By Y. Mamuk. Geneva College.
The labia majora (labia = “lips” buy diltiazem 180mg without prescription; majora = “larger”) are folds of hair-covered skin that begin just posterior to the mons pubis purchase diltiazem 180mg on line. The thinner and more pigmented labia minora (labia = “lips” 180mg diltiazem; minora = “smaller”) extend medial to the labia majora generic diltiazem 60 mg overnight delivery. Although they naturally vary in shape and size from woman to woman, the labia minora serve to protect the female urethra and the entrance to the female reproductive tract. The superior, anterior portions of the labia minora come together to encircle the clitoris (or glans clitoris), an organ that originates from the same cells as the glans penis and has abundant nerves that make it important in sexual sensation and orgasm. An intact hymen cannot be used as an indication of “virginity”; even at birth, this is only a partial membrane, as menstrual fluid and other secretions must be able to exit the body, regardless of penile–vaginal intercourse. The outer walls of the anterior and posterior vagina are formed into longitudinal columns, or ridges, and the superior portion of the vagina—called the fornix—meets the protruding uterine cervix. The walls of the vagina are lined with an outer, fibrous adventitia; a middle layer of smooth muscle; and an inner mucous membrane with transverse folds called rugae. Together, the middle and inner layers allow the expansion of the vagina to accommodate intercourse and childbirth. The hymen can be ruptured with strenuous physical exercise, penile–vaginal intercourse, and childbirth. The Bartholin’s glands and the lesser vestibular glands (located near the clitoris) secrete mucus, which keeps the vestibular area moist. The vagina is home to a normal population of microorganisms that help to protect against infection by pathogenic bacteria, yeast, or other organisms that can enter the vagina. This family of beneficial bacterial flora secretes lactic acid, and thus protects the vagina by maintaining an acidic pH (below 4. However, douching—or washing out the vagina with fluid—can disrupt the normal balance of healthy microorganisms, and actually increase a woman’s risk for infections and irritation. Indeed, the American College of Obstetricians and Gynecologists recommend that women do not douche, and that they allow the vagina to maintain its normal healthy population of protective microbial flora. The ovaries are located within the pelvic cavity, and are supported by the mesovarium, an extension of the peritoneum that connects the ovaries to the broad ligament. Extending from the mesovarium itself is the suspensory ligament that contains the ovarian blood and lymph vessels. The ovary comprises an outer covering of cuboidal epithelium called the ovarian surface epithelium that is superficial to a dense connective tissue covering called the tunica albuginea. The cortex is composed of a tissue framework called the ovarian stroma that forms the bulk of the adult ovary. Beneath the cortex lies the inner ovarian medulla, the site of blood vessels, lymph vessels, and the nerves of the ovary. You will learn more about the overall anatomy of the female reproductive system at the end of this section. During a woman’s reproductive years, it is a roughly 28-day cycle that can be correlated with, but is not the same as, the menstrual cycle (discussed shortly). The cycle includes two interrelated processes: oogenesis (the production of female gametes) and folliculogenesis (the growth and development of ovarian follicles). Oogonia are formed during fetal development, and divide via mitosis, much like spermatogonia in the testis. These primary oocytes are then arrested in this stage of meiosis I, only to resume it years later, beginning at puberty and continuing until the woman is near menopause (the cessation of a woman’s reproductive functions). The number of primary oocytes present in the ovaries declines from one to two million in an infant, to approximately 400,000 at puberty, to zero by the end of menopause. The initiation of ovulation—the release of an oocyte from the ovary—marks the transition from puberty into reproductive maturity for women. From then on, throughout a woman’s reproductive years, ovulation occurs approximately once every 28 days. Just prior to ovulation, a surge of luteinizing hormone triggers the resumption of meiosis in a primary oocyte. The smaller cell, called the first polar body, may or may not complete meiosis and produce second polar bodies; in either case, it eventually disintegrates. Thus, the ovum can be thought of as a brief, transitional, haploid stage between the diploid oocyte and diploid zygote. The larger amount of cytoplasm contained in the female gamete is used to supply the developing zygote with nutrients during the period between fertilization and implantation into the uterus. Therefore, the cytoplasm and all of the cytoplasmic organelles in the developing embryo are of maternal origin. By analyzing these mutational relationships, researchers have been able to determine that we can all trace our ancestry back to one woman who lived in Africa about 200,000 years ago. Scientists have given this woman the biblical name Eve, although she is not, of course, the first Homo sapiens female. They grow and develop in a process called folliculogenesis, which typically leads to ovulation of one follicle approximately every 28 days, along with death to multiple other follicles. The death of ovarian follicles is called atresia, and can occur at any point during follicular development. Recall that, a female infant at birth will have one to two million oocytes within her ovarian follicles, and that this number declines throughout life until menopause, when no follicles remain. As you’ll see next, follicles progress from primordial, to primary, to secondary and tertiary stages prior to ovulation—with the oocyte inside the follicle remaining as a primary oocyte until right before ovulation. These small primordial follicles are present in newborn females and are the prevailing follicle type in the adult ovary (Figure 27. Primordial follicles have only a single flat layer of support cells, called granulosa cells, that surround the oocyte, and they can stay in this resting state for years—some until right before menopause. After puberty, a few primordial follicles will respond to a recruitment signal each day, and will join a pool of immature growing follicles called primary follicles. Primary follicles start with a single layer of granulosa cells, but the granulosa cells then become active and transition from a flat or squamous shape to a rounded, cuboidal shape as they increase in size and proliferate. Within the growing secondary follicle, the primary oocyte now secretes a thin acellular membrane called the zona pellucida 1296 Chapter 27 | The Reproductive System that will play a critical role in fertilization. A thick fluid, called follicular fluid, that has formed between the granulosa cells also begins to collect into one large pool, or antrum. Follicles in which the antrum has become large and fully formed are considered tertiary follicles (or antral follicles). The one that does not die will continue to grow and develop until ovulation, when it will expel its secondary oocyte surrounded by several layers of granulosa cells from the ovary. In fact, roughly 99 percent of the follicles in the ovary will undergo atresia, which can occur at any stage of folliculogenesis. The final stages of development of a small cohort of tertiary follicles, ending with ovulation of a secondary oocyte, occur over a course of approximately 28 days. These gonadotropins leave the pituitary and travel through the bloodstream to the ovaries, where they bind to receptors on the granulosa and theca cells of the follicles. This phase of the ovarian cycle, when the tertiary follicles are growing and secreting estrogen, is known as the follicular phase. As a result of these large follicles producing large amounts of estrogen, systemic plasma estrogen concentrations increase. It produces more estrogen than all of the developing follicles did together before the negative feedback occurred. This degradation of the wall, combined with pressure from the large, fluid-filled antrum, results in the expulsion of the oocyte surrounded by granulosa cells into the peritoneal cavity. In the next section, you will follow the ovulated oocyte as it travels toward the uterus, but there is one more important event that occurs in the ovarian cycle. Instead of estrogen, the luteinized granulosa and theca cells of the corpus luteum begin to produce large amounts of the sex steroid hormone progesterone, a hormone that is critical for the establishment and maintenance of pregnancy. If pregnancy does not occur within 10 to 12 days, the corpus luteum will stop secreting progesterone and degrade into the corpus albicans, a nonfunctional “whitish body” that will disintegrate in the ovary over a period of several months. The Uterine Tubes The uterine tubes (also called fallopian tubes or oviducts) serve as the conduit of the oocyte from the ovary to the uterus (Figure 27. Each of the two uterine tubes is close to, but not directly connected to, the ovary and divided into sections. The uterine tubes also have three layers: an outer serosa, a middle smooth muscle layer, and an inner mucosal layer. In addition to its mucus-secreting cells, the inner mucosa contains ciliated cells that beat in the direction of the uterus, producing a current that will be critical to move the oocyte.
It lines body cavity buy diltiazem cheap online, interior of respiratory & gastro intestinal tracts discount diltiazem master card, blood vessels & ducts and make up along with the nervous tissue (the parts of sense organs for smell order diltiazem with a visa, 28 Human Anatomy and Physiology hearing generic 180mg diltiazem amex, vision and touch). According to the arrangement of layers covering and lining epithelium is grouped in to: a) Simple epithelium: it is specialized for absorption, and filtration with minimal wear & tear. It is a single layered b) Stratified epithelium, it is many layered and found in an area with high degree of wear & tear. Based on the cell shape covering and lining epithelium is grouped in to: a) Squamous: - flattened & scale like b) Cuboidal: - cube shaped c) Columnar: - tall & cylindrical d) Transitional: - combination of cell shape found where there is a great degree of distention or expansion, these may be cuboidal to columnar, cuboidal to polyhydral and cuboidal to Squamous 29 Human Anatomy and Physiology Therefore considering the number of layers and cell shape we can classify covering and lining epithelium in to the following groups: Simple epithelium a) Simple – Squamous epithelium, contain single layer of flat, scale like resemble tiled floor. Stratified epithelium It is more durable, protects underlying tissues form external environment and from wear & tear. These are Non-Keratnized and Keratinized stratified squamous 30 Human Anatomy and Physiology epithelium. Non-Keratnized stratified squamous epithelium is found in wet surface that are subjected to considerable wear and tear. In Keratinized, stratified squamous epithelium the surface cell of this type forms a tough layer of material containing keratin. It is found in seat glands duct, conjunctiva of eye, and cavernous urethra of the male urogenital system, pharynx & epiglottis. Transitional epithelium The distinction is that cells of the outer layer in transitional epithelium tend to be large and rounded rather than flat. Exocrine: Those glands that empties their secretion in to ducts/tubes that empty at the surface of covering. Classification of exocrine glands They are classified by their structure and shape of the secretary portion. According to structural classification they are grouped into: 32 Human Anatomy and Physiology a) Unicellular gland: Single celled. By combining the shape of the secretary portion with the degree of branching of the duct of exocrine glands are classified in to - Unicellular - Multi-cellular Simple tubular Branched tubular Coiled tubular Acinar Branched Acinar 33 Human Anatomy and Physiology - Compound Tubular Acinar Tubulo-acinar 3. Embryonic connective tissue Embrayonic connective tissue contains mesenchyme & mucous connective tissue. Mucous (Wharton’s Jelly) connective tissue is found primarily in the fetus and located in the umbilical cord of the fetus where it supports the cord. Adult connective tissue composes connective tissue proper, cartilage, osseous (bone) & vascular (blood) tissue 34 Human Anatomy and Physiology a) Connective tissue proper, connective tissue proper has a more or less fluid intercellular martial and fibroblast. The various forms of connective tissue proper are: • Loose (areolar) connectives tissue, which are widely distributed and consists collagenic, elastic & reticular fibers and several cells embedded in semi fluid intercellular substances. It is common around the kidney, at the base and on the surface of the heart, in the marrow of long bone, as a padding around joints and behind the eye ball. It is poor conductor of heat, so it decrease heat loss from the body • Dense (Collagenous) connective tissue: Fibers are closely packed than in loose connective tissue. In areas where fibers are interwoven with out regular orientation the forces exerted are in many directions. In other areas dense connective tissue adapted tension in one direction and fibers have parallel arrangement. It helps to form a delicate supporting storma for many organs including liver, spleen and lymph nodes. It consists of a dense network of collagenous fibers and elastic fibers firmly embedded in chondriotin sulfate. The surface of a cartilage is surrounded by irregularly arranged dense connective tissue called perichondrium. Found at joints over long bones as articlar cartilage and forms costal cartilage (at ventral end of ribs). It forms embryonic skeleton, reinforce respiration, aids in free movement of joints and assists rib cage to move during breathing. Elastic cartilage: in elastic cartilage the chondrocyte are located in thread like network of elastic fibers. Elastic cartilage provides strength and elasticity and maintains the shape of certain organs like epiglottis, larynx, external part of the ear and Eustachian tube. They line body cavities, cover surfaces, connect, or separate regions, structures and organs of the body. Mucous membranes line the entire gastro intestine, respiratory excretory and reproductive tracts and constitute a lining layer of epithelium. To 39 Human Anatomy and Physiology prevent dry out and to trap particles mucous membranes secret mucous. Serosa is composed of parietal layer (pertaining to be outer) and visceral layer (pertaining to be near to the organ). Synovial membranes secret synovial fluid that lubricate articular cartilage at the ends of bones as they move at joints. Unicellular glands composed of columnar cells that secrete mucous are known as:- a) Cilia b) Microvilli c) Goblet cell d) Endocrine glands e) Basal cell 2. A group of similar cell that has a similar embryological origin and operates together to perform a specialized activity is called:- a) Organ b) Tissue c) System d) Organ system e) Organism 3. Mucous membranes a) Lines cavities of the body that are not open to the outside b) Secret thin watery serous fluid c) Cover the outside of such organs as the kidney and stomach d) Are found lining the respiratory & urinary passages e) Are described by none of the above. The system functions in protection, in the regulation of body temperature, in the excretion of waste materials, in the synthesis of vitamin D3 with the help of sunrays, and in the reception of various stimuli perceived as pain, pressure and temperature. These are stratum cornium, lucidium, granulosum, spinosum and basale, Stratum cornium is the outer, dead, flat, Keratinized and thicker layer. Stratum basale rests on the basement membrane, and it is the last layer of epidermis next to stratum spinosum. Dermis / true skin/ a strong, flexible, connective tissue mesh work of collagen, reticular and elastic fibers. In some areas papillary layer have special nerve endings that serve as touch receptors (meissner’s corpuscles). It is made of dense connective tissue with course of collagenous fiber bundles that crisscross to form a storma of elastic network. In the reticular layer many blood and lymphatic vessels, nerves, fat cell, sebaceous (oil) glands and hair roots are embedded. Hypodermis is composed of loose, fibrous connective tissue, which is richly supplied with lymphatic and blood vessels and nerves. Protection: against harmful microorganisms, foreign material and it prevents excessive loss of body fluid. The color of blood reflected through the epidermis * The main function of melanin is to screen out excessive ultraviolet rays. The person 47 Human Anatomy and Physiology who is genetically unable to produce any melanin is an albino. Sudoriferous /sweat/ glands Types: Eccrine and Apocrine glands Eccrine glands are small, simple coiled tubular glands distributed over nearly the entire body, and they are absent over nail beds, margins of lips of vulva, tips of penis. The sweat they secret is colorless, aqueous fluid containing neutral fats, albumin, urea, lactic acid and sodium chloride. Apocrine glands are odiferous, found at the armpits, in the dark region around nipples, the outer lips of the vulva, and the anal and genital regions. The female breasts are apocrine glands that have 48 Human Anatomy and Physiology become adapted to secret and release milk instead of sweat. It functions as a permeability barrier, an emollient (skin softening) and a protective a gent against bacteria and fungi. Acne vulgaris is a condition when there is over secretion of sebum, which may enlarge the gland and plug the pore. It covers the entire body except the palms, soles, lips, tip of penis, inner lips of vulva and nipples. Hair consist epithelial cell arranged in three layers from the inside out medulla, cortex and cuticle. Part of the hair follicle is attached with the bundle of smooth muscle about halfway down the follicle. The fastest growth rate occurs over 51 Human Anatomy and Physiology the scalp of women aged 16 to 24 years.