UI: Human Phys Chap 20

Somatic Chromosome Counr

46 (Diploid), 23 Homologous Pairs

Gamete Chromosome Count

23 (Haploid), 1 member/pair

Autosome

22 pairs for general characteristics

Sex Chromosomes

Two types: X and Y

Sex Determination Role

Anatomical and Functional Distinctions

Palindromes

Regions of DNA bases that read the same from either direction.

X Chromosome Inactivation

One active only (either parent)

Barr Body

Inactive X chromosome; stored as dense heterochromatin, compensates for extra X

Primary vs Secondary Reproductive Organs

1°: Testes & Ovaries

2°: Ex-Genitalia, Accessory Glands, Reproductive Tract

Reproductive Tract

Transports gametes after produced

Accessory Sex Glands

Wolffian and Mullerian Ducts

Accessory Sex Glands Purpose

Develops reproductive organs based on whether MIF or Testosterone is present.

SRY Gene

Sex determining gene for excreting testosterone (Testis Determining Factor)

Yes MIF

Mullerian ducts degenerate

No MIF

Uterus & uterine tubes

Yes Testosterone (Accessory)

1) Epididymides, ductus deferentia, ejaculatory ducts

2) Prostate

3) Penis, scrotum

No Testosterone (Accessory)

1) Wolffian ducts degenerate

2) Vagina, Labia, Clitoris

Male Reproduction Difference

1) Mature sperm produced continuously (~30-100 million/day)

2) Testosterone release continuously

3) Reproductive potential continues throughout life

4) Begins at Puberty

Female Reproduction Difference

1) Ova released intermittently in small numbers

2) Cyclical hormone release

3) Reproduction potential ends during menopause

4) Begins at Puberty

(M) Primary Reproductive Organ

Testes: Produce sperm (in seminiferous tubules) and secrete testosterone

(M) Testes Compartments

1) Seminiferous Tubules: Spermatogenesis

2) Interstitial Tissue: Leydig cells (Produce Testosterone)

(M) Secondary Structures

Epididymis: Sperm Storage

Vas Deferens: Transport from scrotum to pelvic cavity

Ejaculator Duct: Joint of vas deferens and seminal vesicles

Seminal Vesicles: Forms semen volume / neutralizer (Prostate)

Urethra: Semen to exterior

(M) Spermatogenesis

Sperm from spermatogonia, continuous, 1 germ cell = 4 sperm

(M) Spermatogenesis Mechanism

Meiosis → (1 primary) → First meiotic division (2 secondary) → Second MD (4 spermatids) → spermiogenesis (4 sperm)

(M) Spermatogenesis Fun Fact

Body is allergic to sperm.

(M) Blood-Testis Barrier / Sertoli Cells

Protects WBC from killing sperm

Testosterone can freely move to mature sperm

Provides nourishment

Secrete androgen-binding protein (Testosterone no leave)

Release inhibin (FSH) to regulate

(M) Sperm parts

Head: DNA

Acrosome: Enzyme vesicle for penetration

Midpiece: Mitochondria (lots of energy)

Tail: Motility (moving against fluid)

(M) GnRH

Formed in hypothalamus to anterior pituitary gland:

LH → Leydig cells → Testosterone → Spermatogenesis

FHS → Sertoli cells → Inhibin or Spermatogenesis

(M) Endocrine Regulation

Testosterone inhibits LH

Inhibin inhibits FSH

(M) Erection/Ejaculation

Dilation of arterioles (PNS; NO), like a sponge

Release (SNS)

(F) Reproduction

Oogenesis (Ova)

Reception and transport of gametes for union (fertilization)

Fetus maintenance / Form placenta (temp. organ lifeline)

Birth (parturition) / milk (lactation)

(F) Primary Organs

Ovaries: Storage and endocrine function

(F) Secondary Organs

Oviducts (FT): close to ovaries, pick-up, fertilization site

Uterus: maintenance / expelling of fetus

Vagina: Uterus to external

Cervix: Lower vagina, passageway

(F) Hormone, Constant cycle

Estrogen: Ova maturation/release, sexual characteristics, breast development

Progesterone: Prep environment (endometrium)

(F) Oogenesis

~2 million primary oocytes at birth:

Oogonia stem cells

~400k at puberty

Primary matures, released from follicle each month

~400 total in lifetime; degenerate

(F) Oogenesis mechanism

Primary (46) → 2nd/Polar (23) → 1 mature, 3 polar (triggered by sperm entry)

(F) Ovarian Follicle

Start of Menstrual: 10-25 follicles mature

After ~1 week, one survives (Dom follicle = Graafian)

Releases estrogen, continues to grow, fluid pressure increases

(F) Corpus Luteum

Begins forming after follicle matures and releases egg:

Ovulation → Corpus Luteum → Corpus Albicans

(F) Ovarian Cycle

Lasts 28 days, begins at puberty, normally interrupted only by pregnancy, terminated by menopause

(F) Follicular Phase

Days 1-13, First Half:

FSH stimulates - follicle growth, granulosa to secrete estrogen

LH stims theca to produce androgens for granulosa for estrogen (estradiol)

Low progesterone, gradual increase of estrogen

(F) Ovulation

Day 14:

Spike in estrogen, LH, & FSH (LH > FSH), ova released

(F) Luteal Phase

Day 15-28, Last Half:

Old follicular cells → Corpus luteum (functional within 4 days after ovulation)

Continues size increase for 4-5 days

Ovum not fertilized = CL degenerates, starting menstrual cycle

Gradual increase of progesterone (“glue”) and estrogen

(F) Uterine / Menstrual Cycle

Lasts ~28 days, same time as Ovarian Cycle

Hormonal changes during OC

Menstrual Bleeding

(F) Menstrual Cycle

Days 1-4, start of new cycle:

Discharge of blood

Release Uterine prostaglandin

• Vasoconstriction of endometrial vessels (endometrium death)

• Stims rhythmic uterus contractions

Blood Clot: Golf (Good), Baseball (Bad)

(F) Proliferative Phase

Days 4-14, same time as last part of Follicular:

Endometrium proliferates, makes new follicles

Lasts from end of menstruation to ovulation

(F) Secretory Phase

Days 14-28, same time as Corpus Luteum:

CL secretes many progesterone and estrogen

PRG stims endometrial glands → glycogen

No fertilization/implantation → CL degens → new FP and MP

(F) Fertilization

Fallopian tubes site

Must occur within 24 hours of ovulation

Reproductive tract aids in migration:

• Myometrium contractions

• Mature eggs release Allurin

(F) Fertilization Race

First sperm to reach ovum:

Fuse with plasma membrane of ovum

Chemically penetrates, and blocks other sperm

Head separates → fuse with egg → zygote

(F) Contraception

Oral, Rhythm (time the days), IUD, Barriers