Reproductive System Unit 1 PDF

Reproductive System Lesson Transcript Unit 1: Structure and Function Lesson 1: Male Reproductive System Title Page Lesson Objectives Your learning objectives for this lesson are to: Describe the similarit...

Reproductive System Lesson Transcript Unit 1: Structure and Function Lesson 1: Male Reproductive System Title Page Lesson Objectives Your learning objectives for this lesson are to: Describe the similarities between the male and female reproductive systems. Describe the functions of the male reproductive system. Identify the parts of the male reproductive system. And explain how male sex cells are formed and travel to the female. Introduction The function of the reproductive system is to produce new life. While both the male and female systems differ in many ways, they are also similar. Some of these similarities include: Gonads, or sex glands, are the primary sex organs for both males and females. In males, gonads are the testes, and in females, they are the ovaries. The gonads secrete sex hormones, including testosterone from the testes and estrogen from the ovaries. The gonads also produce gametes, or sex cells. In males, the gametes are sperm, and in females, they are ova, or egg cells. And both the male and female have accessory organs, such as glands, that play important roles in the function of the reproductive systems. Male Structures Several structures of the male reproductive system are external to the body. These include the testes, or gonads, which are the primary reproductive organs, and the penis, scrotum, epididymis, and urethra, which are accessory, or secondary, reproductive organs. The remaining structures of the male reproductive system are internal structures. These structures are all accessory organs and include the vas deferens, ejaculatory duct, seminal vesicles, the prostate gland, and the bulbourethral [bul-boo-yo-REETH-ruhl ], or Cowper's glands. Page 1 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function The testes, epididymis, vas deferens, seminal vesicles, and bulbourethral glands are all paired structures; meaning, there are two of each structure. Each structure of the pair lies on each side of the median plane. The penis, scrotum, prostate gland, and urethra are all single structures. Testes and Scrotum The testes are the male gonads, or primary sex organs. They are inside the scrotum, a protective sac of skin and smooth muscle located beneath the penis. The two primary functions of the testes are to produce sperm, a process known as spermatogenesis, and secrete androgens, or male sex hormones. Spermatogenesis must occur at temperatures slightly lower than body temperature to develop healthy sperm. This is why the process takes place outside the body, in the scrotum. Testosterone is the primary androgen. It causes many changes during puberty, such as facial and body hair growth, a deepening voice, bone and muscle development, and sperm production. Reproductive Ducts The reproductive ducts are a series of internal structures that store sperm and transport semen out of the body. The reproductive ducts are the epididymis, vas deferens, ejaculatory duct, and urethra. As mentioned earlier, the epididymis, vas deferens, ejaculatory duct are paired structures. The urethra is a single structure. Click on each label to learn more. Epididymis After sperm develops in the testes, they enter the epididymis [ep-uh-DID-uh-miss], a long, coiled tube that sits on the testicle. Over several weeks, sperm travel through the coiled tube while they mature. Mature sperm are stored in the tail end of the epididymis and can survive for about two months before they are reabsorbed by the body. Vas Deferens The epididymis connects to the vas deferens, or ductus deferens, a long, narrow tube that transports mature sperm towards the seminal vesicle. The vas deferens extends upward from the scrotum, into the pelvic cavity, over the bladder, and behind the prostate, where it meets the seminal vesicle. The vas deferens contains a layer of smooth muscle that contracts during ejaculation to rapidly move sperm through the ducts. Page 2 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function Ejaculatory Duct Each vas deferens joins the adjacent seminal vesicle to form a short tube called the ejaculatory duct. Each ejaculatory duct passes through the prostate gland and empties into the urethra. Fluid from the seminal vesicle empties into the ejaculatory duct and mixes with sperm to form semen. Urethra The male urethra is a duct that moves both semen and urine through the penis and outside of the body, but not at the same time. Since the male urethra moves semen and urine, it is part of both the reproductive and urinary systems. Knowledge Check Accessory Glands The male accessory glands include the seminal vesicles, the prostate gland, and the bulbourethral, or Cowper’s glands. These glands are all exocrine glands because their secretions move through ducts. The alkaline secretions from these ducts combine with sperm to form semen. The seminal vesicles and bulbourethral glands are all paired structures, meaning there are two of each structure. The prostate gland is a single structure. Click on each label to learn more. Seminal Vesicles The two seminal vesicles are small, pouch-like tubes that secrete fluid rich in sugar that mixes with the sperm to nourish it. The fluid also protects the sperm because it is alkaline which neutralizes acids found in the surroundings, such as the male urethra and female reproductive tract which protect the sperm. The thick, yellow seminal fluid makes up about 60 to 70% of the total semen volume. Prostate Gland The prostate gland is a chestnut-shaped gland located below the urinary bladder. It secretes a thin, milky fluid that mixes with the existing semen. The fluid serves to nourish the sperm and thin semen, which helps the sperm to move. The fluid makes up about 20 to 30% of semen volume. Muscular tissue in the prostate contracts during ejaculation to help the sperm exit the body. This contraction also closes off the urethra to prevent urine from passing through at the same time. Page 3 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function Bulbourethral Gland The bulbourethral, or Cowper's, glands are two small glands located below the prostate. They connect to the urethra through small tubes. Like the prostate gland, the bulbourethral glands secrete a mucus-like fluid that neutralizes acids and lubricates the inside of the urethra to help semen move. Knowledge Check Knowledge Check Penis The penis is the external male reproductive organ located in front of the scrotum. The penis encloses the urethra. The urethra carries urine and semen out of the body, but not simultaneously. The penis is made of spongy tissue that fills with blood during sexual arousal which causes it to become erect. This allows semen to be more easily deposited into the female vagina during sexual intercourse. Knowledge Check Lesson Summary In this lesson, you: Described the similarities between the male and female reproductive systems. Described the functions of the male reproductive system. Identified the parts of the male reproductive system. And explained how male sex cells are formed and travel to the female. Page 4 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function Lesson 2: Female Reproductive System Title Page Lesson Objectives Your learning objectives for this lesson are to: Describe the functions of the female reproductive system. Identify the parts of the female reproductive system. And explain how female sex cells are formed and travel through the female body. Female Structures As noted in lesson one, the male and female reproductive systems have several similarities. Both have primary sex organs, called gonads, that produce gametes, or sex cells, and secrete hormones and both use ducts to transport the gametes. However, the female reproductive system must also support a developing fetus during pregnancy. These functional differences lead to several structural differences. The majority of the female reproductive organs are located within the body. These internal organs include the ovaries, which are the primary sex organs, and several of the accessory reproductive organs, including the fallopian tubes, uterus, and vagina. The external accessory organs are referred to collectively as the vulva. The vulva includes the labia, clitoris, vestibule, paraurethral glands, and Bartholin’s glands. Breasts, which contain the mammary glands, are secondary sex characteristics because they don’t directly contribute to reproduction. Knowledge Check Ovaries The ovaries are the female gonads, or primary sex organs. They are small, almond-shaped glands located on the lateral walls of the pelvic cavity. Each ovary contains hundreds of thousands of tiny sacs called ovarian follicles. Each follicle holds an oocyte which is an immature ovum, or female sex cell. A function of the ovaries is to release one or more ovum from the follicles during ovulation. Ovulation occurs about every 28 days or four weeks once a female reaches sexual maturity. Page 5 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function The ovaries are also part of the endocrine system and secrete several hormones. The two primary female sex hormones are estrogen and progesterone. These hormones initiate the development of the female reproductive organs, regulate menstruation, and support pregnancy. They also cause secondary female characteristics to appear, such as the enlargement of the breasts, the broadening of the hips, and the growth of pubic hair. Knowledge Check Knowledge Check Fallopian Tubes The fallopian, or uterine tubes, have one end located above the ovaries, but not directly connected to them, and the other end attached to the uterus. The fallopian tubes carry a mature ovum from the ovary to the uterus. After ovulation, a mature ovum is released from one of the ovaries and swept into the associate fallopian tube by finger-like projections called fimbriae [FIM-bree-eh]. Peristalsis, wave-like contractions in the tubes, and cilia, tiny hair-like projections lining the tubes, help guide the ovum toward the uterus. Fertilization, when an ovum and sperm join, usually occurs in the fallopian tubes. After fertilization, the joined sex cells become a zygote. Uterus The uterus, or womb, is a hollow, pear-shaped, highly muscular organ. It lies behind the bladder and in front of the rectum. It is divided into three parts: the top section is the fundus, the middle section is the corpus, or body, and the lower section is the cervix. The uterus provides protection and nourishment for the embryo, and then fetus, during pregnancy. The uterine wall has three layers: the innermost layer is the endometrium, the middle layer is the myometrium, and the outermost layer is the perimetrium. Click each marker to learn more. Page 6 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function Endometrium The endometrium contains a thick lining of blood tissues. If an ovum becomes fertilized, it will implant on this surface, nourishing the developing embryo and fetus. If not fertilized, the surface breaks down and sheds from the body, a process known as menstruation. Menstruation is a visible sign of reproductive maturity in females. Myometrium The myometrium is a thick layer of smooth muscle that stretches and expands as a fetus grows. During childbirth, these muscles contract to help deliver the fetus. During menstruation, they contract to shed the endometrium. Perimetrium The perimetrium is a protective membrane. Knowledge Check Knowledge Check Vagina The vagina is a muscular tube that connects the cervix of the uterus to the outside of the body. It is the female organ for sexual intercourse. Vaginal muscle tissue expands during intercourse and childbirth. Menstrual flow exits the body through the vagina. Knowledge Check Knowledge Check Vulva The external structures of the female reproductive system are known collectively as the vulva. The vulva is made up of the mons pubis, labia majora, labia minora, clitoris, and vestibule. Two exocrine glands in the vulva are the paraurethral [payr-uh-yoo-REETH-ruhl] and Bartholin’s glands. Click each marker to learn more. Page 7 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function Mons Pubis The mons pubis is a pad of fatty tissue that covers the pubic bone. Labia Majora The labia majora are two elongated folds of protective fatty skin on either side of the vaginal opening. Labia Minora The labia minora are two elongated inner folds of skin that are enclosed by the labia majora. Vestibule In the labia minora is a recessed region called the vestibule. The vestibule contains the urethral and vaginal openings, and the paraurethral [payr-uh-yoo-REETH-ruhl] and Bartholin’s glands, which are both exocrine glands. Openings for the Paraurethral Glands The paraurethral glands, or Skene’s glands, secrete mucus for lubrication that contains antimicrobial properties to protect the urethra. Openings for the Bartholin’s Glands The Bartholin's glands, also called the vestibular glands, secrete mucus into the vagina for lubrication during intercourse. Clitoris The clitoris is located anterior, or in front of, the vestibule at the junction of the two folds of the labia minora. When stimulated, the clitoris causes arousal which prepares the vagina for intercourse. Knowledge Check Knowledge Check Menstrual Cycle The menstrual cycle starts in the female body after puberty. It is a hormone-driven series of events that occurs on average every 28 days to prepare the female body for a possible pregnancy. Page 8 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function The cycle is divided into three phases: the follicular phase, the ovulation phase, and the luteal phase. The length of each phase can differ for individuals and change over time. Click each phase to learn more. Follicular Phase The follicular phase starts on the first day of menstruation and ends when ovulation occurs. This phase lasts about 13 days but can vary between individuals. Menstruation is triggered when the corpus luteum from the last cycle deteriorates, causing a decrease in hormone levels. This results in the shedding of the endometrium’s surface in the uterus. Menstruation lasts approximately 5 to 7 days. Throughout this phase, the hypothalamus signals the pituitary gland to secrete the follicle stimulating hormone, or FSH. This hormone stimulates the ovaries to begin maturing several ovarian follicles. Each follicle contains an oocyte, an immature ovum or egg. While several oocytes mature and become ova, in most circumstances, only one becomes dominant. The body reabsorbs the remaining ova. The maturing follicles trigger a surge in the hormone estrogen, which begins to thicken the endometrium. Ovulation Phase Around day 14 of the menstrual cycle, the ovulation phase begins when rising estrogen levels trigger a surge in the luteinizing hormone, or LH. The LH stimulates the dominant follicle to rupture, releasing an ovum, or egg. The egg travels down the fallopian tube toward the uterus to be fertilized by sperm. A pregnancy is most likely to occur during this time. The egg can survive for approximately 12 to 24 hours before the body reabsorbs it. During this phase, estrogen levels decrease, and progesterone levels begin to increase. Luteal Phase The luteal phase is the final phase of the menstrual cycle. It lasts from about day 16 through 28. During this phase, the ruptured follicle closes and becomes a mass of cells called the corpus luteum. The corpus luteum secretes progesterone to help keep the uterine lining thick for pregnancy. Pregnancy begins when a fertilized egg implants in the endometrium. Page 9 of 10 Copyright © 2022 Applied Educational Systems Reproductive System Lesson Transcript Unit 1: Structure and Function Once pregnancy occurs, cells in the developing placenta release human chorionic gonadotropin, or hCG. This hormone helps maintain the corpus luteum, which keeps the fertilized egg nourished. hCG is the hormone detected by standard pregnancy tests. If there is no pregnancy, the corpus luteum deteriorates and is reabsorbed by the body. When this occurs, progesterone and estrogen levels drop, signaling the start of a new menstrual cycle. Mammary Glands Mammary glands are accessory organs to the female reproductive system. They’re a system of ducts located in the breasts that produce milk. The milk is secreted through the breast’s nipple after childbirth to nourish the newborn. Knowledge Check Lesson Summary In this lesson, you: Described the functions of the female reproductive system. Identified the parts of the female reproductive system. And explained how female sex cells are formed and travel through the female body. Page 10 of 10 Copyright © 2022 Applied Educational Systems