Chapter 27: Reproductive System

function of the male reproductive system

make gametes & deliver them to female reproductive tract

function of the female reproductive system

make gametes, receive gametes from male, & support child development

primary sex organs

make gametes & secrete sex hormones

male primary sex organs

testes

female primary sex organs

ovaries

accessory sex organs

ducts, glands, & external genitalia

pathway of sperm

made in testes, travel through epididymus, ductus deferns, ejaculatory duct, & urethra

function of scrotum

protect testicles, control temperature (must be ~3°C cooler than core body temp), & aid in sperm production

in the cold, testes arer pulled toward the body by what 2 muscles

dartos muscle & cremaster muscles

dartos muscle

wrinkles scrotal skin making sac smaller

cremaster muscles

raise testes

external anatomy of testes

~1.5” by 1” & covered by 2 tunics (tunica vaginalis & tunica albuginea)

tunica vaginalis

outer layer of 2 tunics in testes derived from peritoneum

tunica albuginea

inner fibrous capsule of 2 tunics in testes & gives rise to septa

internal anatomy of testes

divided into lobules by septa, in lobules are seminiferous tubules where sperm are made, from seminiferous tubules sperm move through tubes to epididymus, & between seminiferous tubules are Leydig cells which make testosterone

anatomy of penis

3 regions (root, shaft, & glans penis) & prepuce (foreskin) covers penis tip unless removed (circumcision)

internal penile anatomy

spongy urethra & 3 bodies of erectile tissue (corpus spongiosum & 2 corpora cavernosa)

3 parts of male duct system

epidiymus, ductus deferens, & urethra

epididymus

sperm mature here for about 20 days & once matured sperm are stored for up to several months or until needed

ductus deferens

carries sperm from epididymus to body & after it loops over ureter it joins with the seminal vesicle to form ejaculatory duct

urethra

carries urine & semen; has 3 regions (prostatic urethra, membranous urethra, & spongy (penile) urethra

prostatic urethra

within prostate

membranous urethra

in urogenital diaphragm

spongy (penile) urethra

runs length of penis

male accessory glands

seminal vesicles, prostate, & bulbourethal glands

products of seminal vesicles

secretions contain fructose (sugar), ascorbic acid (Vitamin C), coagulating enzyme, & prostaglandins; about 60% of semen volume

prostate gland location

surrounds urethra

prostate gland products

secretions contain citrate, several enzymes, & prostate-specific antigen; about 33% of semen volume

location of bulbourethral glands

under prostate gland

products of bulbourethral glands

secretions released before ejaculation to neutralize traces of urine in the urethra

characteristics of semen

milky white, sticky mixture of sperm & accessory gland secretions

main functions of semen

provdies a transport medium & nutrients (fructose & citrate), protects & activates sperm, & facilitates their movement

content of semen

prostaglandins (from seminal vesicles)

prostaglandins

decrease viscosity of mucous in cervix & stimulate reverse peristalsis in uterus facilitating movement of sperm through female reproductive tract

what does the relative alkalinity ( pH 7.3-7.6) of semen do

neutralizes acid environment found in male urethra & female vagina

what do clotting factors do for semen after ejaculation

coagulate it immediately so fibrinolysin can liquify the sticky mass

how much semen is released during ejaculation

2-5 mL

process of erection

sexual arousal → parasympathetic nervous system → nitric oxide released → vasodilation → increased blood flow fills corpora cavernosa → drainage veins compressed → blood stays trapped, keeping erection → corpus spongiosum fills with blood & stays less rigid → keeps urethra open during ejaculation

erection is inhibited by

touch, mechanical stimulation, erotic sights, sounds, & smells

impotence

inability to attain erection

ejaculation

propulsion of semen from male duct system

ejaculation (sympathetic nerves & genital organs)

contracts reproductive ducts & glands to release semen, closes bladder sphincter to prevent urine mixing with semen, & bulbosongiosus muscle contracts pushing semen through urethra

similarity of spermatogenesis & oogenesis

both are forms of meiosis that produce haploid gametes for sexual reproduction

differences in spermatogenesis & oogenesis

spermatogenesis→ occurs in testes, makes 4 sperm from 1 cell, starts at puberty & continues through life, makes millions of sperm daily

oogenesis→ occurs in ovaries, makes 1 egg from 1 cell, starts before birth, resumes at puberty, ends at menopause, usually 1 egg per month

brain-testicular axis

hormonal regulation of spermatogenesis & testicular androgen production involving the hypothalamus, anterior pituitary gland, & testes

hormonal regulation of testicular function (hormone pathway)

hypothalamus→ releases GnRH

GnRH→ pituitary releases FSH & LH

FSH→ sertoli cells make ABP

LH→ Leydig cells make testosterone

ABP + testosterone→ helps make sperm (spermatogenesis)

testosterone

synthesized from cholesterol, targets all accessory organs, & its deficiency causes these organs to atrophy

male secondary sex characteristics

appearance of pubic, axillary, & facial hair, enhanced chest growth, deepening of voice, skin thickens, oily skin, bones grow & increase in density, skeletal muscles increase in size & mass

basis of libido in males & females

testosterone

ovaries

primary female reproductive organs

function of ovaries

make female gametes (ova) & secrete female sex hormones (estrogen & progesterone)

structure of ovaries

paired organs on each side of the uterus held in place by several ligaments (ovarian, suspensory, & mesovarium)

what surrounds the ovaries

fibrous tunica albuginea

what is embedded in the ovary cortex

ovarian follicles

female accessory ducts

uterine tubes, uterus, & vagina

female internal genitalia

ovaries & internal ducts

female external genitalia

external sex organs

broad ligament

contains suspensory ligament & mesovarium

follicles in ovary

east consists of an immature egg (oocyte)

cells around oocyte

follicle cells (1 cell layer) & granulosa cells (1 or more cell layer)

order of follicle stages

primordial follicle, primary follicle, secondary follicle, graafian follicle, ovulation, & corpus luteum

primordial follicle

1 layer of squamous-like follicle cells surrounds the oocyte

primary follicle

2 or more layers of cuboidal granulosa cells enclose oocyte

secondary follicle

fluid-filled space between granulose cells that coalesces to form a central antrum

graafian follicle

secondary follicle at its most mature stage that bulges from the surface of the ovary

ovulation

ejection of oocyte from ripening follicle

corpus luteum

ruptured follicle after ovulation

structure of uterine tubes

infundibulum, ampulla, isthmus, & intramural (uterine) part

infundibulum

funnel-shaped opening with fimbrae that catch the egg

ampulla

widest part where fertilization usually happens

isthmus

narrow middle part

intramural (uterine) part

passes through uterus & opens to it

function of uterine tubes

carry egg from ovary to uterus, fertilization, move fertilized egg

location of uterus

hollow, thick-walled organ located in the pelvis anterior to the rectum & posterosuperior to the bladder

structure of uterus

body, fundus, isthmus, & cervix

body

major portion of uterus

fundus

rounded region superior to entrance of uterine tubes

isthmus

narrowed region between body & cervix

cervix

narrow neck which projects into vagina inferiorly

structure of uterine wall

perimetrium, myometrium, & endometrium

perimetrium

outermost serous layer; visceral peritoneum

myometrium

middle layer; interlacing layers of smooth muscle

endometrium

mucosal lining on uterine cavity

vagina function

provides a passageway for birth, menstrual flow, & is the organ of copulation

structure of vagina

thin-walled tube lying between bladder & rectum, extending from cervix to exterior of the body

vulva structure

external to vagina & includes mons pubis, labia, clitoris, & vestibular structures

mons pubis

round, fatty area overlaying the pubic symphysis

labia majora

elongated, hair covered, fatty skin folds homologous to the male scrotum

labia minora

hair free skin folds lying within the labia majora; homologous to ventral penis

greater vestibular glands

pea sized glands flanking vagina, homologous to bulbourethral glands, keep vestibule moist & lubricated

clitoris

erectile tissue hooded by prepuce, exposed portion is called the glans; homologous to penis

function of mammary glands

produce milk in lactating women

structure of mammary glands

15-25 lobes of modified sweat glands that radiate around & open at the nipple, areola, lobes containing grandular alveoli to produce milk, compound alveolar glands that pass milk to lactiferous ducts that open on the outside

areola

pigmented skin surrounding nipple

oogenesis

production of female sex cells by meiosis

ovarian cycle

monthly series of events associated with maturation & release of an egg

follicular phase (days 1-14 of ovarian cycle)

hypothalamus releases GnRH making the pituitary gland release FSH & LH, FSH causes egg containing follicle to grow & mature, as follicle grows it releases estrogen

ovulation (day 14 of ovarian cycle)

high estrogen levels trigger massive LH spike causing ovary wall to rupture & expel the mature egg

luteal phase (days 14-28 of ovarian cycle)

LH transforms the ruptured follicle into a temporary gland called the corpus luteum, corpus luteum secretes high levels of estrogen & progesterone stopping the release of FSH & LH to prevent new eggs from maturing, if there is not pregnancy the corpus luteum breaks down, hormone levels drop, & cycle restarts

menstrual cycle

monthly changes in uterine lining (endometrium) in response to hormones