Essentials of Human Anatomy & Physiology Chapter 16 The Reproductive System PDF

Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 16 The Reproductive System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings ...

Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 16 The Reproductive System Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  The Reproductive System Gonads – primary sex organs Testes in males Ovaries in females Gonads produce gametes (sex cells) and secrete hormones Sperm – male gametes Ova (eggs) – female gametes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 16.1  Male Reproductive System Figure 16.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Male Reproductive System Testes Duct system Epididymis Ductus deferens Urethra Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Male Reproductive System Accessory organs Seminal vesicle Prostate gland Bulbourethral gland External genitalia Penis Scrotum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Male Reproductive System Figure 16.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Testes Coverings of the testes Tunica albuginea – capsule that surrounds each testis Figure 16.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Testes Coverings of the testes (continued) Septa – extensions of the capsule that extend into the testis and divide it into lobules Figure 16.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Testes Each lobule contains one to four seminiferous tubules Tightly coiled structures Function as sperm-forming factories Empty sperm into the rete testis Sperm travels through the rete testis to the epididymis Interstitial cells produce androgens such as testosterone Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 16.4  Epididymis Comma-shaped, tightly coiled tube Found on the superior part of the testis and along the posterior lateral side Functions to mature and store sperm cells (at least 20 days) Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 16.5  Male Reproductive System Figure 16.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Ductus Deferens (Vas Deferens) Carries sperm from the epididymis to the ejaculatory duct Passes through the inguinal canal and over the bladder Moves sperm by peristalsis Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue sheath Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Ductus Deferens (Vas Deferens) Ends in the ejaculatory duct which unites with the urethra Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Urethra Extends from the base of the urinary bladder to the tip of the penis Carries both urine and sperm Sperm enters from the ejaculatory duct Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Urethra Regions of the urethra Prostatic urethra –surrounded by prostate Membranous urethra – from prostatic urethra to penis Spongy (penile) urethra – runs the length of the penis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Seminal Vesicles Located at the base of the bladder Produces a thick, yellowish secretion (60% of semen) Fructose (sugar) Vitamin C Prostaglandins Other substances that nourish and activate sperm Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 16.8  Male Reproductive System Figure 16.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Prostate Gland Encircles the upper part of the urethra Secretes a milky fluid Helps to activate sperm Enters the urethra through several small ducts Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 16.9  Bulbourethral Glands Pea-sized gland inferior to the prostate Produces a thick, clear mucus Cleanses the urethra of acidic urine Serves as a lubricant during sexual intercourse Secreted into the penile urethra Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Semen Mixture of sperm and accessory gland secretions Advantages of accessory gland secretions Fructose provides energy for sperm cells Alkalinity of semen helps neutralize the acidic environment of vagina Semen inhibits bacterial multiplication Elements of semen enhance sperm motility Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  External Genitalia Scrotum Divided sac of skin outside the abdomen Maintains testes at 3°C lower than normal body temperature to protect sperm viability Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  External Genitalia Penis Delivers sperm into the female reproductive tract Regions of the penis Shaft Glans penis (enlarged tip) Prepuce (foreskin) Folded cuff of skin around proximal end Often removed by circumcision Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  External Genitalia Internally there are three areas of spongy erectile tissue around the urethra Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Spermatogenesis Production of sperm cells Begins at puberty and continues throughout life Occurs in the seminiferous tubules Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Processes of Spermatogenesis Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty Follicle stimulating hormone (FSH) modifies spermatogonia division One cell produced is a stem cell The other cell produced becomes a primary spermatocyte Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Processes of Spermatogenesis Primary spermatocytes undergo meiosis Haploid spermatids are produced Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Processes of Spermatogenesis Spermiogenesis Late spermatids are produced with distinct regions Head – contains DNA covered by the acrosome Midpiece Tail Sperm cells result after maturing of spermatids Spermatogenesis takes 64 to 72 days Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Female Reproductive System Ovaries Duct System Uterine tubes (fallopian tubes) Uterus Vagina External genitalia Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Female Reproductive System Figure 16.8a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Ovaries Composed of ovarian follicles (sac-like structures) Structure of an ovarian follicle Oocyte Follicular cells Figure 16.7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Ovarian Follicle Stages Primary follicle – contains an immature oocyte Graafian (vesicular) follicle – growing follicle with a maturing oocyte Ovulation – when the egg is mature the follicle ruptures Occurs about every 28 days The ruptured follicle is transformed into a corpus luteum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Support for Ovaries Suspensory ligaments – secure ovary to lateral walls of the pelvis Ovarian ligaments – attach to uterus Broad ligament – a fold of the peritoneum, encloses suspensory ligament Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Support for Ovaries Figure 16.8b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Uterine (Fallopian) Tubes Receive the ovulated oocyte Provide a site for fertilization Attaches to the uterus Does not physically attach to the ovary Supported by the broad ligament Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Uterine Tube Function Fimbriae – finger-like projections at the distal end that receive the oocyte Cilia inside the uterine tube slowly move the oocyte towards the uterus (takes 3–4 days) Fertilization occurs inside the uterine tube Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Uterus Located between the urinary bladder and rectum Hollow organ Functions of the uterus Receives a fertilized egg Retains the fertilized egg Nourishes the fertilized egg Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Support for the Uterus Broad ligament – attached to the pelvis Round ligament – anchored interiorly Uterosacral ligaments – anchored posteriorly Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Support for the Uterus Figure 16.8b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Regions of the Uterus Body – main portion Fundus – area where uterine tube enters Cervix – narrow outlet that protrudes into the vagina Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Walls of the Uterus Endometrium Inner layer Allows for implantation of a fertilized egg Sloughs off if no pregnancy occurs (menses) Myometrium – middle layer of smooth muscle Serous layer – outer visceral peritoneum Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Vagina Extends from cervix to exterior of body Behind bladder and in front of rectum Serves as the birth canal Receives the penis during sexual intercourse Hymen – partially closes the vagina until it is ruptured Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  External Genitalia (Vulva) Mons pubis Fatty area overlying the pubic symphysis Covered with pubic hair after puberty Figure 16.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  External Genitalia (Vulva) Labia – skin folds Labia majora Labia minora Figure 16.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  External Genitalia Vestibule Enclosed by labia majora Contains opening of the urethra and the greater vestibular glands (produce mucus) Clitoris Contains erectile tissue Corresponds to the male penis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Oogenesis The total supply of eggs are present at birth Ability to release eggs begins at puberty Reproductive ability ends at menopause Oocytes are matured in developing ovarian follicles Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Oogenesis Oogonia – female stem cells found in a developing fetus Oogonia undergo mitosis to produce primary oocytes Primary oocytes are surrounded by cells that form primary follicles in the ovary Oogonia no longer exist by the time of birth Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Oogenesis Primary oocytes are inactive until puberty Follicle stimulating hormone (FSH) causes some primary follicles to mature Meiosis starts inside maturing follicle Produces a secondary oocyte and the first polar body Meiosis is completed after ovulation only if sperm penetrates Two additional polar bodies are produced Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Oogenesis Figure 16.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Menstrual (Uterine) Cycle Cyclic changes of the endometrium Regulated by cyclic production of estrogens and progesterone Stages of the menstrual cycle Menses – functional layer of the endometrium is sloughed Proliferative stage – regeneration of functional layer Secretory stage – endometrium increases in size and readies for implantation Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Hormonal Control of the Ovarian and Uterine Cycles Figure 16.12a, b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Hormonal Control of the Ovarian and Uterine Cycles Figure 16.12c, d Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Hormone Production-Ovaries Estrogens Produced by follicle cells Cause secondary sex characteristics Enlargement of accessory organs Development of breasts Appearance of pubic hair Increase in fat beneath the skin Widening and lightening of the pelvis Onset of menses Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Hormone Production by the Ovaries Progesterone Produced by the corpus luteum Production continues until LH diminishes in the blood Helps maintain pregnancy Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Mammary Glands Present in both sexes, but only function in females Modified sweat glands Function is to produce milk Stimulated by sex hormones (mostly estrogens) to increase in size Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Stages of Pregnancy and Development Fertilization Embryonic development Fetal development Childbirth Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Fertilization The oocyte is viable for 12 to 24 hours after ovulation Sperm are viable for 12 to 48 hours after ejaculation Sperm cells must make their way to the uterine tube for fertilization to be possible Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Development from Ovulation to Implantation Figure 16.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Mechanisms of Fertilization Membrane receptors on an oocyte pulls in the head of the first sperm cell to make contact The membrane of the oocyte does not permit a second sperm head to enter The oocyte then undergoes its second meiotic division Fertilization occurs when the genetic material of a sperm combines with that of an oocyte to form a zygote Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  The Zygote First cell of a new individual The result of the fusion of DNA from sperm and egg The zygote begins rapid mitotic cell divisions The zygote stage is in the uterine tube, moving toward the uterus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  The Embryo Developmental stage from the start of cleavage until the ninth week The embryo first undergoes division without growth The embryo enters the uterus at the 16-cell state The embryo floats free in the uterus temporarily Uterine secretions are used for nourishment Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  The Blastocyst Ball-like circle of cells Begins at about the 100 cell stage Secretes human chorionic gonadotropin (hCG) to produce the corpus luteum to continue producing hormones The blastocyst implants in the wall of the uterus (by day 14) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Development from Ovulation to Implantation Figure 16.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Development After Implantation Chorionic villi (projections of the blastocyst) develop Cooperate with cells of the uterus to form the placenta The embryo is surrounded by the amnion (a fluid filled sac) An umbilical cord forms to attach the embryo to the placenta Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Development After Implantation Figure 16.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Functions of the Placenta Forms a barrier between mother and embryo (blood is not exchanged) Delivers nutrients and oxygen Removes waste from embryonic blood Becomes an endocrine organ (produces hormones) and takes over for the corpus luteum Estrogen Progesterone Other hormones that maintain pregnancy Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  The Fetus (Beginning of the Ninth Week) All organ systems are formed by the end of the eighth week Activities of the fetus are growth and organ specialization A stage of tremendous growth and change in appearance Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  The Effects of Pregnancy on the Mother Pregnancy – period from conception until birth Anatomical changes Enlargements of the uterus Accentuated lumbar curvature Relaxation of the pelvic ligaments and pubic symphysis due to production of relaxin Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Effects of Pregnancy on the Mother Physiological changes Gastrointestinal system Morning sickness is common due to elevated progesterone Heartburn is common because of organ crowding by the fetus Constipation is caused by declining motility of the digestive tract Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Effects of Pregnancy on the Mother Physiological changes Urinary System Kidneys have additional burden and produce more urine The uterus compresses the bladder Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Effects of Pregnancy on the Mother Physiological changes Respiratory System Nasal mucosa becomes congested and swollen Vital capacity and respiratory rate increase Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Effects of Pregnancy on the Mother Physiological changes Cardiovascular system Body water rises Blood volume increases by 25 to 40 percent Blood pressure and pulse increase Varicose veins are common Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Childbirth (Partition) Labor – the series of events that expel the infant from the uterus Initiation of labor Estrogen levels rise Uterine contractions begin The placenta releases prostaglandins Oxytocin is released by the pituitary Combination of these hormones produces contractions Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Initiation of Labor Figure 16.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Stages of Labor Dilation Cervix becomes dilated Uterine contractions begin and increase The amnion ruptures Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Stages of Labor Expulsion Infant passes through the cervix and vagina Normal delivery is head first Placental stage Delivery of the placenta Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Stages of Labor Figure 16.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Developmental Aspects of the Reproductive System Gender is determined at fertilization Males have XY sex chromosomes Females have XX sex chromosomes Gonads do not begin to form until the eighth week Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Developmental Aspects of the Reproductive System Testes form in the abdominal cavity and descend to the scrotum one month before birth The determining factor for gonad differentiation is testosterone Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Developmental Aspects of the Reproductive System Reproductive system organs do not function until puberty Puberty usually begins between ages 10 and 15 The first menses usually occurs about two years after the start of puberty Most women reach peak reproductive ability in their late 20s Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide  Developmental Aspects of the Reproductive System Menopause occurs when ovulation and menses cease entirely Ovaries stop functioning as endocrine organs There is a no equivalent of menopause in males, but there is a steady decline in testosterone Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide