Week 10 Flashcards
What is a key advantage of sexual reproduction?
Variability
Sexual reproduction increases genetic diversity among offspring.
What process leads to genetic recombination?
Meiosis
Meiosis is essential for the formation of gametes and genetic variation.
What are gonads?
Primary sex organs
Gonads include ovaries in females and testes in males.
What structures are involved in the male reproductive system?
- Testes
- Epididymis
- Ductus deferens
- Urethra
- Penis
These structures work together for sperm production and transportation.
What is the function of the testes?
Sperm production and sex hormone secretion
Testes must be maintained at a temperature 3°C lower than body temperature for optimal sperm production.
What is the role of the epididymis?
Storage and maturation of sperm
The epididymis is a 6-meter coiled duct where sperm undergo maturation over about 20 days.
What are the accessory reproductive organs?
- Ducts for gamete transport
- Glands for fluid secretion
- External genitalia
- Organs for embryo nurture
- Organs for newborn nurture
These structures support reproductive functions and processes.
What is the function of seminal vesicles?
Produce 70% of semen volume
Seminal vesicles contribute essential fluids to semen.
What does the prostate gland produce?
Approximately 30% of semen
Prostate fluid helps nourish and transport sperm.
What is the purpose of the bulbourethral glands?
- Produce thick clear mucus
- Provide lubrication
- Neutralize residual urine in the urethra
These glands help prepare the urethra for sperm passage.
Fill in the blank: The _______ is a dual-purpose duct for urinary and reproductive systems.
Urethra
The urethra serves both urinary and reproductive functions in males.
What is the volume of ejaculate?
2-5 mL
What are the main components of ejaculate?
- Sperm
- Seminal fluid
- Clotting factors
- Enzymes
What are the ‘sperm factories’ located in the testis?
Seminiferous tubules
What cells in the testis produce androgens?
Leydig cells
What hormone is primarily produced by Leydig cells?
Testosterone
What does ‘2n’ indicate in terms of cell ploidy?
Diploid cell
What does ‘n’ indicate in terms of cell ploidy?
Haploid cell
How many chromosomes are present in a diploid cell?
23 pairs of chromosomes
How many chromosomes are present in a haploid cell?
23 individual chromosomes
What are the three main regions of a sperm structure?
- Head
- Mid piece
- Tail
What is contained in the head of a sperm?
- Genetic material
- Acrosome contains enzymes required for penetration of oocyte
What is the function of the mid piece of a sperm?
Mitochondria
What does the tail of a sperm provide?
Motility
What is the volume of ejaculate?
2-5 mL
What are the main components of ejaculate?
- Sperm
- Seminal fluid
- Clotting factors
- Enzymes
What are the ‘sperm factories’ located in the testis?
Seminiferous tubules
What cells in the testis produce androgens?
Leydig cells
What hormone is primarily produced by Leydig cells?
Testosterone
What does ‘2n’ indicate in terms of cell ploidy?
Diploid cell
What does ‘n’ indicate in terms of cell ploidy?
Haploid cell
How many chromosomes are present in a diploid cell?
23 pairs of chromosomes
How many chromosomes are present in a haploid cell?
23 individual chromosomes
What are the three main regions of a sperm structure?
- Head
- Mid piece
- Tail
What is contained in the head of a sperm?
- Genetic material
- Acrosome contains enzymes required for penetration of oocyte
What is the function of the mid piece of a sperm?
Mitochondria
What does the tail of a sperm provide?
Motility
What is the primary function of the ovaries?
Store eggs, ovulate one egg per cycle, produce sex hormones
Ovaries are essential for female reproductive health and hormone regulation.
What are the oviducts also known as?
Uterine or fallopian tubes
They play a critical role in receiving the ovulated egg and are the site of fertilization.
What is the main role of the uterus?
Site of embryo implantation
The cervix projects into the vagina, serving as a passage for sperm and menstrual flow.
What is oogenesis?
The process of female gamete production
It differs from spermatogenesis, as it produces only one viable gamete.
How many viable gametes are produced during oogenesis compared to spermatogenesis?
One viable gamete in females, four in males
This highlights a significant difference in gamete production between genders.
What remains in the oocyte during oogenesis?
Most cytoplasm
The polar body contains a haploid set of chromosomes and minimal cytoplasm.
What are the three layers of the uterus?
- Perimetrium or serosa
- Myometrium
- Endometrium
Each layer has distinct structural and functional roles in the reproductive process.
What type of tissue makes up the perimetrium?
Simple squamous epithelium and areolar connective tissue
This outer layer provides protection and support to the uterus.
What is the myometrium composed of?
Longitudinal, circular, and oblique layers of smooth muscle
It constitutes about 90% of the uterine mass, facilitating contractions.
What are the two layers of the endometrium?
- Stratum functionalis
- Stratum basalis
The functional layer changes during the menstrual cycle while the basal layer remains permanent.
What happens to the stratum functionalis during the menstrual cycle?
Thickness changes
It is shed during menstruation and rebuilt after each cycle.
What is the role of the stratum basalis?
Permanent layer that gives rise to new stratum functionalis after each menstruation
It is crucial for the regeneration of the functional layer.
What is the endometrial thickness during menstruation?
2-4MM
This thickness is characteristic of the menstrual phase in the menstrual cycle.
What is the endometrial thickness one week after menstruation?
5-7MM
This reflects the proliferative phase of the menstrual cycle.
What is the maximum endometrial thickness reached three weeks after menstruation?
Up to 16MM
This thickness is typically observed during the secretory phase.
What causes variation in endometrial thickness?
Changes in stratum functionalis
The stratum functionalis is the functional layer of the endometrium that undergoes cyclical changes.
How many lobes are present in mammary glands?
15-20 lobes
These lobes are surrounded by connective tissue and fat.
What are lobules in the context of mammary glands?
Smaller units within lobes
Lobules consist of compound alveolar glands that produce milk.
What is the function of lactiferous ducts?
Pass milk into the nipple
These ducts are essential for the delivery of milk during lactation.
What is the lactiferous sinus?
Dilated region of lactiferous ducts
It accumulates milk during nursing.
How many rounds of cell division occur in meiosis?
Two rounds of cell division
Meiosis is essential for the production of gametes.
What is the significance of hormones in reproduction?
Hormones are responsible for the development of sex-specific traits and characteristics.
What are the primary sex organs developed during embryonic and fetal development?
Primary sex organs are developed during embryonic and fetal development.
What are secondary sex characteristics and when do they develop?
Secondary sex characteristics develop at puberty.
Where are major sex hormones secreted from?
Major sex hormones are secreted by the gonads.
Name two types of androgens.
- Testosterone
- Dihydrotestosterone
What are the main types of estrogens?
- Estradiol
- Estrone
- Estriol
What is the role of progesterone in reproductive physiology?
Progesterone is involved in the regulation of the menstrual cycle and pregnancy.
How are sex hormones regulated?
Sex hormones are controlled via the hypothalamus and anterior pituitary.
What is the hypothalamic-pituitary-gonadal axis also known as?
HPO axis
What hormone does the hypothalamus secrete to regulate sex hormones?
Gonadotropin releasing hormone (GnRH)
What are the key gonadotropic hormones secreted by the anterior pituitary?
- FSH (Follicle Stimulating Hormone)
- LH (Luteinizing Hormone)
What are the functions of FSH in females?
- Growth of ovarian follicles
- Ovulation
- Menstruation
What are the functions of FSH in males?
- Promotes development of secondary spermatocytes from primary spermatocytes
- Increases androgen binding protein for binding of androgens
What are the functions of LH in females?
- Promotes follicle maturation
- Surge in mid-cycle helps ovulation
- Production by corpus luteum promotes maturation of the endometrium for implantation
What is the primary function of LH in males?
Stimulates testosterone production.
What does the hypothalamus secrete to regulate male reproductive function?
Gonadotropin-releasing hormone (GnRH)
GnRH stimulates the secretion of FSH and LH.
What hormones are stimulated by GnRH in males?
- FSH
- LH
FSH stimulates spermatogenesis, while LH stimulates testosterone secretion.
What is the role of FSH in male reproductive function?
Stimulates spermatogenesis via secretion of androgen binding protein (ABP)
ABP helps in the transport and concentration of testosterone.
What does LH stimulate in male reproductive function?
Testosterone secretion from interstitial cells
Interstitial cells are also known as Leydig cells.
What are the two distinct cycles controlled in female reproductive function?
- Ovarian cycle
- Uterine cycle
The ovarian cycle produces one ovulated oocyte per cycle, while the uterine cycle prepares the uterus for implantation.
What stimulates the secretion of FSH and LH in females?
Gonadotropin-releasing hormone (GnRH)
GnRH is crucial for the regulation of the menstrual cycle.
What is the primary action of FSH in the ovarian cycle?
Acts on growing follicles and stimulates estrogen secretion
Estrogen is vital for the development of oocytes and the regulation of the menstrual cycle.
How does LH affect estrogen concentration in females?
Increases estrogen concentration via conversion of androgens
This process occurs in the ovaries.
What happens to the dominant follicle during the ovarian cycle?
Continues development for ovulation
Negative feedback from estrogen reduces the development of other follicles.
What marks the beginning of the menstrual phase in the ovarian cycle?
First day of menstruation
This phase is characterized by the shedding of the stratum functionalis.
What role does FSH play during the menstrual phase?
Promotes primordial follicles to develop into primary and then secondary follicles
This growth is essential for future ovulation.
What occurs to the stratum functionalis during the menstrual phase?
It is shed due to low concentrations of progesterone and estrogens
This shedding leads to menstrual bleeding.
What causes an increase in prostaglandins during the menstrual phase?
Low concentrations of progesterone and estrogens
Prostaglandins cause constriction of blood flow to uterine arterioles.
What is the duration of the preovulatory (proliferative) phase?
6 - 13 days
What happens to secondary ovarian follicles during the preovulatory phase?
Some continue to grow and secrete oestrogens
What occurs to the dominant follicle during the preovulatory phase?
It becomes the mature or Graafian follicle, around 20mm in diameter
What is the effect of the dominant follicle on other follicles?
Oestrogen concentration decreases, reducing activation of other follicles
What triggers ovulation?
High oestrogen secretion causes the secretion of FSH and LH from the anterior pituitary
What happens to the mature follicle during ovulation?
It ruptures and releases the secondary oocyte
Where does the secondary oocyte go after ovulation?
It enters the uterine tube
What does the corpus luteum secrete during the secretory phase?
Large concentrations of progesterone
What happens to oestrogen concentrations during the secretory phase?
They drop
What happens to FSH and LH concentrations during the secretory phase?
They reduce
What are the hormone levels during the menstrual phase?
Oestrogen and progesterone are at their lowest levels
What occurs in the uterus during the menstrual phase?
Stratum functionalis sheds
What happens to FSH and LH concentrations during the menstrual phase?
They begin to rise
What triggers the proliferation of the functional layer in the proliferative phase?
Increasing oestrogen levels
What changes occur in the endometrium during the proliferative phase?
Increased synthesis of progesterone receptors and enlargement of glands
What happens to spiral arteries during the proliferative phase?
They increase in number
What prompts further development of the endometrium during the secretary phase?
Progesterone levels
Progesterone is crucial for maintaining the uterine lining for potential implantation.
What are the three key processes prompted by progesterone during the secretary phase?
- Further development of endometrium
- Glandular secretion of glycogen
- Formation of the cervical mucus plug
These processes support implantation and nourishment of a potential embryo.
What are oogonia?
Stem cells that divide by mitosis before birth to form primary oocytes
Oogonia are the precursors to oocytes in female reproductive development.
What stage do primary oocytes enter before birth?
Meiosis, but are arrested in prophase I
This arrest lasts until puberty when further development resumes.
What happens to the first meiotic division of oocytes?
It is unequal, producing a very small first polar body
The first polar body does not participate in further development.
At what stage are oocytes arrested before birth?
Prophase I of meiosis
This arrest ensures that oocytes are not fully developed until ovulation occurs.
When is the first meiotic division completed?
After puberty
This completion occurs during the menstrual cycle.
When is the second meiotic division completed?
Only if fertilization occurs
This division is critical for the maturation of the oocyte into a viable egg.
What is the outcome of the second meiotic division?
It is also unequal, producing a small second polar body
Similar to the first polar body, the second polar body does not contribute to development.
What must sperm do after entering the uterus?
Undergo capacitation
Capacitation prepares sperm for successful fertilization of the oocyte.
What changes occur during capacitation of sperm?
- Sperm flagella beat more vigorously
- Cell membrane prepares for contact with secondary oocyte
These changes enhance the sperm’s ability to fertilize the egg.
What barriers must sperm penetrate to fertilize an egg?
- Corona radiata
- Zona pellucida
These layers protect the oocyte and must be breached for fertilization to occur.
True or False: The first polar body plays a role in subsequent development.
False
The first polar body is a byproduct of meiosis and does not contribute to embryo formation.
What is the role of sperm acrosomal enzymes?
Digest an area of the zona pellucida
The zona pellucida is the protective glycoprotein layer surrounding the oocyte.
What happens after sperm entry into the oocyte?
The secondary oocyte completes meiosis
This process results in the formation of a mature ovum.
What are male and female pronuclei formed from?
The nuclei of the sperm and secondary oocyte
These pronuclei contain the genetic material from both parents.
What is syngamy?
The fusion of pronuclei to form a single nucleus
This results in the formation of a diploid zygote.
What is cleavage in the context of pre-implantation development?
Rapid post-fertilisation cell division
This process begins shortly after fertilization.
When does the first division of the zygote occur?
After 24 hours
This marks the beginning of the cleavage stage.
What are the cells produced during cleavage called?
Blastomeres
These cells are the result of the division of the zygote.
What is formed by days 3-4 of development?
The Morula
The morula is a solid ball of cells resulting from cleavage.
What enters the morula from the endometrium?
Uterine milk
Uterine milk provides nutrients to the developing embryo.
What forms in the center of the morula by day 10?
The blastocyst
The blastocyst is a hollow structure that will implant into the uterine wall.
What are the two distinct regions of the blastocyst?
- Inner cell mass (embryoblast)
- Outer cell ring (trophoblast)
The inner cell mass will develop into the embryo, while the trophoblast will contribute to the placenta.
When does the blastocyst attach to the uterine wall?
Around 6 days post-fertilization
This is known as the implantation stage.
What happens to the endometrium after implantation?
It is known as the decidua
This change supports the developing embryo.
What increases as the blastocyst attaches firmly to the endometrium at 7 days?
Endometrial vascularization
This increase in blood vessels supports the nutrient and gas exchange for the embryo.
What does the blastocyst secrete to aid in implantation?
Enzymes
These enzymes allow the blastocyst to invade the endometrium.
What surrounds the developing embryo and provides nutrients?
Decidua basalis
It will form the Maternal placenta.
What are the two layers formed by the cells of the embryoblast?
- Hypoblast
- Epiblast
Collectively known as the bilaminar embryonic disk.
What cavity forms in the epiblast?
Amniotic cavity
It eventually surrounds the whole embryo.
What does the yolk sac supply until the placenta is formed?
Nutrients
It is also an early source of blood cells and eventually forms gametes and part of the gut.
What forms around the outside of the embryo?
Chorion
Later forms the embryonic part of the placenta.
The bilaminar disk becomes what type of disk in the third week?
Trilaminar disk of primary germ layers
This includes endoderm, mesoderm, and ectoderm.
What does the endoderm develop into?
Epithelial lining of GI tract, respiratory tract, and other organs
It is one of the three primary germ layers.
What does the mesoderm develop into?
Muscles, bones, and other connective tissues
It is one of the three primary germ layers.
What does the ectoderm develop into?
Epidermis and nervous system
It is one of the three primary germ layers.
What is the function of chorionic villi in the placenta?
They permit the transfer of nutrients, waste, and respiratory gases between maternal blood and embryonic blood
Chorionic villi are finger-like projections from the chorion that extend into maternal lacunae.
What occurs during the first trimester of prenatal development?
Conception to 12 weeks, embryological to early fetal development, rudiments of major organ systems appear
This phase is critical for the initial formation of the embryo.
What are the key developments during the second trimester?
12 to 24 weeks, nearly complete development of organ systems
This phase focuses on refining and completing the development of organs.
What significant growth occurs during the third trimester?
Rapid fetal growth, most organ systems become fully functional, deposition of adipose tissue
This stage prepares the fetus for life outside the womb.
What is organogenesis?
The process of organ development during embryonic development from weeks 3 to 8
Weeks 4 to 8 are particularly crucial for the development of main organs.
What happens to the embryo starting from week 4?
The embryo becomes 3D, undergoes rapid growth, extensive vascularization, and neural tube development
These changes are essential for the proper formation of the embryo.
Fill in the blank: Maternal blood vessels are broken down, creating blood-filled spaces called _______.
lacunae
True or False: The chorionic villi are connected to the embryonic heart via umbilical blood vessels.
True
What is the duration of the first trimester in prenatal development?
Conception to 12 weeks
What is the time frame for the second trimester?
12 to 24 weeks
What are the three integrated trimesters of prenatal development?
- First Trimester
- Second Trimester
- Third Trimester
Each trimester has distinct developmental milestones and focuses.
What is the initial shape of the embryo?
Flat plate
The embryo undergoes folding to form a tube at both ends.
What is formed from endodermal folding during embryonic development?
Primitive gut
It forms the epithelial lining of the gastrointestinal tract.
At what week of gestation are all organ systems recognizable?
Week 8
This marks a significant milestone in embryonic development.
Which hormone levels are maintained by hCG during the first trimester of pregnancy?
Estrogen and progesterone
These hormones are secreted by the corpus luteum.
How long do hCG levels last during early pregnancy?
3-4 months
After this period, the placenta takes over hormone production.
When do estrogen and progesterone start being produced by the placenta?
After 3-4 months of pregnancy
This transition is crucial for maintaining pregnancy.
What happens to hCG concentration during pregnancy?
Peaks at quiescence
It is present in maternal urine and used in home pregnancy tests.
What triggers the initiation of labor?
Rising estrogen levels
This occurs in the final weeks of pregnancy due to placental cortisol secretion.
What effect does rising estrogen have on progesterone?
Reduces the effects of progesterone
This change helps prepare the body for labor.
What increases in response to rising estrogen levels before labor?
Oxytocin receptors
This prepares the uterus for contractions during labor.
What is the fetus totally dependent on during gestation?
The mother
This includes delivery of oxygen and nutrients, removal of wastes, and exchange of some antibodies.
What happens to the fetal lungs during gestation?
They are either compressed or contain amniotic fluid
This influences the development of the respiratory system.
When does surfactant production begin in the fetus?
Between 6-7 months
Surfactant is crucial for lung function at birth.
What triggers the respiratory muscles at birth?
Rising CO2 levels
This activates the respiratory center in the CNS.
What occurs during the first breaths of a newborn?
Large initial inspiration inflates lungs
This is followed by a rapid breathing rate.
What closes at birth to stop blood passage between atria?
Foramen ovale
This ensures proper circulation post-birth.
What does the ductus arteriosus become after it closes?
Ligamentum arteriosum
This change prevents blood flow from bypassing the lungs.
How long may it take for the ductus arteriosus to close?
Up to 3 months
This is part of normal cardiovascular adjustment after birth.
What happens to fetal umbilical vessels after birth?
They remodel
This is part of the transition from fetal to postnatal circulation.
Fill in the blank: During gestation, the fetus exchanges some _______ with the mother.
Antibodies
This provides the newborn with some immunity.
