Human Reproduction and Sexual Responses
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Questions and Answers

What hormone does the placenta require from the fetal adrenal cortex for estrogen synthesis during the first trimester?

  • Progesterone
  • Dehydroepiandrosterone (DHEA) (correct)
  • Cholesterol
  • Human chorionic gonadotropin (hCG)

Which of the following is NOT a function of progesterone during pregnancy?

  • Stimulates growth of myometrium musculature (correct)
  • Stimulates development of mammary milk glands
  • Suppresses contractions of uterine myometrium
  • Promotes formation of mucus plug

What is the approximate duration of human gestation calculated from the last menstrual period?

  • 38 weeks
  • 36 weeks
  • 40 weeks (correct)
  • 42 weeks

During pregnancy, which physiological change is primarily stimulated by estrogen?

<p>Retention of sodium and water (C)</p> Signup and view all the answers

What role does human chorionic somatomammotropin (hCS) play during pregnancy?

<p>Prepares breast glands for lactation (D)</p> Signup and view all the answers

What hormone is primarily responsible for maintaining the uterine lining during the first trimester of pregnancy?

<p>Progesterone (B)</p> Signup and view all the answers

Which hormone is secreted by the placenta after 10 weeks of pregnancy?

<p>Estrogen (A)</p> Signup and view all the answers

What is the role of hCG during the first trimester regarding the corpus luteum?

<p>To sustain the corpus luteum for hormone production (C)</p> Signup and view all the answers

What change occurs in the male fetus at the end of the first trimester due to hCG?

<p>Differentiation of male genitalia (A)</p> Signup and view all the answers

Why does the placenta not initially secrete estrogen in the early stages of pregnancy?

<p>The corpus luteum is primarily responsible for hormone output at that time (B)</p> Signup and view all the answers

What role does Parathyroid hormone-related peptide (PTHrp) play during pregnancy?

<p>It mobilizes maternal calcium for fetal bone development. (B)</p> Signup and view all the answers

Which hormone is primarily responsible for the production of Dehydroepiandrosterone (DHEA) in the fetal adrenal cortex?

<p>Placental Corticotropin Releasing Hormone (CRH) (D)</p> Signup and view all the answers

During which stage of labor does cervical dilation occur?

<p>1st stage (A)</p> Signup and view all the answers

What is a common sign that labor has begun?

<p>Rupture of the amniotic sac (A)</p> Signup and view all the answers

What causes the softness of the cervix in preparation for labor?

<p>Breakdown of cervical collagen fibers (B)</p> Signup and view all the answers

What physiological change occurs to the uterus after childbirth?

<p>It shrinks back to pre-pregnancy size. (D)</p> Signup and view all the answers

What triggers the development of glandular structures in the breast during pregnancy?

<p>Increased levels of progesterone and estrogen (C)</p> Signup and view all the answers

Which hormone is primarily involved in stimulating uterine contractions during parturition?

<p>Oxytocin (B)</p> Signup and view all the answers

What may indicate the end of the second stage of labor?

<p>The baby is pushed through the cervix into the vagina. (B)</p> Signup and view all the answers

What primarily initiates the parturition process in mothers?

<p>Corticotropin releasing hormone (CRH) (B)</p> Signup and view all the answers

Which physiological change occurs during the first stage of labor?

<p>Dilation of the cervical canal (C)</p> Signup and view all the answers

What role does relaxin play during childbirth?

<p>Loosens pelvic connective tissue (A)</p> Signup and view all the answers

What is the term for the process of the uterus shrinking to its pre-pregnancy size after delivery?

<p>Involution (A)</p> Signup and view all the answers

Which of the following best describes the function of oxytocin during parturition?

<p>It promotes uterine contractions through increased calcium levels (B)</p> Signup and view all the answers

What physiological change occurs during male orgasm that is not associated with female orgasm?

<p>Ejaculation (D)</p> Signup and view all the answers

Which statement accurately describes the female orgasm compared to the male orgasm?

<p>Only females can experience multiple orgasms immediately. (A), Both experience rhythmic contractions of pelvic muscles. (C)</p> Signup and view all the answers

What effect does vasodilation of the lower third of the vagina have during sexual arousal?

<p>Increases tension around the penis (B)</p> Signup and view all the answers

What triggers the expulsion of semen during ejaculation?

<p>Motor neurone induced rhythmic contractions (C)</p> Signup and view all the answers

Which physiological responses are common to both male and female orgasms?

<p>Increase in respiratory rate (C)</p> Signup and view all the answers

What is referred to as the 'orgasmic platform' during female orgasm?

<p>The rhythmic contractions occurring in the lower third of the vagina (A)</p> Signup and view all the answers

What changes occur to the cervix during orgasm in females?

<p>It raises and enlarges the upper half of the vagina. (D)</p> Signup and view all the answers

What hormonal change occurs at the end of the first trimester in male fetuses due to hCG?

<p>Stimulation of gonads for steroid hormone production (A)</p> Signup and view all the answers

What is the primary source of progesterone during the first trimester of pregnancy?

<p>The corpus luteum (B)</p> Signup and view all the answers

What is the main role of human chorionic gonadotropin (hCG) during early pregnancy?

<p>Sustaining the corpus luteum's function (A)</p> Signup and view all the answers

Why is hCG detected in urine throughout pregnancy?

<p>It is secreted by the chorion (D)</p> Signup and view all the answers

During which event does the placenta take over hormone production from the corpus luteum?

<p>At 10 weeks of pregnancy (C)</p> Signup and view all the answers

What physiological event is primarily triggered by hCG during the first trimester?

<p>Genitalia differentiation in male fetuses (D)</p> Signup and view all the answers

What potential symptom may be triggered by hCG during early pregnancy?

<p>Nausea and vomiting (morning sickness) (B)</p> Signup and view all the answers

What can be inferred about the role of the corpus luteum as pregnancy progresses?

<p>It regresses and is no longer needed for hormone output (A)</p> Signup and view all the answers

What hormonal factor maintains the uterine lining early in pregnancy?

<p>Combined estrogen and progesterone from the corpus luteum (C)</p> Signup and view all the answers

Why doesn't estrogen initially come from the placenta?

<p>The corpus luteum is responsible for early hormone production (B)</p> Signup and view all the answers

What is formed when the boundaries between trophoblast cells disintegrate?

<p>Syncytiotrophoblast (B)</p> Signup and view all the answers

What substance is primarily responsible for preventing the menstruation process from expelling the implanted embryo?

<p>Human chorionic gonadotropin (hCG) (D)</p> Signup and view all the answers

Which structure allows the exchange of gases and nutrients between maternal and fetal blood?

<p>Placenta (B)</p> Signup and view all the answers

What is the role of trophoblast cells during implantation?

<p>To tunnel into the endometrial lining (C)</p> Signup and view all the answers

What happens to the capillaries in the decidua during placenta development?

<p>They break down to form cavities filled with maternal blood (C)</p> Signup and view all the answers

How does the blastocyst become buried in the uterine lining?

<p>Expansion of trophoblast cells (B)</p> Signup and view all the answers

What is the primary function of the syncytiotrophoblast during its development?

<p>To invade the decidua and create cavities (D)</p> Signup and view all the answers

What initiates decidualization of the endometrium?

<p>Invasion by trophoblast cells (C)</p> Signup and view all the answers

What does the term 'placental villi' refer to?

<p>Extensions of chorionic tissue providing nutrient exchange (C)</p> Signup and view all the answers

Which of the following describes the physiological changes that occur in the mother during pregnancy due to increased levels of estrogen?

<p>Enlargement of the uterus and improvements in pulmonary function. (C)</p> Signup and view all the answers

What is one of the primary roles of progesterone during pregnancy?

<p>Suppresses contractions of the uterine myometrium. (B)</p> Signup and view all the answers

During the first trimester, which hormone primarily maintains the production of progesterone?

<p>Human chorionic gonadotropin (hCG) (B)</p> Signup and view all the answers

What is the main source of dehydroepiandrosterone (DHEA) needed for estrogen synthesis during the first trimester?

<p>Fetal adrenal cortex (C)</p> Signup and view all the answers

What change in the body occurs as a result of increased aldosterone during pregnancy?

<p>Retention of sodium and water. (A)</p> Signup and view all the answers

Which of the following hormones is primarily responsible for preparing breast glands for lactation during pregnancy?

<p>Human chorionic somatomammotropin (hCS) (C)</p> Signup and view all the answers

What is the approximate duration of human gestation calculated from conception?

<p>38 weeks (D)</p> Signup and view all the answers

Which of these hormones is secreted by the placenta during gestation?

<p>Human chorionic gonadotropin (hCG) (A)</p> Signup and view all the answers

What is one of the physiological changes regarding nutritional requirements in pregnant women?

<p>Nutritional requirements increase due to fetal development. (C)</p> Signup and view all the answers

Which substance is transformed into cholesterol to support the synthesis of hormones during pregnancy?

<p>Fatty acids (B)</p> Signup and view all the answers

What physiological effect is commonly associated with orgasm in both males and females?

<p>Increased muscle tension (B)</p> Signup and view all the answers

Which of the following correctly describes the physiological changes in the female during orgasm?

<p>Upper half of vagina enlarges (A)</p> Signup and view all the answers

What triggers the expulsion of semen during ejaculation?

<p>Sympathetic response activation (C)</p> Signup and view all the answers

In males, what phenomenon occurs immediately during ejaculation?

<p>Rhythmic contractions every 0.8 seconds (A)</p> Signup and view all the answers

What physiological change allows the cervix to dilate during labor?

<p>Breakdown of cervical collagen fibers (C)</p> Signup and view all the answers

Which region of the female reproductive system experiences rhythmic contractions during orgasm?

<p>Lower third of the vagina (C)</p> Signup and view all the answers

Which hormone plays a significant role in increasing oxytocin sensitivity in the myometrium during parturition?

<p>Estrogen (B)</p> Signup and view all the answers

What is the primary purpose of Braxton-Hicks contractions during pregnancy?

<p>To prepare the uterus for the contractions of labor (A)</p> Signup and view all the answers

What is the primary mechanism that leads to the sensation of intense physical pleasure during orgasm?

<p>Stimulation of mechanoreceptors (A)</p> Signup and view all the answers

What anatomical feature aids in providing 'tenting effect' during arousal?

<p>Uterus lifting (B)</p> Signup and view all the answers

During which stage of labor is the baby delivered through the cervix to the vagina?

<p>Second stage: Delivery of the baby (B)</p> Signup and view all the answers

What triggers involution of the uterus after childbirth?

<p>Decrease in estrogen and progesterone levels (D)</p> Signup and view all the answers

What process must freshly ejaculated sperm undergo to become capable of fertilization?

<p>Capacitation (C)</p> Signup and view all the answers

What is the role of allurin released by the mature ovum?

<p>To attract sperm (C)</p> Signup and view all the answers

Which of the following events does NOT occur during the acrosomal reaction?

<p>Initial sperm activation by weak acids (C)</p> Signup and view all the answers

What leads to the final meiotic division of the secondary oocyte?

<p>Sperm entering the cytoplasm (A)</p> Signup and view all the answers

Which structure assists in moving the ovum into the oviduct?

<p>Fimbriae (C)</p> Signup and view all the answers

What is the approximate number of sperm in a normal ejaculate per 2.75 mL?

<p>180 million (B)</p> Signup and view all the answers

What kind of period do males experience that prevents orgasms in quick succession?

<p>Temporary refractory period (A)</p> Signup and view all the answers

What change occurs in sperm during capacitation?

<p>Increase in motility and cAMP levels (A)</p> Signup and view all the answers

What is the function of integrin in the fertilization process?

<p>Binds with fertilin on the sperm surface (B)</p> Signup and view all the answers

What is the primary role of oestrogen during pregnancy?

<p>Stimulating the development of mammary gland ducts (A)</p> Signup and view all the answers

Which hormone does the placenta primarily synthesize during the early stages of pregnancy?

<p>Progesterone (C)</p> Signup and view all the answers

What is the effect of progesterone on uterine contractions during pregnancy?

<p>It suppresses contractions of the uterine myometrium. (A)</p> Signup and view all the answers

Human gestation is approximately how many weeks from conception?

<p>38 weeks (C)</p> Signup and view all the answers

Which hormone is produced by the fetal adrenal cortex that is necessary for oestrogen synthesis by the placenta?

<p>Dehydroepiandrosterone (DHEA) (B)</p> Signup and view all the answers

One of the functions of human chorionic somatomammotropin (hCS) is to:

<p>Prepare breast glands for lactation. (B)</p> Signup and view all the answers

Which of the following is a physiological change that occurs in the mother during pregnancy due to oestrogen?

<p>Increased pulmonary ventilation. (B)</p> Signup and view all the answers

What initiates the development of the 'foetoplacental unit'?

<p>Fetal adrenal cortex function. (B)</p> Signup and view all the answers

During which trimester does the placenta take over production of hormones like oestrogen and progesterone?

<p>Second trimester (A)</p> Signup and view all the answers

What is one of the effects of increased blood volume during pregnancy?

<p>Increased GFR and urine output. (D)</p> Signup and view all the answers

What hormone is primarily responsible for sustaining the corpus luteum during the early stages of pregnancy?

<p>Human chorionic gonadotropin (hCG) (D)</p> Signup and view all the answers

At what point in pregnancy does the placenta begin to produce oestrogen?

<p>After 10 weeks (A)</p> Signup and view all the answers

Which hormone is detected in urine and is commonly associated with pregnancy tests?

<p>Human chorionic gonadotropin (hCG) (C)</p> Signup and view all the answers

What is the role of hCG in the differentiation of male genitalia at the end of the first trimester?

<p>Stimulates testosterone production (D)</p> Signup and view all the answers

Why is the corpus luteum important during early pregnancy?

<p>It secretes oestrogen and progesterone (A)</p> Signup and view all the answers

Which of the following statements is accurate regarding morning sickness during pregnancy?

<p>It may be triggered by human chorionic gonadotropin (hCG) (B)</p> Signup and view all the answers

What happens to the corpus luteum as pregnancy progresses beyond the first trimester?

<p>It eventually regresses and is no longer needed (B)</p> Signup and view all the answers

What is the primary role of the placenta after 10 weeks of pregnancy?

<p>To take over hormone production from the corpus luteum (D)</p> Signup and view all the answers

What effect does hCG have on morning sickness in pregnant individuals?

<p>It may trigger morning sickness by affecting the vomiting center (B)</p> Signup and view all the answers

What is the connection between hCG and fetal gonads at the end of the first trimester?

<p>hCG stimulates the gonads to produce hormones for genital development (D)</p> Signup and view all the answers

Flashcards

Placental estrogen synthesis

Placenta requires DHEA from fetal adrenal cortex for estrogen production in the first trimester, as it lacks the necessary enzymes.

Progesterone synthesis by placenta

While lower than later in pregnancy, the placenta does synthesize progesterone in the early stages.

Oestrogen roles in pregnancy

Oestrogens stimulate uterine muscle growth for labor and mammary duct development.

Progesterone role in pregnancy

Progesterone prevents uterine contractions, helps form the mucus plug, and promotes milk gland development.

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Gestation timeframe

Human gestation is approximately 38 weeks from conception, or 40 weeks from the last menstrual period.

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hCG function in pregnancy

Human chorionic gonadotropin (hCG) maintains the corpus luteum, stimulating the production of crucial hormones like oestrogen and progesterone, to sustain pregnancy.

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Placental hormone production

After 10 weeks of pregnancy, the placenta takes over producing progesterone and estrogen to sustain pregnancy.

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Hormonal shift in 1st trimester

The first trimester of pregnancy relies on increasing concentrations of progesterone and estrogen for uterine lining maintenance.

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Pregnancy test detection

A pregnancy test detects hCG in the urine throughout the entire pregnancy.

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hCG and Sex Determination

At the end of the first trimester, hCG stimulates fetal gonads to produce steroid hormones, leading to genitalia differentiation.

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PTHrp (Parathyroid hormone-related peptide)

Hormone that moves calcium from mother to fetal bones for calcification in the case of calcium deficiency in the mother's diet.

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Relaxin

Hormone that softens the cervix and loosens pelvic connective tissue during pregnancy.

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Placental CRH

Hormone stimulating DHEA production by the fetal adrenal cortex, potentially initiating parturition.

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Parturition

Process of childbirth including cervical dilation, uterine contractions, and expulsion of the fetus.

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Braxton-Hicks contractions

Practice contractions of the uterus, increasing uterine sensitivity leading to preparation for labor.

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Cervical dilation

Widening of the cervix during labor allowing passage of fetus.

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Oxytocin

Hormone stimulating uterine contractions via IP3 signaling, and plays a crucial role to childbirth.

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2nd stage of labor

Delivery of the baby, typically taking 30-90 minutes, involving cervical passage and abdominal muscle contractions.

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3rd stage of labor

Placental delivery. The separation of the placenta from the uterus during labor.

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Involution

Uterus shrinking back to pre-pregnancy size after birth. It takes 4-6 weeks

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Female Orgasm

Characterized by rhythmic pelvic muscle contractions (every 0.8 seconds) in the lower vagina, increased heart rate, blood pressure, and muscle tension; no ejaculation, and no refractory period.

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Male Ejaculation

A release of semen (combination of fluids from reproductive ducts, prostate, and seminal vesicles) through the urethra, triggered by rhythmic contractions of pelvic muscles induced by motor neurons.

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Vaginal Tenting Effect

The uterine lifting of the cervix and enlargement of the upper vagina during orgasm, creating space for the ejaculate.

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Orgasmic Platform

The lower one-third of the vagina, where the most intense pelvic muscle contractions occur during female orgasm.

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Vasodilation

Widening of blood vessels, especially in the lower one-third of the vagina.

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Ejaculation Trigger

Stimulation of mechanoreceptors in the glans of the penis initiates the rhythmic contraction of skeletal muscles.

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Sympathetic Response

Nervous system response that initiates the contraction of smooth muscle in the prostate and reproductive ducts during ejaculation.

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Implantation

The process where the blastocyst embeds itself in the uterine lining.

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Trophoblast

Outer layer of blastocyst that forms the placenta.

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Syncytiotrophoblast

Multinucleate cell layer formed by trophoblast cells, invading uterine wall.

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Placenta Development

Formation of the placenta from trophoblast and decidual tissues to support the embryo/fetus.

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Placental Villi

Tiny projections of the chorion containing fetal capillaries, embedded in maternal blood.

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hCG

Hormone produced by the blastocyst to maintain the corpus luteum.

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Corpus Luteum of Pregnancy

Modified corpus luteum that remains active until placenta takes over hormone production.

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First Trimester Hormones

Relies upon the corpus luteum (and later placenta) that produces progesterone and estrogen for pregnancy lining.

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Placenta function

Allows 2-way exchange of gasses and nutrients between mother and fetus, with no direct blood contact.

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hCG Function

Human Chorionic Gonadotropin (hCG) maintains the corpus luteum, which produces estrogen and progesterone, supporting early pregnancy.

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Early Progesterone Source

Early in pregnancy, the corpus luteum produces progesterone to maintain the uterine lining.

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Placenta Hormone Takeover

After 10 weeks, the placenta starts producing estrogen & progesterone to maintain pregnancy.

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Pregnancy Test Detection

hCG is detectable in urine throughout pregnancy.

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First Trimester Hormone Focus

The first trimester depends on rising progesterone and estrogen levels to maintain the uterine lining.

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Morning Sickness & hCG

hCG may trigger the vomiting center, contributing to morning sickness.

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1st Trimester Sex Determination

At the end of the 1st trimester, hCG is important for the development of male genitalia from the foetal gonads.

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Corpus Luteum's Role

The corpus luteum produces progesterone and estrogens to maintain the early pregnancy, supported by hCG.

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Placenta Estrogen Delay

The placenta doesn't produce estrogen in large amounts until the 10th week of pregnancy.

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Pregnancy Hormone Levels

Hormone levels increase throughout pregnancy as the placenta grows.

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PTHrp function

PTHrp is a hormone that mobilises calcium from the mother's body to the fetus for bone development if her diet is low in calcium.

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Relaxin's role

Relaxin softens the cervix and loosens pelvic tissues, preparing for childbirth.

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Placental CRH function

Placental CRH stimulates DHEA production in the fetal adrenal cortex, which is important for childbirth.

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Parturition stages

Parturition is the process of childbirth, involving cervical dilation, uterine contractions, and expelling the baby.

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Braxton Hicks contractions

Braxton Hicks contractions are practice contractions that prepare the uterus for labor.

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Placenta's First Trimester Hormone Needs

In the first trimester, the placenta needs DHEA from the fetal adrenal cortex to produce estrogen, as it lacks certain enzymes.

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First Trimester Progesterone Source

Initially, progesterone is mainly produced by the corpus luteum, with the placenta increasing its synthesis later.

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Oestrogen's Role in Pregnancy

Oestrogen stimulates myometrium growth for labor and mammary gland duct development.

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Progesterone's Preg. Role

Progesterone prevents uterine contractions, creates the mucus plug, and supports milk gland formation.

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Gestation Length

Human pregnancy is approximately 38 weeks from conception or 40 weeks from the last menstrual period.

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First Trimester Hormone Shift

Initially, estrogen levels rise gradually, while progesterone concentrations are high to maintain early pregnancy.

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Placenta's Role in Later Pregnancy

The placenta takes over hormone production (particularly progesterone and estrogen) after 10 weeks.

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Fetal Growth & Maternal Changes

During pregnancy, the fetus grows, and mother's uterus, breasts, blood volume, and nutritional needs increase.

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Placental hCS Function

Human Chorionic Somatomammotropin (hCS) lowers maternal glucose use and raises fatty acids in the blood, thus increasing glucose and fatty acid availability for the fetus.

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Maternal Blood Volume Increase

Blood volume increases during pregnancy partly due to oestrogen stimulating angiotensinogen & renin secretion, thereby increasing aldosterone and water retention.

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Female Orgasm

Intense physical pleasure marked by rhythmic pelvic muscle contractions (every 0.8 seconds) in the lower vagina, increased heart rate and blood pressure, and muscle tension. No ejaculation and no refractory period.

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Male Ejaculation

Release of semen (fluid from reproductive ducts, prostate, seminal vesicles) through the urethra, triggered by rhythmic contractions of pelvic muscles initiated by motor neurons.

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Vaginal Tenting Effect

Uterus lifting and enlarging upper vagina during orgasm, creating space for ejaculate.

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Orgasmic Platform

Lower one-third of the vagina. Pelvic muscle contractions are most intense here during female orgasm.

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Ejaculation Trigger

Stimulation of mechanoreceptors in the glans of the penis initiates the rhythmic muscular contractions responsible for ejaculation.

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Sympathetic Response (Ejaculation)

Nervous system response involving smooth muscle contractions in prostate and reproductive ducts during ejaculation.

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Vasodilation (Orgasm)

Widening of blood vessels, notably in the lower one-third of the vagina, during orgasm.

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Number of Sperm per Ejaculate

A healthy ejaculate contains approximately 180 million sperm in 2.75 mL, averaging 66 million sperm per milliliter.

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Capacitation

A process that occurs in the female reproductive tract, altering sperm to become capable of fertilization.

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Fertilin

Protein on the sperm surface that binds to integrin, an adhesion molecule on the egg, to allow for fusion of sperm and egg.

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Implantation

The process where the blastocyst embeds itself in the uterine lining.

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Acrosomal Reaction

Release of enzymes from the acrosome, a vesicle at the tip of a sperm, that helps the sperm penetrate the egg's outer layers.

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Temporal Refractory Period (Males)

Time after orgasm during which males cannot experience another orgasm.

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Olfactory Receptor hOR17-4

A receptor in sperm that detects attractant chemicals released from the ovum.

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Implantation (stage 2)

The blastocyst forms initial contact with the uterine lining, and then it burrows into it.

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Fimbriae

Finger-like projections that sweep the ovum into the fallopian tube.

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2nd stage of labor

The process of delivering the baby, requiring cervical passage and abdominal contractions.

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First Trimester Hormones

The first trimester of pregnancy relies on increasing progesterone and estrogen levels for maintaining the uterine lining.

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hCG Function

Human chorionic gonadotropin (hCG) maintains the corpus luteum, stimulating the production of progesterone and estrogen.

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Placenta Hormone Takeover

After 10 weeks, the placenta assumes the role of producing progesterone and estrogen for maintaining pregnancy.

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Pregnancy Test Detection

hCG is detectable in urine throughout pregnancy.

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Morning Sickness & hCG

Human chorionic gonadotropin (hCG) may trigger nausea and vomiting during pregnancy.

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1st Trimester Sex Determination

Towards the end of the first trimester, hCG influences the development of male sex organs.

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Corpus Luteum's Role

The corpus luteum produces progesterone and estrogen to support early pregnancy.

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Placenta Estrogen Delay

The placenta doesn't produce significant amounts of estrogen until the tenth week of pregnancy.

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Early Progesterone Source

Early in pregnancy, the corpus luteum primarily produces progesterone to support the uterine lining.

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First Trimester Hormone Focus

The first trimester primarily relies on high levels of progesterone and estrogen for uterine lining maintenance.

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PTHrp

Hormone that moves calcium from mother to fetus for bone growth, especially if mother's diet is low in calcium.

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Relaxin

Hormone that softens the cervix and loosens pelvic ligaments during pregnancy.

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Placental CRH

Hormone that triggers DHEA production in the fetal adrenal cortex, which can start labor.

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Parturition

Process of childbirth, involving dilation of the cervix, uterine contractions, and fetal expulsion.

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Braxton Hicks contractions

Practice contractions of the uterus that help prepare the mother's body for labor.

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Placenta's 1st Trimester Estrogen Need

In the first trimester, the placenta requires DHEA from the fetal adrenal cortex to synthesize estrogen, as it lacks the necessary enzymes.

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Progesterone's Early Source

Initially, the corpus luteum produces most of the progesterone needed to maintain the uterine lining in early pregnancy.

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Oestrogen's Roles

Oestrogens stimulate uterine muscle growth for labor and mammary duct development during pregnancy.

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Progesterone's Roles

Progesterone suppresses uterine contractions, forms the mucus plug, and stimulates milk gland development in pregnancy.

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Gestation Period

Human pregnancy is approximately 38 weeks from conception or 40 weeks from the last menstrual period.

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Placenta's Hormone Takeover

After about 10 weeks of pregnancy, the placenta starts producing most of the progesterone and estrogen needed to sustain the pregnancy.

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hCG's Function

Human chorionic gonadotropin (hCG) maintains the corpus luteum in early pregnancy, which helps produce estrogen and progesterone.

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Maternal Blood Volume Change

Blood volume increases during pregnancy partly due to hormonal changes that stimulate water retention.

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Placenta's Nutrient Exchange

The placenta facilitates the exchange of gases and nutrients between the mother and fetus, without direct blood mixing.

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hCS function

Human Chorionic Somatomammotropin (hCS) decreases maternal glucose use and increases fatty acids in the mother's blood; this is critical for providing glucose and fatty acids to support fetal growth.

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Study Notes

Human Reproduction, Pregnancy, and Parturition

  • Human reproduction, pregnancy, and parturition are covered.
  • Learning outcomes include explaining male and female sexual response, implantation, placenta development, changes in endocrinology during pregnancy, maternal adaptations, gestation maintenance, parturition phases, lactation, suckling response, and weaning.

Sexual Arousal and Ejaculation

  • Sexual arousal involves four stages: excitement, plateau, orgasm, and resolution.
  • Excitement involves heightened sexual awareness, vasocongestion, and engorgement.
  • Plateau involves intensification of excitement.
  • Orgasm involves intense physical pleasure and rhythmic contractions.
  • Resolution involves the return of the body to a pre-excitement state.
  • Male and female sexual response have similar stages. The male experience also includes a refractory period after orgasm.
  • Different parts of the nervous system are involved in male sexual response.
  • Ejaculation is the expulsion of semen, a process involving sympathetic and parasympathetic responses. The number of sperm per ejaculate can be an indicator of infertility in males.

Implantation and Pregnancy

  • Fertilization typically occurs in the ampulla of the fallopian tube.
  • Sperm must go through capacitation once inside the female reproductive tract.
  • Key stages of fertilization include zona pellucida binding, acrosome reaction, and cortical reaction.
  • The resulting zygote undergoes cleavage to form a morula, then a blastocyst.
  • Implantation occurs when the blastocyst attaches to the uterine wall and embeds itself.
  • Key factors in implantation include the trophoblast (surface layer of the blastocyst), cords of trophoblastic cells, and the endometrium (lining of the uterus).
  • The implanted blastocyst is nourished by the development of the placenta.

Development of Placenta

  • The placenta originates from both trophoblast and decidual tissue.
  • Trophoblastic cells differentiate into multinucleate syncytiotrophoblasts, which invade the decidua and form cavities filled with maternal blood.
  • Developing embryo's capillaries enter the syncytiotrophoblast projections, forming placental villi.
  • Each villus contains fetal capillaries separated from maternal blood by a thin tissue layer.
  • The placenta plays a crucial role in nourishing the developing embryo/fetus, exchanging respiratory gases, nutrients, and metabolites.

Hormonal Maintenance of Pregnancy

  • Human chorionic gonadotropin (hCG) maintains the corpus luteum, preventing menstruation, and supporting the development of progesterone and estrogen.
  • Progesterone and estrogen are crucial for maintaining the uterine lining and preparing for parturition.
  • Late in the first trimester, the placenta begins to produce these vital hormones that maintain pregnancy.
  • The hormones produced during pregnancy help to maintain the uterine lining and prepare the breast tissues for lactation.
  • Different hormones play specific roles in supporting pregnancy over the different trimesters.
  • Oestrogen and progesterone are critical in maintaining pregnancy, but the source varies throughout gestation (placenta takes over production of these hormones).

Parturition and Lactation

  • Parturition (labor) involves cervical dilation to allow passage of the fetus and uterine contractions to expel the fetus.

  • Stages of labor include cervical dilation, the delivery of the baby, and delivery of the placenta.

  • Labor preparation includes Braxton–Hicks contractions and softening of the cervix.

  • Hormonal changes, such as increased estrogen and a rise in corticotropin releasing hormone, trigger labor.

  • Lactation is the secretion of milk by the mammary glands.

  • Suckling triggers a neuroendocrine reflex that leads to the secretion of prolactin and oxytocin.

  • Prolactin stimulates milk production, while oxytocin causes milk ejection.

  • Cessation of breast milk production after weaning is linked to decreased prolactin and oxytocin secretion.

Development of the Breast

  • In non-pregnant women, the breasts comprise mostly adipose tissue and rudimentary ducts.
  • Duct development, lobule formation, and synthesis of milk-producing enzymes are stimulated by oestrogen and placental hormones, such as human chorionic somatomammotropin.
  • Prolactin continues to stimulate milk production after delivery.
  • Breast milk composition includes factors like water, lactose, lipids, vitamins and minerals, proteins and immunological agents, with colostrum being the milk produced in the first few days after birth.

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Reproductive Endocrinology II PDF

Description

Explore the intricacies of human reproduction, pregnancy, and parturition. This quiz covers stages of sexual arousal and ejaculation, including the physiological changes associated with male and female sexual responses, as well as key aspects of pregnancy and childbirth.

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