A&P Quiz 9 (Ch 28 pt 1)

4 Functions of Reproductive System

gametogenesis

fertilization of oocyte by the sperm

development of nourishment of a new individual

production of reproductive hormones

Gametogenesis

function of reproductive system, production of gametes (reproductive cells) in the gonads

males: sperm cells produced in the testes

females: oocytes produced in the ovaries

Fertilization of Oocyte by the Sperm

function of reproductive system, duct system of males nourishes sperm cells until deposited in the female reproductive tract, female reproductive system receives sperm and allows it to travel to the site of fertilization (fallopian tube)

Development and Nourishment of a New Individual

function of reproductive system, female reproductive system nurtures a developing fetus in the uterus and provides nourishment after birth

Production of Reproductive Hormones

function of reproductive system, hormones control development of the reproductive system and sex-specific body form, essential for routine functions of the reproductive system and reproductive behavior

Human Meiosis

somatic (diploid) cells have 46 (2n) chromosomes and are formed by fertilization

haploid cells have 23 (n) chromosomes

Gametes (In Terms of Meiosis)

have one chromosome from each homologous pair

Human Chromosome Count

23 homologous pairs divided into 22 autosomal pairs and 1 pair of sex chromosomes

Meiosis

type of cell division that produces gametes (reproductive cells), only occurs in the testes and ovaries, two divisions, genetic material is duplicated prior to meiosis I

Testes Role in Meiosis

produces sperm cells

Ovaries Role in Meiosis

produces oocytes

2 Divisions of Meiosis

meiosis i

meiosis ii

5 Phases of Meiosis I

early prophase i

middle prophase i

metaphase i

anaphase i

telophase i

Early Prophase I

first phase of meiosis i, 46 duplicated chromosomes consists of two sister chromatids connected at a centromere

Middle Prophase I

second phase of meiosis i, chromosomes become visible, synapsis and crossing over occur

Synapsis

in middle prophase i of meiosis i, process that brings homologous pairs together

Crossing Over

in middle prophase i of meiosis i, exchange of genetic material at the tetrad between maternal and paternal chromosomes

Metaphase I

third phase of meiosis i, homologous pairs of chromosomes line up at the center of the cell, arrangement of maternal and paternal chromosomes are random

Anaphase I

fourth phase of meiosis i, homologous pairs separate and move to opposite sides

Telophase I

fifth phase of meiosis i, new nuclei form, cell completes division

Reduction Division

reduces chromosomes number from 46 to 23 in meiosis i

Meiosis I Diagram

Meiosis II

separates chromatids similar to mitosis

4 Phases of Meiosis II

prophase ii

metaphase ii

anaphase ii

telophase ii

Prophase II

first phase of meiosis ii, chromosomes condense and have two chromatids

Metaphase II

second phase of meiosis ii, duplicate chromosomes line up near the middle of the cell

Anaphase II

third phase of meiosis ii, chromatids separate at centromere and move to opposite ends of the cell, chromatids are called chromosomes once centromere separates

Telophase II

last phase of meiosis ii, new nuclei form, forms four daughter cells each with 23 chromosomes

Meiosis II Diagram

Male Reproductive System Consists of

testes

series of ducts (epididymides, ducta differentia, urethra)

accessory glands (seminal vesicles, prostate gland, bulbourethral gland)

supporting structures (scrotum, penis)

Scrotum

saclike structure containing the testes, divided into two internal compartments by an incomplete connective tissue septum, muscle movement in important for the regulation of temperature in sperm development as sperm cannot be produced in body temp

Raphe

irregular ridge at the midline of the scrotum externally marking the separation, extends posteriorly to the anus and anteriorly to the inferior surface of the penis

Wall of Scrotum Includes

skin

layer of superficial fascia consisting of loose connective tissue

dartos muscle (smooth muscle layer)

Dartos Muscle of Scrotum in Cold Temperatures

contracts causing skin of scrotum to become firm and wrinkled reducing size

Cremaster Muscle of Scrotum in Cold Temperatures

extensions of abdominal skeletal muscles into the scrotum, contract and help to pull testes nearer the body

Scrotum Muscles in Warmer Temperatures

dartos and cremaster muscles relax causing skin of the scrotum to become loose and thin and testes descend away from the body

Perineum

area between the thighs, divided into two triangles by superficial transverse muscles and deep transverse perineal muscles between the two ischial tuberosities

Perineum is Bound By

pubic symphysis (anteriorly)

coccyx (posteriorly)

ischial tuberosities (laterally)

2 Triangles of Perineum

urogenital

anal

Urogenital (Anterior) Triangle

region of perineum, contains the base of the penis and scrotum

Anal (Posterior) Triangle

region of perineum, contains the anal opening

Testes

small oval shaped organs, 4-5 cm long, housed in the scrotum, have both endocrine and exocrine functions

Endocrine Function of Testes

secreting testosterone

Exocrine Function of Testes

production of sperm cells

5 Components of Testicular Histology

tunica albuginea

seminiferous tubules

tubuli recti

rete testis

efferent ductules

Tunica Albuginea

thick white capsule of fibrous connective tissue surrounding testes

Septa

extensions of tunica albuginea that divide the testis into 300-400 lobules

Seminiferous Tubules

fill each lobule of testes, site of sperm production, adult male can produce 100 million mature sperm each day, almost half a mile lone in both testes

Interstitial (Leydig) Cells

endocrine cells that secrete testosterone in the loose connective tissue around seminiferous tubules

Tubuli Recti

straight tubule that receives products of the seminiferous tubules

Rete Testis

tubular network formed by the tubuli recti

Efferent Ductules

15-20 tubules that receive products from the rete testis and pass through the tunica albuginea to exit the testes, lined with ciliated pseudostratified columnar epithelium

Descent of Testes

testes develop initially in the abdominal cavity and descend into the scrotum, descend through the inguinal canals

Descend of Scrotum Occurs In

79% of male infants delivered prior to 28 weeks

97% of male infants delivered after 28 weeks

98.2% of males by 9 months of age

Cryptorchidism

failure of one or both testes to descend

Spermatogenesis

sperm cell development, occurs in seminiferous tubules, takes 74 days for sperm to be produced (spend 50 days in seminiferous tubules)

Spermatogenesis Before Puberty

testes remain unchanged from time of initial development

Spermatogenesis at 12-14 Years Old

interstitial cells increase in number and size, lumen develops in each seminiferous tubule, sperm cell production begins

2 Types of Cells in Seminiferous Tubules

germ

sustentacular

Germ Cells

in seminiferous tubules, divide and differentiate during spermatogenesis to form sperm cells

Sustentacular (Sertoli, Nurse) Cells

larger cells that extend from periphery to the lumen of the seminiferous tubule and nourish germ cells and produce hormones (androgens, estrogens, inhibin)

Blood-Testis Barrier

formed by tight junctions between sustentacular cells, isolates sperm cells from immune system

Sperm Development in Spermatogenesis

spermatogonia

primary spermatocytes

secondary spermatocytes

spermatids

spermatozoon

Spermatogonia

first cells of spermatogenesis, germ cells adjacent to basement membrane of seminiferous tubules, divide by mitosis

Primary Spermatocytes

second cells of spermatogenesis, daughter cells that differentiate from spermatogonia, divide by meiosis beginning spermatogenesis

Secondary Spermatocytes

third cells of spermatogenesis, produced by first meiotic division, haploid cells

Spermatids

fourth cells of spermatogenesis, smaller cells produced by secondary meiotic division

Spermatozoon

mature sperm cells, produced when spermatid undergoes spermiogenesis

3 Developments of Spermatid During Spermiogenesis

head

midpiece

tail (flagellum)

Head of Sperm

contains the nucleus, acrosome is vesicle anterior to the nucleus that contains enzymes necessary to penetrate oocyte

Midpiece of Sperm

contains many mitochondria

Tail (Flagellum) of Sperm

move sperm forward

Duct Pathway of Male Reproductive System

seminiferous tubules

tubuli recti

rete testes

efferent ductules

epididymis

ductus deferens

ejaculatory duct

urethra

Epididymis

comma-shaped structure on the posterior side of the testis, sperm complete maturation here, take 12-16 days for sperm to travel through

3 Regions of Epididymis

head

body

long tail

Head of Epididymis

contains convoluted efferent ductules that empty into the duct of the epididymis

Body of Epididymis

contains the duct of the epididymis

Duct of the Epididymis

a single convoluted tube several meters long and lined with pseudostratified columnar epithelium with stereocilia to allow for absorption of fluid

Long Tail of Epididymis

at the inferior border of the testes where the duct of the epididymis ends

Sperm Maturation in Epididymis

cytoplasm is reduced, acrosome matures, sperm develop the ability to bind the zona pellucida of the secondary oocyte

Ductus Deferens

emerges from the tail of the epididymis, ascends on the posterior side of the testis medial to the epididymis as part of the spermatic cord, lined with pseudostratified columnar epithelium surrounded by smooth muscle

Path of Ductus Deferens

ascend and pass through the inguinal canal to enter the pelvic cavity, crosses the lateral and posterior walls of the pelvic cavity, travels over the ureter and loops over posterior surface of the urinary bladder toward the prostate gland, end enlarges to form the ampulla

Spermatic Cord Consists of

ductus deferens

testicular artery and venous plexus

lymphatic vessels

nerves

fibrous remnants of process vaginalis

Spermatic Cord is Covered By

external spermatic fascia

cremaster muscle (extension of the muscle fibers of the abdominal oblique muscle)

internal spermatic fascia

Ejaculatory Duct

formed by a short duct from the seminal vesicle joining the ampulla of the ductus deferens, 2.5 cm long, extends into the prostate gland, opens into the urethra

Urethra

20 cm long, extends from the urinary bladder to the distal end of the penis, passageway for urine and male reproductive fluids

3 Parts of Urethra

prostatic urethra

membranous urethra

spongy (penile) urethra

Prostatic Urethra

region of urethra connected to the bladder and passing through the prostate gland, receives secretions from 15-30 ducts from the prostate and the 2 ejaculatory ducts

Membranous Urethra

shortest part of the urethra that passes through the perineum

Spongy (Penile) Urethra

longest part of urethra that passes through the penis

External Urethral Orifice

exterior opening of the urethra on the end of the penis

Urethral Glands

small glands that empty into the urethra

Lining of Urethra

transitional epithelium in prostatic urethra

stratified columnar epithelium for most of the length

stratified squamous epithelium near the external urethral orifice

Penis

male organ of copulation, transfers sperm cells from the male to the female, contains three columns of erectile tissue that are composed of smooth muscle tissue with sinusoids that fill with blood

Engorgement

when erectile tissue fills with blood causing the penis to enlarge and become firm (erection)

3 Layers of Erectile Tissue

corpora cavernosa

corpus spongiosum

Corpora Cavernosa

two columns of erectile tissue that form the dorsum and sides of the penis

Corpus Spongiosum

single column of erectile tissue that forms the ventral portion of the penis, extends from the gland penis that covers the distal end of the penis, contains the spongy urethra

Root of Penis Consists of

bulb

crus

Bulb of Penis

part of the root of the penis, expanded region at the base of the corpus spongiosum