Chapter 26 Adv physiology

Sexual reproduction

Process where two parents produce offspring using gametes (eggs and sperm) that combine to form a zygote

Gamete

Haploid reproductive cell (egg or sperm) with 23 chromosomes

Gonad

Organ that makes gametes and sex hormones (testes in males, ovaries in females)

Testes

Male gonads that make sperm and testosterone

Ovaries

Female gonads that make eggs and estrogen/progesterone

Sex chromosomes

X and Y chromosomes that determine genetic sex (XX

SRY gene

Gene on Y chromosome that triggers development of testes in an embryo

Sex determination

Process where chromosomes (XX or XY) decide genetic sex at fertilization

Sex differentiation

Development of internal and external reproductive structures into male or female

Bipotential gonad

Early embryonic gonad that can become either ovary or testis

Müllerian ducts

Embryonic ducts that become female internal structures (uterus, fallopian tubes, upper vagina) if not suppressed

Wolffian ducts

Embryonic ducts that become male internal structures (epididymis, vas deferens, seminal vesicles) if stimulated by testosterone

Anti-Müllerian hormone (AMH)

Hormone from fetal Sertoli cells that causes Müllerian ducts to regress in males

Testosterone

Main male sex steroid that supports Wolffian duct development and male secondary sex traits

Dihydrotestosterone (DHT)

More potent androgen made from testosterone that drives development of male external genitalia and prostate

Primary sex characteristics

Reproductive organs and genitalia present at birth

Secondary sex characteristics

Sex-specific traits that develop at puberty (body hair, voice changes, breast development)

Gametogenesis

Formation of gametes by meiosis in testes or ovaries

Spermatogenesis

Production of sperm from spermatogonia in the testes

Oogenesis

Production of eggs from oogonia in the ovaries

Spermatogonium

Male germ cell that divides to eventually form sperm

Primary spermatocyte

Cell that begins meiosis I and will give rise to 4 sperm

Spermatid

Haploid male cell that matures and differentiates into a sperm

Spermatozoon (sperm)

Mature male gamete specialized to deliver paternal DNA to the egg

Oogonium

Female germ cell present in the embryo that forms primary oocytes

Primary oocyte

Female cell arrested in meiosis I from before birth until it resumes during the ovarian cycle

Secondary oocyte

Cell released at ovulation that completes meiosis II only if fertilized

Polar body

Small cell produced during oogenesis that contains extra chromosomes and later degenerates

Follicle

Oocyte plus its surrounding granulosa and thecal cells in the ovary

Granulosa cells

Follicle cells around the oocyte that support it and make estrogen and inhibin

Thecal cells

Outer follicle cells that make androgens, which granulosa cells convert to estrogens

Corpus luteum

Yellow endocrine structure formed from an ovulated follicle that secretes progesterone and estrogen

GnRH (gonadotropin‑releasing hormone)

Hypothalamic hormone that stimulates release of FSH and LH from the anterior pituitary

FSH (follicle‑stimulating hormone)

Pituitary hormone that promotes gamete production (spermatogenesis and follicle growth)

LH (luteinizing hormone)

Pituitary hormone that stimulates sex steroid production and triggers ovulation in females

Inhibin

Hormone from Sertoli and granulosa cells that selectively inhibits FSH secretion

Androgens

Class of male sex steroids (like testosterone) that support male traits and sperm production

Estrogens

Class of female sex steroids (like estradiol) that support follicle growth and female traits

Progesterone

Ovarian hormone important for preparing and maintaining the uterus for pregnancy

Hypothalamic‑pituitary‑gonadal axis

Hormone control system linking hypothalamus, pituitary, and gonads in reproduction

Leydig cells

Testicular cells in the interstitial space that produce testosterone in response to LH

Sertoli cells

“Nurse” cells in seminiferous tubules that support developing sperm and secrete AMH, inhibin, and ABP

Androgen‑binding protein (ABP)

Protein from Sertoli cells that keeps testosterone concentrated in seminiferous tubules

Seminiferous tubules

Highly coiled tubes in the testes where spermatogenesis occurs

Epididymis

Coiled tube on the testis where sperm mature and are stored

Vas deferens

Muscular tube that carries sperm from epididymis to ejaculatory duct

Seminal vesicles

Accessory glands that add fructose‑rich fluid to semen to nourish sperm

Prostate gland

Accessory gland that adds alkaline, enzyme‑rich fluid to semen

Bulbourethral glands

Small glands that secrete mucus‑rich fluid for lubrication before ejaculation

Semen

Mixture of sperm and secretions from male accessory glands

Erection

Increase in penile blood flow and rigidity due to parasympathetic‑mediated vasodilation

Ejaculation

Reflex expulsion of semen from the urethra driven by sympathetic and somatic activity

Ovarian cycle

Monthly cycle of follicle development, ovulation, and corpus luteum function in the ovary

Follicular phase

First half of ovarian cycle when follicles grow and estrogen levels rise

Ovulation

Release of a mature secondary oocyte from the dominant follicle

Luteal phase

Second half of ovarian cycle when the corpus luteum secretes progesterone and estrogen

Uterine cycle

Monthly changes in the endometrium: menstrual, proliferative, and secretory phases

Menstrual phase

Shedding of the functional layer of the endometrium with bleeding at start of the cycle

Proliferative phase

Estrogen‑driven regrowth and thickening of the endometrium after menstruation

Secretory phase

Progesterone‑driven phase where endometrium becomes secretory and ready for implantation

Fertilization

Fusion of sperm and secondary oocyte to form a diploid zygote

Capacitation

Final maturation steps of sperm in the female tract that enable them to fertilize the egg

Acrosome reaction

Release of enzymes from the sperm head that help it penetrate egg layers

Cortical reaction

Changes in egg membrane after fertilization that prevent entry of additional sperm

Zygote

Single‑cell diploid product of fertilization that will begin cleavage divisions

Blastocyst

Early hollow ball of cells with inner cell mass and trophoblast that implants in the uterus

Implantation

Embedding of the blastocyst into the endometrium

Trophoblast

Outer cell layer of the blastocyst that forms the fetal part of the placenta

Inner cell mass

Cluster of cells in the blastocyst that forms the embryo proper

Placenta

Temporary organ formed from maternal and fetal tissues for nutrient, gas, and waste exchange

Human chorionic gonadotropin (hCG)

Placental hormone that maintains the corpus luteum early in pregnancy and is detected in pregnancy tests

Human placental lactogen (hPL)

Placental hormone that helps shift maternal metabolism to support fetal growth

Gestation

Time period from fertilization to birth (about 38–40 weeks in humans)

Trimester

One of three roughly equal time divisions of pregnancy

Parturition

Process of giving birth involving uterine contractions and expulsion of the fetus and placenta

Positive feedback in labor

Cycle where cervical stretch increases oxytocin and prostaglandins, which increase contractions and more stretch

Oxytocin in labor

Hormone from posterior pituitary that strengthens uterine contractions during birth

Lactation

Production and secretion of milk from the mammary glands after birth

Prolactin

Anterior pituitary hormone that stimulates milk synthesis in the mammary glands

Oxytocin in lactation

Hormone that causes milk ejection by contracting myoepithelial cells around alveoli

Colostrum

First milk after birth, rich in antibodies and protein but low in fat

Puberty

Developmental period when the reproductive system matures and becomes functional

Menopause

Natural end of female reproductive cycles when ovarian follicles are depleted and menstruation stops

Andropause

Age‑related decline in testicular function and testosterone in some older men