The Reproductive System, etc. Flashcards
Testes
The organs that produce spermatozoa, They’re paired and lie in a sac called a scrotum, which keeps the spermatozoa at a constant temperature.
Tunica Albuginea of the Testes
A connective tissue capsule which surrounds each testis.
Septa of the Testes
Inward extensions which divide the testis into different compartments
Seminiferous Tubules
The sperm factory. Highly convoluted tubules inside the septal compartments, the site of spermatogenesis.
Rete Testis
A network of tubes where the seminiferous tubules join. They empty into the efferent ductules. The sperm then leaves through these.
Interstitial Cells of Leydig
Produce androgens, mostly testosterone.
Spermatic Cord
Encloses the nerve fivers, blood vessels, and lymphatics.
Epididymis
A structure that sits on top of each testis. It’s full of highly convoluted tubules which reice secretions from the testes via the efferent ductule. It has some smooth muscle that surround the tubules.
Functions of the Epididymis
- Monitors and adjusts the composition of tubular fluid
- Recycles damaged spermatozoa
- Stores spermatozoa and facilitates their maturation.
Vas Deferens
A continuation of the epididymis, lined by ciliated columnar epithelium. The cord swings over the urinary bladder and joins the duct of the seminal vesicle forming an ejaculatory duct that passes through the prostate gland and joins the urethra. The sperm moves along this due to peristaltic contractions. Functions to move the sperm from storage and into the urethra.
Seminal Vesicles
Produce about 60% of semen. It’s yellow, and very rich in fructose, which nourishes sperm, ascorbic acid, amino acids, and prostaglandins.
Prostate
Produces an alkaline fluid, rich in enzymes. It’s function isn’t completely clear. The alkalinity of the prostate fluid neutralizes the acidity of the female tract. It accounts for about 1/3 of semen.
Bulbourethral Glands
Small glands, lie at the bast of the penis. Produce a fluid which lubricates the urethra and neutralizes any uric acid present. Also called Cowpers glands.
Urethra
The common urogenital tract of the male. It carries both the semen and urine.
Penis
The copulatory organ of the male. It has an elongated shaft and an enlarged end, the glans.
Connective Tissue of the Penis
- The corpora cavernosa is the paired cylindrical bodies which contain the erectile tissue in the penis
- The corpora spongiosum is the single ventral column which surrounds the urethra
Erection
This process may be initiated by both psychic and tactile stimuli. Parasympathetic stimulation causes dilation of the arterioles that supply the erectile tissue. The increasing volume of erectile tissue compresses the veins which drain the penis so the blood stays.
Ejaculation
Caused by a sympathetic reflex causing rhythmic contractions of the epididymis, vas deferens, seminal vesicles, and the prostate gland. Normally between 2-6 mL are ejaculated. Following ejaculation, the arterioles to the penis constrict and pressure is taken off the veins. The blood leaves the penis and it returns to the flaccid state.
Impotence
The failure to attain or maintain an erection. It can be psychological, due to an ANS malfunction, a congenital problem with the shunt arterioles, or due to alcohol.
Hormonal Regulation in Males
FSH, LH, and testosterone are responsible for the hormonal regulation of reproductive processes.
FSH Stimulation in Males
FSH stimulates the production of sperm my acting on the sustentacular cells of the seminiferous tubules. Sustentacular cells act as nurse cells to sperm producing cells. FSH causes the sustentacular cells to release androgen binding protein which causes the cells to bind to testosterone. Testosterone then stimulates spermatogenesis.
Inhibin
Inhibits FSH
LH Stimulation in Males
LH stimulates the Leydig cells to produce testosterone. The Leydig cells are the interstitial cells between the seminiferous tubules. Since testosterone is required for sperm production, LH indirectly stimulates sperm production.
Testosterone
A steroid hormone, produced under the influence of LH. It initiates sexual differentiation in the fetus at about 5-6 weeks of gestation, and the descent of the testes from the body cavity into the scrotum.
Testosterone Effects on the Body
- Maturation and enlargement of the primary sex organs
- Initiates growth of body hair
- Initiates the lowering of the voice
- Stimulates development of male muscle and skeletal growth
- Helps FSH to stimulate spermatogenesis
- Regulates sex drive
- Affects the CNS
Sperm Structure
It has a head, an acrosome, which contains DNA and enzymes. The midpiece contains mitochondria and golgi apparatuses to produce ATP to allow for the tail movement.
Testis-Blood Barrier
Protection of sperm from the immune system. it prevents the membrane antigens of the sperm from escaping to the blood, which could provoke an immune response.
Anatomy of the Female
The female reproductive tract provides the same general functions as that of the male, but in addition, provides for the development of the fetus.
Germinal Epithelia of the Ovary
The outer covering of the ovary. Composed of simple columnar epithelium
Tunica Albuginea of the Ovary
Composed of fibrous connective tissue which connects to the germinal epithelium.
Ovarian Cortex
The outer layer of the ovary, where the primary follicles are found
Ovarian Medulla
The inner part of the ovary, it maintains the major blood vessels
Follciles
Contain an immature egg. Primary ones have a sigle layer of follicle cells
Corpus Luteum
A ruptured follicle
Ovarian Ligament
Anchors the ovary to the uterus
Uterine (Fallopian) Tubes
These are the tubes that receive the mature ovum from the ovaries and conduct it to the uterus. They’re connected to each ovary by ciliated finger-like projections, fimbriae. They’re lined by mucosa composed of ciliated columnar epithelium.
Infundibulum
Part of the uterine tube, it’s funnel shaped.
Uterus
A muscular hollow organ, shaped like a pear, which connects to the uterine tubes. The enlarged upper portion is referred to as the body and it tapers out into the isthmus which terminates with the cervix
Uterine Serosa
The outer layer
Uterine Myometrium
The very thick, muscular layer beneath the serosa
Uterine Endometrium
The lining of the uterus. It’s composed of thick, highly cellular connective tissue and simple columnar epithelium. This is where the embryo embeds itself and where the placenta forms. This is the layer which undergoes changes during the menstrual cycle.
Vagina
A muscular tube that leads from the cervix of the uterus to the outside. It serves as the female copulatory organ as well as the birth canal. It has a mucosal lining with a surface composed of stratified squamous epithelium.
External Genitalia
The collective name for all of the external genitalia is the vulva. Consists of the following: The mons pubis, labia minora, labia majora, vestibule, the clitoris, and surrounding glands.
Mammary Glands
Not involved In the actual reproductive process. Their function is to nourish the offspring
Composition of the Breasts
Nipple: the protruding tip surrounded by an areola. Both are pigmented and contain smooth muscle.
Adipose tissue: found in the breast, the more tissue, the larger the breast.
Glandular tissue: There to produce milk, about 20 glands arranged around the nipple.
Sexual Response in the Female
Brought about by both tactile and psychological factors. The clitoris will become erect due to blood engorgement. Erectile tissue at the opening of the vagina also becomes erect. The lining of the vagina becomes lubricated by secretions of glands around the cervix and uterus. After sufficient stimulation, a female will orgasm but there is no ejaculation.
FSH Stimulation in Females
It stimulates maturation of the ovarian follicle and the ovum. It also stimulates production of estrogen by follicle cells.
LH Stimulation in Females
It stimulates ovulation. It then stimulates the conversion of the ruptured follicle into the corpus luteum. The corpus luteum produces both estrogen and progesterone.
Estrogen Effects on the Body
They initiate puberty.
- Maturation and enlargement of the primary sex organs and characteristics
- Enlargement of the breasts
- Development of the female torso, primarily by regulating skeletal and adipose tissue changes
- Stimulates body hair growth
- Stimulation of skeletal growth in certain patterns, but the growth of the long bones is terminated.
- Plays a big role in the menstrual cycle
Progesterone
A hormone produced by the corpus luteum. It plays a key role in the menstrual cycle and pregnancy. It stimulates the development of the glandular apparatus in the breast.
Menstrual Cycle
A cycle of fertility that occurs every 28 days which invovles careful coordiation of all associated organs. The two features are ovulation, which occurs midway, and menstruation or bleeding, which occurs at the end of the cycle.
Maturation of the Ovum
At the beginning of the cycle, the primitive ovum is surrounded by a single layer of follicle cells, a primary follicle. FSH stimulates the cells to proliferate and the ovum to mature. As the follicle matures, a secondary follicle, it develops a fluid filled cavity in which the ovum is enclosed. At maturity, a tertiary follicle, the ovum sits on a pedestal inside of the fluid filled cavity.
Ovulation
Under hormonal stimulation, the follicle ruptures and ovum washes into the uterine tube.
Corpus Luteum
LH induces the ruptured follicle to fill with new cells and become the corpus luteum which is an endocrine gland that produces both estrogen and progesterone.
Endometrial Changes
The endometrium is where the fertilized egg will implant. Estrogen stimulates proliferation of the endometrium during the first two weeks of the cycle. Progesterone maintains the integrity of the endometrium during the second two weeks of the cycle. If pregnancy doesn’t occur then the endometrium sloughs off during the menstrual period.
Menstrual Cycle Details
Begins at the end of a cycle when all the hormone levels are low. There is a gradual increase of FSH. It stimulates several follicles to start the maturation process. Normally only one follicle will mature, the others will abort. Follicle cells begin to produce estrogen and inhibin, which depress FSH. Estrogen levels rise, stimulating the release of LH. This LH surge causes ovulation. LH converts the ruptured follicle into a corpus luteum which then produces high levels of progesterone and estrogen.
GNRH
A hormone released by the hypothalamus. It causes FSH and LH to be released by the anterior pituitary gland.
Menopause
A cessation of the menstrual cycle which occurs around age 52.
Gametogenesis
The formation of the sex cells, the sperm and the egg. Happens through a type of cell division called meiosis
Meiosis
A special kind of cell division that occurs only in the gonads. The overall result is the reduction of the chromosome number by half. The normal human chromosome number is 46, meiosis decreases the number to 23.
Karyotype
The complete set of chromosomes, all the alleles.
Genotype
The actual alleles or genes present
Phenotype
The physical characteristics that show through.
Sex determination
Two of the chromosomes, the X and Y, are non-homologous, and are designated the sex chromosomes because their presence determines sex. The X chromosome is a complete chromosome with a full compliment of genes while the Y is almost genetically inert. Thy is why men are more likely to express rare sex-linked recessive traits.
Abnormalities in Chromosome Number
Failure is the meiotic process can lead to sex cells with more or less than the 23 number. Generally cells that are missing a whole chromosome will not be viable, but those with an extra one might still be. Ex: Trisomy 21 produces Down’s syndrome; extra Y chromosomes don’t seen to have an effect; and an extra X in males leads to Klinefelter’s syndrome.
Spermatogenesis
Male aspect of gametogenesis. Sperm are generated in the seminiferous tubules.
- A diploid cell, a spermatogonia, begins meiosis and gives rise to a primary spermatocyte.
- The primary spermatocyte continues meiosis and undergoes the reductional division to create two haploid cells.
- Each secondary spermatocyte now undergoes the second meiotic division to form four haploid spermatids.
- Each spermatid undergoes a metamorphosis (spermiogenesis) to give rise to mature sperm.
Oogenesis
The female gametogenesis. In this, the cell divisions are unequal.
- A diploid oogonium begins the meiotic process yielding a primary oocyte
- The diploid primary oocyte undergoes reduction division to form a single haploid secondary oocyte and a polar body.
- The secondary oocyte undergoes the equation division resulting in the ovum and another polar body.
- Ovulation occurs while the female cell is still a secondary oocyte. If it’s fertilized, then it will complete meiosis and development.
Fertilization
The union of the sperm and egg which restores the diploid number. It happens high in the uterine tube. Only one sperm actually fertilizes, but a large number of them are needed to accomplish fertilization.
Roadblocks to Fertilization
The cells around the ovum are held together by hyaluronic acid. Each sperm produces an enzyme hyaluronidase which breaks down hyaluronic acid and separates the cells surrounding the ovum. Because the sperm are so small, it takes a combined effort of many individuals to break the corona radiata.
Fast Block to Polyspermy
As soon as the first sperm’s plasma membrane contacts the egg’s membrane, sodium channels open allowing Na+ to flood into the egg, depolarizing the membrane. This depolarization prevents other sperm from making contact.
Cortical Reaction
After the sperm penetrates the membrane, depolarization of the egg also leads to an increase in intracellular calcium. Calcium preps the egg for division, and causes the rupture of the cortical granules around the ovum pushing all the sperm away from the membrane and forming a barrier.
Granulation
While still in the uterine tube, the fertilized ovum begins to divide mitotically and by the time it reaches the uterus it has become a hollow ball of cells. It goes from a zygote —> 4-cell stage (2 days) —> Morula, a solid ball of blastomeres (3 days) —> Early Blastocyst, a hollow morula (4 days) —> Implanting Blastocyst, an inner cell mass, a cavity, and a layer of trophoblast layer (7 days)
Trophoblast
This layer of cells will acquire mesoderm and become the chorion which helps from the placenta and the umbilical cord.
Implantation
The process by which the embryo burros into the endometrium. Upon arrival at the uterus, the embryo produces an enzyme which erodes a hole into the endometrium. The embryo then implants itself into this hole.
Placentation
The formation of the placenta, the life line between the mother and the fetus. The principle membrane of the placenta is the chorion which separates the maternal circulation from the fetal circulation.
Human Chorionic Gonadotropin
Maintains the corpus luteum. Initially produced by cells of the embryo and then by the placenta, produced for about 3 months. It’s usually detectable in the urine and blood for a week after fertilization.
The Amnion
A membrane that forms inside of the chorion and around the fetus. It is filled with fluid and the fetus floats inside of it. Its there for protection, it absorbs shock.
Yolk Sac
A vestigial membrane in humans because there is virtually no yolk in the ovum. It serves as a source of cells which migrate to the developing gonads. The earliest site of blood formation.
Allantois
Another membrane derived from the fetus it serves as a storage site for embryonic wasters in most animals. In humans it serves as the structural base for the umbilical cord. It along with the yolk sac is found in the umbilical cord.
Cleavage
Rapid mitotic division occurring from the zygote to the pre embryonic form.
Parturition
The process of birth. The movement of the fetus from the uterus into the birth canal and its expulsion, brought about strong contractions of the smooth muscle in the uterus.
Expulsion Stage
The forceful expansion of the baby from the birth canal.
Twinning
- Fraternal: Two eggs have formed and each is fertilized independently of the other by two separate sperm. Each embryo forms it’s own placenta.
- Identical: Result from a single fertilization. Shortly after development begins, the blastocyst is broken in two. Each part goes on to form a complete individual. They share a common placenta and as they resulted from a single fertilization, they’re genetically identical.
In Vitro Fertilization
Infertility is a problem experienced by many couples. Modern technology has permitted the actual harvesting of eggs and sperm and subsequent fertilization in test tubes.
Infertility
A major problem in infertility is low sperm counts in men.
