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Bio Mod 5 > 5.1.2 Pregnancy and Birth in Mammals > Flashcards

5.1.2 Pregnancy and Birth in Mammals Flashcards

1
Q

Placental Mammals

Types of Mammals

A

A uterus provides nourishment and protection (through the placenta and umbilical cord) to the embryo until birth, after which they are nourished with milk.

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2
Q

Marsupial Mammals

Types of Mammals

A

The offspring is birthed prematurely before being protected and nourished in an eternal pouch.

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3
Q

Monotreme Mammals

Types of Mammals

A

Lay leathery eggs (oviparous) to be hatched and then protected and nourished by its mother’s milk.

ONLY platypus and echidna

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4
Q

Scrotum

Male Reproductive System

A

A sac that houses the testes and epididymis.

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5
Q

Testicle

Male Reproductive System

A

The site of sperm production, composed of several lobes of seminiferous tubules which are filled with Leydig cells and Sertoli cells.

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6
Q

Leydig Cells

Male Reproductive System: Testicles

A

Produce testosterone

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7
Q

Sertoli Cells

Male Reproductive System: Testicles

A

Produces androgen-binding protein (ABP)

Androgen - hormone that binds to testosterone to promote the production of sperm when signalled by the anterior pituitary gland in the brain by sending the hormones gonadotropins.

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8
Q

Luteinizing Hormone

Male Hormones

A

Stimulates Leydig cells to produce testosterone binding protein.

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9
Q

Follicle-Stimulating Protein

Male Hormone

A

Stimulates Sertoli cells to produce androgen binding protein.

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10
Q

Epididymis

Male Reproductive System

A

Structure that lines the outside of the testicles to store, mature and transport sperm into the net stage.

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11
Q

Vas Deferens/Ductus Deferens

Male Reproductive System

A

Transports sperm around the bladder to the seminal vesicle gland.

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12
Q

Seminal Vesicle

Male Reproductive System: Spermatic Cord

A

Produces two-thirds of the liquid of semen, including fructose, the energy source for sperm.

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13
Q

Prostate

Male Reproductive System

A

A gland below the bladder that includes the merged urethra from the bladder and the ejaculatory duct carrying semen.

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14
Q

Penis

Male Reproductive System

A

A structure made up of spongiform tissue for transporting sperm into the female reproductive system.

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15
Q

Erection

Male Reproductive System: Penis

A

The parasympathetic nervous system that causes the blood vessels in the penis to dilate.

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16
Q

Ejaculation

Male Reproductive System: Penis

A

The sympathetic nervous system causes the spermatic cord to contract and force the semen through.

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17
Q

Vulva

Female Reproductive System

A

The eternal genitalia of the female reproductive system, including the mons pubis and labia.

18
Q

NEED TO FINISH FEMALE REPRODUCTIVE SYSTEM

A
19
Q

Spermatogenesis

Stages of Mammalian Reproduction

A

The male productive system is required to produce and supply sperm, which occurs inside the testes.

  • When signals come from the pituitary glands, the antiunitary gland will release gonadotropin (including luteinising hormone and follicle-stimulating hormone), which stimulate the Leydig and Sertoli cells to produce testosterone and androgen-binding protein respectively.
  • These products bind to promote sperm production through meiosis
  • These mature sperm will be stored in the epididymis, then the vas ductus/deferens.
20
Q

Ovarian/Menstrual Cycle

Stages of Mammalian Reproduction

A

While males continually produce sperm, females are born with immature egg cells, which arrest at prophase 1.

Once the organism reaches maturity, the ovarian cycle commences, continuing meiosis until fertilisation occurs. Meiosis only completes after fertilisation.

21
Q

Follicular Phase (Days 1-12)

Stages of the Ovarian/Menstrual Cycle

A

Under the influence of follicle stimulating hormone (FSH), one or more of the oocytes will resume its meiotic division up to metaphase II and matures within a group of nutrivitie cells called a follicle.

Only one egg forms from each oocyte during meiosis. When the oocyte is maturing it grows much larger by adding nutrients and extra organelles. The nutrients are stored in the cytoplasm for use after fertilisation, when cleavage begins and rapid mitotic division forms new smaller cells.

  1. Menstruation: The endometrium of the uterus breaks down after the previous reproductive cycle over about four days.
  2. Pre-Ovulation: A new endometrial lining will form over 5-12 days.
  3. 10-20 primordial follicles begin to develop into primary follicles by surrounding themselves with follicle cells for nourishment.
  4. The hypothalamus releases gonadotropin releasing hormone, which stimulate the anterior pituitary gland to release gonadotropin. The released gonadotropins, which include follicle-stimulating hormones and luteinizing hormones. The follicle-stimulating hormone allows the primary follicle to develop into a secondary follicle, which has surrounded itself with a zona pellucida, granular cells and theca cells.
  5. The granular cells and theca cells both produce estrogen. The hormone estrogen stimulates the uterus to prepare its uterine lining (endometrium) for implantation. It will become thicker, softer and richly supplied with blood vessels.
  6. The secondary follicle develops into a mature follicle, or a graafian follicle. This has the zona pellucida, thicker granular cells, and theca cells. These begin to protrude on the edges of the ovary and produce even more estrogen.
  7. The overproduction of estrogen feeds back to the hypothalamus to stop the production of FSH. As even more estrogen produces, a positive surge of FSH and especially luteinizing hormone, which then drops quickly.
22
Q

Ovulation (Days 13-15)

Stages of the Ovarian/Menstrual Cycle

A
    1. A watery mucus is secreted by the glands of the endometrium, cervix and uterine tubes.
  2. The spike in luteinizing hormone begins to weaken the wall of the ovary, causing the mature follicle to protrude out. The ovum is released from the follicle and drawn by fluid currents and fimbriae into the fallopian tubes and oviduct, leaving a cluster of cells, the corpus luteum.
  3. The oviduct contracts and moves in synchronisation with the cilia to propel the egg towards the uterus.
23
Q

Luteinising Phase

Stages of the Ovarian/Menstrual Cycle

A
  1. The corpus luteum, now without the egg inside, enlarge and changes colour in order to build up the protein lutein. This stimulates the secretion of both progesterone and estrogen, causing the uterus to thicken its endometrial wall even further and vascularise (blood vessels). This hormone release continues to occur for 10 days.
  2. If after 10 days, the oocyte has not been fertilised, the corpus luteum will begin to break down, dropping progesterone levels. The built-up vascularised tissue of the uterus and egg begin to fall off and bleed out of the vaginal opening.
    Fertilisation: If the ovum does become fertilised, pregnancy results. Progesterone and estrogen maintain constant secretion in order to maintain the uterine wall and a placenta forms to attach the embryo. The pregnancy is also maintained by human chorionic gonadotropin (HCG).
24
Q

Fertilisation

Stages of Mammalian Reproduction

A

the fusion of two haploid gametes (egg and sperm) to form a single diploid zygote cell. The zygote contains equal genetic information of both the sperm and the egg. In humans this is called conception.

The male is required to insert his penis into the female’s vagina, and ejaculate semen from the urethra into her vagina. The sperm’s flagellum allows it to travel through the cervix and into the oviduct, where fertilisation occurs as it penetrates the egg. Fertilisation also depends on timing as this must occur during the female’s ovulation phase, but the sperm can survive for 3-5 days.

Four steps:

  1. The sperm uses enzymes in the acrosome to dissolve and penetrate the protective layer (zona pellucida) surrounding the egg to reach the cell membrane.
  2. Molecules on the sperm surface bind to receptors on the egg’s cell membrane to ensure that a sperm of the same species fertilises the egg, then the nucleus of the sperm enters the cytoplasm in the egg cell.
  3. Changes at the surface of the egg occur to prevent the entry of multiple sperm cells.
  4. Fusion of the haploid egg and sperm nuclei result in a diploid zygote cell.
25
Q

Implantation

Stages of Mammalian Reproduction

A
  • Cleavage is a period of rapid cell proliferation during which the single-celled zygote is divided into many hundreds of smaller cells by mitosis. This continues to occur for 3-4 days until it consists of 16 unspecialised stem cells. This is a morula and resembles a mulberry.
  • By day 8-9, the morula has become a blastocyst, ready to attach to the wall of the uterus. The blastocyst consists of a layer of surface cells and an inner cell mass. The outer cells send out finger-like projections to attach to the uterus and develop placenta.
  • Gastrulation occurs over approximately five days, as the blastocyst becomes a gastrula, which has three layers of cells. This becomes an embryo, and then finally a fetus.
  • By the fifth week, the placenta forms an umbilical cord, which provides nutrition for the embryo and remains attached until birth. It does this by diffusing the nutrients and oxygen of the maternal blood into the umbilical vein, the reverse occurring to remove waste. The amniotic sac is another feature that surround the fetus to protect it from injury and regulate temperature.
26
Q

Pregnancy Hormones (Post-Implantation)

A
  • Follicle-Stimulating Hormone (FSH)
  • Luteinising Hormone
  • Oestrogen
  • Progesterone
  • Oxytocin
  • Maternal Thyroxine
  • Insulin
  • Human Chorionic Gonadotropin (hCG)
27
Q

Follicle-Stimulating Hormone (FSH)

Pregnancy Hormones

A

Purpose:
* Stimulates the primary follicle to develop into the secondary follicle

Rises over the first few days, then plateaus and begins to drop when estrogen begins to produce in larger amounts

28
Q

Luteinising Hormone

Pregnancy Hormones

A

Rises exponentially around day 4 before quickly decreasing and plateauing near zero.

Purpose:

  • Promotes final maturation of the ovarian follicle, ovulation and development of the corpus luteum
  • Stimulates the secretion of testosterone
29
Q

Oestrogen

Pregnancy Hormones

A

Made by the placenta lining the uterus

Purpose:
* Stimulate the female’s body to release the egg
* Aids blood flow to the developing animal
* Aids the development of different organs (lungs, liver etc.)
* Secreted in the later months of pregnancy to stimulate the production of progesterone

30
Q

Progesterone

Pregnancy Hormones

A

Initially released by the ovaries (corpus luteum), then the placenta

Purpose:

  • Stimulates the thickening of the uterus lining
  • Keep the placenta working properly and uterus relaxed
  • Helps mother’s immune system tolerate the growing infant
  • Encourages the growth of blood vessels in the uterus to increase the nutrients surrounding the embryo
  • Strengthens the muscles of the pelvic floor to support delivery
  • Suppresses uterine activity to support foetal development
  • Prevent uterine contractions from expelling or disturbing the fetus
  • Reduces the immune response of the mother to foetal antigens
31
Q

Oxytocin

Pregnancy Hormones

A

Purpose:

  • Stimulates the production of milk
  • Causes the uterine muscles to contract (go into labour)
32
Q

Maternal Thyroxine

A

Secrete by the mother’s thyroid gland from 12th week of pregnancy

Purpose:

  • Decrease risk of detachment of placenta and pregnancy loss
33
Q

Insulin

Pregnancy Hormones

A

Secreted by the foetal pancreas

Purpose:
* Promotes foetal growth

34
Q

Human Chorionic Gonadotropin (hCG)

Pregnancy Hormones

A

Secreted by the developing embryo

Purpose:

  • Maintains the corpus luteum which maintains the endometrium
35
Q

Birth Hormones

A
  • Oxytocin
  • Endorphin
  • Adrenaline
  • Relaxin
  • Human Chorionic Gonadotropin (hCG)
  • Progesterone
  • Oestrogen
36
Q

Oxytocin

Birth Hormones

A

Produced by the hypothalmus and stored in the pituitary gland until release into bloodstream.

Purpose:

  • Released stimulate uterine muscles to increase the strength and frequency of dilation and contraction of the cervix, which allows the parent to deliver the offspring by pushing out placenta.
  • Promotes the protective mother instinct and stimulates lactation
37
Q

Endorphin

Birth Hormones

A

Peaks as the strength and frequency of cervix dilations and contractions increase to combat pain.

Purpose:

  • Released to increase concentration and relief pain to focus on the delivery of offspring
38
Q

Adrenaline

Birth Hormones

A

Released during birth due to the body’s response to fear and pain

Purpose:

  • Provides energy for the parent to continue delivering the offspring by producing stronger dilation and contractions of the cervix.
  • May also cause the opposite response which is decreasing cervix contractions due to fear
39
Q

Relaxin

Birth Hormones

A

Purpose:
* Loosens the uterine muscles to prepare the body for birth

40
Q

Human Chorionic Gonadotropin (hCG)

Birth Hormones

A

Purpose:

  • Stimulates increased blood flow to the pelvic area and helps regular the ovarian hormones
41
Q

Progesterone

Birth Hormones

A

Required at high levels throughout pregnancy and rise until birth

Purpose:

  • Prevents lactation and uterine contraction until time of birth
42
Q

Oestrogen

Birth Hormones

A

Work in partnership with progesterone for organ development and growth of breast tissue for milk production

Bio Mod 5 (10 decks)

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