Reproductive system.docx

Female reproductive system Female anatomy and physiology Ovaries Responsible for oogenesis Fallopian tubes Connects the ovaries to the uterus. Important location for egg fertilisation. Uterus Where the fertilised egg will implant Contains a developing embryo and foetus for entire pregnan...

Female reproductive system Female anatomy and physiology Ovaries Responsible for oogenesis Fallopian tubes Connects the ovaries to the uterus. Important location for egg fertilisation. Uterus Where the fertilised egg will implant Contains a developing embryo and foetus for entire pregnancy. Has an endometrial lining that sheds monthly = bleeding period. Has capability to expand during pregnancy. Cervix Located at the bottom most marrow part of uterus. Continuously produces mucous. The viscosity of the mucous is regulated by female sex hormones and effects sperm’s ability to reach the egg. (supports or blocks sperm) Dilates when giving birth. Vagina Extends from vestibule to the cervix. Elastic muscular canal. Lengthens and dilates during arousal due to muscle relaxation. Has Bartholin’s gland at the entrance. Secrete small amount of mucous during arousal. Hymen No biological function. Scientifically impossible to tell if someone is virgin. Clitoris Only known biological function of the clitoris is to provide sexual pleasure. Clitoris and penis have many anatomical similarities. Both Clitoris and penis has erectile tissue (corpus cavernosum) Menstrual cycle Usually lasts 4-8 days. Counted from 1st day of menstruation. Lasts for 28 days. Continues until menopause. The highest chance of pregnancy is after ovulation. Oogenesis Females are born with millions of primary oocytes in the ovaries, and they still have 46 chromosomes therefore not ready for fertilisation. When the primary oocyte matures, it undergoes meiotic division to have 23 chromosomes instead and ready to be fertilised. Ovulation Regulated by female sex hormones like oestrogen and progesterone. Every month after menstruation, hundreds of primary follicles start maturing but only one of them reaches full maturation and be released. Releasing more than one oocyte leads to non-identical twins. The other unmatured follicles will be reabsorbed by the body. After ovulation After ovulation, the remains of follicle keep growing and swells therefore forms corpus leteum. Corpus leteum secretes hormones that prepares the endometrium in the uterus to receive fertilised oocyte. If no fertilised oocyte is implanted in the endometrium, the endometrial lining sheds and a period occurs. Male reproductive system Testes Responsible for spermatogenesis. Epididymis Sperm transits from testis to epididymis to be stored and matured further. Secretes immobilin (glycoprotein) that mechanically keeps the sperm immobile until ejaculation. Vas deferens Transports sperm towards urethra through peristaltic movement (muscle contraction). Seminal vesicle Dilutes the sperm to form semen- produces the largest quantity of semen. Contains fructose, citric acid etc. Prostate Secretes fluid that becomes a part of semen. Contains zinc that helps sperm’s mobility and fertilisation. Has muscular control during urination and ejaculation to ensure the sperm goes out the correct way and to avoid backflow of urine. Urethra Transports both sperm and urine through penis. Penis Swells during arousal as it contains erectile tissue. Erectile tissue becomes filled with blood due to nitric oxide release. Cause due to cGMP increase. After ejaculation, phosphodiesterase (PDE5) is produced to break down the cGMP therefore erection goes. Spermatogenesis Spermatozoa is produced in the testis specially in the seminiferous tubules. Spermatogenesis continues through life, but prosecution decreases after age of 35. Regulated by testosterone. It is the process by which a spermatic elongates, grows a tail and officially becomes a mobile sperm. Also start with 46 chromosomes, but after meiotic division, it becomes 23 chromosomes then it’s able to fertilise. Sexual response cycle Divided into 4 stages: Excitement Controlled by PNS Both male and female experience Increased heart rate Increase blood flow. Swelling of corpus cavernosum which leads to erection in males and swelling of clitoris in females. Not every male is able to maintain erection= erectile dysfunction and affect between ages 40-70. Plateau Many of the PNS effect continues such as increase breathing rate. Males Internal urethral sphincter contracts to prevent urine from mixing with semen= prevents retrograde ejaculation. Pre-ejaculate fluid which contains some sperm. Females Bartholin’s glands produce mucous. Clitoris becomes sensitive. Orgasm Multiple brain regions involved at the same time. Release of pelvic Vaso congestion and neuromuscular tension. In males= accompanied by ejaculation but not always. (ejaculate contains 37 million sperm and volume of 1.5cl) In females= accompanied by vaginal contractions. Resolution Body return to normal levels of functioning such as: Heart rate goes back to normal. Blood pressure goes normal. Fertilisation of oocyte The oocyte will move along the fallopian tube towards the uterus and can survive for 24 hours. Sperm swims from vagina through cervix, up to the uterus and meets the oocyte in the fallopian tube. Sperm can survive up to 3-5 days. 23 chromosomes from oocyte and 23 chromosome from sperm combine and forms 46 chromosomes in the embryo. The oocyte always contains X chromosome. The sperm can have either X or Y chromosome after second meiotic division. XX= female XY= male Implantation of embryo Pregnancy starts when blastocyst implants into the uterus walls. Implantation stage is divided into 4 stages: Hatching- shedding of outer layer occurs called zona pellucida. Apposition- trophoblasts mediates a weak attachment to the endometrium. Adhesion- a stronger attachment mediated by microvilli and glycoproteins. Invasion- trophoblasts starts growing invasively into the endometrium. Forms placenta Healthcare counts pregnancy from the first day of period. (counts 2 weeks more than when the actual implantation). Testing for pregnancy Tests for hCG in the urine which is produced by trophoblast that forms the placenta. What is placenta? A temporary organ that provides nutrition for the foetus. Mothers blood brings oxygen and nutrition to placenta and the baby receives it via umbilical cord= blood circulation system for mother and baby is not directly connected. Placenta produces hormones such as hCG oestrogen and progesterone these are essential to maintain pregnancy. Amniotic sac? Membrane that surrounds the foetus. Contain amniotic fluid which is generated from mothers plasma, also contains urine from foetus and is important for exchange of nutrients. Childbirth give birth between week 37-42 contractions occurs and water breaks (amniotic fluid) Stage 1 dilation of cervix- over 10 cm Stage 2 birth of the child- head comes first followed by the anterior shoulder and then posterior shoulder. Stage 3 delivery of placenta- it detaches from uterus walls and given birth to can be surgically removed as its important for uterus to contract back.