Reproductive System

Reproductive System

1. Female Anatomy & functions

   • Ovaries: produce eggs & hormones
   • Uterus- Endometrium: lining of uterus, site of implantation, nourishes embryo, forms placenta
   • Fallopian Tube: site of fertilization, conducts egg to uterus
   • Fimbriae: cilia that sweeps egge into fallopian tube
   • Uterus- Myometrium: muscular wall, large contractions during labor, small contractions during menstruation
   • Cervix: nearly closes off uterus holding fetus in, expands during contractions & parturition
   • Vagina: accepts semen, birth canal
   • Pathway of egg: Ovaries> Fallopian Tube> Uterus

2. Male anatomy & functions

   • Epididymis: store & conduct sperm
   • Urethra: conducts demen out of the body through penis
   • Glands: secret fluid in semen to nourish & support sperm
     • Seminal Vesicles: provide high in sugar, supplying mitochondria inside sperm with energy
     • Prostate: provides fluid that counters the acidity of the vagina & clotting enzymes that alter the consistency of semen
     • Bulbourethral glands: neutralizes traces of acidic urine that may be left in the urethra; also lubricates
   • Penis: deposits sperm in female reproductive tract
   • Vas Deferens: conducts semen from testes to urethra
   • Testes: produce sperm & testosterone
   • Increased blood flow to the penis causes an erection allowing for vaginal penetration
     • Increased stimulation causes ejaculation- muscle in the penis contract, forcing semen out through urethra
   • Pathway of sperm: Testes> Epidiymis> Vas Deferens> Urethra

3. Sex Differentiation

   • Genotypic Sex: combination of sex chromosomes at conception
     • Female= XX, Male= XY
   • Gonadal Sex: development/ presence of ovaries or testes
     • Controlled by one gene at the Sex-determining region of Y chromosome (SRY)
       • SRY stimulates production of testis-determining factor (TDF) by gonadal cells
         • TDF present= testes
         • TDF absent= ovaries
   • Phenotypic Sex: apparent anatomical makeup (penis or vagina)
     • If testes are present they produce testosterone which causes phenotypic male anatomy
     • If ovaries develop, no testosterone is produce and female anatomy develops
       • Female hormones play no role is sex determintiation

4. Intersex possibilites

   • Intersex: conditions in which a person is born with reproductive anatomy that doesn't fir the typical definition of female or male
     • Klinefelter syndrome/ XXY syndrome: someone born with at least 1 extra X chromosome (often labeled male)
       • may show breast enlargement, small penis/ testes, reduced facial hair, reduced fertility
     • Androgen Insensitivity Syndrome: person born with the XY genotpye has cells that do not respond to androgens in varying degrees
       • causes differences genotypic & gonadal sex and phenotypic external sex

5. Puberty & hormones

   • Puberty: development stage with rapid growth & appearance of secondary sex characteristics
     • Kicked off by Gonadotropin releasing hormone (GnRH)
       • GnRH causes the release of LH and FSH
         • Stimulate gonads
     • Secondary characteristics from testosterone
       • pubic, underarm, and facial hair, penis & testes enlarge, more erections, larynx enlarges, muscular development, libido develops
         • Negative feedback keep hormones constant throughout life span
     • Secondary characteristics from estrogen
       • breasts enlarge, wider hips, pubic & underarm hair, menstruation begins, libido develops
         • Hormones fluctuate on a semi-monthly basis

6. Menstrual Cycle

   • Uterine lining sloughed off periodically throughout each year
     • Egg development
       • each egg starts meiosis before birth and completes it at puberty one egg at a time
       • Roughly every month after puberty, a surge of Lh and Fsh kicks off the development of a new follicle
         • Follicle= egg + layer of smaller cells
     • Ovulation occurs when the egg & some accompanying follicle cells burst through the ovary
       • After the burst, the rest of the follicle remains in the ovary, enlarging & forming the corpus luteum
         • Secretes estrogen and progesterone that stimulates the development of the endometrial lining
           • If pregnancy doesn't occur, the corpus luteum breaks down and hormones drop
             • Drop in hormones causes the thickened endometrium to disintegrat
   • Hormonal Contraception
     • supress GnRH, LH, and FSH by inhibiting follicular development & preventing ovulation
     • Disrupt endometrial lining, making implantation less likely