st sci

• it is the process through which the level of one substance influences the level of another substance


  feedback mechanism
• it amplifies changes, the original stimulus is promoted rather than negated


  positive feedback
• it increases the change, meaning there will be more of product or a moving away from the target


  positive feedback
• a pathway triggered by deviation in output and produces changes in output in the opposite direction of the initial deviation


  negative feedback
• it decreases the change, meaning there will be less of a product or an action that moves towards a target point


  negative feedback
• it happens when a response to a stimulus is decreased or reduced


  negative feedback
• FSH stimulates the ovaries to release estrogen
• high levels of estrogen then prevent the further production of FSH
• estrogen also stimulates the release of LH from the Pituitary Gland
• luteinizing hormone controls the production of progesterone
• high levels of progesterone inhibits the further release of LH
• This is a period where the menstrual cycle starts and lasts for an average of 3-7 days


  The Menstrual Phase or Period
• The unfertilized egg from the previous menstrual cycle and uterine lining that was not used will be shed from the vagina


  The Menstrual Phase or Period
• Period blood is usually a combination of blood, mucus, unfertilized egg, and uterine lining
• this starts from the first day of the period until ovulation

  follicular phase
• this lasts an average of 14-16 days


  follicular phase
• the pituitary gland produces follicle-stimulating hormone to produce mature follicles
• a cell in an ovary which may undergo meiotic division to form an ovum.


  oocyte
• out of all the 5-20 follicles, only the healthiest oocyte will remain and mature
• this will then signal the estrogen in the ovaries to thicken the uterine lining in preparation for fertilization


  follicular phase
• this usually pccurs around day 12 to 14 in the menstrual cycle


  ovulation phase
• the pituitary gland releases luteinizing hormone, which then causes the release of the mature ovum from the follicle


  ovulation phase
• the mature ovum will travel down to the uterus to await fertilization by sperm

  ovulation phase
• this lasts an average of 14 days


  luteal phase
• when the follicle releases the mature ovum, the follicle then changes into the corpus luteum which then releases progesterone


  luteal phase
• it is a completely normal cyst that forms in the ovary every single month in women of childbearing age


  corpus luteum
• the corpus luteum is a group of cells inside the ovaries that forms during the menstrual cycle
• the corpus luteum appears right after an egg leaves your ovary (ovulation)
• the average menstrual cycle lasts 28 days
• cycles that last 21-40 days are also normal menstrual cycles
• some women can predict the day and time their period will come

  regular
• the menstrual cycle, including the physical symptoms, are controlled by reproductive hormones
• fertile days include the day an egg cell is released (ovulation) and the 5 days prior
• as girls get older, their menstrual cycle changes due to reasons like aging and underlying medical conditions
• periods may be heavier when women are younger then lighter as they age into their 20's and 30's
• in their 40's as the body transitions to menopause, the menstrual cycle can become more irregular, stopping and coming until menopause happens
• the feeling of discomfort or pain and cramps experienced around the time of period


  dysmenorrhea
• these are caused by high levels of prostaglandins, which are substances released from the uterine lining when it is about to sloughed off


  dysmenorrhea
• women who have heavier and longer periods are most likely to have painful cramps
• if the sperm reaches an ovum within several days of ovulation, fertilization occurs