Physiology Sheet 18

1|P a g e Physiology Sheet number 18 2|P a g e Erectile dysfunction/impotence is found in old age. However, most users of Viagra are below 40 years and many of these do not have any erectile dysfunction. Remember that the most common cause of impotence is physiological disturbances, but it can also be due neurological issues, heart problems, severe diabetes. These conditions nothing can solve them. So Viagra doesn’t solve all the problems of impotence. ….. Remember there are 2 cycles that occur in females from puberty till menopause: The Ovarian Cycle and The Uterine Cycle. These 2 cycles don’t stop unless there’s pregnancy or disease. They occur at the same time/ have the same duration which is normally 28 days. Ovarian cycle dominates uterine cycle. So uterine cycle can’t occur without the ovarian cycle. Ova are produced in the females even during fetal life but no ovulation happens. • The Ovarian Cycle The ovarian cycle can be divided into 3 phases. Ovulation occur at day 14 (If the ovarian cycle is 28 days which is the normal). Before ovulation, there’s the follicular phase in which follicles develop. After ovulation, we have the luteal phase. 3|P a g e Note that even before the previous cycle ends, the primordial follicles are already activated genetically even if there are no hormones. Usually the follicles in ovaries are inactivated until they are activated by hormones like FSH and LH. In IVF (in vitro fertilization)- when they inject hormones, 50 follicles are activated then some of these are chosen to be fertilized. At the start of each menstrual cycle a limited number of primordial follicles are triggered to develop to primary follicles. Usually the primary follicle that continues to grow is the follicle that is the most sensitive to FSH. This follicle will start to secrete estrogens which inhibit the FSH. Why only one follicle grows? Because the FSH is only sufficient for one follicle but not the others so the others degenerate. 4|P a g e The follicle then grows to form secondary then Grafiaan follicle (at day 14/ovulation). The ovulated body is called the Corpus luteum. Then the luteal stage starts when Corpus luteum is produced. It then starts to secrete progesterone and estrogen. If there’s pregnancy, then it continues to grow. However, if there’s no pregnancy the corpus luteum will start to shrink and transforms to corpus albicans. Remember that ovarian cycle dominates uterine cycle This figure shows hormones- anterior pituitary hormones and ovarian hormones. Day 14 is the ovulation day and before that we have the follicle phase in which follicles develop. At day 10 estrogen rises, estradiol level increases then after that LH increase. So in this case there’s a positive feedback between estrogens and LH; when estrogens increase they cause an increase in LH. 5|P a g e USUALLY ESTROGENS INHIBIT LH, BUT JUST IN THIS CASE ESTROGENS INCREASE THE LH. LH then causes ovulation. No LH no ovulation, no estrogens no LH. The dr asked why only in this case estrogens have a positive feedback on LH when usually it has a –ve feedback? He didn’t answer but I found this info in 2017 sheets: “this is the only positive feedback here, because the estrogen has exceeded the normal level then it stimulates FSH AND LH (LH for ovulation)” After that, corpus luteum produces progesterone- the pregnancy hormone, and estrogen. If pregnancy occurs, then progesterone levels remain high. So in the first week, multiple follicles develop which are genetically activated. After that dominant follicle matures then ovulation occurs then corpus luteum is produced and starts to act. In 2 weeks if there’s no pregnancy the corpus luteum will shrink gradually. At the end of the cycle there’s a stop of production of progesterone and estrogen and the corpus luteum becomes corpus albicans. To sum up: At first multiple follicles develop →dominant follicle selected (day 7) → dominant follicle matures (from day 7-14) →ovulation day 14→ corpus luteum (luteum phase) (day 14-25) → progesterone and estrogen→ corpus luteum degenerated (day 25-28) • The Uterine Cycle 6|P a g e Uterine cycle also can be divided into 3 stages: Menstrual, Proliferative, Secretory), and is also 28 days. At the end of the ovarian cycle, we said that the progesterone and estrogen level becomes zero. So, blood vessels suppling the endometrium will be affected and will become necrotic as they can no longer supply the endometrium so menstrual phase begins. Menstrual phase normally ranges from 3 to 5 days but can reach as short as one day and as long as 8 days. Very little women below 3 and above 5. Blood shed is normally 30 ml ranging from spots up to 80 ml. Other than that it’s abnormal. After menstrual phase, proliferative phase begins. The uterus here prepares itself for the next cycle by elongating uterine glands, and by developing blood vessels to supply the new endometrium. The proliferative phase coincides with the estrogen so it can be also called the estrogen phase. 7|P a g e After that we have the secretory phase (phase 3). Here changes which occur in the proliferative phase are prolonged- more glands, more blood vessels due to more estrogen and progesterone. This phase coincides with progesterone so can also be called progesterone phase. This cycle ends in ovulation but sometimes cycles don’t end in ovulation and is called anovulatory cycle like at beginning of puberty and at beginning of menopause. The anovulatory cycle is shorter than the normal one because there’s no corpus luteum so there’s no progesterone. …. 2 hormones are produced by the ovaries: estrogen and progestins. Estrogens are divided into estradiol, estrone and estriol. What do theca cells do? They produce androgens, and androstenedione and testosterone. Estradiol is the major estrogen and little estrone is also secreted. Estriol is derived from both estradiol and estrone. Normal level of esteriol indicated the health of fetus; low level of esteriol means there’s a problem in the health of the fetus. Progestins are progesterone (mainly) and hydroxyprogesterone. ….. Remember: Progesterone pregnancy hormones. Estrogens feminine hormones Lifestyle of women has improved so menopause occurs late. 8|P a g e Women 2-3 years before menopause they need to take estrogens, vitamin D and calcium. Why? 1. To maintain the density of bones and prevent osteoporosis. Osteoporosis usually occurs in the old age but can sometime occur in the young age. Females are at higher risk than males. People who are inactive are at higher risk. 2. To maintain the beauty of complexion and prevent wrinkles 3. For the treatment of extreme facial and body hair. 4. For the low desire for sex compared to spouse. (taking estrogen increases libido) 5. For the maintaining of the size of breasts and preventing atrophy especially in menopause. 6. To prevent urine incontinence in ladies (involuntary). As we know bladder has two sphincters (internal, external), internal sphincter is involuntary and is weaker in females than in males. If the estrogen level is low the internal sphincter becomes even more weak. Taking estrogen should be under supervision of doctors since high concentration of hormones cause cancer. 7. It has been proven that estrogen has an important role in the treatment of Alzheimer and amnesia All of these are advantages of estrogens. … 9|P a g e Progesterone increases body temperature. Some women measure their body temperature every morning and if it increases from 0.5 to 1 degree then ovulation have occurred one day before. However, this method isn’t reliable. … 10 | P a g e The 1st sign of puberty in females is the development of the breasts which occurs early (can be at age 8-9). The 1st sign of puberty of males is the growth of the testis which is at age 10. Males show signs of puberty LATER than females. This slide shows that women can get pregnant after 60 (menopause is late) 11 | P a g e Ova is produced in the body and is then taken by the projection of the uterine tubes but sometimes it isn’t taken and will fall in the abdominal cavity so pregnancy can occur outside the uterus- ectopic pregnancy. When sperm is transferred to the fertilization site and fertilization occurs, the zygote is transferred to the uterus in 6-10 days then implantation occurs in the dorsal part of the uterus. Fertilization means pregnancy began and that corpus luteum starts to grow larger producing more estrogens and progesterone. Corpus luteum continues to grow until the 4th month then the placenta takes over producing the same hormones as the corpus luteum. This is called the taking over period. If this doesn’t occur properly then abortion occurs. To prevent abortion, they give them progesterone injection. During pregnancy, no menstrual cycles. Pregnancy is 9 months then delivery occurs. Delivery starts due to the increase in ACTH hormone but there are other factors as you can see in the figure. Even if there’s no oxytocin delivery occurs but it’s harder. 12 | P a g e 13 | P a g e Pills are made of hormones, estrogen and progesterone, or progesterone only to prevent pregnancy. Pills are not dangerous but it’s not good to use them as they may cause cancer due it having HIGH concentration of these hormones. Then, why they’re used the most? Because they’re the easiest to take. Pills have a high percentage to prevent pregnancy- more than 99%. Female sterilization: ligation/ cutting of Fallopian tubes. It is reversible. Male sterilization: ligation/ cutting of Vas Deferens which moves the sperms from the testes to the urethra. Intrauterine device: device inserted in uterus to prevent implantation almost has no side effects. For women to use intrauterine device she should have children (one or two) otherwise she could become sterile (unable to get pregnant). Rhythm: Remember that duration of cycle is 28 days. Ovulation is day 14. Sperms can remain fertile for 2 days (we give an extra day just in case), the same thing for the ova it can survive 2 days (we assume it’s 3). 14 | P a g e So if sexual intercourse occurs in the period between days 11-17 then fertilization occurs. This period is called Unsafe period. If a couple doesn’t want a child, then they should avoid this period. This is applicable if the cycle is 28 days. We said that the menstrual phase is 3 to 5 days. If any change occurs in the duration of the ovarian cycle, it will occur in the duration BEFORE the ovulation. So from day 5 to 11 it’s a probable safe period. After 17 always constant, it’s always a safe period. Normal cycle is 28 days +- 7 days so the cycle can range from 21 to 35 days. To calculate ovulation day, we subtract 14 from this number. So ovulation day is 7 for the woman with the 21-day cycle and it is day 21 for the woman that has a 35-day cycle. Then we can find the safe, unsafe and probable safe period. 15 | P a g e ALWAYS between the end of the cycle and the ovulation day is 14 days whatever the duration of the cycle is even if it was abnormal like 41 days. So this method can be used for couples wanting to have a child and for couples wanting to avoid having a child. (It can work both ways)