Reproductive System Flashcards

Flashcards covering the key vocabulary and concepts related to the reproductive system, hormones, and processes.

Gonads

The primary reproductive organs responsible for producing gametes and hormones, including the testes in males and ovaries in females. The gonads produce haploid gametes and secrete gonadal hormones

Reproductive Systems Components

Gonads, External & Internal Genitalia / Reproductive tracts, Ducts, Accessory sex glands

Mullerian duct

Female reproductive system development

Wolffian duct

Male reproductive system development

Gonads (primary reproductive organs)

Testes in males, Ovaries in females

Gametes

Germ cells

Gametogenesis

Production of haploid gametes

Steroid hormones

(testosterone, progesterone, estrogens); produced from cholesterol (ovaries, testes, adrenal cortex)

Gonadotropins

peptide/protein hormones; Follicle-stimulating hormone (FSH), Luteinising hormone (LH), Chorionic gonadotropin (hCG)

Oxytocin

a peptide/protein hormone; produced in the hypothalamus, excreted by the pituitary gland

Enzymes Involved in Steroidogenesis

CYP & HSD enzymes, which perform sequential enzymatic reactions to convert cholesterol into steroid hormones.

Testis Main Steroid Hormone

Testosterone (androgen)

Ovary Main Steroid Hormones

Estradiol (estrogen) and progesterone (progestogen)

Genetic Sex Determination

Combination of sex chromosomes (XX = Female, XY = Male). The sex determining region of the Y chromosome codes for production of testis determining factor which directs differentiation to testes and degeneration of mullerian ducts. The abscence of this factor leads to ovarian development and the degeneration of wolffian ducts.

Testosterone Reproductive Actions

Growth & maturation of genitalia, spermatogenesis, libido at puberty

Testosterone Non-Reproductive Actions

Protein anabolic effect, Bone growth at puberty

Folliculogenesis

production of ovulatory follicle

Oogenesis

production of haploid oocyte

Hormones made by follicle

androstenedione & estradiol

Hormones made by corpus luteum

progesterone & estradiol

Estradiol Main Actions

oocyte maturation & release (ovulation), development of secondary female sexual characteristics (e.g. breast growth / proliferation), transport of sperm

Progesterone Main Actions

early embryo nutrition, breast differentiation (development of lobuloalverolar tissue – ability to produce milk)

Menstrual Cycle Phases

menstrual phase (days 1-5), proliferative phase (days 5-14), secretory phase (days 15-28)

Ovarian Cycle Phases

follicular phase, luteal phase

Follicular Phase

oogenesis & estradiol secretion, controlled by FSH, LH & estradiol

Ovulation

mid-cycle, maturing follicle releases mature secondary oocyte, triggered by LH surge, high level of estradiol

Luteal Phase

LH differentiates follicular remnants (granulosa and theca cells) into CL, CL produces progesterone & estradiol

LH and FSH Source

Anterior pituitary gland

Estradiol Source

Follicle and CL

Progesterone Source

CL only

Testis Location

Scrotum. remains cool due to sperm needing cool environment. not due to its external environment

Seminiferous Tubules Definition

Site of spermatogenesis where sertoli cells are found

Sertoli Cells Functions

Stimulated by FSH to release ABP to create a large concentration of Testosterone for spermiogenesis, secrete inhibin to regulate FSH levels, support and nourish developing sperm, and form the blood-testis barrier.

Leydig Cells

Synthesise / secrete testosterone (stimulated by LH) for the development of male secondary sexual characteristics and spermatogenesis in the testes.

Hypothalamo-Pituitary-Testicular Axis

GnRH (Hypothalamus) -> FSH & LH (Anterior Pituitary) -> Sertoli and Interstitial cells (Testis) -> Gametogenesis and Testosterone Production

Spermatogenesis

testosterone (synthesised by leydig cells) and FSH stimulate spermatogenesis. Testosterone stimulates mitotic & meiotic divisions, FSH stimulates remodelling of haploid spermatids -> spermatozoa

Spermatogenesis Phases

mitotic proliferation (spermatogonia), meiosis (I & II), packaging / sperm maturation (spermiogenesis)

FSH Importance in Spermatogenesis

Stimulate the maturation of spermatids into spermatozoa and support Sertoli cell function. important in early stages of meiosis

Androgens Importance in Spermatogenesis

Latter stages plus spermiogenesis

Epididymis Role

Sperm complete spermiogenesis in caput epididymis, Stored in cauda epididymis prior to ejaculation

Seminal Vesicles Secretion

Fructose (anaerobic fructolysis) provides energy for sperm motility

Prostate Gland

produces fluids to nourish and transport sperm.

Physiological Adaptations in Pregnancy

Increased blood flow, respiration, nutrient diversion, increased hepatic and renal function, hypercalcaemia for the fetal skeleton

Placenta Function

Exchange maternal & foetal blood, secretes hormones for embryo develoment and maintains pregnancy.

Placenta Hormones

human chorionic gonadotropin (hCG), estrogens (estrone, estradiol and estriol), progesterone

hCG Function

Maintains CL of pregnancy for progesterone synthesis, stimulates testosterone synthesis in developing testes of XY embryos

Estrogens (Placental) Function

Stimulate endometrial growth, stimulate proliferation of mammary tissue

Progesterone (Placental) Function

Promotes formation of cervical mucus plug, suppresses uterine contractions, stimulates differentiation of lobulalveolar system, prevents follicle development

Human Chorionic Somatomammotropin Function

increase availability of glucose & NEFA for foetus development

Relaxin Function

Softens cervix / loosens CT, cervical dilation

Placental PTHRP

Increases maternal calcium

1st Trimester Hormonal Changes

Placenta secretes hCG – activates LH-chorionic gonagotropin receptors in CL to stimulate progesterone & estradiol synthesis / secretion

2nd & 3rd Trimester Hormonal Changes

Placenta secretes progesterone & estradiol, produces estriol from fetal adrenal androgen substrate

Parturition Triggers Theories

High levels of estrogen, Oxytocin (OT), CRH (from placenta), Inflammation

High Estrogen Level Role in Parturition

Upregulate connexins, myometrial receptors for oxytocin, stimulate local prostaglandin synthesis

Oxytocin Role in Parturition

Increases Ca2+ – activates MLCK

CRH Role in Parturition

May increase estrogen synthesis, increases cortisol

Inflammation Role in Parturition

Increased nuclear factor κ-B upregulates inflammatory cytokines & increases local prostaglandin synthesis

Fergusson Reflex

Positive feedback spiral; oxytocin secretion neuroendocrine reflex & prostaglandin production

Prolactin Function

Milk Production

Oxytocin Function

Milk Ejection

Phenotypic sex

determined by presence or absence of masculinizing hormones