Lecture 4: Female Reproductive System and Hormones

Uterus

Myometrium and endometrium structure of the female reproductive system.

Ovary

Organ where oogenesis and ovulation occur.

Oocyte

The female gamete or egg.

Vagina

The muscular tube leading from the external genitals to the cervix of the uterus.

Cervix

The lower part of the uterus that opens into the vagina.

Clitoris

A small sensitive organ located at the top of the vulva.

Oviduct (Fallopian tube)

The tube through which an egg passes from an ovary to the uterus.

Follicle

A fluid-filled sac in the ovary that contains an immature egg.

Corpus luteum

A hormone-secreting structure that develops in an ovary after an ovum has been discharged.

Corpus albicans

The scar tissue that replaces the corpus luteum if pregnancy does not occur.

Zona pellucida

The thick transparent membrane surrounding a mammalian ovum before implantation.

Corona radiata

A layer of cells that surround the oocyte and provide nutrients.

Myometrium

The smooth muscle layer of the uterus responsible for contractions.

Endometrium

The inner lining of the uterus that provides a nutritious environment for implantation.

GnRH

produced in the brain that stimulates the release of FSH and LH.

FSH

produced in the brain that stimulates the growth of ovarian follicles.

LH

produced in the brain that triggers ovulation.

Estrogen

Hormone produced in the ovaries that regulates the menstrual cycle and reproductive system.

Progesterone

Hormone produced in the ovaries that prepares the endometrium for a potential pregnancy.

Oogenesis

The process of egg formation in the ovaries.

Ovulation

The release of an oocyte from the ovary.

Menstrual cycle

The monthly cycle of changes in the female reproductive system.

Menstrual cycle length

Variable among women: 21 to 35 days.

Menstrual cycle definition

Length defined from start of menstruation to start of menstruation.

Ovulation timing

Occurs almost always 14 days before the start of menstruation.

Menstrual phase duration

Assumed to be 5 days.

Phases of the menstrual cycle

Includes menstrual phase, follicular phase, and luteal phase.

Hormones produced in the brain

GnRH, FSH, LH.

Hormones produced in ovaries

Estrogen, progesterone.

Positive feedback

A feedback loop that enhances the output of a system.

Negative feedback

A feedback loop that reduces the output of a system.

Ovarian cycle

The cycle that includes the growth of follicles and ovulation.

Growth of follicle

Occurs during the follicular phase of the menstrual cycle.

Degenerating corpus luteum

Occurs during the luteal phase.

GnRH (Gonadotropin releasing hormone)

Promotes FSH and LH release.

FSH (Follicle stimulating hormone)

Promotes follicle development.

LH (Luteinizing hormone)

Promotes ovulation and corpus luteum maintenance.

Estrogen (estradiol)

Promotes maturation of female reproductive structures and secondary sexual characteristics.

Progesterone (progestin)

Promotes secretory function of uterus.

Primary follicle

Developing structure in the ovary that produces estrogen.

Hypothalamus

Brain region that controls the release of GnRH.

Anterior pituitary

Gland that releases FSH and LH in response to GnRH.

LH surge

Triggers ovulation and corpus luteum formation.

Secretory phase

Phase in the menstrual cycle where the endometrium prepares for potential implantation.luteal

Negative feedback loops

Mechanisms that inhibit hormone release to maintain homeostasis.

Positive feedback loops

Mechanisms that enhance hormone release to promote physiological changes.

Menstruation

Triggered by low levels of estrogen.

hCG

Human chorionic gonadotropin secreted by a fertilized egg that maintains the corpus luteum.

Home pregnancy test kits

Detects the presence of hCG in urine, can give a result 15 days after fertilization.

Pre-ovulatory phase

Phase before ovulation characterized by follicle growth and estrogen secretion.

Post-ovulatory phase

Phase after ovulation characterized by corpus luteum activity.

Menstruation begins

Occurs when estrogen and progesterone levels decrease.

FSH levels rise

Occurs when negative feedback stops due to decreased estrogen and progesterone.

Uterine lining

Does not shed if estrogen and progesterone levels remain high.

New follicle growth

Does not start if estrogen and progesterone levels remain high.

Male reproductive system

The system responsible for the production and delivery of sperm.

Sperm

The male gamete involved in reproduction.

Semen

The fluid containing sperm and other secretions from male reproductive glands.

Gamete

A reproductive cell that contains half the genetic material of an organism.

Penis

The external male reproductive organ used for sexual intercourse and urination.

Acrosome

A cap-like structure on the head of a sperm cell that contains enzymes to help penetrate the egg.

Sperm head

The part of the sperm that contains the nucleus and genetic material.

Nucleus

The part of the sperm cell that contains the genetic information.

Middle piece

The part of the sperm that contains mitochondria to provide energy for movement.

Tail (flagellum)

The whip-like structure that propels the sperm forward.

Seminiferous tubule

The site in the testes where sperm production occurs.

Spermatogonia

The precursor cells that develop into sperm cells.

Leydig cell (interstitial cell)

Cells in the testes that produce testosterone.

Sertoli cell (nurse cell)

Cells that support and nourish developing sperm cells. in testis

Scrotum

The pouch of skin that contains the testes and regulates their temperature.

Testis

The male reproductive organ that produces sperm and hormones.

Epididymis

The structure where sperm mature and are stored.

Vas deferens

The duct that transports sperm from the epididymis to the ejaculatory duct.

Seminal vesicle

Glands that produce a fluid that nourishes sperm and forms part of semen.

Prostate gland

A gland that produces fluid that nourishes and protects sperm.

Cowper's gland

Glands that produce a pre-ejaculatory fluid that lubricates the urethra.

Ejaculatory duct

The duct through which sperm is expelled during ejaculation.

Urethra

The tube that carries urine and semen out of the body.

Testosterone

The primary male sex hormone responsible for the development of male reproductive tissues.

Sertoli cells

These cells are lipoid in character; they can be colourless or can be stained yellowish, and they have light vesicular nuclei.

Sperm cell parts

Nucleus, tail, middle piece, mitochondrion, head, acrosome (penetrator)

Semen composition

Semen contains 10% sperm; the rest is made up of fluids from various glands.

Seminal vesicles

Contribute nutrients and enzymes to semen.

Pathway of sperm

Sperm travels through the epididymis, seminal vesicles, Cowper's gland, prostate gland.

Hormone

A chemical signal that regulates body activities.

Anabolic steroid

Synthetic substances that mimic testosterone to increase strength and muscle mass.

Benefits of steroids

Increased strength and faster recovery.

Side effects of steroids

Acne, rage and hostility, heart damage and disease, decreased sperm count, testicular atrophy.

Insulin

Hormone produced by the pancreas that regulates blood sugar levels.

Epinephrine

Hormone released in response to stress that increases heart rate and blood pressure.

Gland

An organ that produces and releases substances that perform specific functions in the body.

Leydig cell

Cell that produces testosterone in the testes.

Androgen

A group of hormones that includes testosterone and is involved in male traits and reproductive activity.

Pituitary gland

Gland that releases hormones affecting growth and reproduction.

Feedback loops

Mechanisms that regulate hormone levels and effects in the body.

Leydig cells

Cells that produce testosterone in response to LH.

Anabolic steroids

Synthetic substances that mimic testosterone; can lead to testicular atrophy and reduced sperm counts.

Trenbolone acetate

An anabolic steroid that is 3x stronger than testosterone.

Testicular atrophy

Shrinkage of testicles due to lack of LH and FSH production.

Seminiferous tubules

Structures in the testes where sperm production occurs.