Chapter 46

Front 1

sexual reproduction

Back 1

fusion of haploid gametes forms a diploid cell

Front 2

zygote

Back 2

diploid cell formed by sexual reproduction

Front 3

egg

Back 3

female gamete
large, nonmotile cell

Front 4

sperm

Back 4

male gamete
much smaller, motile cell

Front 5

asexual reproduction

Back 5

generation of new individuals without fusion of egg and sperm
-mostly relies entirely on mitotic cell division

Front 6

fission

Back 6

separation of a parent organism into 2 individuals of approximately equal size

Front 7

budding

Back 7

new individuals arise from outgrowths of existing ones
ex: coral and hydra

Front 8

fragmentation

Back 8

breaking of body into several pieces

Front 9

regeneration

Back 9

regrowth of lost body parts

Front 10

parthogenesis

Back 10

form of asexual reproduction in which egg develops without being fertilized

Front 11

sexual reproduction pros

Back 11

enhances reproductive success/survival
-unique combination of parental genes
-speed up adaption
-allow population to rid itself of sets of harmful genes more readily

Front 12

ovulation

Back 12

release of mature eggs

Front 13

hermaphroditism

Back 13

individual has both male and female reproductive systems

Front 14

fertilization

Back 14

union of sperm and egg
-either external or internal

Front 15

external fertilization

Back 15

female releases eggs into environment where male then fertilaze them

Front 16

internal fertilization

Back 16

sperm are deposited in or near female reproductive tract and fertilization ovvurs within the tract

Front 17

spawning

Back 17

individuals clustered in same area release gametes into water at same time

Front 18

phermones

Back 18

chemicals released by one organism that can influence the physiology and behavior of other indiciduals of the same species

Front 19

gonads

Back 19

organs that produce gametes in most animals

Front 20

external female reproductive structures

Back 20

clitoris and 2 sets of labia
-surround clitoris and vaginal opening

Front 21

ovarie

Back 21

female gonads that flank the uterus and held in place in obdaminal cavity by ligaments (pair of them)

Front 22

follicles

Back 22

oocyte surrounded by group of support cells found in outer layer of each ovary packed in

Front 23

oocyte

Back 23

partially developed egg

Front 24

oogenesis

Back 24

formation and development of an ovum
-born w/ 1-2 million follicles, only 500 mature
-prior to ovulation follicle produce estradiol

Front 25

corpus luteum

Back 25

growth of residual follicular tissue w/in ovary after ovulation
-secretes additional estradiol and progesterone, (helps maintain uterine lining during pregnancy)
-degenerates if egg cell not fertilized

Front 26

oviduct

Back 26

fallopian tube
extends from uterus toward each ovary
-at ovulation egg released into abdominal cavity near funnel-like opening of oviduct
-cilia on epithelial lining of duct help collect egg by drawing fluid from body cavity into oviduct
-diameter near uterus extremely narrow

Front 27

uterus

Back 27

womb, thick muscular organ that can expand during pregnancy to accomadate 4kg fetus

Front 28

endometrium

Back 28

richly upplied with blood vessel

Front 29

cervix

Back 29

neck of uterus, opens into vagina

Front 30

vagina

Back 30

muscular but elastic chamber
-site for insertion of penis and deposition of sperm during copulation

Front 31

vulva

Back 31

collective term for external female genitals

Front 32

labia majura

Back 32

pair of thick fatty ridges
-encloses and protects rest of the vulva

Front 33

labia minora

Back 33

pair of slender skin folds that border cavity of the vaginal opening and seperate opening of the urethra

Front 34

hymen

Back 34

partly covers the vaginal opening in humans at birth and reptures during vigorous physical activity/intercourse

Front 35

clitoris

Back 35

located at upper intersection of labia minora consists of short shaft supporting rounded glans

Front 36

glan

Back 36

head covered by prepuce

Front 37

prepuce

Back 37

small hood of skin

Front 38

mammary glands

Back 38

-pressent in both sexes but normally produce milk only in females
-low level of estradiol in male limits development of fat deposits (remain small)

Front 39

testes

Back 39

male gonad, consist of highly coild tubes surrounded by several layers of CT
-semineferous tubules
-leydig cells
-scrotum
-testicle

Front 40

seminferous tubules

Back 40

tubes where sperm form

Front 41

leydig cells

Back 41

scattered btween semineferous tubules, produced testosterone and other androgens

Front 42

scrotum

Back 42

fold of body wall
-maintains testis temp about 2 degrees below that in abdominal cavity

Front 43

testicle

Back 43

tetis within a scrotum

Front 44

epididymis

Back 44

takes 3 weeks for sperm to pass thru 6m-long tubules

Front 45

ejaculation

Back 45

sperm are propelled from each epididymis through a muscular duct

Front 46

vas deferns

Back 46

muscular duct, extends around and behind urinary bladder and joins duct from seminal vesicle

Front 47

ejaculatory duct

Back 47

opens into urethra

Front 48

urethra

Back 48

outlet tube for both the excretory system and reproductive system

Front 49

semen

Back 49

fluid that is ejaculated

Front 50

seminal vesicles

Back 50

2
contribute around 60% volume of semen
-thick yellowish, alkaline
-contains mucus, sugar fructose (promotes most of sperm's energy), coagulating enzyme

Front 51

prostate gland

Back 51

secretes products directly into urethra thru several small ducts
-fluid is thin and milky
-anticoagulant enzyme and citrate
-->enlargement of prostate occurs in more than 1/2 of all men over 40
-->almost all men over 70

Front 52

bulbourethral glands

Back 52

pair of small glands along urethra below prostate
-before ejaculation secrete clear mucus that neutralizes many acidic urine remaining in urethra
-carries some sperm (why withdrawl is not adequate birth control)

Front 53

penis

Back 53

contains urethra and three cylinders of spongy erectile tissue
-main shaft covered by relatively thick skin, head/glans has thinner covering (more sensitive to stimulation)
-prepuce/foreskin

Front 54

prepuce

Back 54

foreskin
fold of skin covers human glans-may be removed by circumcision

Front 55

vasocongetion

Back 55

filling of a tissue with blood

Front 56

myotonia

Back 56

increased muscle tension

Front 57

4 phases of sexual response cycle

Back 57

excitement, plateau, orgasm and resolution

Front 58

excitement phase

Back 58

continue as result of direct stimulation of genitals
-females: outer third vagina vasocongested, inner 2/3 slightly expands
-->forms depression for recieving sperm at back of vagina

Front 59

orgasm

Back 59

chacterized by rhythmic, involuntary contractions of reproductive structures
males: emission, ejaculation
female: uterus and outer vagina contract

Front 60

emission

Back 60

glands and ducts of reproductive tract contract, forcing semen into urethra

Front 61

expulsion/ejaculation

Back 61

urethra contracts and semen is expelled

Front 62

resolution phase

Back 62

reverses responses of earlier stages
-organ return to normal size and outer muscles relax
-female no refractory period

Front 63

gametogenesis

Back 63

production of gametes

Front 64

spermatogenesis

Back 64

formation of development of sperm

Front 65

spermatogonia

Back 65

formed from stem cells developed in embryonic testes that have differentiated
-->generate spermatocytes, also by mitosis

Front 66

spermatocyte

Back 66

gives rise to 4 spermatids through meiotic cell divisions (reduce chromosome numbers from diploid to haploid)

Front 67

semineferous tubules and stem cell differentiation

Back 67

stem cells near outer edge->closer as spermatogensis proceeds mature sperm released into lumen->epididymis->motile

Front 68

acrosome

Back 68

special vesicle on head which contain enzymes that help sperm penetrate the egg
-tail=flagellum

Front 69

spermatogenesis pathway

Back 69

primordial germ cell in embryo->mitotic division->spermatogonial stem cell (2n)->mitotic divisions->primary spermatocyte (2n)->meiosis I->2 secretory permatocyte (n)->meiosi II->4 early spermatid (n)->differntiation (sertoli cells provide nutrients)->sperm cell

Front 70

oogenesis

Back 70

development of mature oocytes (eggs)
-immature eggs form in ovary of female embryo but do not complete development til years later

Front 71

oogonia

Back 71

divide mitotically to form cells that begin meiosis, but stop process at prophase I

Front 72

primary oocytes

Back 72

contained w/in small follicles they arrest development before birth

Front 73

secondary oocyte

Back 73

released at ovulation, arrested in metaphase of meiosis II
-follicle breaks down
-only if sperm penetrates oocyte does meiosis II resume

Front 74

oogenesis pathway

Back 74

primordial germ cell->mitotic diviion-->oogonium (2n)-->mitotic divisions->primary oocyte(2n, present@ birth, arrested in prophase of meiosis I)-> completion of meiosis I and onset of meiosis II-> firt polar body and secondary oocyte (arrested at metaphase of meiosis II, n)--> ovulation, sperm entry--. completion of meiosis II-->second polar body (n), fertilized egg (n)

Front 75

spermatogenesiss vs. oogensis

Back 75

1. only in spermatogenesis do all 4 products of meiosis develop into mature gametes
-in oogenesis, cytokinesis during meiosis is unequal
-almost all cytoplasm segregated into single
-daughter cell secondary oocyte, large cell destined to become the egg, other products are polar bodies and degenerate
2. spermatogenesis including mitotic divisions of stem cells and differentiated spermatogonia, occurs throughout adolescence and adulthood
-->oogenesis, mitotic divisions are completed before birth and production of mature gametes causes at about age 50
3. spermatogenesis produces mature sperm from precursor cells in a continous sequence, whereas oogenesis has long interruptions

Front 76

sertoli cells

Back 76

within semineferous tubules and help nourish developing sperm

Front 77

leydig cells

Back 77

located in intersitital space between semineferous tubules
-secrete testosterone and other androgens which promote spermatogenesis in tubules

Front 78

inhibin

Back 78

hormone that males produce by sertoli cells
-acts on anterior pituitary to reduce FSH secretion

Front 79

menstruation

Back 79

cyclic shedding of the endometrium from the uterus (occurs in flow through the cervix and vagina)

Front 80

menstrual cycle

Back 80

changes int he uterus
average 28 days in length

Front 81

ovarian cycle

Back 81

cyclic events that occur in the ovaries

Front 82

ovarian cycle pathway

Back 82

-begins with release of GnRH from hypothalamus
-stimulates anterior pituitary to secrete small amounts of FSH and LH
-follicle stimulating hormone stimulates follicle growth aided by LH
-cells of growing follicles start to make estradiol
-follicular phase
-low levels of estradiol inhibit secretion of pituitary hormones (keeping levels of FSH and LH relatively low)
-high concentration of estradiol has opposite effect-->stimulates gonadotropin secretion by acting on hypothalamus->increase in GnRH (positive feedback)
-final maturation of the follicle
-follicular phase ends at ovulation, about day after LH surge
-peak in LH level->follicle and adjacent wall ov ovary rupture->releases secondary oocyte
-luteal phase: follows ovulation
-->LH stimulates follicular tissue left behind in ovary to transform into corpus luteum (glandular structure)
-corpus luteum secretes prgesterone and estradiol
-excites negative feedback on hypothalamus and pituitary
-->reduces secretion of LH and FSH to very low levels

Front 83

follicular phase

Back 83

part of ovarian cycle during which follicles grow and oocytes mature

Front 84

uterine menstrual cycle pathway

Back 84

-prior to ovulation, ovarian steroid hormone stimulates uterus to prepare for support of an embryo
-estradiol signals endometrium to thicken
-follicular phase of ovarian cycle coordinated with proliferative phase
-estradiol and progesterone continue development and maintenance of uterine lining
-->enlargement of arteries and growth of endometrial glands-secrete nutrient fluid that can sustain early embryo even before it implants in uterine lining
-luteal phase coordinated with secretory phase
-disentigration of corpus luteum->rapid drop in ovarian hormone levels->arteries in endometrium constrict->uterine lining disintegrates->mestrual flow phase

Front 85

endometriosis

Back 85

disorder in which some cells of the uterine lining migrate to an abdominal location that is abnormal

Front 86

ectopic

Back 86

abnormal because cells migrated to location such as an oviduct, ovary or large intestine

Front 87

menopause

Back 87

cessation of ovulation and menstruation
btwn ages 46-54
-ovaries lose reponsiveness to FSh and LH resulting in decline in estradiol production by ovary

Front 88

estrous cycles

Back 88

absence of a pregnancy the uterus reabsorbs endometrium and no extensive fluid flow occurs

Front 89

conception

Back 89

fertilization, occurs when a perm fuses with an egg in the oviduct

Front 90

blastocyst

Back 90

sphere of cells surrounding a central cavity
-several days after impass into endometrium