Reproductive system/Pregnancy and Development

deleterious mutation hypothesis

sex exists to purge a species of damaging genetic mutations. Ex. A person with down syndrome can't pass down the gene which is good

red queen hypothesis

the hypothesis that sexual selection allows hosts to evolve at a rate that can counter the rapid evolution of parasites

meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

each gamete contains

23 chromsomes

Offspring are genetically different because

• Independent assortment

• Recombination

• Fusion of haploid gametes during fertilization

The reproductive system becomes active after

puberty

Male and female reproductive structures are

homologous structures

Male and female reproductive structures share the same tasks

Gametogenesis, copulation, fertilization, gestation and parturition

male and female reproductive structures are governed by

HPG axis

gametogenesis

production of gametes

spermatogenesis. Where does it occur?

formation of sperm, occurs in seminiferous tubules

oogenesis

egg production

testes are protected by

scrotum

tunica vaginalis

outer layer derived from peritoneum, vascularized

tunica albuginea

inner layer; fibrous capsule that extends between lobules

some spermatogonia become

primary spermatocytess

sperm transport

seminiferous tubules --> rete testis --> efferent ductule --> epididymis

spermatic cord

encloses nerve fibers, blood vessels, and lymphatics that supply testes

spermatogonium

A diploid cell that can undergo mitosis to form more spermatogonium, and can also be triggered to undergo meiosis to form sperm.

primary spermatocyte

a diploid cell in the testis that undergoes meiosis I

secondary spermatocyte

2 haploid cells that are product of meiosis I

spermatids

four haploid cells that are product of meiosis II

spermiogenesis

transformation of spermatids to spermatozoa during spermatogenesis

immature spermatozoa

sperm that hasn't matured yet: can't move or fertilize

sertoli cells

cells found within the seminiferous tubules that nourish spermatogenesis

maturation of sperm occurs in the

epididymis

semen is formed by

accessory sex glands

fructose (SV)

source of ATP production for sperm movement

epididymis

stores sperm for several months, propels sperm into vas differentia during sexual arousal

prostaglandins (SV)

stimulate uterine smooth muscle contractions

fibrinogen (SV)

allows semen to coagulate after ejaculation

citric acid (PG)

nutrient for atp production by sperm

clotting and proteolytic enzymes (PG)

activates fibrinogen and eventually breaks it down

seminal plasmin (PG)

antibiotic that kills bacteria

alkaline mucus (BG)

lubricates tip of penis and urethral lining and neutralizes acids in urethra (pre cum)

how long does sperm live outside a vaginal canal?

5 minutes

semen re-liquifies due to

proteolytic enzymes, releasing the trapped sperm

Why remove the prepuce?

for religious reasons and to reduce the chance of getting STDs and bacteria

corpus cavernosa

fills with blood during erection

corpus spongiosum

prevents urethra from closing when the corpus cavernosa fills with blood

an erection is a

parasympathetic reflex

as long as you have enough nitric oxide

you are able to maintain an erection

smooth muscle cells relax then

dilate the vessels, compressing the veinsej

ejaculation is a

sympathetic and somatic reflex

smooth muscle contractions in wall of duct system

propels sperm into urethra

emission

persistalsis

smooth muscle sphincter

closes off urinary bladder

bulbospongiosus muscles contract at base of penis and ...

expel semen at 11 mph

Erectile dysfunction

(impotence) The inability to produce or maintain an erection. Involves too little nitric oxide being released and blood flow to the penis is too low

benign prostatic hyperplasia

enlarged prostate causes constriction of the urethra

prostate cancer

most common cause of cancer in males, on par with breast cancer with women. It's the third deadliest cancer in men

androgens

1. development of male reproductive structures

2. development of secondary sex characteristics

3. drive male reproductive behaviors

4. stimulate spermatogenesis

5. promote muscle and bone growth

6. contribute to male (and female libido)

female reproductive system consists

ovaries, oviducts, uterus, vagina, vulva, and mammaryglands

estradiol (E2), progesterone, FSH, and LH

urogenital triangle consist of

clitoris, labia majora, labia minora, vestibule

vestibule contains

1. Urethral opening

2. Vaginal opening

3. Paraurethral glands

4. Greater vestibular glands

anal triangle

fat, loose connective tissue, and anus

mammary glands

modified sweat glands, produce milk

milk production

glandular alveoli --> lactiferous ducts --> lactiferous sinuses --> opening at nippleb

breast cancer

most common cause of cancer in females. Second deadlines cancer for women in the US. Epithelial cells of lactiferous ducts metastatize

mastectomies

surgical operation to remove breast to treat breast cancer

ovarian cycle

events in the ovaries leading to the development and release of a mature egg

uterine cycle

events in the endometrium to prepare it for the arrival for a fertilized egg

ovaries are held in place by

tunica albuginea and germinal cuboidal epithelium

gametes and follicles are formed within the

cortex

nerve fibers, blood vessels, and lymphatics that supply the ovaries are in the...

medulla

geminal cuboidal epithelium

outer layer; extension of peritoneum

oogenesis begins during

fetal development

most cells in ovaries

degenerate (atresia)

remaining oogonia become

primary oocytes

primordial follicle

one layer of cells around oocyte

oogenesis process

Oogonium -> Primary oocyte -> secondary oocyte + first polar body -> ovulated 2nd oocyte + sperm cell -> ovum and second polar body -> ovum results in zygote

oogenesis vs spermatogenesis differences

• 1 gamete/oogonium, error rate of 20%, begins in fetal life, has several stop-go points, stops after menopause

• 4 gametes/spermatogonium, error rate of 4%, begins after puberty, continues throughout lifeo

oogenesis and spermatogenesis similarities

produce haploid gametes, occur in gonads, regulated by HPG axis

ovarian cycle consist of what two consecutive phases and what comes in between?

follicular phase, ovulation, luteal phase

follicular phase

• days 1-14

• several primary follicles become sensitive to FSH and are stimulated to grow

Luteal phase

days 14-28
-corpus luteum secretes high levels of E2 and P

uterus, zygote implantation, fetal development

hollow, thick, muscular organ that is the site of _____ and _____ and is supported by perimetrium, myometrium, and endometrium

endometrium contains 2 inner layers:

stratum basalis and stratum functionalis.

uterine (menstrual) cycle

this cycle encompass the series of events associated with changes in the endometrium in response to fluctuating ovarian hormones

_____ is sloughed off during menstruation. Blood vessels, epithelium, connective tissue, and glands

endometrium

uterine cycle consists of what two phases:

proliferative phase, secretory phasep

proliferative phase

• influenced by estrogen

• the thickness of the endometrium rapidly increases

secretory phase

• influenced by progesterone

• the lining becomes highly vascular and edematous

estrogens

development of female reproductive structures, development of secondary sex characteristics, drive female reproductive behaviors, stimulate oogenesis and folliculogenesis, promote short lived growth spurt at puberty, facilitate calcium uptake into bones

progesterone

maintain uterine cycle, maintains pregnancy, helps prepare breasts for lactation

What happens when a female gets excited?

the clitoris, vaginal mucosa, vestibule, and nipples become hard and fill with blood

orgasm

_____ is accompanied by muscle tension and rhythmic uterine contractions

Do females have a refractory period after orgasm?

no, they can experience multiple orgasms in single sexual experience and keep going

eggs

23 total chromosomes with 1 being a sex chromosome (X)

sperm

have 23 total chromosomes with 1 being a sex chromosome (X or Y)

sex

____ is determined by the sperm the moment it fertilizes the egg`

bipotential

the early embryo is ____

SRY gene (sex determining region of Y)

Male pattern of development initiated by _____ (only in males)

7

SRY genes in males only cause development of testes around week __

• Leydig cells start to release T

• Sertoli cells releases Mullerian-inhibiting hormone

Around week 8, what happens?

androgens

Which hormone (androgen/estrogen) control sex differentiation?

DHT

Some T released by the developing embryo is converted to ____ by 5a-reductase

What does DHT do?

causes the development of male external genitalia

STI

aka venereal diseases

zygote

product of sperm and secondary oocyte fusion