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- Allopregnanolone - Allopregnanolone is a molecule derived from progesterone in the brain.
- Cervical mucus - Also called “cervical fluid”, it is the secretion produced within the cervix that acts as a medium in which sperm can travel.
Its presence and quality are directly related to the production of estrogen and progesterone. Analogous to a man’s seminal fluid. It is one of the three primary fertility signs, along with cervical position and waking temperature. The cervical fluid typically gets progressively wetter as ovulation approaches.
- Cervix - The lower portion of the uterus that projects into the vagina.
- Cesarean delivery - In this procedure a doctor surgically opens the abdominal cavity and uterus to remove the baby. This is typically done following complications during labor. There are certain risks associated with this procedure including infection, postpartum hemorrhaging, and blood clots. Healthcare professionals recommend this procedure be used only if there is a clear benefit for the baby or mother.
- Corpus luteum - The corpus luteum develops during the luteal phase in the ovaries. It is formed from an ovarian follicle after the release of a secondary oocyte. It secretes progesterone - mainly - and estrogens. Progesterone helps to create a more suitable environment for fertilization and the development of an embryo. If the egg is not fertilized, the corpus luteum is shed along with the endometrium lining. If the egg is fertilized, the corpus luteum becomes a vital component of the pregnancy and begins secreting human chorionic gonadotropin (hCG).
- Cortisol - Mainly known as “the stress hormone”, it is a steroid hormone primarily responsible for increasing sugar levels in the blood.
- Dopamine - An important neurotransmitter with different functions, mostly involved in the control of movement, pleasure and reward.
Inside the nervous system, dopamine plays important roles in executive function, motivation, reinforcement, reward and pleasure as well as lower-level functions including lactation and sexual gratification. Dopamine does not cross the blood–brain barrier, so there is only a little fraction of free dopamine acting outside the brain, where its role is still not completely discovered, although some functions are well known, like the vasodilatation effect.
- Endometrium - The uterus is made of three layers, which together form the uterine wall. The innermost layer is the endometrium, which has, in turn, a basal layer and a functional layer; the functional one thickens during the menstrual cycle to provide the best environment for implantation and growth of the embryo. During pregnancy, the endometrium further expands and increases vascularization to help placenta formation and sustain fetus growth.
On the other hand, if there is no embryo implantation, at the end of a menstrual cycle, the endometrium is shed, leading to menstruation.
- Estrogen - Major female sex hormone, involved in the control and regulation of the menstrual cycle.
Like all steroids hormones, the estrogens derive from cholesterol. The three major natural forms of estrogen in women are; estrone (E1), estriol (E3), and estradiol (E2, with the latter being the strongest of the family). Another type of estrogen called esteretrol (E4) is produced only during pregnancy. Estradiol is the predominant estrogen during the reproductive years both in terms of serum levels as well as in terms of estrogenic activity. The main functions of estrogens are the control and regulation of the menstrual cycle, thickening of the uterus lining, triggering the Luteinizing Hormone surge and stopping the menses. They also promote the development of female secondary sexual characteristics, such as breast development. During menopause, the predominant circulating estrogen is estrone, while during pregnancy it is estriol. In males, estrogens regulate certain functions of the reproductive system, important to the maturation of sperm and libido regulation. Estrogens also have many other essential roles such as regulation of lipidic metabolism, bones metabolism, regulation of coagulation process, sexual behavior and more.
- Fallopian tubes - Pair of tubes connected to either side of the uterus. Sperm travel up to potentially unite with an egg in the outer third of the tube, after which the fertilized egg is transported toward the uterus through the tube.
- Follicular Phase - This phase is called pre-ovulatory phase is the variable-length of the cycle from the onset of menstruation to ovulation.
This is the phase of your cycle in which the follicles into your ovary mature under the effect of Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH). Only one follicle will complete the maturation process, becoming dominant, that will lead to the production of an egg (oocyte) which will be released with the ovulation.
- Ghrelin - A hormone that is secreted by cells present in the stomach and the small intestine. One of its functions is to signal hunger to the brain.
Ghrelin, mainly known as the hunger hormone, helps to decide how the food that you consume is to be used by your body (i.e. stored as fat, stored as glycogen, as a direct source of energy for your cells or to be burned as heat). It does so by regulating hunger signals and energy needs in the body. For example, it tends to be higher before you eat. The results of these processes are directly reflected in body weight by regulating how hungry you feel.
- hCG - hCG (Human chorionic gonadotropin) is produced by specialized cells, called syncytiotrophoblasts, that surround the embryo. These cells create the placenta after implantation. The role of hCG is crucial in the first trimester of pregnancy, when it interacts with the ovary and promotes the maintenance of the corpus luteum (a structure that derives from the cells of the follicle, after its rupture for the egg release, during the ovulation). hCG stimulates the corpus luteum to secrete progesterone, which thickens the lining of the uterus and its capillarization, so that it can sustain the growing fetus.
- hPL - hPL (Human placental lactogen) is produced by specialized cells, called syncytiotrophoblasts, that surround the embryo, when the production of hCG begins to diminish. The levels of hPL reflect placental well-being. In the fetus, hPL promotes production of molecules called “growth factors”. These molecules are important for the development of the fetal tissues. They are also important in the mother, where hPL stimulates a series of metabolic changes in order to increase the availability of glucose (sugar) for fetal consumption.
- HPO axis - Stands for “Hypothalamic-pituitary-ovarian” axis. It refers to the hypothalamus, pituitary gland and ovaries as a single system and plays a critical part in the development and regulation of a number of the body's systems, mostly through control of the reproductive system.
To better study and describe complex functions, some organs can be considered like a whole. In this case the hypothalamus (the portion of the brain responsible for the link between nervous system and endocrine system), the pituitary gland (an endocrine gland controlling many body processes) and the ovaries are considered as a single entity. They often act in concert, sending feedback to each other, regulating the menstrual cycle in women and the spermatogenesis in men. The activation of the HPO axis during puberty causes the development of secondary sex characteristics.
- HTR - Stands for "Hormonal replacement therapy". is a form of hormonal therapy used to treat symptoms associated with female menopause.
- Hypothalamic amenorrhea - Hypothalamic amenorrhea occurs because of a problem with the hypothalamus, which is responsible for producing GnRH (gonadotropin-releasing hormone). This condition often occurs due to stress or an insufficient diet. Patients suffering from hypothalamic amenorrhea have low levels of Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), and Estradiol (E2).
- Hypothalamus - It is a portion of the brain with a variety of functions, the most notable is linking the nervous system and the endocrine system.
The hypothalamus has a central neuroendocrine function, most notably by its control of the anterior pituitary gland, which in turn regulates various endocrine glands and organs. Releasing hormones (also called releasing factors) are produced by the hypothalamus and released as needed to regulate the pituitary gland function.
- Inner labia - Two folds of skin between the outer labia, they enclose the vulvar vestibule, urethra and vagina.
They are also called labia minora and vary in size, colour shape from woman to woman. In some women, they are almost nonexistent. In some others, they are fleshy and stick out of the outer labia.
- IUD - Stands for "intra-uterine device". A device placed in the cavity of the uterus to prevent pregnancy. Certain types release hormones while in place.
The copper-coated IUD prevents pregnancy by not allowing the sperm penetration and for fertilizing the egg. It may also make it harder for a fertilized egg to implant in the uterus. The progestin-coated IUD works also by thickening the cervical mucus and thinning the uterine lining, preventing the ideal condition for the implantation of the fertilized egg
- Luteal phase - The phase of the menstrual cycle from ovulation to the onset of the next menstruation. It typically lasts from 12 to 16 days, but rarely varies by more than a day or two within individual women.It typically lasts from 12 to 16 days, but rarely varies by more than a day or two within individual women.
- Menopause - The permanent cessation of ovulation, and hence menstruation. A woman is said to have gone through menopause after not having had a period for a full year.
- Menstruation - The cyclical bleeding from the uterus as the endometrium is shed. True menstruation is usually preceded by ovulation 12 to 16 days earlier. Day 1 of menstruation is the first day of true red bleeding.
- Natural family planning - involves identifying the signs and symptoms of fertility like cervical fluid state during your menstrual cycle to plan or avoid pregnancy.
- Ovulation - The release of a mature egg (ovum) from the ovarian follicle. The ovulation occurs with the rupture of the dominant follicle and the release of the oocyte which is now available for the fertilization by the sperm. In this phase also the uterine lining changes, becoming thicker to promote the implant of the fertilized egg. If the fertilization does not happen, the layer of the uterus will be shed and discarded during the menstruation.
- Ovum - The ovum, or egg cell, is situated on the inside of the follicle, which grows with the help of Follicle-stimulating hormone (FSH). As the ovum grows, the follicle expands and adds more cells to its outer walls. When the follicle matures, the ovum is released from the ovary into the fallopian tubes. The ovum is primarily responsible for the determined inherited characteristics of the child, as it contains the female genetic material.
- Oxytocin - In women’s physiology, oxytocin plays an important part in the period around childbirth. During labor, as the cervix and vagina start to widen, oxytocin is released. It promotes the uterine motility and its muscles contractions. It is also involved in breastfeeding and mother-baby-bond developing. In general, oxytocin also plays a role in social functions, being involved in processes such as the creation of group memories and social recognition. Oxytocin levels also increase through orgasms and hugging.
- PCOS - Stands for "Polycystic ovary syndrome", a common endocrine disorder that usually leads to irregular cycles and other hormonal problems. With PCOS, developing follicles often remain trapped inside the ovary, later becoming cysts on the internal ovarian wall. Thought to be caused by high blood insulin levels.
- Pituitary gland - Also called hypophysis, is an endocrine gland and it has a part directly connected to the hypothalamus, at the base of the brain. It plays an important role in regulating and orchestrating many other organs and vital functions.
It is a small gland, about the size of a pea, directly connected to the nervous system. It is composed of three lobes and each one has a specific function. The anterior lobe (or adenohypophysis) regulates several different physiological processes such as stress, growth, reproduction, and lactation. The intermediate lobe synthesizes and secretes melanocyte-stimulating hormone, important for the pigmentation of the skin, and the posterior lobe (or neurohypophysis), is functionally connected to the hypothalamus by a small tube called the pituitary stalk or infundibulum. In general, the pituitary gland releases hormones that control growth, blood pressure, sex organ fuctions, energy management and metabolism as well as some other aspects such as water/salt concentration at the kidney level, temperature regulation and pain relief.
- Plasma - liquid portion of blood that remains after removing cells, platelets and other corpuscular components.
- PMDD - Stands for "Premenstrual dysphoric disorder". It is an intense form of PMS that is often disabling.
PMDD can have overlapping symptoms to PMS such as anxiety, irritability, and various physical conditions such as breast tenderness and muscle ache.
- PMS - Stands for "Premenstrual Syndrome". It is a collection of physical and emotional signs and symptoms that appear during the post-ovulatory (luteal) phase and disappear at the onset of menstruation.
Premenstrual syndrome (PMS) is an array of predictable physical, cognitive, affective and behavioral symptoms that occur cyclically during the luteal phase of the menstrual cycle. Evidence suggests that PMS is not a single condition but a set of interrelated symptom complexes. Premenstrual symptoms occur in 90% of all women of reproductive age and about 10% are diagnosed as having premenstrual dysphoric disorder Over 200 premenstrual symptoms have been reported and individuals with underlying disorders such as affective or anxiety disorder may be particularly vulnerable to menstrual triggers but do not show symptomatology at other times because of factor which prevent them from being vulnerable outside of the premenstrual time frame However, many conditions are also subject to menstrual magnification in which symptoms are triggered or exacerbated by the menstrual cycle. (e.g., include depressive disorders, seizures, migraine headache, allergies and asthma). Recognising this phenomenon it is important in distinguishing PMS from chronic underlying conditions.
- Progesterone - A hormone produced mainly by the corpus luteum in the ovary following ovulation.
The progesterone increases 24-36h after ovulation and it is chiefly produced by the corpus luteum, which is a specialized structure that origins from the cells of the ruptured dominant follicle after the release of the egg. A massive dose of progesterone is responsible for thickening the endometrium of the uterus, creating the ideal environment for the implant of the fertilized oocyte. It is also responsible for the rise in basal body temperature, and for the change in cervical fluid in the post-ovulatory infertile state. The Progesterone level is low during the menstruation and the follicular phase. It rises after ovulation and it stays high for a few days. If the implantation of the egg in the uterus does not happen the progesterone level drops, as a consequence of the deterioration of the corpus luteum.
- Progestin - Synthetic version of progesterone.
Progestin acts similarly to natural progesterone but depending on the molecule and the dosage these synthesised hormones have a wide range of medical application, like hormonal contraception, menopausal treatment, hormone-sensitive cancer treatment and gynaecological disorders treatment. In the field of birth control progestins are often components of contraceptive pills combined with oestrogen (or progestin alone). They prevent pregnancy by acting on many levels like cervical fluid composition, thickness on uterus lining, ovulation etc.
- Prolactin - As suggested by its name, prolactin is mainly responsible for stimulating mammary glands to produce milk. During pregnancy, the increase of the serum concentrations of prolactin cause the enlargement of the mammary glands and prepare for milk production. At the end of the pregnancy, while the prolactin levels are still high, the fall of the progesterone level triggers the “lactation” process.The nipple sucking by the baby is a large stimulus for prolactin production.
- Relaxin - In women, relaxin is produced mainly by the corpus luteum, and it rises to a peak within approximately 14 days after ovulation. In absence of pregnancy, relaxin will drop down as a consequence of corpus luteum degradation. On the contrary, during pregnancy, especially in the first trimester, relaxin levels stay hig h, produced also by the placenta. It regulates the volume of blood pumped by the mother’s heart to the kidney and to the placenta, in order to guarantee the turnover of nutrients and oxygen exchange between mother and fetus. It is also involved in softening the cartilaginous joint of pubic bone, extremely stressed in pregnant women.
- Serotonin - A neurotransmitter produced by special neurons inside the brain and special cells that reside into the digestive tract. Despite its complex function, it is commonly associated with feelings of well-being and happiness.
It is popularly known as a contributor to feelings of well-being and happiness, but its biological function is complex and involves cognition modulation, reward, learning, memory, alongside with other physiological processes. Many antidepressant drugs work by increasing the extracellular levels of serotonin.
- Steroid hormones - Any hormone that belongs to the class of steroids, characterized by a typical molecular structure of 17 carbon atoms arranged in four rings.
- Uterine lining - is the inner layer of the uterus (womb), anatomically referred to as endometrium.
- Uterus - The uterus is made of three layers, which together form the uterine wall. The innermost layer is referred to as “endometrium”. The middle layer is the myometrium and mostly consists of smooth muscle tissue. Finally, there is the external perimetrium, which consists of a superficial single layer of cells and a thin layer of loose connective tissues beneath it.
- Vulva - The external female genitalia comprising the clitoris and two sets of labia (inner and outer labia).