Between the labia are openings to the urethra the canal that carries urine from the bladder to the outside of the body and vagina. Once girls become sexually mature, the outer labia and the mons pubis are covered by pubic hair. The vagina is a muscular, hollow tube that extends from the vaginal opening to the uterus. The vagina is about 3 to 5 inches 8 to 12 centimeters long in a grown woman. Because it has muscular walls, it can expand and contract.
This ability to become wider or narrower allows the vagina to accommodate something as slim as a tampon and as wide as a baby. The vagina's muscular walls are lined with mucous membranes, which keep it protected and moist. A very thin piece of skin-like tissue called the hymen partly covers the opening of the vagina. Hymens are often different from female to female. Most women find their hymens have stretched or torn after their first sexual experience, and the hymen may bleed a little this usually causes little, if any, pain.
Some women who have had sex don't have much of a change in their hymens, though. The vagina connects with the uterus, or womb, at the cervix which means neck. The cervix has strong, thick walls. The opening of the cervix is very small no wider than a straw , which is why a tampon can never get lost inside a girl's body. During childbirth, the cervix can expand to allow a baby to pass. The uterus is shaped like an upside-down pear, with a thick lining and muscular walls — in fact, the uterus contains some of the strongest muscles in the female body.
These muscles are able to expand and contract to accommodate a growing fetus and then help push the baby out during labor. When a woman isn't pregnant, the uterus is only about 3 inches 7. At the upper corners of the uterus, the fallopian tubes connect the uterus to the ovaries. The ovaries are two oval-shaped organs that lie to the upper right and left of the uterus.
They produce, store, and release eggs into the fallopian tubes in the process called ovulation. There are two fallopian tubes, each attached to a side of the uterus. The fallopian tubes are about 4 inches 10 centimeters long and about as wide as a piece of spaghetti. Within each tube is a tiny passageway no wider than a sewing needle. At the other end of each fallopian tube is a fringed area that looks like a funnel. This fringed area wraps around the ovary but doesn't completely attach to it.
When an egg pops out of an ovary, it enters the fallopian tube. Once the egg is in the fallopian tube, tiny hairs in the tube's lining help push it down the narrow passageway toward the uterus. The ovaries are also part of the endocrine system because they produce female sex hormones such as estrogen and progesterone.
Sexual reproduction couldn't happen without the sexual organs called the gonads. Although most people think of the gonads as the male testicles, both sexes actually have gonads: In females the gonads are the ovaries. The female gonads produce female gametes eggs ; the male gonads produce male gametes sperm. After an egg is fertilized by the sperm, the fertilized egg is called the zygote. When a baby girl is born, her ovaries contain hundreds of thousands of eggs, which remain inactive until puberty begins.
At puberty, the pituitary gland, located in the central part of the brain, starts making hormones that stimulate the ovaries to produce female sex hormones, including estrogen. The secretion of these hormones causes a girl to develop into a sexually mature woman.
Toward the end of puberty, girls begin to release eggs as part of a monthly period called the menstrual cycle. Approximately once a month, during ovulation, an ovary sends a tiny egg into one of the fallopian tubes. Unless the egg is fertilized by a sperm while in the fallopian tube, the egg dries up and leaves the body about 2 weeks later through the uterus — this is menstruation.
Blood and tissues from the inner lining of the uterus combine to form the menstrual flow, which in most girls lasts from 3 to 5 days. A girl's first period is called menarche. It's common for women and girls to experience some discomfort in the days leading to their periods. Premenstrual syndrome PMS includes both physical and emotional symptoms that many girls and women get right before their periods, such as acne, bloating, fatigue, backaches, sore breasts, headaches, constipation, diarrhea, food cravings, depression, irritability, or difficulty concentrating or handling stress.
PMS is usually at its worst during the 7 days before a girl's period starts and disappears once it begins. Many girls also experience abdominal cramps during the first few days of their periods caused by prostaglandins, chemicals in the body that make the smooth muscle in the uterus contract.
These involuntary contractions can be either dull or sharp and intense.
Antagonistic Hormones Hormones Quiz: The endomitrial tissue that is left after menstruation begins to grow. Lymphatic drainage is primarily to the lateral aortic, pelvic, and iliac nodes that surround the iliac vessels. The luteal phase describes the secretion of estrogen and progesterone from the corps luteum previously the follicle after ovulation. The following features are observed: Removing book from your Reading List will also remove any bookmarked pages associated with this title.
It can take up to 2 years from menarche for a girl's body to develop a regular menstrual cycle. During that time, her body is adjusting to the hormones puberty brings.
On average, the monthly cycle for an adult woman is 28 days, but the range is from 23 to 35 days. If a female and male have sex within several days of the female's ovulation, fertilization can occur. Ovulation occurs when a secondary oocyte and its first polar body, surrounded by the zona pellucida and corona radiata, rupture from their mature follicle and are expelled from the surface of the ovary. The oocyte is then swept up into the uterine fallopian tube and advances toward the uterus. If a sperm cell penetrates the corona radiata and zona pellucida and enters the secondary oocytes, meiosis II resumes in the secondary oocytes, producing an ovum and a second polar body.
If a first polar body is present, it too, may resume meiosis II, producing daughter polar bodies. Fertilization occurs when the nuclei of the sperm cell and ovum unite, forming a zygote fertilized egg. Any polar bodies present ultimately degenerate. The human female reproductive cycle is characterized by events in the ovary ovarian cycle and the uterus menstrual cycle. The purpose of these cycles is to produce an egg and to prepare the uterus for the implantation of the egg, should it become fertilized.
The ovarian cycle consists of three phases: The follicular phase describes the development of the follicle, the meiotic stages of division leading to the formation of the secondary oocytes, and the secretion of estrogen from the follicle. The luteal phase describes the secretion of estrogen and progesterone from the corps luteum previously the follicle after ovulation. The proliferative phase describes the thickening of the endometrium of the uterus, replacing tissues that were lost during the previous menstrual cycle. The secretory phase follows ovulation and describes further thickening and vascularization of the endometrium in preparation for the implantation of a fertilized egg.
The menstrual phase menstruation, menses describes the shedding of the endometrium when implantation does not occur. A description of the events follows: The hypothalamus and anterior pituitary initiate the reproductive cycle: The hypothalamus monitors the levels of estrogen and progesterone in the blood. FSH stimulates the development of the follicle from primary through mature stages. The follicle secretes estrogen: LH stimulates the cells of the theca interna and the granulosa cells of the follicle to secrete estrogen.
Inhibin is also secreted by the granulosa cells. Positive feedback from rising levels of estrogen stimulate the anterior pituitary through GnRH from the hypothalamus to produce a sudden midcycle surge of LH. This high level of LH stimulates meiosis in the primary oocyte to progress toward prophase II and triggers ovulation. The corpus luteum secretes estrogen and progesterone: After ovulation, the follicle, now transformed into the corpus luteum, continues to develop under the influence of LH and secretes both estrogen and progesterone.
Estrogen and progesterone stimulate the development of the endometrium, the inside lining of the uterus. The hypothalamus and anterior pituitary terminate the reproductive cycle: Negative feedback from the high levels of estrogen and progesterone cause the anterior pituitary through the hypothalamus to abate the production of FSH and LH. The endometrium either disintegrates or is maintained, depending on whether implantation of the fertilized egg occurs, as follows:.
In addition to influencing the reproductive cycle, estrogen stimulates the development of secondary sex characteristics in females. These include the distribution of adipose tissue to the breasts, hips, and mons pubis , bone development leading to a broadening of the pelvis, changes in voice quality, and growth of various body hair. Removing book from your Reading List will also remove any bookmarked pages associated with this title. Are you sure you want to remove bookConfirmation and any corresponding bookmarks?
The Female Reproduction System. What is Anatomy and Physiology? Atoms, Molecules, Ions, and Bonds Quiz: Cell Junctions Movement of Substances Quiz: Epithelial Tissue Connective Tissue Quiz: Nervous Tissue Muscle Tissue Quiz: The Epidermis The Dermis Quiz: Types of Bones Bone Structure Quiz: Bone Structure Bone Development Quiz: Functions of Bones Types of Bones Quiz: Bone Growth Bone Homeostasis Quiz: Hyoid Bone Vertebral Column Quiz: Vertebral Column Organization of the Skeleton Quiz: Organization of the Skeleton Skull: Cranium and Facial Bones Thorax Quiz: Thorax Pectoral Girdle Quiz: Pectoral Girdle Upper Limb Quiz: Upper Limb Pelvic Girdle Quiz: Pelvic Girdle Lower Limb Quiz: Classifying Joints Muscle Tissue Quiz: Nervous System Organization Quiz: Spinal Nerves Reflexes Quiz: The Somatic Senses Vision Quiz: Vision Hearing Sensory Receptors Quiz: Taste The Endocrine System Quiz: Antagonistic Hormones Hormones Quiz: The Blood Blood Formation Quiz: Blood Formation Hemostasis Quiz: Blood Groups Circulatory Pathways Quiz: Circulatory Pathways The Heart Quiz: Lymphatic Vessels Lymphoid Cells Quiz: Lymphatic System Components Quiz: Nonspecific Barriers Nonspecific Defenses Quiz: Major Histocompatibility Complex Lymphocytes Quiz: Structure of the Respiratory System Lungs Quiz: Lungs Mechanics of Breathing Quiz: Gas Exchange Gas Transport Quiz: Gas Transport Control of Respiration Quiz: Digestive Enzymes The Mouth Quiz: The Esophagus Deglutition Swallowing Quiz: Deglutition Swallowing The Stomach Quiz: Large Intestine The Pancreas Quiz: Regulation of Urine Concentration Ureters Quiz: Ureters Urinary Bladder Quiz: Urinary Bladder Anatomy of the Kidneys Quiz: Urethra The Reproductive System Quiz: The Male Reproductive System Quiz: Pulsating cilia on the fimbriae draw the secondary oocyte into the uterine tube.
The ampulla is the widest and longest region of the uterine tube. Fertilization of the oocyte by a sperm usually occurs here.
The isthmus is a narrow region of the uterine tube whose terminus enters the uterus. The wall of the uterine tube consists of the following three layers: The serosa, a serous membrane, lines the outside of the uterine tube. The middle muscularis consists of two layers of smooth muscle that generate peristaltic contractions that help propel the oocyte forward. The inner mucosa consists of ciliated columnar epithelial cells that help propel the oocyte forward, and secretory cells that lubricate the tube and nourish the oocyte.
The uterus womb is a hollow organ within which fetal development occurs. The uterus is characterized by the following regions: The fundus is the upper region where the uterine ducts join the uterus. The body is the major, central portion of the uterus. The isthmus is the lower, narrow portion of the uterus. The cervix is a narrow region at the bottom of the uterus that leads to the vagina. The inside of the cervix, or cervical canal, opens to the uterus above through the internal os and to the vagina below through the external os.
Cervical mucus secreted by the mucosa layer of the cervical canal serves to protect against bacteria entering the uterus from the vagina. If an oocyte is available for fertilization, the mucus becomes thin and slightly alkaline. These are attributes that promote the passage of sperm. At other times, the mucus is viscous and impedes the passage of sperm. The uterus is held in place by the following ligaments: