Reproductive System

Reproductive System • Reproductive system functions in gamete • Production • Storage • Nourishment • Transport • Fertilization • Fusion of male and female gametes to form a zygote

Figure 28.3 The Male Reproductive System in Anterior View Figure 28.3

Figure 28.1 The Male Reproductive System Figure 28.1

Male Reproductive System • Pathway of spermatozoa • Epididymis • Ductus deferens (Vas deferens) • Ejaculatory duct • Accessory organs • Seminal vesicles • Prostate gland • Bulbourethral glands • Scrotal sac encloses testes • Penis

Figure 28.1 The Male Reproductive System Figure 28.1

Figure 28.3 The Male Reproductive System in Anterior View Figure 28.3

Figure 28.4 The Structure of the Testes Figure 28.4

Spermatogenesis • Seminiferous tubules • Contain spermatogonia • Stem cells involved in spermatogenesis • Contain sustentacular cells • Sustain and promote development of sperm

Figure 28.5 The Seminiferous Tubules Figure 28.5a, b

Figure 28.5 The Seminiferous Tubules Figure 28.5c

Figure 28.7 Spermatogenesis Figure 28.7

Male reproductive tract • Testes produce mature spermatozoa • Sperm enter epididymus • Elongated tubule with head, body and tail regions • Monitors and adjusts fluid in seminiferous tubules • Stores and protects spermatozoa • Facilitates functional maturation of spermatozoa

Figure 28.9 The Epididymus Figure 28.9

Sperm Neck • A short region that connects head to tail • Region contains the most cytoplasm. rings

Accessory glands • Seminal vesicles • Active secretory gland • Contributes ~60% total volume of semen • Secretions contain fructose, prostaglandins, fibrinogen

Accessory glands • Prostate gland • Secretes slightly acidic prostate fluid • Bulbourethral glands • Secrete alkaline mucus with lubricating properties

Figure 28.10 The Ductus Deferens and Accessory Glands Figure 28.10a-e

Contents of Semen • Typical ejaculate = 2-5 ml fluid • Contains between 20 – 100 million spermatozoa per ml • Seminal fluid • A distinct ionic and nutritive glandular secretion

Figure 28.11 The Penis Figure 28.11

Hormones and male reproductive function • FSH (Follicle stimulating hormone) • Targets sustentacular cells to promote spermatogenesis • LH (leutinizing hormone) • Causes secretion of testosterone and other androgens • GnRH (Gonadotropin releasing hormone) • Testosterone • Most important androgen PLAY Animation: Male Reprroductive System Flythrough

Figure 28.12 Hormonal Feedback and the Regulation of the Male Reproductive Function Figure 28.12

Before birth, HCG secreted by the placental causes the embryonic(still developing) testes to secrete testosterone, masculinization the fetus. **Fetuses not exposed to testosterone or insensitive to testosterone look female.** After birth, there is little testosterone secreted until puberty. At puberty, two hormonal changes occur that signal the beginning of sexual maturity. First, testosterone secretion of the testes increases dramatically. Second, there is a change in the relationship between testosterone and GnRH, LH and FSH. Before puberty, the small amount of testosterone that is secreted by the testes inhibits GnRH secretion . After puberty, testosterone does not inhibit GnRH secretion.

So after puberty,GnRH, and therefore FSH and LH also enhance testosterone secretion in a major positive feedback loop,but after the onset of puberty. Testosterone secretion at puberty is also responsible for the obvious physical change of male secondary sexual characteristics. **controlled in the same way in males and females. LH and FSH stimulates gamete development. ANDROGEN INSENSITIVITY SYNDROME: -A genetic disorder that can result in a broad range of malfunctions of the male reproductive system, from complete lack of external genitalia or internal male genitalia . Testicular feminization --- individuals look female though they are genetically male)to patients with ambiguous genitalia, to patients who have typical male genitalia but are sterile.

(3) Male secondary sexual characteristics, masculization of the body, and enhancement of FSH and LH are caused by? • LH • FSH • ESTROGEN • TESTOSTERONE • inhibin • What structure in the male reproductive system produces alkaline mucus with lubricating properties? • Bulbourethral gland • Seminal vesicle • Prostate gland • testicles

THE COMBINATION OF SPERM,SUGARS,CHEMICALS AND MUCUS IS: • SEMEN • URINE • SPERMATOZOA • ALL OF THE ABOVE • SPERMATIDS

Which of the accessory glands of the male reproductive system produces secretions that makes up 60% the total volume of semen? • Seminal vesicle • Bulbourethral gland • Prostate gland • Penis • Epididymis

SECTION 28-3The Reproductive System of the Female

Principle organs of the female reproductive system • Ovaries • Uterine tubes • Uterus • Vagina

Figure 28.13 The Female Reproductive System Figure 28.13

The uterus is in the pelvic cavity, posterior and superior to the urinary bladder and anterior to the rectum. The major portion of the uterus is called the body. The rounded superior portion between the uterine tubes is the fundus, and the narrow inferior path is the isthmus. The cervix is called valvelike portion of the uterus that protudes into the vagina, where the cervical canal connects with the vagina. Like the ovaries, the uterus is suspended and anchored by a series of ligaments. The mesometrium attaches the uterus to the lateral pelvic walls. (the combination of the mesometrium and the mesovarium is called the broad ligament.) The lateral cervical(cardinal) ligaments attach the cervix and vagina to the lateral pelvic walls. The uterus is anchored to the anterior wall of the pelvic cavity by the round ligaments

The walls of the uterus consists of three layers: The perimetrium, the outermost layer, is also the visceral peritoneum. The middle layer, consists of smooth muscle, and the endometrium, or inner linning, is a mucosa of columnar epithelium and secretory cells. The mucosa has two divisions: -basal layer (responsible for regenerating the uterine linning each month) -functional layer (sheds about every 28days when a woman has her period (menses). The vagina is a tube, approximately 10cm centimeters long that runs from the uterus to the outside of the body. External genitalia: -collectively known as the vulva, the vulva is sorrounded on each side by two prominences called the labia majora. The labia majora are rounded fat deposits that meet and protect the rest of the external genitalia. The labia majora meet anteriorly to form the mons pubis. Both the mons pubis and L. majora are covered by pubic hair.

Figure 28.14 The Ovaries and Their Relationships to the Uterine Tube and Uterus Figure 28.14a, b

Reproductive organs are called genitalia: The primary genitalia are the ovaries and the secondary genitalia are all the other structures that aid in the reproduction process i.e uterine tubes, the uterus, the vagina and the external genitalia, called the vulva. The ovaries are 3cm long, found in the peritoneal cavity, the ovary is covered by a fibrous capsule called the tunica albuginea made of cuboidal epithelium, several ligaments suspend or anchor each ovary. The mesovarium suspends the ovary, the suspensory ligament attaches the ovary to the lateral pelvic wall, and the ovarian ligament anchors the ovary to the uterine wall. The fallopian tube is constructed of sheets of smooth muscle lined with highly folded, ciliated simple columnar epithelium.

Figure 28.15 Oogenesis Figure 28.15

The process by which eggs are produced is called oogenesis. Oogenesis begins with the birth of oogonia, or egg stem cells, in the ovary. The oogonia undergoes mitosis, producing millions of primary oocytes produced in a fetus. **women have all the eggs they will ever have five months before they are born.**** The primary oocytes are born via mitosis, hence they 46 chromosomes. The primary oocytes eventually are sorrounded by helper cells, called granulosa cells. Once sorrounded by granulosa cells , the primary oocyte and the sorrounding cells are known as primodial follicles. These primodial cells stay dormant until puberty. Hormonal signals during puberty cause some primordial follicles to enlarge and increase the no of the granulosa cells. These enlarged cells are then called primary follicles. Once a girl reaches puberty, each month one primary follicle will become 2 follicle. The secondary follicle will not complete is development unless it is ovulated and fertilized.

The successful fertilized egg has 46 chromosomes and is now called a ZYGOTE . THE RUPTURED FOLLICULE LEFT BEHIND IN THE OVARY DURING OVULATION WILL BECOME THE CORPUS LUTEUM(LUTEAL PHASE). CORPUS LUTEUM secretes hormones to help maintain the thickened endometrium which will now serve to nourish the growing fetus. If there is no implantation within a few days, the uterine lining will begin to degenerate, and the woman will have her period. The corpus luteum will become the corpus albicans and eventually disappear.

Figure 28.16 The Ovarian Cycle Figure 28.16

Figure 28.17 The Uterine Tubes Figure 28.17a-c

Female Reproductive System oviduct ovary uterus cervix vagina Video of fertilization Click here

The uterus • Muscular organ • Mechanical protection • Nutritional support • Waste removal for the developing embryo and fetus • Supported by the broad ligament and 3 pairs of suspensory ligaments

Uterine wall consists of three layers: • Myometrium – outer muscular layer • Endometrium – a thin, inner, glandular mucosa • Perimetrium – an incomplete serosa continuous with the visceral peritoneum

Figure 28.18 The Uterus Figure 28.18a, b

Figure 28.18 The Uterus Figure 28.18c

Figure 28.19 The Uterine Wall Figure 28.19a

Figure 28.19 The Uterine Wall Figure 28.19b

Oogenesis • Ovum production • Occurs monthly in ovarian follicles • Part of ovarian cycle • Follicular phase (preovulatory) • Luteal phase (postovulatory)

Uterine cycle • Repeating series of changes in the endometrium • Continues from menarche to menopause • Menses • Degeneration of the endometrium • Menstruation • Proliferative phase • Restoration of the endometrium • Secretory phase • Endometrial glands enlarge and accelerate their rates of secretion

Menses: is the time period when the uterine lining is shed/ time during which a woman is having her period” Menstration : is the actual shedding of the endothetrium/ this is the actual period itself. Once menses is over, the endometrium begins to proliferate, or build up, readying itself for the egg that is about to be released from the ovary during ovulation. From day 1 to 14, the ovary is also busy . in the ovary an egg cell, oocyte, is undergoing a number of developmental changes getting ready for ovulation on day 14. The time between the end of menses and ovulation is known as the FOLLICULAR PHASE OR THE PROLIFERATIVE PHASE.(because the endometrium is proliferating and follicles in ovaries are maturing in the ovary.

Reproductive System