A&P - Unit H: The Reproductive System

Study Set for Anatomy and Physiology 12.

Male External Genitalia

Male External Genitalia

Outer structures that identify the male sex; include the penis and scrotum.

Penis

A cylindrical-shaped organ that hangs in front of the scrotum.

Scrotum

Thin reproductive structure that surrounds the testes; maintains the testes at a cooler temperature in order to produce viable sperm.

Testes (Testicles)

Paired organs that organs develop from gonads found within the abdomen of the fetus.

Spongy Tissue

Located inside the shaft of the penis; flaccid (soft) with normal blood flow, and is filled with blood during an erection.

Erection

The result of a blood flow increase that fills the spongy tissue.

Gonads

Found within the abdomen of the fetus; develop the testes.

Seminiferous Tubules

Coiled and packed into lobes of the testes, and produce sperm.

Sertoli Cells

Located inside the seminiferous tubules; these cells nourish the developing sperm cells.

Interstitial Cells / Leydig Cells

Located in the testes; these cells surround the seminiferous tubules and produce the male hormone testosterone.

Sperm

The male sex cell, composed of three parts: the head, middle piece, and tail. This is produced in the testes, inside the seminiferous tubules.

Acrosome Cap

Located on the tip of the sperm head; contains enzymes needed to penetrate the outer barriers of the egg.

Egg (Ovum)

The female sex cell.

Spermatogenesis

The production of sperm. Men can produce up to 1 000 000 000 sperm per day, and the entire process takes about 9 to 10 weeks.

Epididymis

Located behind each testes; sperm mature and are stored here.

Vas Deferens

Sperm is sent here from the epididymis for storage.

Semen

Contains sperm and secretions from the seminal vesicles, prostate gland, and bulbourethral glands (Cowper’s glands).

Accessory Glands

Include the seminal vesicles, prostate gland, and bulbourethral / Cowper’s glands.

Seminal Vesicles

Secretes nutrients for sperm at the time of ejaculation.

Prostate Gland

Secretes alkaline and milky fluid that aids sperm motility and survival.

Bulbourethral Glands / Cowper’s Glands

Secretes mucus with a lubricating effect.

Vagina

The elastic muscular canal of the female reproductive system, with a relatively acidic environment.

Urethra

Delivers semen during ejaculation; extends through the length of the penis. Also carries urine from the bladder during urination.

Ejaculation

A process in which semen is forced out of the penis; can be caused by sexual arousal, when this occurs at the peak of arousal.E

Ejaculatory Duct

When sperm enters this duct, the accessory glands release their respective secretions, combining together to become semen.

Testosterone

The male sex hormone; promotes and regulates the normal function and development of the primary male sex organs. A high level of this causes male puberty.

Functions of Testosterone

1. Necessary for the development of sperm.

2. Increases secretions from the oil and sweat glands (contributes to acne and body odor).

3. Contributes to aggressiveness and aggressive behavior.

4. Regulation of sex drive.

Male Puberty

Caused by high levels of testosterone, which stimulate maturation of the penis and the testes. This will result in the development of secondary sexual characteristics (ie., facial/armpit/pubic hair growth, muscle growth, deepened voice).

Ovaries

Two egg-shaped organs to each side of the uterus in the pelvic abdominal cavity. Each of these measures about 3 cm by 1 cm, and are held in place by ligaments to the oviduct and the uterus. These produce eggs, estrogen, and progesterone.

Estrogen / Progesterone

The sex hormones produced by the ovaries.

Ovulation

Each month, an ovary produces an egg that bursts from the ovary during this process.

Oviduct / Fallopian Tube

A tube that connects the uterus to the ovaries, bringing ova to the uterus. It is the site of fertilization where sperm meet and fertilize the egg.

Cilia

Hair like projections that line the fallopian tubes; sweep up eggs from the ovary.

Fimbriae

Finger like ends that line the fallopian tubes; sweep up eggs from the ovary.

Uterus

A thick walled, muscular, hollow, pear shaped organ for nurturing an embryo. It is primarily the region where the fetus develops.

Cervix

A canal that forms the lower, narrow end of the uterus, and connects the uterus to the vagina.

Vagina

A muscular tube lined with mucosa. It serves to receive the penis during sexual intercourse, as well as serve as the birth canal during childbirth.

Endometrium

The lining of the uterus; composed of glands, blood vessels, and connective tissue.

Placenta

Forms from the endometrium if pregnancy occurs, which removes wastes from and provides oxygen and nutrients to a developing baby’s blood.

Vulva

The external genitals of the female reproductive system, collectively referred to as this.

Female External Genitalia

Includes the mons pubis, labia, and clitoris.

Mons Pubis

A fatty prominence under the pubic hair, functioning as a source of cushioning during sexual intercourse.

Labia

Two sets of skin folds (Majora and Minora) that surround and protect the urethra, vagina, and clitoris.

Clitoris

An erectile organ, which is partly enclosed by the labia minora. It is sexually sensitive to stimulation and is prominent in the processes of the female orgasm. It is considered to be homologus (similar) to the male penis.

Clitoral Glans

A pea shaped gland that contains many sensory nerve receptors; caps off the shaft of erectile tissue in the clitoris.

Menstrual Cycle

The regular cycle of events the body of a female undergoes over the course of 28 days. This occurs each month after puberty.

Uterine Cycle

This cycle governs the preparation and maintenance of the lining of the uterus (womb) to receive an embryo.

Ovarian Cycle

This cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone.

Follicular Phase

This phase occurs during days 1 to 14 of the menstrual cycle.

Menstruation

During this process, part of the lining of the uterus (plus a small amount of blood) is released through the vagina. The lining of the uterus (the endometrium) is at its thinnest at this point. While this process occurs, the system is ready to repeat the whole cycle once more.

Days 1-5 of the Menstrual Cycle

During days ______ the uterus contains low levels of female hormones, which cause menstruation. These female hormones are:

• Estrogen

• Progesterone

• Follicle-Stimulating Hormone (FSH)

• Luteinizing Hormone (LH)

The low levels of female hormones are detected by the hypothalamus, which responds by releasing gonadotropin-releasing hormone (GnRH), which acts on the anterior pituitary gland to release FSH and LH.

Days 6-13 of the Menstrual Cycle

During days ______, FSH stimulates follicle development in the ovary to mature and get bigger.

• The follicle then produces estrogen. The rising levels of estrogen cause the uterus lining to get thicker.

• As estrogen levels rise, this causes what is known as a positive feedback loop.

• As estrogen is released, this causes more GnRH to release, and therefore more LH is released.

• Further heightened levels of estrogen will finally cause the hypothalamus to release a sudden “LH surge”, which causes ovulation to occur on day 14.

Day 14 of the Menstrual Cycle

On ______, ovulation results in the now mature follicle to rupture and release the egg from the ovary.

• The remaining follicle cells will then be referred to as the corpus luteum.

• Meanwhile, the high levels of estrogen will also cause a negative feedback loop on the pituitary gland, which reduces the release of FSH, ending the follicular phase.

Luteal Phase

This phase occurs during days 15-28 of the menstrual cycle.

Days 15-28 of the Menstrual Cycle

The following events occur during _______:

• Once the corpus luteum forms, the luteal phase begins. The corpus luteum begins producing progesterone.

• Progesterone makes the endometrium get thicker, which then causes mucus to be secreted from the mucus glands.

• When the progesterone levels reach their highest level, negative feedback causes the release of less LH from the anterior pituitary gland.

• Since the corpus luteum requires high levels of LH to maintain itself, the corpus luteum degenerates as LH levels drop.

• Since the corpus luteum is what makes progesterone, it makes less and less progesterone as it degenerates.

  • Without high levels of progesterone, the endometrium disintegrates, which causes menstruation to occur on day 1.

Hypothalamus

A brain structure that detects the low levels of female hormones, and it responds by releasing gonadotropin-releasing hormone (GnRH); GnRH acts on the anterior pituitary gland to release FSH and LH.

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

Female hormones that cause menstruation; released by the anterior pituitary gland.

Gonadotropin-Releasing Hormone (GnRH)

A hormone released by the hypothalamus; acts on the anterior pituitary gland, causing the gland to release FSH and LH.

Corpus Luteum

The remaining follicle cells after ovulation occurs.

Positive Feedback Loop

Caused by the rising levels of estrogen; as estrogen is released, more GnRH is released, and therefore more LH is released.

Negative Feedback Loop

Caused by the high levels of estrogen on Day 14 of the Menstrual Cycle; this loop acts on the pituitary gland, reducing the release of FSH. This ends the Follicular Phase.