Ch 27- Reproductive System

Question 1

Human somatic cells

Answer 1

-contain 23 pairs of chromosomes, or a total of 46 chromosomes (diploid)

Question 2

Mitosis vs Meiosis

How does this contribute to reproduction

Answer 2

Mitosis makes identical diploid cells.

Meiosis makes gametes (sperm/egg) with 23 chromosomes – called haploid.

Fertilization joins two haploid cells → makes a diploid zygote with 46 chromosomes.

Gametes must have half the number so the zygote has the right total (one from each parent)

Question 3

The distinct reproductive anatomy of males and females is adapted fo

Answer 3

-Producing gametes.
-Facilitating fertilization.
- In females, sustaining the growth of the embryo and fetus

Question 4

reproductive organs

Answer 4

Gonads gland – testes and ovaries produce gametes

-Accessory sex glands – protects and moves gametes

Supporting structures – the penis, vagina, etc assist the joining of gametes

Question 5

Sexual reproduction and gametes

Answer 5

Sexual reproduction is the process by which humans produce offspring
by making and “joining” germ cells called gametes

Question 6

Fertilization

Answer 6

occurs when a male gamete (sperm) unites with a female gamete making a zygote

Question 7

Prenatal Hormones and Sexual Differentiation

Answer 7

fetus undifferentiated

Y chromosome uses TDF protein that
starts development of male parts.
Around 8–9 weeks, testes form and make testosterone.

Testosterone builds male reproductive system and blocks female parts from forming

Females develop when no testosterone is present — not because of estrogen.

Question 8

what does the scrotum do

Answer 8

protect the testes
-two seperate sacs with ridge called raphne

Question 9

regulation of testes (heat and muscles)

Answer 9

Sperm needs cooler temps (1–2°C below body temp).

Scrotum holds testes outside to stay cool.

Veins cool arteries by absorbing heat from blood going to testis in arties (countercurrent exchange).

Muscles used to keep testes warm

Dartos wrinkles skin to reduce heat loss.

Cremaster pulls testes closer for warmth.

Question 10

The testes anatomy

Answer 10

1. Tunica vaginalis – outer serous membrane that covers most of testes, visceral and parietal
2. Tunica albuginea –makes lobules
3. Seminiferous tubules – coiled tubules in each lobule, sperm production occurs here.

Two types of cells inside:
-Spermatogenic cells – sperm-forming cells that become active
starting at puberty.
-nurse cells - maintains growth and provides nutrients

Question 11

cryptorchidism

Answer 11

for fetus, Testes form near kidneys and move into scrotum around month 7 of fetal life.

Cryptorchidism = when testes don’t descend.

Usually fixes itself in 1 year; if not, surgery by 18 months.

If untreated → risk of sterility and testicular cancer due to higher body temp.

Question 12

Spermatogenesis

Answer 12

Begins at puberty and continues for life.

Takes ~9 weeks, makes ~500 million sperm/day.

Happens in seminiferous tubules of testes

Question 13

Spermatogenesis steps

Answer 13

Spermatogonia (stem cells, diploid) divide by mitosis →
one stays a stem cell, one becomes a primary spermatocyte (diploid).

Primary spermatocyte does meiosis I →
makes 2 secondary spermatocytes (haploid).

Each secondary spermatocyte does meiosis II →
makes 2 spermatids (haploid).

Spermatids → spermatozoa (mature shape but still immature functionally).

Final sperm head toward the epididymis.

1 primary spermatocyte = 4 sperm cells

all about quality

Question 14

structure of a sperm cell

Answer 14

-adapted for reaching and
penetrating a secondary oocyte

-Head – contains the nucleus, acrosomal cap (filled with enzyme),
Middle piece – mitochondria
-Tail – a flagellum

-not every sperm is perfect- eg two heads

Question 15

process of ejaculation

Answer 15

Sexual stimulation → epididymis walls contract, pushing sperm into ductus deferens.

Ductus deferens uses peristalsis to move sperm toward the ejaculatory duct.

Ejaculatory duct passes through the prostate and connects to the urethra.

During ejaculation:

Internal urethral sphincter closes to block urine from mixing with semen.

Prevents semen from entering bladder.

Semen Composition:
95% fluid from accessory glands.

5% spermatozoa.

Question 16

Vasectomy

Answer 16

Ductus deferens are cut or sealed.

Sperm production continues, but sperm are reabsorbed.

No effect on:

Testosterone

Sex drive

Secondary sexual traits

Question 17

accessory male sex glands

Answer 17

seminal vesicles secrete approximately 60% of semen, Fructose – used as fuel for ATP, prostaglandins, neutralizes

prostate- about 30% of
semen, destroy bacteria

bulbourethral gland- 5% semen, lubrication, neutralizes acidic environment

Question 18

The penis- forming of erection

Answer 18

The penis has erectile tissue that fills with blood.

Sexual stimulation triggers nerves to release nitric oxide (NO), opening arteries putting blood into corpus cavernosum and causing an erection.

Veins that usually drain penis are compressed, keeping blood in.

When the arteries tighten, veins decompress and the erection ends

Question 19

Erectile dysfunction and treatments

Answer 19

Definition: Inability to get or maintain an erection.

Causes:

-Physical (e.g., nerve damage, blood flow issues)
-Psychological (e.g., stress, anxiety)
-Physiological (e.g., hormonal imbalances, circulatory problems)

treatments:
-surgery
-Viagra (or similar drugs) may help.

Question 20

hormones before birth and at puberty

Answer 20

Before Birth:
Testosterone helps develop male reproductive organs and causes testicular testes to go to scrotum

At Puberty:
Testosterone stimulates the enlargement of male sex organs, body hair, muscle, voice deepens, increases sweat

Testosterone- boosts sex drive.

Question 21

the ovaries

Answer 21

• located on either side of the uterus, size of almonds

-Their structure includes:
1. Tunica albuginea – the ovarian capsule
2. Ovarian cortex- contains follicles
3. Ovarian medulla- contains vessels and nerves

Question 22

uterine tubes

Answer 22

Females have two uterine (fallopian) tubes.

Tubes transport sperm to the oocyte and carry the oocyte/zygote to the uterus.

Cilia in the tubes help move the ovum.

Fertilization occurs within 24 hours of ovulation.

Zygote reaches the uterus 6-7 days after ovulation.

Question 23

the uterus

Answer 23

the uterus and ovaries are held in the pelvic cavity by mesenteries and ligaments.

The broad ligament - blanket over everything

The ovarian ligament and suspensory ligament hold the ovaries in position.

The uterus is pear-shaped with three layers:
Perimetrium – outer layer

Myometrium – middle layer, responsible for contractions during childbirth.

Endometrium – inner, shed in menstrua, functional sheds, basil rebuilds

Question 24

Endometriosis

Answer 24

Endometriosis is the growth of endometrial tissue outside the uterus.

It continues to respond to hormonal

This can cause inflammation and pain

Question 25

Vagina

Answer 25

A tubular canal Functions: Receives penis during intercourse, outlet for menstrual flow, and passage for childbirth. Resident bacteria create an acidic environment, which prevents pathogen growth. The acidic environment harms sperm, but semen's alkaline components raise pH, aiding sperm viability.

Question 26

Vaginitis

Answer 26

Inflammation caused by fungi (e.g., yeast infections), bacteria (e.g., BV), or parasites (e.g., Trichomonas).

Question 27

Female Reproductive Cycle:

Answer 27

Two cycles Components: Ovarian Cycle: Involves oocyte maturation and oogenesis (egg production). Uterine Cycle: Changes in the uterus' endometrium to prepare for a fertilized egg. (menstrual cycle) Average cycle length: 28 days (range 21-35 days).

Question 28

Oogenesis

Answer 28

production of oocytes

Question 29

development of egg means

Answer 29

oogenesis

Question 30

Oogenesis begins

Answer 30

before birth, accelerates at puberty, and ends at menopause. Unlike spermatogenesis, which starts at puberty, oogenesis involves multiple steps throughout a female's life.

Question 31

Oogenesis before puberty

Answer 31

During fetal development, oogonia (stem cells) divide by mitosis into another oogonium (stem cell) and a primary oocyte. Primary oocytes are surrounded by follicle cells Each primary oocyte starts meiosis I, but doesn't complete it until puberty from FSH triggering. Atresia is the process where most oogonia degenerate.

Question 32

Oogenesis after puberty

Answer 32

Oogenesis occurs monthly between puberty and menopause as part of the 28-day ovarian cycle, coordinated by changes in GnRH levels. The ovarian cycle has two phases: Follicular Phase: Period of follicular and oocyte development before ovulation. GnRH levels increase during this phase. Luteal Phase: Period of hormonal control by the empty follicle after ovulation. GnRH levels decrease during this phase.

Question 33

Follicular Phase

Answer 33

Follicular development: -forming primary follicles, secrete estrogens. Estrogens promote follicle growth -become secondary follicles and secrete follicular fluid. -One secondary follicle becomes dominant and outgrows others. Estrogens cause follicles to undergo atresia. -becomes a tertiary follicle with an antrum. Meiosis I completion: LH surge causes primary oocyte to complete meiosis I, resulting in a secondary oocyte and a polar body. The secondary oocyte undergoes meiosis II but stops at metaphase (only completed if fertilization occurs)

Question 34

Ovulation:

Answer 34

The tertiary follicle releases the secondary oocyte into the pelvic cavity Twins: If two follicles ovulate and are fertilized, fraternal twins can result.

Question 35

Luteal Phase

Answer 35

-After ovulation, the empty tertiary follicle becomes the corpus luteum, which secretes progesterone (prepares the uterus for pregnancy) If No Fertilization: The secondary oocyte dies the uterine tubes, turns into scar tissue - uterine lining to shed (menstruation). If Fertilization Occurs: The secondary oocyte completes meiosis II, forming a mature ovum (egg) and a second polar body. The sperm and ovum unite form a diploid zygote. The corpus luteum is produce progesterone and estrogens for 3-4 months until the placenta takes over.

Question 36

The Uterine Cycle

Answer 36

The uterine cycle occurs alongside the ovarian cycle, involving changes in the endometrium. Menarche is the first menstruation, typically occurring around ages 11-12. The cycle continues until menopause.

Question 37

Uterine Cycle three phases

Answer 37

Menses (7 days): Progesterone drop causes arterial constriction, leading to shedding of the endometrium, Proliferative Phase (6-13 days): Estrogen from growing ovarian follicles stimulates endometrial repair and thickening, with mucus secretion to support fertilized egg survival. Secretory Phase (14 days): Progesterone and estrogen from the corpus luteum promote further endometrial growth and mucus secretion. If fertilization doesn't occur, oocyte die and menstruation occur

Question 38

Amenorrhea

Answer 38

Amenorrhea: The absence of menstruation, classified as: Primary (1°): Failure to initiate menses by age 16. Secondary (2°): Interruption of normal cycle for 6+ months, eg due to stress

Question 39

Menopause

Answer 39

Perimenopause: The period of irregular cycles leading up to menopause, typically occurring between ages 45-55. Menopause: The permanent cessation of menstrual cycles, caused by ovarian aging and a decline in primary follicles. Estrogen levels decrease, and ovulation no longer occurs. Symptoms: Many women experience hot flashes and heavy sweating, linked to bursts of GnRH and LH due to the absence of negative feedback from the ovaries.

Question 40

mammary glands

Answer 40

Mammary glands: Modified sweat glands that produce milk. Nipple: Contains lactiferous ducts where milk is released. Internal structure: 15-20 lobules separated by adipose tissue; breast size is determined by adipose tissue, not milk production. Suspensory ligaments: Connective tissue that supports the breasts, becoming looser with age or strain. Lactation: Milk production is stimulated by prolactin; milk ejection is stimulated by oxytocin in response to suckling

Question 41

Pregnancy

Answer 41

Pregnancy Timeline: Begins with fertilization, followed by implantation, embryonic and fetal development, and ends with birth (about 38 weeks after conception). Trimesters: three 3-month periods called trimesters. Length: 40 weeks from the first day of the last menstrual period

Question 42

Trimesters

Answer 42

First Trimester: -Major organ systems begin to form. -The fetus is very vulnerable to harmful substances (drugs, radiation, microbes). Second Trimester: -Organ systems continue to develop. -By the end, the fetus has distinct human features. Third Trimester: -Rapid growth and fat (adipose tissue) buildup. -Most organ systems become fully functional in preparation for birth.

Question 43

Fetal Alcohol Syndrome

Answer 43

can result from alcohol use, leading to skeletal, heart, and brain defects.

Question 44

prenatal development

Answer 44

Conceptus = everything formed from conception: baby, placenta, and membranes. Blastocyst = tiny hollow ball of cells in the first 2 weeks. Embryo = from day 16 to week 8. Fetus = from week 9 until birth. Baby is connected to the placenta by the umbilical cord. The placenta gives the baby nutrients, removes waste, and makes hormones for pregnancy and development. Neonate = a newborn to 6 weeks

Question 45

Hormones during pregnancy

Answer 45

* Estrogens * Progesterone * Human chorionic gonadotropin * Human chorionic somatomammotropin

Question 46

what produces the hormones

Answer 46

Placenta makes most pregnancy hormones. Corpus luteum produces them in the first few weeks, then placenta takes over If removed before 7 weeks, the pregnancy ends.

Question 47

Human chorionic gonadotropin (HCG)

Answer 47

hCG is made by the blastocyst and placenta. It shows up in urine 8–9 days after conception (what pregnancy tests detect). helps the corpus luteum grow to make progesterone and estrogen to support the pregnancy.

Question 48

Estrogen

Answer 48

Estrogen rises a lot during pregnancy (30x more). First made by corpus luteum, then by placenta. Helps mother and baby grow: -Enlarges uterus, breasts, and genitals -Loosens joints and widens pelvis for birth

Question 49

Progesterone

Answer 49

Made by the corpus luteum and placenta Prevents ovulation and menstruation Stops uterine contractions to avoid early labor Nourishes the embryo - milk production

Question 50

Human chorionic somatomammotropin

Answer 50

Secreted by the placenta starting around Week 5. Similar to growth hormone but with weaker effects. Reduces the mother’s insulin sensitivity, making more glucose available for the fetus.

Question 51

Woman’s pituitary gland grows

Answer 51

50% during pregnancy

Question 52

Physiological Adjustments to pregnancy

Answer 52

Fetus depends on the mother for nourishment, breathing, and waste removal, so the mother must "eat, breathe, and excrete for two." Respiratory: Increased tidal volume (30%). Cardiovascular: Blood volume increases 30-50% to support the placenta. Nutrient needs: Increase 10-30%, causing increased hunger. Urinary: Glomerular filtration rate increases 40-50%, leading to more frequent urination. Reproductive: Uterus grows from 40g to 1,100g. Mammary glands enlarge.

Question 53

Labour

Answer 53

process by which the fetus is expelled from the uterus through the vagina. -myometrium greatly increases in size, as well as contractions -During pregnancy, progesterone inhibits contractions -near the end of the third trimester, three factors begin to oppose the calming action of progesterone

Question 54

Contractions

Answer 54

-During pregnancy, progesterone inhibits contractions -near the end of the third trimester, three factors begin to oppose progesterone: -Rising estrogen levels -Rising oxytocin levels -Prostaglandin production

Question 55

Labour and delivery: hormonal regulation

Answer 55

Rising estrogen levels: -Increase sensitivity of the uterus to oxytocin causing contractions Rising oxytocin levels: -Stimulated by estrogen, increasing the strength/ frequency of contractions. -Contractions release of more oxytocin. -The baby’s head moving down the birth canal leads to more cervical stretching, increasing oxytocin and contractions (positive feedback). -Positive feedback stops once the baby is born. Prostaglandins: -Stimulated by estrogen and oxytocin, prostaglandins enhance uterine contractions.

Question 56

False labour, braxton hicks, true labour, premature labour

Answer 56

False labor: Weak, irregular contractions that don’t lead to cervical dilation. Braxton Hicks contractions: Mild, irregular contractions that strengthen late in pregnancy but don’t start true labor. True labor: Regular, intensifying contractions that help move the fetus toward birth. Premature labor: True labor before the fetus is fully developed (before 36 weeks).

Question 57

Labour occurs in three stages

Answer 57

-Dilation stage (early and late) -Expulsion stage -Placental stage

Question 58

Dilation stage

Answer 58

Dilation Stage (8-24 hours): From the start of true labor until the cervix is fully dilated (10 cm). Contractions: Initially last 30 seconds, occurring every 10-30 minutes. By the end, last 60 seconds, occurring every 2-3 minutes. Amniotic sac typically ruptures (water breaks) during this stage.

Question 59

Expulsion stage

Answer 59

Duration: 10 minutes to 2 hours, from complete cervical dilation to delivery of the baby. Urge to push: The mother feels a strong urge to push. Episiotomy: An incision through the perineum may be needed if the vaginal canal is too small for the baby, usually in emergencies. Prolonged stage: Can lead to inadequate oxygen for the fetus, possibly causing brain damage. C-section: If vaginal birth isn't possible, a cesarean section may be performed (horizontal incision in the abdomen and uterus).

Question 60

placental stage

Answer 60

Duration: About 1 hour, from delivery until the afterbirth is expelled. Uterine contractions: Residual contractions tear the connection between the placenta and uterine wall. Placenta detachment: The placenta is removed from the uterus (afterbirth). Blood loss: Some blood is lost during detachment, but the increased maternal blood volume can handle it.

Question 61

Lactation

Answer 61

Suckling increases oxytocin, triggering the milk let-down reflex. Colostrum is released initially, rich in antibodies and low in fat. True milk appears by day 4, containing proteins, fats, sugars, and lysozymes. Milk secretion stops if suckling stops for a few days, as prolactin levels decline. Lactation takes time to establish (several weeks), and bottle feeding during this time may interfere with breastfeeding

Question 62

benefits of lactation

Answer 62

-baby nutrient absorption -Immune benefits: Contains white blood cells, T cells, plasma cells, and lysozymes with antibiotic properties. -Disease prevention: Reduces risks of allergies, respiratory, GI, and ear infections. -Parent-child bonding: Enhances connection. -Introduces the baby to different flavors