Reproductive System Flashcards
Gametogenesis
Process of producing gametes
What are the male and female gametes?
sperm and ova
Where goes gametogenesis occur?
Only occurs in gonads
What cellular process is used production of gametes?
meiosis
Chromosome
piece of DNA containing genes
Chromatid
½ of replicated chromosome
Haploid
having one copy of each chromosome (1N)
Diploid
having 2 copies of each chromosome (2N)
Homologous pairs
2 copies of the same chromosome
Zygote
cell that is formed by fusion of gametes
Meiosis
2 cell divisions with only one DNA replication
- Halves the chromosome number
Interphase
normal cell growth and functioning;
- DNA replication happens here
Meiosis I: Prophase l
- Chromosomes condense; nuclear membrane disappears
- Synapsis: homologous pairs come together to form a tetrad
- Crossover
- Formation of spindle
Meiosis I: Metaphase I
tetrads line up in middle
Meiosis I: Anaphase I
homologous pairs separate
Meiosis I: Telophase I
reforming of nucleus
Meiosis I: Cytokinesis
splitting of cytoplasm
- 2 haploid cells
Meiosis II: Prophase II
- chromosomes condense
- nuclear membrane disappears
- formation of spindle
Meiosis II: Metaphase II
Chromosomes line up in center
Meiosis II: Anaphase II
separation of sister chromatids
Meiosis II: Telophase II & cytokinesis
reforming of
nucleus and division of cytoplasm
Results of Meiosis
4 haploid cells
- All genetically different due to crossover
Scrotum
External sac that contains testes
What is the function of the scrotum?
Function is to regulate temperature of testes
Why does the temperature of sperm need to be regulated?
Human sperm do not develop normally at body temperatures (so put on outside of the body)
What muscles are used by the scrotum to regulate its temperature?
Cremaster and dartos muscles (rise and lower for temp regulation)
Testes
Paired glands in the scrotum
What is the function of the testes?
Site of sperm production
The testes contain what structures?
lobules
Lobules
compartments containing seminiferous tubules
What cells are present in the lobules?
Sertoli cells (nurse cells)
Spermatogenic cells
Leydig cells (interstitial cells)
Sertoli cells (nurse cells)
supporting cells that protect and secrete nutrients for developing sperm
Spermatogenic cells
give rise to sperm through meiosis (through lots of complex process become sperm)
Leydig cells (interstitial cells)
produce testosterone
Epididymis
- joins to the ductus deferens
- Comma shaped organ located on the surface of each testis
Epididymis function
- Sperm travel from testes to epididymis
- Functions as a site of sperm maturation and short-term storage
Ductus (Vas) deferens
- Tubule that stores sperm and conveys them to the urethra
- Can store sperm for one month
Ejaculatory ducts
- Located posterior to bladder, just before the urethra
- Receive fluid from seminal vesicles and sperm from vas deferens
Seminal vesicles
Pouch like structures posterior to bladder, just above rectum
Seminal vesicles function
- Produce 60% of volume of semen
- Secrete alkaline fluid containing fructose, prostaglandins and clotting proteins
Prostate gland
Gland located at base of bladder and surrounding the urethra
Prostate gland function
Secretes a slightly acidic fluid containing seminalplasmin and enzymes
- Produces 25% of semen’s volume
- Contributes to sperms motility and viability
Bulbourethral (Cowper’s) glands
Size of a pea, located on either side of urethra below prostate
Bulbourethral (Cowper’s) glands function
- Secrete alkaline fluid to neutralize acid environment in urethra
- Secrete lubricating mucus (pre-…..yes)
Penis
- Male copulatory organ
- Contains urethra
- Contains erectile tissue that fills with blood
What are the erectile tissues of the penis?
Corpora cavernosa (2 chambers)
Corpora spongiosum
Glans penis (head of penis) is extension of corpora spongiosum
An erection is what kind of reflex?
parasympathetic reflex
What factors contribute or cause an erection?
Visual, tactile (touch), olfactory, auditory or imagined
Release of Nitric Oxide (NO) causes vasodilation
- Increased blood flow
Corpora fill with blood, putting pressure on veins that normal drain penis
Priapism
penis maintains a prolonged, rigid erection in the absence of appropriate stimulation
Ejaculation is what kind of reflex?
sympathetic reflex
How does ejaculation occur?
- Smooth muscle at base of urinary bladder closes to prevent urine from being expelled or sperm from entering bladder
- Peristaltic contractions
Spermatogenesis
Sperm production
Sperm production
- takes 65-75 days
- Occurs from puberty till death
Spermatogenesis process
Spermatogenic cells (precursor cells) become 2N spermatogonium
Spermatogonium divide to produce primary spermatocyte (2N)-mitosis
Primary spermatocyte undergoes meiosis I to form secondary spermatocytes (1N)
Secondary spermatocytes undergo meiosis II to form 4 spermatids (1N)
- Joined by cytoplasmic bridges
Spermatids undergo differentiation (no make more) to form sperm
- Spermiogenesis
What hormones control Spermatogenesis?
- Gonadotropin-releasing hormone
- Luteinizing hormone
- Follicle-stimulating hormone
- Testosterone
Gonadotropin-releasing hormone
stimulates the anterior pituitary which stimulates the release of:
- Luteinizing hormone
- Follicle-stimulating hormone
Luteinizing hormone
stimulates Leydig cells to secrete testosterone (targets testes…i think)
Follicle-stimulating hormone
works with testosterone on Sertoli cells to control the rate of spermatogenesis
Testosterone
stimulates spermatogenesis and secondary sexual characteristics
Semen characteristics
Mixture of sperm and seminal fluid
Mean volume: 2.5 - 5 ml
Sperm count: 20 – 100 million/ml
pH 7.2 - 7.7
Also contains antibiotics to kill bacteria in the urethra and vagina
What sperm count is needed for a male to be considered infertile?
Counts below 20 million/ml
- High numbers because few numbers reach secondary oocyte
Ovaries
- Homologous to testes
- Located to either side of the uterus, in the pelvic cavity
- Covered by germinal epithelium
Structures of the ovary
- Tunica tissue albunea
- Ovarian cortex
- Ovarian medulla
- Ovarian follicles
- Mature follicle
- Corpus luteum
Tunica tissue albunea
capsule of dense connective
Ovarian cortex
dense connective tissue containing ovarian follicles
Ovarian medulla
loose connective tissue containing blood and lymph vessels and nerves
Ovarian follicles
Composed of öocytes in various stages
- Surrounded by support cells
- Follicular cells
- Granulosa cells
Follicular cells =
primordial foilicles
Granulosa cells =
developing follicle
What is the function of the follicular and granulosa cells?
Secrete nutrients for developing oocyte and secrete estrogens
Mature follicle
releases secondary oocyte during ovulation
Corpus luteum
- remains of ovulated mature follicle
- produces progesterones, estrogens, relaxin, and inhibin
Fallopian tubes
- Small tubes that extend from near the ovaries to the uterus
- Functions to transport the secondary öocyte to uterus
- contain Cilia and muscular contractions that push oocyte along
- Fertilization usually occurs here
Infundibulum
End of Fallopian tube near ovary
- Open to pelvic cavity
Funnel-like structure that helps guide oocyte to Fallopian tube
- Fimbriae (finger-like projection) (be trying to grab the oocyte)
Uterus
- Located between the urinary bladder and the rectum
- Site of implantation of embryo, development of fetus, and labor
What are the three parts of the uterus?
- Fundus
- Body
- Cervix : part that opens into vagina
What are the three tissue layers of the uterus?
- Perimetrium
- Myometrium
- Endometrium
Perimetrium
Outer layer, simple squamous
Myometrium
Middle layer
Has 3 layers of smooth muscle (push da baby)
Endometrium
Inner layer, highly vascularized (blood vessels)
Sloughed off during menstruation
The endometrium contains what structures?
Uterine glands = contain nutrients for embryo
Spiral arteries = blood vessels; these motherfuckers are responsible for cramping
Vagina characteristics
Passageway from the cervix to the outside
The mucosal layer is continuous with the uterus
Made of stratified squamous epithelium, 2 layers of smooth muscle and connective tissue
pH is acidic to retard bacterial growth
Vulva
- Protective external structure
- Plays role in sexual arousal
- Composed of:
- Mons pubis
- Labia minor and labia major
- Clitoris (homologous to glans penis)
Oogenesis
Production of ova
How is male and female gamete production different?
males produce sperm from puberty to death; females are born with all the eggs they’ll ever have
Oogenesis: First part
Ovarian germ cells differentiate into oogonia
Öogonia develop into primary öocytes (2N)
Primary öocyte enters into prophase I of meiosis during fetal development and stops
Do not complete meiosis I until after puberty
Each month after puberty, a primary oocyte will resume meiosis I to form a secondary öocyte and a polar body
Atresia
the degeneration and resorption of several follicles and their ovules (a form of apoptosis) prior to the maturation and release of one ovule from a healthy follicle
Oogenesis: Second part
Secondary öocyte proceeds with meiosis II up to metaphase II (dis also no finish but get further)
Secondary öocyte is released from mature follicle during ovulation
If fertilization does not occur the secondary oocyte degenerates
If fertilization does occur
- The secondary oocyte resumes meiosis II forming ovum and polar body
- Sperm and egg nuclei fuse and a zygote is formed
Female Reproductive Cycle
- Monthly cycle in nonpregnant females from puberty to menopause
- Average 28 days in length
What are the 2 cycles of the Female Reproductive Cycle?
Ovarian
- Maturation of oocyte
Menstrual cycle (in uterus)
- Preparation of endometrium for implantation
What hormones are responsible for regulating the female reproductive cycle?
- Gonadotropin-releasing hormone
- Luteinizing hormone
- Follicle-stimulating hormone
- Estrogen
- Progesterone
- Relaxin
- Inhibin
Female Reproductive Cycle: Gonadotropin-releasing hormone
Controlled by gonadotropin releasing hormone from hypothalamus
GnRH stimulates the release of FSH and LH from anterior pituitary
Female Reproductive Cycle: Luteinizing hormone
- stimulates further development of the follicle
- full secretion of estrogens
- ovulation
- development of the corpus luteum
- stimulates production of hormones
Female Reproductive Cycle: Follicle-stimulating hormone
initiates follicular growth and secretion of estrogens
Estrogen
- Promotes the development and maintenance of female reproductive structures, secondary sexual characteristics, and breast development
- Increases protein anabolism
- Lowers blood cholesterol
- Inhibits release of GnRH, LH, FSH
Progesterone
- Secreted by corpus luteum
- Acts synergistically with estrogen for endometrial development
- Helps maintain pregnancy
- Inhibits release of GnRH and LH
Relaxin
Released by corpus luteum
Relaxes uterus, improving chances of implantation
During pregnancy, released by placenta the relax uterus for fetal growth
Increases flexibility of pubic symphysis at end of pregnancy
Inhibin
only want to expel one oocyte at one type so stops growth of other follicles and hormones
Secreted by growing follicle and corpus luteum
Inhibits secretion of FSH
What are the phases of the female monthly cycle?
- menstrual phase
- pre-ovulatory phase
- ovulation
- post-ovulatory phase
Menstrual phase
- At beginning of cycle
- Lasts approximately 5 days
Several follicles begin to mature into secondary follicles
- GnRH and FSH are high
- May take several months to develop
Menstrual flow
- Endometrial lining is shed due to lack of progesterone
- 50-150 ml of blood, fluid and tissue
Pre-ovulatory phase
- Between menstruation and ovulation
- Follicles continue to grow under influence of FSH
- At about day 6, one follicle outgrows others
- Dominant follicle secretes estrogens and inhibin
- FSH levels decrease
- Other follicles undergo atresia (degrade)
- Endometrial lining begins to thicken
LH levels begin to rise at end of phase
Ovulation
- Occurs generally on day 14
- High levels of LH caused by high levels of estrogen
Release of the secondary oocyte
- ~9 hrs after LH spike
Oocyte then travels into Fallopian tube or is lost in abdominal cavity
Post ovulatory phase
- Lasts approximately 14 days (has the most variation in women)
LH stimulates ruptured follicle to become corpus luteum
Corpus luteum secretes progesterone and some estrogens, relaxin and inhibin
Estrogens and progesterone stimulate growth of endometrium
- Wall thickens in preparation for implantation
- Is thickest about one week after ovulation
Female monthly cycle: If oocyte is not fertilized
Corpus luteum only survives about 2 weeks
Progesterone and estrogen levels decrease (endometrium lining begins to degrade again)
Levels of GnRH and FSH begin to rise
Cycle begins again
Female monthly cycle: If oocyte is fertilized
Embryo implants into endometrial lining
Embryo produces human chorionic gonadotropin (hCG)
hCG stimulates growth of corpus luteum
Corpus luteum continues to secrete hormones and pregnancy develop
