Week 5 Flashcards

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1
Q

Sperm

A

Sperm are immobile at body temperature;
therefore, the testes are external to the body so
that a correct temperature (2 C° lower than body
temp) is maintained for motility.
* Semen is a mixture of sperm (about 5% of the
total) and fluids from accessory glands that
contribute most of the semen’s volume.
* Sperm are haploid cells, consisting of a
flagellum for motility, a neck that contains the
cell’s energy-producing mitochondria, and a
head that contains the genetic material.
* This structure contains enzymes that can digest
the protective coverings that surround the egg
and allow the sperm to fuse with the egg. An
ejaculate will contain from 50–120 million
sperm per milliliter.
* Sperm form in the walls of seminiferous
tubules that are coiled inside the testes.

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2
Q

Scrotum and testes

A
  • The scrotum houses the testicles and provides
    passage for blood vessels, nerves, and muscles
    related to testicular function.
  • The testes are a pair of male gonads that produce
    sperm and reproductive hormones.
  • Each testis is divided into wedge-shaped lobes by
    septa. Coiled in each wedge are seminiferous
    tubules that produce sperm.
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3
Q

Semininferous tubules

A

The walls of the seminiferous tubules are
made up of the developing sperm cells,
with the least developed sperm at the
periphery of the tubule and the fully
developed sperm next to the lumen.
* The sperm cells are associated with Sertoli
cells that nourish and promote the
development of the sperm.
* Other cells present between the walls of
the tubules are the interstitial cells of
Leydig, which produce testosterone once
the male reaches adolescence.
* When the sperm have developed flagella,
they leave the seminiferous tubules and enter
the epididymis

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4
Q

Epididymis

A

The epididymis lies along the top and
posterior of the testes and is the site of
sperm maturation. The sperm leave the
epididymis and enter the vas deferens,

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5
Q

Vas deferens

A

carries the sperm behind the bladder, and
forms the ejaculatory duct with the duct from
the seminal vesicles.
* During a vasectomy, a section of the vas
deferens is removed, preventing sperm from
being passed out of the body during
ejaculation and preventing fertilization.

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6
Q

Spermatogenesis

A
  • Spermatogenesis occurs in the wall of the Spermatogenesis seminiferous tubules, with the most primitive cells
    at the periphery of the tube and the most mature
    sperm at the lumen of the tube.
  • Immediately under the capsule of the tubule are
    diploid, undifferentiated cells. These stem cells,
    each called a spermatogonium, go through mitosis
    to produce one cell that remains as a stem cell and
    a second cell called a primary spermatocyte.
  • The diploid primary spermatocyte goes through
    meiosis I to produce two haploid cells called
    secondary spermatocytes.
  • Each secondary spermatocyte divides after meiosis
    II to produce two cells called spermatids.
  • Spermiogenesis is the last stage wherein the
    formation of spermatozoa takes place. In the last
    stage, the spermatid cells see an increase in the
    size of the tail and a decrease in the spermatozoa
    head.
  • Four sperm result from each primary spermatocyte
    that goes through meiosis.
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7
Q

FSH in males

A
  • FSH enters the testes and stimulates the Sertoli cells
    located in the walls of the seminiferous tubules to
    begin promoting spermatogenesis.
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8
Q

LH in males

A

LH also enters the testes and stimulates the interstitial
cells of Leydig, located in between the walls of the
seminiferous tubules, to make and release
testosterone into the testes and the blood.

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9
Q

Testosterone

A
  • Testosterone stimulates spermatogenesis. This
    hormone is also responsible for the secondary sexual
    characteristics that develop in the male during
    adolescence.
  • Secondary sex characteristics in males include a
    deepening of the voice, the growth of facial, axillary,
    and pubic hair, an increase in muscle bulk, and the
    beginnings of the sex drive.
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10
Q

Negative feedback system in males

A
  • A negative feedback system occurs in the male
    with rising levels of testosterone acting on the
    hypothalamus and anterior pituitary to inhibit
    the release of GnRH (gonadotropin-releasing
    hormone), FSH, and LH.
  • In addition, the Sertoli cells produce the
    hormone inhibin, which is released into the
    blood when the sperm count is too high.
  • This inhibits the release of GnRH and FSH,
    which will cause spermatogenesis to slow
    down. If the sperm count reaches a low of 20
    million/mL, the Sertoli cells cease the release
    of inhibin, and the sperm count increases.
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11
Q

Ovary

A

The outermost layer of the ovary is made up of
follicles, each consisting of one or more
follicular cells that surround, nourish, and
protect a single egg.

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12
Q

Fallopian tubes/oviducts

A
  • The oviducts, or fallopian tubes, extend
    from the uterus in the lower abdominal
    cavity to the ovaries, but they are not in
    contact with the ovaries.
  • The lateral ends of the oviducts flare out
    into a trumpet-like structure and have a
    fringe of finger-like projections called
    fimbrae.
  • When an egg is released at ovulation, the
    fimbrae help the nonmotile egg enter into
    the tube.
  • The walls of the oviducts have a ciliated
    epithelium over smooth muscle. The cilia
    beat, and the smooth muscle contracts,
    moving the egg toward the uterus.
  • Fertilization usually takes place within the
    oviduct and the developing embryo is
    moved toward the uterus. It usually takes
    the egg or embryo a week to travel through
    the oviduct
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13
Q

Uterus

A
  • The uterus is a structure about the size of
    a woman’s fist. The uterus has a thick
    muscular wall and is lined with an
    endometrium rich in blood vessels and
    mucus glands that develop and thicken
    during the female cycle.
  • Thickening of the endometrium prepares
    the uterus to receive the fertilized egg or
    zygote, which will then implant itself in
    the endometrium. The uterus supports
    the developing embryo and fetus during
    gestation.
  • The endometrium builds up again in
    preparation for implantation.
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14
Q

Cervix

A

Part of the uterus, called the cervix,
protrudes into the top of the vagina.

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15
Q

Vagina

A

The vagina is a muscular tube that serves
several purposes. It allows menstrual flow
to leave the body. It is the receptacle for
the penis during intercourse and the
pathway for the delivery of offspring.

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16
Q

Oogenesis

A
  • Oogenesis occurs in the outermost layers of the
    ovaries.
  • Oogenesis starts with a germ cell. In oogenesis,
    this germ cell is called an oogonium and forms
    during the embryological development of the
    individual.
  • The oogonium undergoes mitosis to produce about
    one to two million oocytes by the time of birth.
  • The primary oocytes begin meiosis before birth.
    However, the meiotic division is arrested in its
    progress in the first prophase stage.
  • At the time of birth, all future eggs are in prophase I.
    This situation is in contrast with the male reproductive
    system in which sperm are produced continuously
    throughout the life of the individual.
  • Starting at adolescence, anterior pituitary hormones
    cause the development of a few follicles in an ovary
    each month. This results in a primary oocyte finishing
    the first meiotic division.
  • The cell divides unequally, with most of the cytoplasm
    and organelles going to one cell, called a secondary
    oocyte, and only one set of chromosomes and a small
    amount of cytoplasm going to the other cell. This
    second cell is called a polar body and usually dies.
  • Cell division is again arrested, this time at metaphase II.
  • At ovulation, the secondary oocyte is released and
    travels toward the uterus through the oviduct.
  • If the secondary oocyte is fertilized, the cell continues
    through meiosis II, producing a second polar body and
    haploid egg, which fuses with the haploid sperm to
    form a fertilized egg (zygote) containing all 46
    chromosomes.
17
Q

Gonads

A

a specialized organ that contains germ cells which are responsible for producing
the haploid cells required for sexual reproduction.

18
Q

Gonadotropim

A

Any hormone having a stimulating effect on the gonads.
Two such hormones are secreted by the anterior pituitary gland:
▪ Follicle-stimulating hormone (FSH)
▪ Luteinizing hormone (LH)

19
Q

Yellow Body

A

After ovulation, the follicle in which the egg was located becomes a so-called
yellow body and begins to produce progesterone in addition to estrogen.

20
Q

Endometrium

A

The inner mucous membrane lining of the womb (uterus) that undergoes changes
in structure and thickness at different stages of the menstrual cycle, and much of
which is shed at menstruation

21
Q

Ovulation

A

Ovulation is the process in which a mature egg is released from the ovary

22
Q

Menstural Phase

A
  • The menstrual phase is the first stage of the menstrual
    cycle when the period (bleeding) occurs
  • This phase starts when an egg from the previous cycle
    isn’t fertilized.
  • Because pregnancy hasn’t taken place, levels of the
    hormones estrogen and progesterone drop.
  • The thickened lining of the uterus, which would support
    a pregnancy, is no longer needed, so it sheds through
    the vagina.
  • During the period, a combination of blood, mucus, and
    tissue from your uterus are released.
  • On average, women are in the menstrual phase of their
    cycle for 3 to 7 days.
23
Q

Follicular Phase

A
  • Starts when the hypothalamus sends a signal
    to the pituitary gland to release folliclestimulating hormone (FSH).
  • FSH stimulates the ovaries to produce
    around 5 to 20 small sacs called follicles.
    Each follicle contains an immature egg.
  • The follicular phase starts on the first day of
    the period (so there is some overlap with
    the menstrual phase)
  • The maturing follicle sets off a surge in
    estrogen that thickens the lining of the
    uterus. This creates a nutrient-rich
    environment for an embryo to grow.
  • The average follicular phase lasts for about
    16 days.
  • Only the healthiest egg will eventually
    mature. (On rare occasions, a woman may
    have two eggs mature.)
  • The rest of the follicles will be reabsorbed
    into the body.
  • Follicular phase ends when ovulation
    occurs.
24
Q

Ovulation Phase

A
  • Rising estrogen levels during the follicular
    phase trigger the pituitary gland to release
    luteinizing hormone (LH). This is what
    starts the process of ovulation.
  • Ovulation is when your ovary releases a
    mature egg. The egg travels down the
    fallopian tube toward the uterus to be
    fertilized by sperm.
  • The ovulation phase is the only time
    during the menstrual cycle when a female
    can get pregnant.
  • Symptoms of Ovulation:
    oa slight rise in basal body temperature
    othicker discharge that has the texture
    of egg whites
  • Ovulation happens at around day 14 if you have a 28-day cycle — right
    in the middle of your menstrual cycle. It lasts about 24 hours. After a
    day, the egg will die or dissolve if it isn’t fertilized.
25
Q

Luteal Phase

A
  • After the follicle releases its egg, it changes
    into the corpus luteum.
  • The corpus luteum releases hormones, mainly
    progesterone and some estrogen. The rise in
    hormones keeps the uterine lining thick and
    ready for a fertilized egg to implant.
  • If a female gets pregnant, her body will
    produce human chorionic gonadotropin
    (hCG). This is the hormone pregnancy tests
    detect. It helps maintain the corpus luteum
    and keeps the uterine lining thick.
  • If pregnancy does not occur, the corpus
    luteum will shrink away and be resorbed.
    This leads to decreased levels of estrogen
    and progesterone, which causes the onset of
    the period.
  • The uterine lining will shed during the
    period.
  • The luteal phase lasts for 11 to 17 days. The
    average is 14 days.