reproductive system

spermatogenesis

1. testes

   1. structure of testes

      1. seminiferous tubules lines with spermatogenic cells

      2. interstitial cells

         1. make testosterone

         2. outside seminiferous tubules

   2. formation of sperm cells

      1. within sustentacular cells

         1. all stuff in background

         2. provide comforting and nurturing place for sperm cells

         3. “nurse cells”

      2. primary spermatocytes (diploid)

         1. undergo mitosis

         2. each chromosome has copy

            1. separated homologous pairs

      3. secondary spermatocytes (haploid)

         1. second meiotic division

            1. break up sister pairs

         2. 1 chromatid per chromosome

      4. spermatids and sperm (haploid)

         1. physical shape of sperm

male reproductive anatomy

1. penis

   1. urethra

      1. carries urine and sperm out of the body

   2. corpora cavernosa and corpus spongiosum

      1. changes in blood flow allow tissue to accumulate causing erection

2. internal accessory organs

   1. epididymides

      1. store, mature, and transport sperm

   2. ductus deferentia

      1. carry sperm to urethra

      2. inside prostate gland

   3. seminal vesicles, prostate gland, and bulbourethral glands

      1. secretions into urethra

      2. join together to make semen

      3. secrete fructose

         1. for energy (anaerobic)

            1. as biproduct: lactic acid

      4. secrete buffer for the acid

      5. smooth muscle constricts so during ejaculation urine isnt secreted

hormonal control of male reproductive functions

1. hypothalamic and pituitary hormones

   1. gonadotropic releasing hormone

      1. tells pituitary gland to release hormones

   2. follicle stimulating hormone

      1. stimulates cells to undergo division to make eggs and sperm

   3. interstitial cell stimulating hormone (males)

      1. in females: luteinizing hormone

      2. testes to make testosterone and androgen

      3. stimulates release of hormones

2. male sex hormones

   1. testosterone and dihydrotesterone

      1. androgens

      2. testosterone

         1. primary

         2. development of male reproductive organs and characteristics

      3. dihydrotesterone

         1. more potent

         2. male genitalia during fetal development

         3. secondary sexual characteristic during puberty

   2. inhibin

      1. controls FSH

         1. secrete less

      2. testes and ovaries make

   3. regulation of male sex hormones

      1. feedback loop with brain, pituitary gland, and testes

SRY- sex determining region of Y

1. encodes for transcription factor

2. genes that promote development of male features are now activated

3. y is smaller than x

what if SRY region is damaged

• chromosomally have Y

• dont show characteristics

• male structures not developed during fetal stages but do respond during adult puberty

• fetal testosterone is problem

• called intersex

what if receptors arent sensitive

• never develop external genitalia

• not even during adult puberty

• always look like female

• called intersex

nondisjunction

• multiple X chromosomes

• look male but isnt

• ex) XXY: extra x chromosome inhibited

• also called intersex

Oogenesis and follicle development

1. Oogenesis- female

   1. primary oocyte (diploid) suspended in prophase I

      1. at birth female born with all primary Oocytes she will have

      2. will not continue to next phase until puberty

      3. then only a few per month will travel to next phase

   2. unequal cytokinesis in meiosis I

      1. fertilized egg has to go on multiple day journey

         1. takes all its nutrients it’ll need

         2. reduce chromosome number

         3. doesn’t happen unless egg is fertilized

      2. secondary Oocyte (haploid)

         1. gets most of mass

            1. to survive journey

      3. first polar body (haploid, degenerates)

         1. reduce number of chromosomes

            1. wont develop

         2. get rid of genetic material

         3. medically, can harvest and see if bad gene is located here, if it is than secondary Oocyte doesn’t have it

            1. assures wont pass gene onto next generation

   3. Meiosis II at fertilization

      1. zygote

      2. second polar body (degenerates)

2. follicle maturation

   1. primordial follicle

      1. thin single layer of cells (squamous)

      2. suspended at birth

   2. primary follicle

      1. thin layer now more cuboidal

         1. follicle changing

      2. size of oocyte never really changes

      3. 20-25 start to develop

         1. 290 days from start to ovulation

   3. pre antral (secondary) follicle

      1. a lot of transitions

      2. start forming fluid filled cavity

         1. antrum

         2. very small

   4. mature antral follicle

      1. large antrum

      2. increase in pressure

         1. makes oocyte rupture through wall

   5. zona pellucida

      1. immediately surrounding oocyte

      2. non cellular material

      3. takes many sperm to break through

   6. corpus alabans

      1. pregnancy not achieved

      2. corpus luteum dies off and reabsorped

   7. corpus luteum

      1. remnant of follicle

      2. emits hormones

      3. maintain pregnancy

female internal accessory organs

1. uterine tubes (fallopian tubes)

   1. transport eggs from ovaries to uterus

2. uterus

   1. superior to urinary bladder

   2. proximal 1/3 is the cervix that dilates close to delivery

   3. receives fertilized egg and protects fetus during development

3. vagina

   1. pathway for menstruation

   2. birth canal

hormonal control of female reproductive functions

1. hypothalamic and anterior pituitary hormones

   1. gonadotropic-releasing hormone

      1. travels through infundibulum

      2. stimulates pituitary gland to secrete FSH and LH

   2. follicle stimulating hormone

      1. promotes developmeny of gametes

      2. 1st meiotic division

      3. development of eggs

   3. luteinizing hormone

      1. men: intertsitial cell stimulating hormone

      2. stimulates release of sex hormones- 2 weeks pattern in feedback

         1. estrogens- secondary sex characteristics

         2. progesterone

         3. androgens

2. female sex hormones

   1. estrogens and progesterone

      1. estrogen: thicken uterine lining

      2. progesterone: prepare uterus for potential implantation

   2. androgens

   3. inhibin

      1. inhibit follicle stimulating hormone

homologous anatomical structures

1. testes and ovaries

2. penis and clitoris

3. scrotum and labia

• same innervation

• same blood flow

female reproductive cycles

1. ovarian activity

   1. follicular phase

      1. day 1-14

      2. developing antral follicle → mature antral follicle

   2. ovulation

      1. surges of LH and FSH

      2. 14-21

      3. oocyte breaking through

      4. corpus luteum

   3. luteal phase

      1. 21-28

      2. degenerating corpus luteum

      3. corpus albicans

2. uterine activity

   1. menstrual phase

      1. blood vessels constrict

      2. lining of uterus dies off and sheds

      3. 28-5

   2. proliferative phase

      1. estrogens increase number of cells

      2. cells increase in size

      3. 5-19

   3. secretory phase

      1. progesterone make lining thick and spongy

      2. perfect for implantation (day 21)

      3. 19-28

3. if fertilization does occur

   1. corpus luteum remains functional

   2. estrogen, progesterone levels remain elevated

      1. menstruation prevented, cycle interrupted

      2. promotes corpus luteum for 3 months

      3. maintain lining of uterus

      4. prevent developing of more follicles

4. if fertilization doe not occur

   1. corpus luteum degenerates into corpus albicans

   2. estrogen and progesterone levels drop

      1. menstruation occurs, cycle begins anew

      2. lining sheds

      3. corpus luteum dies

      4. development of more follicles

5. menopause (female climacteric)

   1. unique to few members of mammals (humans, whale, etc)

   2. 2ish year period where lose period

fertilization and pregnancy

1. transport of sex cells

   1. oocyte move through fallopian tube

      1. down toward uterus

2. importance of semen composition

   1. fructose and protoglandins

      1. seminal vesicles

   2. citrate and prostate specific antigen

      1. prostate gland

         1. important to detect prostate cancer

   3. lubricant and buffer

      1. bulborethral glands

         1. buffer for the acidic sperm and eggs

3. fertilization to form a zygote

   1. fertilization in ovary

   2. only begins 2nd meiotic division if sperm breaks through corona radiata/ zona pellucida and then reach cell membrane

      1. opening then needs to close so no more sperm can penetrate- zona pellucida stays closed for about 4 days before dissolving

   3. acromosome containing enzyme helps dissolve pellucida

early embryonic development and implantation

1. cleavage by mitosis to form morula

   1. day 1-5

      1. right away

      2. collection of cells

         1. identical

         2. morula

      3. don’t gain size

         1. no resources- still in fallopian tubes

      4. increase cell number

   2. day 6

      1. cell differentiation

      2. hollow structure with cell mass inside

      3. inside- develop into child (embryonic cells)

      4. outside- extra embryonic cells- placenta, etc

      5. cant implan by itself

      6. cant go back

2. implantation of blastocyst- come in contact with uterine wall

   1. embryoblast (inner cell mass)

      1. develop child

      2. embryonic cells

      3. does not produce umbilical cord/placenta

   2. trophoblast

      1. attaches to uterine wall

      2. extra embryonic cells

      3. beginning of placenta (implantation)

placenta

1. embryonic and maternal portions

   1. everything in brown

   2. fetus and mother blood never come in contact

2. exchange across placental membrane

   1. nutrient from mother → fetus

   2. waste from fetus → mother

fetal circulation

• gas exchange at placenta, not lungs

• blood returning to heart well oxygenated

1. ductus venosus

   1. to shunt blood (detour)

   2. in liver

      1. blood being delivered to liver and instead of going through luver get put into inferior vena cava

   3. we don’t need the liver as fetuses

      1. bc we don’t have food by mouth

   4. becomes a ligament as an adult

2. foramen ovale

   1. shunt blood

   2. opening between right and left atrium

      1. no need to go to lungs

   3. when take first breath, flap of tissue sealed it off

3. ductus arteriosus

   1. shunt blood

   2. pulmonary trunk→ aorta

   3. blood from right vetricle goes into pulmonary trunk and right into aorta

   4. when take first breath constricts and wont work anymore

4. umbilical vessels

   1. red= umbilical vein

   2. blue= umbilical artery

      1. goes away from heart

5. circulatory changes at birth

   1. decreased vascular resistance

   2. increased pulmonary blood flow

   3. closure of fetal circulatory shunts

hormonal changes during pregnancy

1. human chorionic gonadotrophin

   1. trophoblast cells make

   2. tells to implant

   3. tell corpus luteum to persist

      1. continue to secrete estrogen and progesterone to promote uterine wall and placenta

   4. only 3 months

2. FSH and LH

   1. FSH: inhibin prevents FSH

   2. LH: less important

      1. don’t have ovulation

3. role of corpus luteum in first trimester

   1. make estrogen and progesterone

4. placental estrogen, progesterone, and lactogen

   1. lactogen: stimulating mammary glands to develop

   2. estrogen: uterine lining development, enlarge reproductive organs, inhibit FSH and LH

   3. progesterone: uterine lining development, inhibit uterine contractions, inhibit FSH and LH

      1. binds to spots on uterus that oxytocin binds to- prevents contractions

   4. from placenta

5. relaxin

   1. in childbirth

   2. relax cervix and symphysis joint (more flexible)

6. aldosterone

   1. conserve Na, water follows

   2. larger body mass

      1. need to conserve fluid

      2. need more volume

7. parathyroid hormone

   1. raises blood levels of calcium

      1. helps develop fetus skeleton

birth (parturition)

1. hormonal changes

   1. progesterone

      1. binds to same spot on uterus that oxytocin does

      2. prevents contractions

   2. oxytocin

      1. stimulates uterine contraction

2. role of positive feedback

   1. make sure your answer on the exam is a loop

   2. response continues trend

3. afterbirth

   1. amniotic sac ruptures

      1. “water breaks”

      2. birth under way

   2. need to deliver placenta at end of birth

      1. “afterbirth”

      2. less estrogen and androgens promotes delivery

      3. if not all delivered can become sick with sepsis due to dead tissue in body

4. involution

   1. uterus shrink back to prepregnancy size

positive feedback birth

mammary glands

1. breast changes during pregnancy

   1. placental estrogens, progesterone, lactogen

      1. estrogens: ductal growth

      2. progesterone: increase size and number of milk producing glands

      3. lactogen: modified sweat gland, stimulate mammary glands

         1. increase in size= increase in breast size

         2. lactigen goes away after birth

         3. prepares breast

   2. prolactin

      1. cause sweat glands to produce milk

      2. begina after delivery

2. milk production and secretion

   1. prolactin

      1. cause glands to produce milk

      2. begin after delivery

   2. oxytocin

      1. helps ejection of milk using the neuroendocrine reflex

      2. stimulate myoepithelial cells to contract

         1. myoepethelial cells surround alveolar glands

   3. colostrum and breast milk

      1. first milk produces

      2. lack fats and carbohydrates

      3. primarily proteins and antibodies

         1. babies born without antibodies

            1. rely on mom for immunity (the first 6 months most important)

            2. still protected after 6 months if mom stops reast feeding due to passive immunity

neuroendocrine reflex