reproduction system

Male and Female Reproductive Systems

• Both include gonads (produce gametes and sex hormones)

• Sex hormones ctrl primary and secondary sex characteristics

Male reproductive System

• Allows for system to produce semen and for it to leave the body

• Also pathway for urine

  *Semen is that fluid that carries sperm

  *Sperm is the male reproductive cell

Male Reproductive System structures
(What structures does scrotum contain?)

Scrotum:

• Descend from abdominal cavity

• Resp for temp control for proper sperm development

• Contains:

  • Testes: Produce testosterone and sperm

  • Epididymus: Coiled tubules, site of sperm maturation (where motility is developed)

  • Vas Deferens: Tube that conducts sperm from epididymus to ejaculatory duct (before urethra)

  • Ejaculatory Duct: Tubule where vas deferens meets seminal vesicle which sends sperm to urethra

Semen is a combination of sperm and secretions from where?

• Seminal Vesicles: Produce fluid (alkaline and fructose), for mibility = ATP production

• Cowper’s Gland: liquid environment fro mobility and protection (Gives mucus protection from acidic conditions)

• Prostate Gland: Secrete fluid that is alkaline with cholesterol and phospholipids

  • Activate sperm motility

Mature sperm

• Small cells built for speed

• Very little cytoplasm (lose as they get more mature)

• Helps to increase cell mobility

Parts of sperm cell

Mid piece: large # of mitochondria for production

Acrosome: Pouch with special enzymes that allow penetration of outer layers surrounding sperm cells

Head: Contains half the DNA needed for fertilization

Flagellum: for locomotion

Spermatogenesis (Parts and role)

• Happens inside seminiferous tubules (in testes)

  • Where meiosis occurs

• Sertoli cells: Nourish developing cells, produce inhibin

• When ready, sperm cells move to epididymus to complete maturation

Sketch seminiferous tubule

Interstitial cells

• Found between seminiferous tubules

• Testosterone produced here which affects primary and secondary characteristics of males

Testosterone and puberty

• GnRH released when puberty begins

• Release of GnRH increases releasal of LH and FSH

LH and FSH in males

LH: Promotes production of testosterone in interstitial cells

FSH: Stimulates production of sperm in seminiferous tubules

*Both hormones regulated by (-) feedback system

Draw Male feedback loop!

Aging effects on male reproductive system

• Most males experience decrease in testosterone starting at 40y/o

• AKA andropause

• Hormonal changes result in growth of prostate gland increasing the risk of prostate cancer

Female reproductive system structures

• Ovary: Fluid filled containing immature ova (or primary follicles) → mature ovum = egg

  • Ovaries contain tissues that secrete estrogen and progesterone

• Oviduct/Fallopian Tube: end near ovary with finger like projections (fimbria) which helps sweep egg into oviduct to go to UTERUS

• Uterus: Organ that provides space for fertilized egg to develop

  • Inner lining called endometrium

• Endometrium: Sheds each month during menstruation if egg not implanted within it

  • Also forms placenta

• Cervix: Separates uterus from vagina

  • Creates sterile environment for development and keeps fetus in uterus until birth

• Vagina: Passageway for menstrual flow and birth canal, recieves sperm, acidic area to prevent microbes from entering

Tubual Ligation

• Cutting/pinching off fallopian tubes as a form of birth control

• Blocks sperm from meeting the egg

Vasectomy

• Cutting and tieing vas deferens so no sperm in semen

Pregnancy issues

Ectopic: implantation outside the uterus

Tubual: implantation in oviduct which will eventually rupture bcuz not meant to expand

*Both pregnancies will be terminated bcuz no fully functioning placenta

Oogenesis

• Ovary contains many groups of cells known as primary follicles which contain immature ovum

• When undergoing meiosis they become ovum

• Ovum created contains 23 chromosomes (haploid = N) and most of cytoplasm

Sketch female follicle!!!

Ovulation

• When mature follicle ruptures ovary wall and releases the ovum

Corpus luteum

• After pregnancy, formed by remaining follicular cells

• If no pregnancy, forms scar known as corpus albicans

Sketch oogenesis diagram!

Hormonal control of female repro system

• Pituitary and hypothalamus ctrl production of estrogen and progesterone through FSH and LH

• WHen starting puberty, GnRH released to signal anterior pituitary to start production of FSH and LH

• Progesterone prevents pregnancy

FSH in females effect

• Stimulate follicular development

• Increase estrogen levels

Effect of estrogen release from follicular cells

• Increase thickness of endometrium

• Responsible for female secondary characteristics

• Increased levels of estrogen halt production of FSH but increase release of LH from pituitary

*Estrogen positive to LH, (-) to FSH

Rising LH

• Results in ovulation

• Leftover follice = corpus lutem

Corpus Luteum role

• Produce some estrogen and lots of progesterone to help:

  • Maintain and develop endometrium

  • Suppress LH and FSH so no further follicles develop and ovulate (1 child/pregnancy)

What happens if no fertilization happens:

• COrpus luteum detoriates as not enough estrogen and progesterone occurs to maintain endometrium so menstruation occurs

• Menstruation happens bcuz of loss of endometrium

• As a result, FSH and LH no longer suppressed

draw female feedback loop!

Menstrual cycle and significant events

1) Flow phase; Menstruation (day 1-5)

2) Follicular phase: follicle maturation and endometrium thickens (day 6-13)

3) Ovulation - creation of ovum (day 14)

4) Luteal phase: corpus luteum formed and endometrium thickens further (day 15-28)

Birth Control pills

• Women can prevent ovulation by inhesting progesterone and estrogen

• Prevent development and release of ovum

• Suppress FSH and LH so you can’t develop follicles and have ovulation

Aging and Menstrual Cycle

• Limited number of cycles due to limited number of follicles

• As number of follicles decrease so does amt of estrogen and progesterone

• Menopause: cycles become irregular until they stop

Fertilization to Implantation

• Ovulation: egg to fallopian tube

• Fimbraie sweeps egg to fallopian tube where fertilization occurs → creationof zygote

  • Acrosome allows sperm to break through egg’s barriers

  • Only contents of head of sperm enter egg to form the zygote

  • AKA only DNA enters

• Zygote then undergoes # of cellular divisions on it’s way to uterus

• Cleavage: Cell division without any cell growth until morula (ball of cells form )

• Blastocyst: Cells move around to create outer ring of cells and inner mass (day 5)

• Implantation: Blastocyst completely surrounded by endometrium

numbered fertilization process

1. Ovulation

2. Fertilization (egg sweeped from fimbraie and head of sperm meets egg)

3. Zygote (fertilized egg)

4. Morula (ball of cells)

5. Stages of Blastocyst

6. Implantation

Development (blastocyst prouces what 3 membranes)

• Forms 3 membranes (all from fetus)

• Chorion: finger like projections that implant into endometrium and are fetus’s contribution to placenta

  • Chorionic villi (projections) create a large surface area between maternal and fetal blood supply

• Amnion: Creates protective sac that encloses fetus in a fluid filled environment

• Cushions fetus and prevents temp fluctuations

• Allantois: Blood vessels found in placenta, extension of endoderm and blood vessels give rise to umbilical cord

hCG

• Produced during development of blastocyst

• Maintains corpus luteum fro 1st 3 months until placenta becomes fully functioning and able to produce estrogen and progesterone

• Pregnancy tests identify hCG in women from urine

Further development

• Gastrulation: Process of inner layer cell mass forming different germ layers create a 3 layer structure called

  *drumroll*

• GASTRULA!!!!!

Gastrulation germ layers

Ectoderm: forms exoskeleton (skin, hair, nails, nervous system, eyes, teeth, mouth lining)

Mesoderm: develops into organs (muscles, blood vessels, kidney, reproductive structures, connective tissue, cartilage and bone)

Endoderm: forms inner lining of organs (liver, pancreas, thyroid, bladder, digestive system lining and respitary tract)

Placenta

• Forms from cells from endometrium and fetus (chorionic villi)

• Site of nutrient and waste exchange through diffusion

• Blood supplies of mother and fetus do not mix until birth

• Allows passage of drugs, some antibodies and some viruses

Trimester Development

1st (starting with fertilization): All organ systems develop, most vulnreable to teratogens (substances that can affect development)

2nd: Growth and systems continue to mature and fetal movements and reflexes occur (e.g baby kicking)

3rd: Rapid growth systems continue to mature, fat layers develop

Teratogens

• Anything that can cross placental system and affect development of fetus

• Whatever the mother inhales/ingests can end up in circulating blood

• Can pass across placental system and into fetal blood

• Number of substances can affect development of embryo and fetus

Sex determination

• Sex of zygote determined by sex chromosomes

• Any zygote with Y chromosome is therefore male

• Y chromosome contains gene known as TDF (testes determining factor)

• Zygote with 2 X chromosomes is female

Birth/Parturition

• At the end of the 3rd trimester, fetus turns so that front of head faces backbone and fetus drops in to birth canal

Draw labour feedback loop (positive feedback loop)

Hint: Posterior pituitary releases Oxytocin → causes uterine muscles to contract → pushes head against cervix so it can dilate → Prostaglandin → uterus contracts

Stages of Birth

Stage 1:

• Cervix dilates bcuz of muscle contraction caused by oxytocin and prostaglandins

  • Progesterone levels drop which no longer inhibits contractions

• Form a positive feedback

• Amniotic sac breaks cuz of contractions “water breaking“

• Active stage (stage 1) ends when cervix is 10cm dilated

Stage 2 (birf):

• Fetus is moved down birth canal

• relaxin causes loosening of ligaments in pelvis

• Uterine contractions and active pushing push baby out of birth canal

Stage 3 (Afterbirth):

• When baby is born, umbililcal cord is clipped

• Contractions expel placenta and umbilical cord

Lactation

• High levels of estrogen and progesterone prepare breasts for milk

• Prolactin: from anterior pituitary

  • rises dramatically after birth to stimulate milk production in glands

  • Stimulation of nerve endings causes oxytocin to release breast milk

Lactation feedback loop

Hypothalamus → RF →Anterior Pituitary → prolactin → Breast increases milk production → baby feeds

IVF

• woman’s egg and sperm in a lab dish

• need muliple ovulations from a women