Anatomy and Physiology 1 - Reproductive System

Introduction to Reproductive Systems The reproductive system is a network of organs and tissues that work together to produce sex cells and support the development of a fetus during pregnancy. The male reproductive system and female reproductive system have different structures and functions, but both play a crucial role in the production of offspring. Sexual Reproduction Sexual reproduction requires two parent organisms, a male and a female. The advantage of sexual reproduction is that it increases the variety of genetic characteristics in the population. The reproductive system of each parent produces sex cells (called gametes), which are the ovum (female) and sperm (male). Definitions “A gamete is a sex cell that contains half the number of chromosomes of a normal body cell. Spermatogenesis is the process of sperm production in the male reproductive system. Oogenesis is the process of egg production in the female reproductive system.” Male Reproductive System The male reproductive system consists of the following organs: Testes (gonads): produce sex cells (sperm) Epididymis: ducts that carry sperm from the testes to the exterior Vas deferens: muscular tubes that transport sperm from the epididymis to the ejaculatory duct Seminal vesicles: glands that produce a significant portion of the seminal fluid Prostate gland: gland that produces enzymes that aid in sperm motility and neutralize the acidity of the female reproductive tract Bulbourethral glands: glands that produce a mucus-like fluid that lubricates the urethra and neutralizes any residue of sperm-damaging acidic urine Penis: external genitalia that contains the urethra and is responsible for ejaculation Male Reproductive System Table Organ Function Testes Produce sex cells (sperm) Epididymis Carry sperm from testes to exterior Vas deferens Transport sperm from epididymis to ejaculatory duct Seminal vesicles Produce seminal fluid Prostate gland Produce enzymes that aid in sperm motility and neutralize acidity Bulbourethral glands Produce mucus-like fluid that lubricates urethra Penis External genitalia responsible for ejaculation Female Reproductive System The female reproductive system consists of the following organs: Ovaries (gonads): produce sex cells (eggs) Oviducts (fallopian tubes): ducts that carry eggs from the ovaries to the uterus Uterus: muscular organ that supports the development of a fetus during pregnancy Vagina: distensible tube that receives the penis during sexual intercourse and is the birth canal for normal delivery of a baby Breasts: glands that produce milk for nourishment of a baby Vestibular glands (Bartholin's glands): glands that produce a mucus-like fluid that lubricates the vulva Female Reproductive System Table Organ Function Ovaries Produce sex cells (eggs) Oviducts Carry eggs from ovaries to uterus Uterus Support development of fetus during pregnancy Vagina Receive penis during sexual intercourse and birth canal for baby Breasts Produce milk for nourishment of baby Vestibular glands Produce mucus-like fluid that lubricates vulva Key Points The reproductive system is essential for the production of offspring. The male reproductive system and female reproductive system have different structures and functions. Spermatogenesis and oogenesis are the processes of sperm and egg production, respectively. The reproductive system is controlled by hormones, which regulate the development and maintenance of secondary sex characteristics.## Female External Genitals The female external genitals include the labia majora, vagina, and perineum. The perineum is the area between the vaginal opening and the anus. In some cases, a surgical cut called an episiotomy may be made during childbirth. Menstrual Cycle The menstrual cycle involves many changes in the uterus, ovaries, vagina, and breasts. The length of the menstrual cycle is approximately 28 days, but it can vary from month to month among individuals and in the same individual. Phases of the Menstrual Cycle The menstrual cycle has several phases: Menses: The first 4 or 5 days of the cycle, characterized by the sloughing of bits of endometrium (uterine lining) with bleeding. Proliferative phase: The days between the end of menses and the secretory phase, during which the endometrium thickens. Secretory phase: The days between ovulation and the beginning of the next menses, during which the endometrium further thickens and secretes substances in preparation for implantation of a fertilized ovum. “The endometrium is the lining of the uterus that thickens and sheds each month during the menstrual cycle.” Menstrual Cycle Timeline The following table summarizes the menstrual cycle: Phase Description Length Menses Sloughing of endometrium with bleeding 4-5 days Proliferative phase Thickening of endometrium varies Secretory phase Further thickening of endometrium and secretion 14 days Ovulation Release of an ovum from the ovary 1 day Ovulation and Fertility Ovulation typically occurs 14 days before the next menses begins. The timing of ovulation is important because of the possibility of fertilization. A woman's fertile period lasts only a few days each month, and most sperm retain their fertilizing power for only 24 to 72 hours after being deposited into the female reproductive tract. Endocrine Control of the Ovarian Cycle The menstrual cycle is controlled by the secretion of gonadotropin-releasing hormone (GnRH), which stimulates the secretion of FSH and LH from the anterior pituitary gland. Ovulation occurs because of the combined actions of these two hormones. Birth control pills that contain estrogen substances suppress FSH secretion. Comparison of Reproductive Systems The following table summarizes the similarities and differences between the male and female reproductive systems: Structure Male Female Gametes Sperm Ovum Sex hormones Testosterone Estrogen and progesterone Secondary sex characteristics Facial hair, deep voice Breast development, wide hips Summary of Reproductive Systems The reproductive systems in both sexes revolve around the production of reproductive cells (gametes) and the production of sex hormones, which are required for the development of secondary sex characteristics and for normal reproductive functions. Both men and women have similar structures to accomplish complementary functions. Introduction to Reproductive Hormones and the Menstrual Cycle The menstrual cycle is controlled by reproductive hormones, which are mainly testosterone in men and estrogen in women. Puberty is the period during which adolescents start to develop secondary sexual characteristics, such as facial hair in men and breasts in women. Definition of Key Terms “Puberty: the period during which adolescents start to develop secondary sexual characteristics Secondary sexual characteristics: physical characteristics that distinguish one sex from the other, such as facial hair in men and breasts in women Reproductive hormones: hormones that control the reproductive cycle, including testosterone, estrogen, progesterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH)” The Female Reproductive System The female reproductive system consists of the uterus, ovaries, and fallopian tubes. The ovaries produce eggs, which are transported through the fallopian tubes to the uterus. The uterus lining is where a fertilized egg would implant and develop into a fetus. The Menstrual Cycle The average length of a menstrual cycle is around 28 days, but it can vary from person to person. The cycle consists of four stages: Stage 1: Menstruation - the period of bleeding that normally lasts about 4 days, due to the breakdown of the uterus lining Stage 2: Uterus lining buildup - the uterus lining starts to build up again and becomes a thick, spongy layer with lots of blood vessels Stage 3: Ovulation - the egg is released from one of the ovaries Stage 4: Uterus lining maintenance - the uterus lining is maintained in preparation for a fertilized egg Hormone Levels During the Menstrual Cycle The following table shows the hormone levels during each stage of the menstrual cycle: Stage Estrogen Progesterone LH FSH 1 Low Low Low Low 2 Increasing Low Low High 3 High Low High Low 4 High High Low Low Hormone Interactions The hormones interact with each other in the following ways: FSH stimulates the ovaries to produce estrogen Estrogen inhibits FSH and stimulates the release of LH LH stimulates the release of the egg from the ovary Progesterone inhibits both LH and FSH Progesterone maintains the uterus lining in preparation for a fertilized egg Key Hormones and Their Functions The following table summarizes the key hormones and their functions: Hormone Function Estrogen Stimulates the growth of the uterus lining Progesterone Maintains the uterus lining in preparation for a fertilized egg LH Stimulates the release of the egg from the ovary FSH Stimulates the ovaries to produce estrogen and mature an egg Introduction to the Reproductive System The reproductive system is a complex system that enables humans to produce offspring. It is the only system that varies dramatically between males and females. The primary function of the reproductive system is to produce gametes, which are haploid cells that are the products of meiosis. Male Reproductive System The male reproductive system consists of the following components: Testes: The primary sex organs in males, responsible for producing testosterone and sperm cells. Scrotum: A sac of skin that houses the testes, providing a suitable environment for sperm production. Epididymis: A duct that stores sperm cells until ejaculation. Vas deferens: A muscular tube that transports sperm cells from the epididymis to the urethra. Penis: A copulatory organ that delivers sperm into the female reproductive tract. The process of sperm production, known as spermatogenesis, occurs in the seminiferous tubules of the testes. The tunica albuginea and tunica vaginalis are layers of tissue that surround the testes, providing protection and support. Accessory Glands in the Male Reproductive System The following accessory glands play a crucial role in the male reproductive system: Gland Function Seminal vesicles Produce a fluid called semen that enhances sperm motility and fertilizing ability. Prostate Contracts during ejaculation to release prostatic secretion into the urethra, activating sperm. Bulbourethral glands Produce a mucus that lubricates the glans penis during sexual arousal. “The semen is a fluid that makes up the majority of the ejaculate by volume, and is not to be confused with sperm cells. It is a mixture of hormones and other compounds that suppress the immune response in the female reproductive tract, destroy bacteria, and help sperm stick to the walls of the vagina.” Female Reproductive System The female reproductive system consists of the following components: Ovaries: The primary sex organs in females, responsible for producing egg cells and sex hormones such as estrogen and progesterone. Uterine tubes: Ducts that connect the ovaries to the uterus, providing a pathway for fertilization to occur. Uterus: A muscular organ that receives the fertilized egg and nourishes it during fetal development. Vagina: A copulatory organ that receives the penis during intercourse. The process of egg cell production, known as oogenesis, occurs in the follicles of the ovaries. The germinal epithelium and tunica albuginea are layers of tissue that surround the ovaries, providing protection and support. Mammary Glands The mammary glands are accessory organs that play a crucial role in the female reproductive system. They are responsible for producing milk during pregnancy and lactation. Component Function Lobes Contain smaller units called lobules, which produce milk. Alveoli Structures that produce milk, which is then transferred to the lactiferous duct. Lactiferous duct A duct that leads to the lactiferous sinus, where milk collects during nursing. The lecture will now delve into more complex subjects that require a basic understanding of human anatomy and physiology. In-Depth Exploration of Bodily Systems For those interested in pursuing a career in the medical field or simply wanting to expand their knowledge, the following topics will be explored in greater detail. Revisiting the systems of the human body Examining highly specific bodily functions Gaining a deeper understanding of anatomy and physiology Key Concepts The following concepts will be crucial in understanding the upcoming topics: Concept Description Human Anatomy The study of the structure and organization of the human body Physiology The study of the functions and processes that occur within the human body “A medical profession requires a strong foundation in human anatomy and physiology, as well as a deep understanding of the complex interactions between different systems of the body.” Next Steps To further explore these topics, it is recommended to: Review the basics of human anatomy and physiology Be prepared to learn about highly specific bodily functions and their relationships to different systems of the body Engage with additional resources, such as tutorials and educational content, to supplement learning