Epididymis - PowerPoint Presentation

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Epididymis

Ductus

deferens

Seminiferoustubules

The cells of Leydig in testes secrete testosterone (T) T secreted at puberty produces 2o sex characteristics, spermatogenesis, & maintain tracts

Sperm productionSlide2

Spermatogenesis

: spermatogonia (2N) spermatozoa (N)

Epididymis

Ductusdeferens

Seminiferous

tubules

Sperm productionSlide3

Lumen of

seminifeous

tubuleSertoli cellSpermatidsSecondary

spermatocytePrimaryspermatocyteSpermatogonium

Mitosis

Meiosis

Sertoli

cellSlide4

Controlling sperm productionUnlike females, males produce sperm from puberty onward

Spermatogenesis controlled by LH and FSHSlide5

LH & FSH in males

LH acts on Leydig cells for T prod’n

FSH acts on Sertoli cells for sperm prod’n (inhibin provides negative feedback)Slide6
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Sperm production, viability influenced by:

Smoking, marijuana useAlcohol abuseAnabolic steroids, overly intense exercise, stressTight underwear, pantsEnvironmental pollutants (pesticides, lead, paint, radiation, heavy metals)Causes of infertility?Slide8

Spermatids become motile and are stored in epididymis and ductus deferens

Sperm storageSlide9

Seminal vesicles supply fructose, prostaglandins for muscle contraction, & fibrinogenProstate gland secretes alkaline fluid and clotting enzymesBulbourethral glands

add mucus for lubricationMaking something to swim inProstate gland

TestisDuctus deferens

BulbourethralglandUrinary bladderSeminal vesicleSlide10

Signals for erection and ejaculationArousalPudenal

nerves carry signals from penis to lower spinal cord & brain Spinal reflex and brain send PNS signals to penile arteriolesArousal causes muscle contractions that incr. physical stimulation – positive feedbackEjaculationDramatic shift to SNS – contractions move semen to urethra and outSlide11
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Viagra blocks PDE5, a enzyme that breaks down a local signal that causes dilation in response to NO There are many PDE’s – PDE5 is mainly in the penis

How does Viagra work?Slide13

Female reproductive anatomyOvaries produce

estrogen, progesterone, and are site of oogenesisEstrogen: maintenance of the female tracts, 2o sex characteristics, ova maturation and releaseSlide14

Oogonia divide mitotically Meiosis I produces a primary oocyte

(diploid), surrounded by follicle cells These oocytes develop into secondary oocytes on a cyclical basis Oogenesis overviewSlide15

Follicular phase - first half of cycle when follicles mature and are ovulatedLuteal phase - second half of cycle when uterus is prepared for implantation

Ovarian cycleFollicular LutealSlide16

Primary follicle

oocyte

Follicle cells

Looking within the ovary…follicular phase

FSH and LH levels are increasingSlide17

Follicle cells secrete estrogen

Dividing

follicular cells

Thecal cells

Primary

oocyte

Looking within the ovary…follicular phaseSlide18

antrum

Antrum collects fluid with estrogen

Estrogen inhibits FSH and LH, so FSH

Looking within the ovary…follicular phaseSlide19

Low to moderate levels of estrogenSlide20

Follicle (thecal) cells

Follicle (granulosa) cells

Antrum

primary oocyte

Late follicular phase

High estrogen levels promote LH secretion w/ positive feedback loopSlide21

High levels of estrogenSlide22

Late follicular phase

Mature

follicle

Antrum

Oocyte finishes meiosis Iit now is a 2o oocyteSlide23

Follicle

remains

secondary oocyte

Egg is flushed out

Pop! Ovulation!Slide24

How do fraternal vs. identical twins occur?Why are male and female gametes produced in different ways?Student questionsSlide25

corpus

luteum

Luteal phase

Corpus luteum secretes progesterone and estrogenSlide26

Estrogen and progesteroneEstrogen initiates preparation of

endo- and myometrium, ‘prime’ uterus for progesterone (follicular phase)Progesterone endometrium vascularization, glycogen, decrease contractions (luteal phase)Progesterone inhibits LH and FSH (this is how birth control pills work)Slide27

If the corpus luteum degenerates, progesterone drops and menstruation occursChanges in endometrium

Degenerating

corpus luteumSlide28

Why cramping during periods?What is the physiology of menstruation?Why do birth control pills effect periods?Often estrogen levels are lower w BCPStudent questionsSlide29
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Fertilization normally occurs within a day of ovulation

Contractions of the myometrium help some sperm reach the oviductBut if there are sperm around…

acrosomein actionSlide31

Embryo

Trophoblast

Implants the embryo

Blastocyst

Cleavage

Fertilization

Ovulation

Implantation

Embryo forms before reaching the uterusSlide32

Blastocyst secretes chorionic gonadotropin

Endometrium has glycogen, and becomes more vascularized from progesterone40% of blastocysts never implantSettling into the uterus…Slide33

Trophoblast

enzymes digest proteins of the endometrium. This carves a hole for implantation.Settling into the uterus…

Endometrium

Trophoblast

Embryo

Embryo

EndometriumSlide34

Embryo

Eventually forms

chorionSlide35

Placenta = chorion from embryo and uterine lining from mother. These tissues interlock like ‘fingers’

Projections of chorion have capillaries to form placental villi. They extend into the mother’s blood. Placenta developmentSlide36

Gasses, wastes, nutrients diffuse

bw capillaries of mother and fetusDrugs, pollutants, chemicals also diffusePlacenta development

mother’s blood

Placental villus

Amniotic sac

ChorionSlide37

What does alcohol do to cause fetal alcohol syndrome? How does drug use during pregnancy affect a fetus?Question:Slide38

Human chorionic gonadotropin (hCG)

Estrogen

Progesterone

Fertilization

DeliverySlide39

Relaxin from placenta softens the cervix and pelvisUterus has mild contractions. Baby’s head is down in pelvis

High levels of estrogen make the uterus more sensitive to oxytocin. Progesterone levels dropGetting ready for birth....Slide40

Stretching the cervix causes more oxytocin to be releasedOxytocin induces stronger contractions

Positive feedback with oxytocinSlide41

Lactation