Study of Body Function - Sexual Reproduction

Flashcards covering key vocabulary and concepts related to sexual reproduction from lecture notes.

Sexual Reproduction

Combining genes from two individuals in random ways to produce a new individual, allowing for genetic variation and adaptability.

Germ Cells or Gametes

Cells (sperm and ova) formed in the gonads (testes and ovaries) via meiosis, which cuts the chromosome number in half.

Fertilization

The process where ova and sperm fuse to restore the original chromosome number.

Autosomal Chromosomes

Having the same (but not identical) genes on them; 22 pairs in humans.

Genomic Imprinting

An epigenetic change that silences the allele from one parent.

X Chromosomes

Females have two of these, while males have one along with a Y chromosome.

Y Chromosome

Males have one of these, which determines the sex of a child.

X Chromosome Inactivation

The inactivation of one of the two X chromosomes in females, producing a visible Barr Body.

Barr Body

A visible structure that can easily help to determine the sex of a cell.

Testis-Determining Factor (TDF)

The signal that determines whether embryonic gonads become testes or ovaries; coded for by the SRY gene.

SRY Gene

A gene on the short arm of the Y chromosome that codes for testis-determining factor (TDF).

Germinal Cells

Cells that differentiate into sperm within the seminiferous tubules.

Sertoli Cells

Supporting cells that differentiate within the seminiferous tubules.

Leydig Cells

Cells that appear around day 65 and make testosterone; clustered in the interstitial tissue between the seminiferous tubules.

Testosterone

The major androgen produced by Leydig cells, stimulating the development of male reproductive organs.

Cryptorchidism

The condition of undescended testes.

Kleinfelter's Syndrome

The male has 47 chromosomes (XXY), leading to genetic infertility and lower testosterone levels.

Turner's Syndrome

The female has only one sex chromosome (X) and a total of 45 chromosomes, leading to genetic infertility and lower estrogen levels.

Wolffian (Mesonephric) Ducts

Ducts that can become the male tract.

Müllerian (Paramesonephric) Ducts

Ducts that can become the female tract.

Anti-Müllerian Hormone (AMH)

Secreted by Sertoli cells, causing the Müllerian ducts to regress.

Testosterone

Stimulates the development of the Wolffian duct into the epididymis, ductus deferens, seminal vesicle, and ejaculatory duct.

Testosterone

Masculinizes the urogenital sinus, labioscrotal swelling, genital tubercle, and urethral folds into male external genitalia.

DHT (Dihydroxytestosterone)

Converted from testosterone, it is necessary for the development and maintenance of male external genitalia.

Hermaphroditism

Both ovarian and testicular tissue exist in the body due to problems in zygotic mitosis.

Pseudohermaphroditism

The individual has ovaries or testes, but accessory structures are incomplete or inappropriate for the genetic sex.

Female Pseudohermaphroditism

May be due to excessive secretion of adrenal androgens in a female, leading to male external genitalia.

Male Pseudohermaphroditism

May be due to testicular feminization syndrome, where testes make testosterone but receptors don't work, or due to inability to make 5α-reductase.

Gonadotropic Hormone

Hormones that the anterior pituitary releases at puberty.

Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

Produced in the anterior pituitary gland of both males and females, stimulating spermatogenesis or oogenesis, gonadal hormone secretion, and maintenance of gonadal structures.

Gonadotropin-Releasing Hormone (GnRH)

Controls the release of FSH and LH from the hypothalamus.

Inhibin

Secreted by Sertoli cells in testes and granulosa cells of ovarian follicles, specifically inhibiting the release of FSH.

Kisspeptins

An excitatory neuropeptide that helps establish the cyclical female pattern of GnRH secretion.

Secondary Sex Characteristics

Includes growth spurt, breast development, and menarche (first menstrual flow) in girls.

Secondary Sex Characteristics

Includes later growth spurt, body, muscle, penis, and testis growth in boys.

Excitation Phase of Sexual Response

Characterized by increased muscle tone, vasocongestion of sexual organs; also called arousal.

Plateau Phase of Sexual Response

Continued vasocongestion during sexual response.

Orgasm Phase of Sexual Response

Contraction of the uterus/vagina and male ejaculatory organs during sexual response.

Resolution Phase of Sexual Response

The body returns to pre-excitation condition during sexual response; men experience a refractory period.

Seminiferous Tubules

Compartments that is where spermatogenesis occurs; FSH receptors are found on Sertoli cells here and FSH influences spermatogenesis.

Interstitial Tissue

Compartment that is where Leydig (interstitial endocrine) cells make testosterone; also filled with blood and lymphatic capillaries; LH receptors are found on Leydig cells.

FSH Secretion Control

Maintained by testosterone and inhibin secretion.

Testosterone Derivatives

Converted by 5α-reductase to DHT and other androgens; converted to estradiol-17β by aromatase enzyme.

Estradiol

Secreted by Sertoli cells, Leydig cells, and developing sperm; role in spermatogenesis, regulating the environment of developing sperm, fluid reabsorption, and sealing epiphyseal plates.

Spermatogonia

Diploid cells that first go through mitosis to increase the number of cells, one of the daughter cells (the primary spermatocyte) continues through meiosis; the other daughter cell remains a spermatogonial cell.

Spermiogenesis

Maturation of spermatids into functioning spermatozoa; protamines replace histones, cytoplasm removed by Sertoli cells, acrosome forms, mitochondria concentrated in spirals.

Acrosome

Cap of digestive enzymes that forms during spermiogenesis.

Sertoli Cells

Creates a blood-testis barrier, secretes FAS ligand, envelops developing sperm, phagocytoses spermatid cytoplasm, and secretes androgen-binding protein (ABP).

Androgen-Binding Protein (ABP)

Binds to testosterone and concentrates it in the seminiferous tubule lumen; production stimulated by FSH.

Epididymis

The site of sperm maturation and storage; sperm become motile here.

Seminal Fluid

Contains fructose (energy for sperm).

Prostate Fluid

Contains citric acid, calcium, and vesiculase; enzyme that causes semen to coagulate after ejaculation.

Vasectomy

Most widely used and reliable form of male contraception; vas deferens is cut and tied to prohibit sperm transport.

Ovaries

Female gonads; site of oocyte and sex steroid production.

Uterine (Fallopian) Tubes

Have fimbriae that partially wrap around the ovaries and “catch” the oocyte after ovulation; most common site of fertilization.

Endometrium

Inner layer of the uterus, where embryo implants and develops; made of the stratum basale and stratum functionale.

Myometrium

Middle muscle layer of the uterus; contracts to expel baby at birth.

Uterine Fibroids (Leiomyomas)

Benign tumors that form in the uterine smooth muscle (myometrium); stimulated by estrogen and progesterone.

Primary Oocytes

Begin meiosis to produce primary oocytes; oogenesis is stopped at prophase I of meiosis I.

Primary Oocytes

Contained within primary follicles that have one layer of cells; some develop fluid-filled vesicles called secondary follicles.

Corona Radiata and Zona Pellucida

Cell layers around the oocyte that serve as a barrier for sperm entry.

Secondary Oocytes

Finishes meiosis I to become a secondary oocyte (plus a polar body); begins meiosis II, but stops at metaphase II; meiosis II will complete, only if there is fertilization of the ovum.

Ovulation

The Graafian follicle becomes so big it bulges out of the ovary when hormones stimulate the follicle to burst and release the secondary oocyte.

Corpus Luteum

After ovulation, the remaining follicle becomes this--which secretes both estradiol and progesterone and the hormones play a role in the menstrual cycle and maintaining a pregnancy.

Menstrual Cycle

Describes the 28-day cycle of endometrial buildup and sloughing in response to ovarian hormones.

Ovarian Follicular Changes

Includes the follicular phase, ovulation, and luteal phase.

Ovarian Follicular Phase

Initiated by FSH; also upregulates the number of FSH receptors on the follicles → sensitivity to FSH increases

Ovulation

FSH causes the Graafian follicle to bulge out of the ovary wall and LH surge begins around 24 hours before.

Ovarian Luteal Phase

After ovulation, LH stimulates the ruptured follicle to become a corpus luteum which secretes estradiol and progesterone.

Proliferative Phase

Occurs while ovary is in the follicular phase; increasing levels of estradiol stimulate the growth of the stratum functionale of the endometrium.

Secretory Phase

Occurs while the ovaries are in the luteal phase; secretion of progesterone stimulates the development of uterine glands, which store glycogen.

Menstrual Phase

Occurs as a result of the fall in estradiol and progesterone when the corpus luteum degenerates; arteries constrict and cells die.

Polycystic Ovarian Syndrome (PCOS)

The ovaries contain follicles that become fluid filled cysts and secrete excessive amounts of androgens.

Pheromones

Odor molecules that can synchronize the menstrual cycle.

Functional Amenorrhea

Cessation of menstruation caused by inadequate FSH and LH from inadequate GnRH; comes from intense physical exercise, stress, and very low body fat.

Contraceptive Pill

Includes synthetic estradiol and progesterone; acts like a prolonged luteal phase producing a negative-feedback inhibition of GnRH, so ovulation never occurs.

Menopause

Characterized by cessation of ovarian activity and menses due to changes in the ovaries, not to decreases in FSH and LH.

Capacitation

Must occur for a sperm to fertilize the ovum--takes at least 7 hours after ejaculation and the pH increases, which leads to hyperactivation of the flagellum due to progesterone and the opening of CatSper channels.

Acrosomal Enzymes

The association between the acrosome cap and zona pellucida cells stimulates the entry of Ca2+ and then the release of these. This enables the sperm to "digest" the zona pellucida on its way into the oocyte.

Cleavage

Rapid mitosis that begins 30 to 36 hours after fertilization, which forms a ball of cells called a morula. It enters the uterus about 3 days after fertilization.

Blastocyst

Forms from continued division and has an inner cell mass which will become the fetus and trophoblast which will become the chorion à placenta.

Trophoblast cells

Secrete an enzyme that allows the blastocyst to “eat” into the endometrium; the side containing the inner cell mass goes in first.

Totipotent

Cells of early cleavage that are will divide to become every cell in the body .

Pluripotent Embryonic stem cells

Inner cell mass cells cultured in vitro which are able to become any type of cell in the body and form the three embryonic germ layers.

Adult Stem Cells

Found in the hippocampus, subventricular zone of the brain, intestinal crypts, bulge of the hair follicle, and bone marrow; can give rise to several types of related cells.

Induced Pluripotent Stem (IPS) Cells

Adult fibroblast cells changed into pluripotent stem cells using retroviruses; could serve many purposes

Regenerative Medicine

Developing future medical treatments using stem cells.

Chorionic Gonadotropin (hCG)

Released by the blastocyst during implantation and acts like LH to keep the corpus luteum functional, releasing estradiol and progesterone.

Chorionic Membranes

Formed from day 7 to day 12, the chorion splits into: Cytotrophoblast (inner) and Syncytiotrophoblast (outer).

Inner Cell Mass of the Blastocyst

The developing inner mass cells will become--Endoderm: will become the gut organs, Ectoderm: will become the skin and nervous system, and the Mesoderm will develop later to become--the muscles, bones, and connective tissues.

Genetic Abnormalities

Amniocentesis is used for this purpose--samples from the amniotic fluid can help diagnose genetic abnormalities such as Down syndrome.

Umbilical Arteries

These deliver fetal blood to placental vessels.

Protein Hormones

Placenta secretes these

Chorionic gonadotropin

Acts like LH in the ovary and as a thyroid-stimulating hormone

Growth hormone-variant (hGH-V or placental growth hormone)

Works like growth hormone and supplants maternal GH; work to increase lipolysis to increase blood fatty acid levels and glucose- sparing to increase blood glucose levels.

Chorionic somatomammotropin (hCS or placental lactogen)

Acts similar to growth hormone and prolactin; Works with GH from the mother to produce a diabetic-like effect in the pregnant woman and this diabetic-like effect helps ensure a sufficient supply of glucose for the placenta and fetus and May lead to gestational diabetes.

Labor-Promoting Uterine Proteins

These are inhibited by Progesterone in the uterus.

Human Chorionic Gonadotropin (hCG)

The secretion of this hormone declines by the 10th week as the placenta takes over hormone production to maintain the pregnancy.

Oxytocin

The powerful contractions needed to expel the fetus occur in response to this from the mother’s hypothalamus and prostaglandins from the placenta.

Cortisol

It stimulates the production of surfactant in the fetal lungs.