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Hormone levels in ovarian and menstrual cycles

The top panel of this image shows the stages in the follicular phase and how one follicle is selected at the end of this phase. The middle part of this image shows the ovarian cycle phases and the uterine cycle phases. The bottom panel shows the levels of different hormones as a function of time.
The correlation of the hormone levels and their effects on the female reproductive system is shown in this timeline of the ovarian and menstrual cycles. The menstrual cycle begins at day one with the start of menses. Ovulation occurs around day 14 of a 28-day cycle, triggered by the LH surge.

Proliferative phase

Once menstrual flow ceases, the endometrium begins to proliferate again, marking the beginning of the proliferative phase    of the menstrual cycle (see [link] ). It occurs when the granulosa and theca cells of the tertiary follicles begin to produce increased amounts of estrogen. These rising estrogen concentrations stimulate the endometrial lining to rebuild.

Recall that the high estrogen concentrations will eventually lead to a decrease in FSH as a result of negative feedback, resulting in atresia of all but one of the developing tertiary follicles. The switch to positive feedback—which occurs with the elevated estrogen production from the dominant follicle—then stimulates the LH surge that will trigger ovulation. In a typical 28-day menstrual cycle, ovulation occurs on day 14. Ovulation marks the end of the proliferative phase as well as the end of the follicular phase.

Secretory phase

In addition to prompting the LH surge, high estrogen levels increase the uterine tube contractions that facilitate the pick-up and transfer of the ovulated oocyte. High estrogen levels also slightly decrease the acidity of the vagina, making it more hospitable to sperm. In the ovary, the luteinization of the granulosa cells of the collapsed follicle forms the progesterone-producing corpus luteum, marking the beginning of the luteal phase of the ovarian cycle. In the uterus, progesterone from the corpus luteum begins the secretory phase    of the menstrual cycle, in which the endometrial lining prepares for implantation (see [link] ). Over the next 10 to 12 days, the endometrial glands secrete a fluid rich in glycogen. If fertilization has occurred, this fluid will nourish the ball of cells now developing from the zygote. At the same time, the spiral arteries develop to provide blood to the thickened stratum functionalis.

If no pregnancy occurs within approximately 10 to 12 days, the corpus luteum will degrade into the corpus albicans. Levels of both estrogen and progesterone will fall, and the endometrium will grow thinner. Prostaglandins will be secreted that cause constriction of the spiral arteries, reducing oxygen supply. The endometrial tissue will die, resulting in menses—or the first day of the next cycle.

Disorders of the… feature

Female reproductive system

Research over many years has confirmed that cervical cancer is most often caused by a sexually transmitted infection with human papillomavirus (HPV). There are over 100 related viruses in the HPV family, and the characteristics of each strain determine the outcome of the infection. In all cases, the virus enters body cells and uses its own genetic material to take over the host cell’s metabolic machinery and produce more virus particles.

HPV infections are common in both men and women. Indeed, a recent study determined that 42.5 percent of females had HPV at the time of testing. These women ranged in age from 14 to 59 years and differed in race, ethnicity, and number of sexual partners. Of note, the prevalence of HPV infection was 53.8 percent among women aged 20 to 24 years, the age group with the highest infection rate.

HPV strains are classified as high or low risk according to their potential to cause cancer. Though most HPV infections do not cause disease, the disruption of normal cellular functions in the low-risk forms of HPV can cause the male or female human host to develop genital warts. Often, the body is able to clear an HPV infection by normal immune responses within 2 years. However, the more serious, high-risk infection by certain types of HPV can result in cancer of the cervix ( [link] ). Infection with either of the cancer-causing variants HPV 16 or HPV 18 has been linked to more than 70 percent of all cervical cancer diagnoses. Although even these high-risk HPV strains can be cleared from the body over time, infections persist in some individuals. If this happens, the HPV infection can influence the cells of the cervix to develop precancerous changes.

Risk factors for cervical cancer include having unprotected sex; having multiple sexual partners; a first sexual experience at a younger age, when the cells of the cervix are not fully mature; failure to receive the HPV vaccine; a compromised immune system; and smoking. The risk of developing cervical cancer is doubled with cigarette smoking.

Development of cervical cancer

The left panel shows cell cycle. An arrow from the G2 phase leads to the right panel. The top half of the right panel describes the next steps in the absence of HPV and the bottom half describes the next steps in the presence of HPV.
In most cases, cells infected with the HPV virus heal on their own. In some cases, however, the virus continues to spread and becomes an invasive cancer.

When the high-risk types of HPV enter a cell, two viral proteins are used to neutralize proteins that the host cells use as checkpoints in the cell cycle. The best studied of these proteins is p53. In a normal cell, p53 detects DNA damage in the cell’s genome and either halts the progression of the cell cycle—allowing time for DNA repair to occur—or initiates apoptosis. Both of these processes prevent the accumulation of mutations in a cell’s genome. High-risk HPV can neutralize p53, keeping the cell in a state in which fast growth is possible and impairing apoptosis, allowing mutations to accumulate in the cellular DNA.

The prevalence of cervical cancer in the United States is very low because of regular screening exams called pap smears. Pap smears sample cells of the cervix, allowing the detection of abnormal cells. If pre-cancerous cells are detected, there are several highly effective techniques that are currently in use to remove them before they pose a danger. However, women in developing countries often do not have access to regular pap smears. As a result, these women account for as many as 80 percent of the cases of cervical cancer worldwide.

In 2006, the first vaccine against the high-risk types of HPV was approved. There are now two HPV vaccines available: Gardasil ® and Cervarix ® . Whereas these vaccines were initially only targeted for women, because HPV is sexually transmitted, both men and women require vaccination for this approach to achieve its maximum efficacy. A recent study suggests that the HPV vaccine has cut the rates of HPV infection by the four targeted strains at least in half. Unfortunately, the high cost of manufacturing the vaccine is currently limiting access to many women worldwide.

Questions & Answers

What is Sodium Potassium Pump?
Mwamba Reply
The process of moving sodium and potassium ions across the cell membrance is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+-ATPase
yes men.
does it mean that there are two definitions of gross anatomy
Esther Reply
what is anatomy?
Hridy Reply
I think it's the study of the internal and external features of the body and its physical relationship between body parts
anatomy is the study of all the structure of body parts of living organisms
jaundice causes by when bilirubin blockage of bilary system
mahamed Reply
Yeah, when there is a blockage in the bilary system( bile ducts) which lead to obstruction of the bile pigments called bilirubin leading to a characteristically yellowish appearance of the eyes.
there are three main resons why bilirubin levels in the blood may rise: 1. pre-hepatic jaundice,2. hepatic jaundice, 3. post hepatic
hi pls what causes jaundice
Umar Reply
where the love feelings emotions and hate lies in the body?
Loving Reply
what is Regional anatomy
Sharon Reply
Please information on dialysis
Agbo Reply
what is the relationship between Clinical officer general, unqualified professionals and traditional healers?
Purity Reply
is that how the microscopic anatomy is
Elizabeth Reply
to understand the structures of the body. to understand how the structures of the body work . To understand how the structures of the body work and support the functions of life.
Dora Reply
procedures that removes waste from body when kidneys dont function properly..
maribel Reply
Want to join
dialysis is a process to remove extra fluid , impurities and waste product from the blood and to correct electrolytes imbalance such as sodium, potassium and calcium with the help of dialysis machine. when the kidneys can't do their job.
what will lead a person to dialysis
what's metabolic acidosis
A condition in which too much acid accumulates in the body. Causes of metabolic acidosis can include buildup of body toxins, kidney failure, and ingestion of certain drugs or toxins, such as methanol or large doses of aspirin. It can be a rare complication of diabetes.
What is dialisis
Friday Reply
When kidney is not functioning properly than with the help of dialysis blood filtration is occur Or we can say that it is a process through which filtration of blood is done
dialysis is a process of removing wastes, excess fluid ,impurities from the blood and to correct electrolytes imbalance such as sodium, potassium and calcium etc with the help of dialysis machine.when the kidney can't do their job.
describe anatomical position
Getrude Reply
The erect position of the body with the face directed forward, the arms at the side, and the palms of the hands facing forward, used as a reference in describing the relation of body parts to one another
Somebody to explain for me the duties of specialist obstetrician
Definition of an anatomy
Oppong Reply
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the study of the body's structures scientifically

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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