Chapter 46: Animal reproduction Flashcards by Bruno Hoeltgebaum

Fission

Individual separates into two which each become an individual

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Budding

Individual starts growing another organism clone on itself

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Parthogenesis

Individuals develop from unfertilized eggs

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Fragmentation

Individual is broken into pieces and the parts can become clones of the original

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Regeneration

Individual is hurt and regenerates

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Hermaphroditism

One individual has both sexes

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Follicle

Found in the ovary, made up of the egg and its supporting cells

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Oocyte

Undeveloped egg cell

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Oviduct

Path the ovum take after leaving the ovaries

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Uterus

Place where the ovum stays while it waits for a sperm, ideal for the development of a fetus

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Endometrium

The structure the lines the uterus

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What is meant by the “twofold cost” of sexual reproduction?

It is good for more genes to be created and higher variability, however it leads to less passing on of one’s own genes

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What are the possible advantages of sexual reproduction compared to asexual reproduction?

Easier to get rid of aliments, more adaptable, and more genetic recombination

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What are the similarities and differences between internal and external fertilization?

They both aim to reach fertilization, external requires very good timing between members of the species, internal is more selective

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What are the external and internal organs of the human female reproductive system?

External are called the vulva (labia majora, labia minora, and clitoris)
Internal are ovaries and a system of ducts and chambers for the ovum

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What happens during ovulation? What happens to the remaining follicular tissue?

The follicle leaves the ovaries, they follow the ovum as support for it

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What are the external and internal organs of the human male reproductive system?

External, penis and scrotum
Internal, testes and a series of tubes

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Why are the testes of many mammals held outside the abdominal cavity?

Because if the testes were inside they would heat up too much and kill the sperm

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What is the sequence of structures through which a sperm cell passes after leaving the seminiferous tubules?

Move through the epididymis then through the Vas deferens during ejaculation, ultimately leaving through the urethra

What is semen composed of?

Sperm, different mucous, and enzymes

What substances comprise the secretions of the seminal vesicles, prostate gland, and bulbourethral gland?

Seminal vesicles: mucous, fructose, enzymes, and local regulators
Prostate gland: anticoagulated enzymes and citrate
Bulbourethral gland: mucous which neutralizes urine in urethra

What is meant by the term gametogenesis and how does it differ between females and males?

Production of gametes by meiosis
Females: Oogenesis, Produces less gametes from meiosis, occurs not continually only for a portion of lifetime
Males: Spermatogenesis, produces more gametes from meiosis, occurs continuously through whole life

What are the steps involved in spermatogenesis?

Spermatogonial stem cells through mitosis becomes spermatogonium, which through mitosis becomes primary spermatocyte, which through meiosis becomes secondary spermatocyte, which through meiosis becomes early spermatid, which through meiosis becomes sperm

What is the acrosome and what is its function?

The head of the sperm which carries enzymes that help it penetrate into the egg

What are the steps involved in oogenesis?

Oogonium undergoes mitosis to become Primary Oocyte, which undergoes meiosis to become Secondary Oocyte

Development of the primary oocyte is paused at which stage of development?

Before birth

What stimulates a primary oocyte to resume growth?

Puberty, specifically the hormone FSH

Development of the secondary oocyte is paused at which stage of development?

Metaphase

Under what conditions does the secondary oocyte complete meiosis?

Only if a sperm gets in

What are three key differences between spermatogenesis and oogenesis?

Spermatogenesis: four sperm from each meiosis cycle, no interruptions in production, goes on for the lifetime Oogenesis: One egg from each meiosis cycle, long interruptions in production, stops at menopause

What secretes gonadotropin-releasing hormone (GnRH), and what does this hormone do?

The hypothalamus, it has the purpose of telling the anterior pituitary to start producing FSH and LH

What is the function of FSH and LH?

Tell the gonads to start producing sex hormones

What are the sex hormones and what do they regulate?

Androgens, progesterone, and estrogens. They are important for primary sexual characteristics, secondary sexual characteristics (like height and voice deepness), and sex drive

In response to LH, what do Leydig cells secrete?

Testosterone

What is the function of inhibin?

Reduces FSH secretion

What is the function of the negative feedback circuit in the hormonal control of the male reproductive system?

To stop the body from creating too much testosterone the hormones created by the cycles (inhibin and testosterone) act to stop the hypothalamus from producing GnRH, and the anterior pituitary from producing FSH and LH

What are the two cycles of female reproduction?

Uterine and ovarian

What is the role of FSH and LH in the ovarian cycle?

They cause the follicle to mature and become a full egg

What is the stimulus for the rupture of the ovary and release of the secondary oocyte (ovulation)?

A sharp increase in LH

What is the source of estradiol in the ovarian cycle?

The follicle that is maturing releases it

What is the effect of estradiol on the hypothalamus and anterior pituitary? Be sure to take into account the different estradiol concentrations occurring during the ovarian cycle.

High levels of estradiol cause the hypothalamus to produce more GnRH (unless progesterone is present). Low levels cause the anterior pituitary to produce less FSH and LH

What hormone or combination of hormones are responsible for transforming the ruptured follicle into the corpus luteum? degeneration of the corpus luteum?

LH (luteinizing hormone, it is in the name), in low enough concentrations (which is what happens when pregnancy does not happen) then the corpus luteum will break down

What is the relationship between the levels of progesterone and estradiol produced by the corpus luteum and the secretion of LH and FSH by the anterior pituitary?

If the amount of both rise then the hypothalamus will stop producing as much GnRH, which causes FSH and LH levels to drop

What happens during the proliferative phase of the uterine cycle?

The endometrium becomes thicker, estradiol levels rise because the follicle is developing

The level of which hormone coordinates the follicular phase of the ovarian cycle with the proliferative phase of the uterine cycle?

Estradiol, increasing estradiol levels increase LH production (which leads to ovulation) and causes the menstrual cycle to begin

What effect does disintegration of the corpus luteum have on the endometrium of the uterus?

Causes the lining of the endometrium to be shed

What happens if the egg is not fertilized and an embryo does not implant?

Then the corpus luteum dissipates and the egg dies, which can start a new cycle