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CBIO2210 Exam 4: Male/Female Reproductive System

Terms in this set (162)

What are examples of human gametes?
egg (ovum) and sperm
In males, what organ produces the gametes/sex hormones?
testes produce sperm and androgens
In females, what organ produces the gametes/sex hormones?
ovaries produce oocytes and estrogen
Zygote
a diploid (2n) cell resulting from the fusion of two haploid gametes; a fertilized ovum
Fertilization
Fusion of an egg (oocyte) and sperm cell
What determines if zygote develops into a male or female?
combination of sex chromosome donated by each gamete (X,Y)
Biological definition of female
individual that produces eggs
Biological definition of male
individual that produces sperm
Genetic/chromosomal definition of female
any individual lacking a Y chromosome
Genetic/chromosomal definition of male
any individual with a Y chromosome
What chromosome can eggs contribute to zygote?
only X chromosomes
What chromosome can sperm contribute to zygote?
a X or a Y
For what species is sex determined according to the incubation temp of eggs?
crocodiles, most turtle, and some lizards
What do temp different in sex involve?
steroids (mainly estrogen) and the enzymes involved in their synthesis
-aromatase
Aromatase
enzyme that converts testosterone to estradiol
How is sex determined in fruit flies?
by the ratio of X chromosomes to the individuals "ploidy" (# of chromosome sets

X:A ratio
Primary sex organs (gonads)
organs that produce gametes

ex: ovary, testis
Secondary sex organs
other organs necessary fro reproduction

ex: prostate, penis, vagina, uterus
Male external genitalia
penis and scrotum
Male internal genitalia
testes, epididymides, ductus deferentes, seminal vesicles, prostate, bulbourethral glands
Female external genitalia
vulva (mons pubis, labia, clitoris, vaginal orifice, vestibular bulbs/glands, paraurethral glands)
Female internal genitalia
ovaries, uterine tubes, uterus, vagina
Secondary sex features
features that distinguish the sexes and play a role in mate attraction
Embryo
unborn offspring in the process of development

in humans offspring from approximately the 2nd to the 8th week after fertilization
Fetus
unborn human after 8 weeks of gestation
T/F: initially, a fetus is sexually undifferentiated
true
Gonadal ridges
gonads that begin to develop at 5 to 6 weeks; each lying alongside a primitive kidney

can form either ovaries or testes
What triggers the choice of male/female?
the presence /absence of Y chromosome
SRY (sex-determining region of Y)
at 6-8 weeks of development, the SRY genes become activated in XY embryos
Testis-determining factor (TDF)
protein encoded by a gene in the SRY that triggers testes formation
If the Y chromosome and SRY are present:
1) primitive gonads begin to secrete testosterone
2) also secrete mullerian-inhibiting factor (MIF)
Mullerian inhibiting factor (MIF)
A substance secreted by embryonic testes that causes the regression of the Mullerian ducts.
Mullerian ducts
Earlier embryonic ducts that can develop into female internal genitalia in the absence of testosterone
What does female development result from?
the absence of androgens (default pathway)
By 6 weeks, an embryo has:
1) genital tubercle
2) urogenital folds
3) labioscrotal folds
When do fetus show sexual differentiation?
by 9 weeks
Cryptochidism
undescended testes
Perinium
external genitalia occupy this area
The Scrotum
contains the testes

divided into right and left compartments by the median septum

contains the spermatic cord
Scrotum Function
keeps the testes out of the pelvic cavity b/c of temp needed for sperm production
What temp are humans adapted to produce sperm at?
35 degrees Celcius
The cremaster
strips of abdominal oblique muscle that encircles spermatic cord

moves tested closer/further from pelvic cavity

cold temp: constrict closer
hot temp: relax away
The dartos fascia
subcutaneous layer of smooth muscle; sits right underneath skin

responsible for wrinkles in scrotum
The pampiniform plexus
network of veins that surrounds the testicular artery (countercurrent system)

ensures proper temp is kept (regulation)
The testes
slightly oval structure, supplied by blood vessels and nerves

anterior and lateral surfaces covered by tunica vaginalis
Tunica vaginalis
covering, particularly of a tubular structure; the sheath of the testis and epididymis
Tunica albuginea
surrounds testes and divides them into 250-300 lobes (each contains 1-3 seminiferous tubules)

produces testosterone
Interstitial endocrine cells
between seminiferous tubules

produce/release testosterone
Germinal epithelium
surrounds lumen

develop germ (sperm) cells
Each seminiferous tubules leads into a ____ ____.
rete testis
Rete testis
network of tubules between the seminiferous tubules and the epididymis

collects produced sperm/starts directing sperm out of testicles to ducts
The Spermatic Ducts
1) efferent ductules
2) epididymis
3) ductus (vas) deferens
4) ejaculatory duct
5) urethra
Efferent ductules
connect rete testis to epididymis
Epididymis
where sperm maturation takes place/storage
Ductus deferens
transports sperm to ampulla/ejaculatory duct
Ejaculatory duct
receives sperm and materials from seminal vesicles to produce semen
Accessory Glands of Male
1) seminal vesicles
2) prostate
3) bulbourethral gland
Seminal vesicles
release 60% of semen as watery solution into the ejaculatory duct to ensure sperm survives
Prostate
30% semen; milky substance

reason why semen appear milky white
Bulbourethral gland
aids in sexual reprouction

produces clear liquid (pre-ejaculate) which lubricates head of penis and helps buffer acidic environment of vagina
The penis
consists of an internal root and external shaft and glans

surrounded by loosely attached skin (prepuce)
Penis function
external release of semen and urine
What are the 3 eractile tissues in the shaft of a penis?
1) corpus spongiosum (surrounds urethra)
2) corpus cavernosum (tunica albuginea separates corpus cavernosum)
Lacunae in Penis
white, empty sinuses

when not filled with blood, will collapse/be limp

when filled, penis will become erect
Trabeculae in Penis
separate lacunae
When does the reproductive system awaken?
remains dormant until puberty
List of changes that happen during puberty
1) body color will change
2) testicles will enlarge
3) more distinctive body odor
4) ejaculation (wet dreams)
5) penis enlarges
6) pubic hair starts to grow
7) male breast develop
8) height spurt
Puberty
period from the onset of pituitary gonadotropin hormones secretion until the first ejaculation of viable sperm (10-15 years)
Adolescence
period of time including puberty and extending until a person attains full adult height
What brings about the many bodily changes that are observed during puberty and adolescence?
hormonal changes

testosterone: responsible for internal changes

dihydrotestosterone (DHT): responsible for external changes
Gonadotropin releasing hormones (GnRH) in males
stimulates anterior pituitary to release gonadotrophs (LH and FSH)
Luteinizing hormone (LH) in males
stimulates interstitial cells to secrete androgens (promotes sperm production)
Follicle-stimulating hormone (FSH) in males
stimulate nurse cells to secrete androgen-binding protein
Androgens
male sex hormones
Androgen-binding protein (ABP)
binds testosterone and accumulates it in the lumen of the seminiferous tubules and epididymis
What is testicular and sperm development dependent on
both the hypothalamus and pituitary
Spermatogenesis
process of sperm production (4 daughter cells with unique info-half of original chromosome)
3 principal events of spermatogenesis
1) division of a large germ cell into 4 smaller, motile cells
2) reduction of chromosomes by half
3) shuffling of genes
Meiosis
form of cell division that produces haploid cells (n)
Diploid (2n)
cell where each chromosome represented twice as part of a homologous pair
Homologous pair of chromosomes
two chromosomes that have the same kinds of genes (alleles) in the same order (results of fertilization)
Haploid (n)
cell where each chromosome is represented once
Diploid cells characteristics
somatic cells

cells with 23 sets of paired chromosomes

created by mitosis
Haploids cells characteristics
gamete cells

cells with 23 single chromosomes

created by meiosis
Meiosis I
reduces chromosome # from diploid to haploid

crossing over results in genetic variation

produces 2 cells that contain one member of each chromosome
Meiosis II
separate sister chromatids

four haploid cells result (genetically unique)
Why reduce the chromosome number by half?
polyploids
Polyploids
organisms with three or more complete sets of chromosomes

not viable in humans-will die within a month
Primordial germ cells
the first stem cells specifically destined to become sperm
What type of stem cell exists in ridges on primordial germ cells?
spermatogonia (remain dormant until puberty)
Spermatogenesis Process
1)spermatogonia divides by mitosis

2) type B spermatogonium gives rise to a primary spermatocyte (type A will serve as stem cell; keep reproducing spermatogonia)

3) primary spermatocyte undergoes meiosis I (secondary spermatocytes) - genetically unique (2n)

4) undergo meiosis II (four spermatids) (n)

5) spermatids undergo spermiogenesis


each process occurs a little closer to the lumen than the earlier stages
Spermiogenesis
spermatids become sperm
Spermatozoon
sperm cell

head: contains nucleus, acrosome, and flagellar basal body

tail:
midpiece (contain mitochondria)
principal piece (most of tail)
endpiece (thin axoneme at tip)
Acrosome
lysosome that helps sperm penetrate into an eggs
Sperm are an example of what?
unity if form and function, as they are made to be light streamlined, motile and effective at delivering DNA
Semen Makeup
10% sperm
30% prostatic fluid
60% seminal vesicle fluid
Prostatic fluid
contribute thin, milky white

1) calcium, citrate, and phosphate ions
2) clotting enzyme
3) protein-hydrolyzing enzyme
Seminal vesicle fluid
contributes viscous yellowish fluid

1) fructose and other carbs
2) citrate
3) prostaglandins
Female Sexual Differentiation and Development
due to lack of male androgens, the paramesonphoric duct develops
What is the most important primary sex organ in females?
ovaries (active egg production)
The Ovaries Organization
similar to testes -- has tunica albuginea (early stages of egg development)

interior divided into central medullar and outer cortex

-medulla: look for presence of vessels:
-cortex: where developing eggs will take place
What happens in the cortex of the ovaries?
site of ovarian follicles
How to the ovaries change with age?
smooth-surfaced during childhood

as we age, surface gets dimpled and eventually shrivels up/goes away (menopause)
Female ligaments
1) ovarian ligament (connects ovary to uterus)
2) suspensory ligament (blood supply)
3) mesovarium (attaches ovaries anteriorly)
How do the ovaries get blood?
supplied by the ovarian and uterine arteries
The Uterine Tubes (fallopian tubes)
lots of smooth muscle in the wall

mucosa is highly folded with lots of cilia
The uterus function
harbor a fetus, nourish it, and expel it at the end of development
The uterus
muscular chamber
Why is the uterus known as a potential space?
b/c of what can happen if successful fertilization
Cervix
The opening to the uterus
How does the uterus communicate with the vagina?
through cervix
Uterus wall consists of what 3 layers?
1) perimetrium
2) myometrium
3) endometrium
What shape is the uterus?
upside-down pear
Perimetrium of Uterus
serosa, simple squamous

helps anchor
Myometrium of uterus
thickest, initiates contractions during labor

consists of bundles of smooth muscle
Endometrium of uterus
most important, lines inner lumen

mucosa, columnar epithelium

WBC and small vessels (spiral arteries)

important for menstrual cycle and embryonic development
-functional layer is eliminated during menstruation
-basal layer helps regenerate new functional layer/month
-site of implantation of fertilized egg
Why is the endometrium of the uterus very important for the menstrual cycle?
-functional layer is eliminated during menstruation
-basal layer helps regenerate new functional layer/month
-site of implantation of fertilized egg
Why is the endometrium of the uterus very important for embryonic development?
-site of implantation of fertilized egg
Blood flow in uterus
internal illiac artery > vaginal artery > uterine artery > sprial artery > arcuate artery
The vagina
end of cervix, tube-like extension

8-10cm long
Vagina function
allows for discharge of menstrual blood, childbirth and penile penetration
Vaginal walls
very thin

adventitia > muscular > lamina propia > epithelium
Function of vaginal ridges
help stimulate sexual excitement

help provide acidic environment: bacteria ferment glycogen

pH:3.8-4.5 (reason why semen must have buffers)
The female external genetalia
collectively called the vulva or pudendum
Labia majora
bilateral fold of skin and adipose tissue
Labio minora
thinner fold, hairless & encloses vsetibule
Vestibule
where urethra & vaginal orifices are located
Clitoris
female penis, primary center of sexual stimulation

-glans and crura
Breasts
mound of tissue that overlies the pectoralis muscle
What happens to the breast at puberty and pregnancy?
enlarges, contains glands that develop/become large when pregnant/actively breastfeeding
Axillary tail of breast
vessels lead away from armpit to breast

where breast cancer usually develops
Body of breast
central point is the nipple
Nipple
surrounded by darker region named areola
Areola
sensory receptors to release milk
bumps = glands that make sure it doesn't dry out
What is the breast made up of in a non-breastfeedig female?
mainly adipose tissue
What is the breast mainly made up of in a breast feeding female?
glandular tissue develops

structures deteriorate once female stops breast feeding
Lobes of breast
secretory cells that release milk

each is drained by a lactiferous duct which leads to the nipple
Breast cancer mutation
mutations in BRCA1 (chromo 17) and BRCA2 (chromo 13) genes can predispose women to breast and ovarian cancer, depending on genotype
What percentage of breast cancer cases do the BRCA mutations account for?
15-20%
Breast cancer
tumors begin will cells of the mammary ducts and may metastasize
Breast cancer treatment
usually lumpectomy (only takes out mass) or mastectomy (removes entire breast)
When does puberty begin in females?
at ages 8-10 for most well-nourished girls
What hypothalamic and pituitary hormones trigger puberty in females?
LH & Gonadotropin-releasing hormone (same as males)
What is an important requirement for puberty to happen in females?
increased body fat levels: 20-25% (leptin hormone)
Leptin hormone: how does the brain know if fat reserves are adequate?
produced and secreted by fat cells

signals brain and pituitary when there is enough fat

if this isn't produced efficiently, puberty is delayed until the body has correct amount of body fat
Testosterone and Estrogen in female puberty
amped up during puberty

together they initiate stereotypical characteristic
What is the earliest sign of puberty in females?
thelarche (development of breast tissue)

depends on leptin
What is the 2nd sign of puberty in females?
pubarche (development of body hair in pubic/axillary areas and glands will also develop)
What is the last sign of puberty in females?
menarche (menstrual period)

happens around age 12-13
How do the first few cycles of menstruation differ from the rest?
no egg is actually released
Estradiol
stimulates growth of the ovaries and secondary sex organs in females

drives development of the feminine physique
Progesterone
acts on the uterus to prepare it for a possible pregnancy

also regulates LH and FSH
Inhibin
selectively regulates FSH
What is clamacteric and what folllows it?
midlife change in the hormone secretion

accompanied by menopause
When does menopause begin?
when a women has about 1,000 follicles left
Reproductive cycle
encompasses the sequence of events from fertilization to giving birth and returning to a state of fertility
Sexual cycle
events that recur every month when pregnancy does not intervene

-ovarian and menstrual cycles
Ovarian cycle
events in the ovaries
Menstrual cycle
parallel changes in the uterus
Oogenesis
egg production in a female, producing haploid (n) gametes by meisosis
How many functional gametes are released per month in a female?
only 1
When does oogenesis begin?
before birth

germ cells migrate and colonize gonadal ridges at 5-6 weeks and differentiate into oogonia
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