote with a diploid number of chromosomes

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8
Q

What is internal fertilization?

  • What does this increase?
  • Do females usually produce more or less eggs?
A

Practices by terrestrial vertebrates and provides a direct route for sperm to reach the egg cell

  • Increases chance of fertilization success
  • Females produce fewer eggs
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9
Q

What factors effect egg production in females?

A
  • If early development of offspring occurs outside mothers body, more eggs will be produced to increase change of offspring survival
  • Parental care after birth (care for young = fewer eggs)
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10
Q

Describe the male reproductive system:

  • Testes
  • Scrotum
  • Vas deferens
  • Ejaculatory duct
  • Urethra
  • Penis
  • Glans
  • Testosterone
A
  • Testes are located in the scrotum; an external pouch that maintains testes temperature at 2-4C (essential for sperm survival)
  • Sperm pass from testes through vas deferents to ejaculatory duct then urethra
  • Urethra passes through penis until terminates at external opening at glans of the penis
  • Testes are also sight of production for testosterone which regulates secondary male sex characteristics including facial and pubic hair, and voice changes
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11
Q

Where does spermatogenesis occur? How does it occurs?

A

Occurs in the seminiferous tubules

  • Diploid cells (spermatogonia) differentiate into diploid cells (primary spermatocytes) which undergo meiotic diction to yield 2 haploid secondary spermatocytes of equal size; a second division produces 4 haploids (spermatids) of equal size
  • After meiosis, the spermatids undergo final series of changes to increase mobility resulting in mature sperm (spermatozoa)
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12
Q

What does mature sperm look like?

A

Elongated cell with a head, neck, body, and tail

  • Head consists of nucleus
  • Tail propels the sperm
  • Neck and body possess mitochondria to provide energy for locomotion
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13
Q

What does the acrosome do and where is it located?

A

On head of sperm

- Contains enzymes needed to penetrate tough outer coating of ovum

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14
Q

How much sperm does a mature male produce a day?

A

3 million

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15
Q

Describe the female reproductive system:

  • Ovaries
  • Follicle
  • Oviduct
  • Fallopian tube
  • Uterus
  • Cervix
A
  • Ovaries are found in abdominal cavity below digestive system; consist of thousands of follicles
  • Follicles are multilayered sac of cells that contain, nourish, and protect immature ovum; also produces estrogen
  • Once a month mature ovum is released from ovary and drawn by cilia into the nearby oviduct (fallopian tube) which open into the uterus where fetal development occurs
  • Lower end of uterus is the cervix which connects with the vaginal canal; site of sperm deposition during intercourse and passageway where baby is expelled during childbirth
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16
Q

Where does oogenesis occur?

- Describe the process

A

Ovarian follicles

  • At birth, immature ovum (primary oocytes) are all that a female will have during her lifetime; they form by mitosis in the ovary
  • After menarche (first menstruation), one primary oocyte per month completes meiosis I to yield 2 daughter cells of unequal size (secondary oocyte and polar body)
  • Secondary oocyte is expelled from follicle during ovulation
  • Meiosis II does not occur until fertilization; when the 2 layers of the oocyte are penetrated during fertilization, 2 haploid cells are formed (mature ovum and polar body)
  • Mature ovum is large containing organelles, RNA, cytoplasm, nutrients needs for developing embryo; polar bodies lack resources and degenerate
17
Q

What is the oocyte membrane surrounded by?

A

Two Layers:

  • Inner zona pellucide
  • Corona radiata
18
Q

What are the female sex hormones?

- Describe each

A

Ovaries synthesize and secrete female sex hormones which include estrogen and progesterone - the secretion of both these hormones are regulated by luteinizing hormone (LH) and follicle stimulating hormone (FSH) which in turn are regulated by gonadotropin-releasing hormone (GnRH)

1) Estrogen: Steroid hormone necessary for female maturation; stimulate development of female reproductive tract, development of secondary sexual characteristics, and influence libido; thicken endometrium; secreted by ovarian follicle and corpus luteum
2) Progesterone: Steroid hormone secreted by corpus lute during luteal phase of menstrual cycle; stimulates development/maintenance of endometrium in preparation for implantation

19
Q

What is the menstrual cycle? Describe the 4 stages:

A

Hormonal secretions of ovaries, hypothalamus, and anterior pituitary play important roles in female reproductive cycle; interaction between hormones result in menstrual cycle (4 phases):

1) Follicular Phase: Cessation of menstrual flow from previous cycle; FSH from ant. pituitary promotes development of follicle which grows and secretes estrogen

2) Ovulation: Midway through the cycle, ovulation occurs where a mature ovarian follicle bursts and releases an ovum; causes by a surge in LH that is preceded, and in part, caused by a peak in estrogen levels
- Once every four weeks until menopause (45-50)
- Menopause = ovaries less sensitive to hormones that stimulate follicle development (LH and FSH) and eventually atrophy
- Remaining follicles disappear, estrogen/progesterone decline, ad ovulation stops

3) Luteal Phase: After ovulation, LH maintains remnant of ruptured follicle (corpus luteum) which secretes estrogen/progesterone
- Progesterone causes glands of endometrium to mature and produce secretions that prepare for implantation of embryo

4) Menstruation: If ovum not fertilized, corpus lute atrophies which results in a drop of progesterone/estrogen labels and the endometrium sloughs off giving rise to menses
- If fertilization occurs, development of placenta and hCG maintaining corpus lute and supply of estrogen/progesterone to maintain the uterus; eventually placenta takes of over production of hormones

20
Q

What occurs during fertilization?

A

Egg can be fertilized during 12-24h after ovulation and often occurs in lateral, widest part of fallopian tube

  • Sperm must travel through vaginal canal, cervix, uterus, and fallopian tubes to reach the ovum
  • Sperm remains viable for 1-2 days after intercourse
  • Sperm must penetrate corona radiate (acrosome) then forms a tubelike structure (acrosomal process) which extends and penetrates the cell membrane to fuse with the ovum
  • Sperm nucleus enters and meets ovums nucleus (meiosis II)
  • Acrosomal reaction triggers cortical reaction in the ovum causing Ca to be released into the cytoplasm which initiates a series of reactions the result in formation of fertilization membrane which prevents multiple fertilizations
  • Release of Ca also stimulates metabolic changes of ovum to increase metabolic rate which is followed by fusion of sperm nucleus with ovum nucleus to form diploid zygote
  • First mitosis division soon follows
21
Q

What are the 2 types of multiple births - explain each:

A

1) Monozygotic (Identical) Twins: When a single zygotes splits into two embryos
- Genetically identical - sae sex, blood type, etc.
- Splitting at 2 cell stage = separate chorions and placentas
- Splitting at blastula stage = one chorionic sac and share placenta and possible amnion
- If division is incomplete = shames twins

2) Dizygotic (Fraternal) Twins: When two ova are released in one ovarian cycle and are fertilized by two different sperm
- Both impact in uterine wall individually and develop their own placenta, amnion, chorion
- Share no more characteristics than siblings because come from two distinct zygotes

DAT - Biology (16 decks)

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