human reproduction

• gonad

  organ that produces sex cells
• testes

  - produces sex cells

  - testes are out the body in the scrotum

  - temperature kept at 35, allows meiosis to occur producing heslthy sperm
• teste structure

  - consist of tubules lines diploid sperm producing cells

  - meiosis occurs produce haploid sperm cells ( half chromosome number )

  - cells produce testosterone
• epididymis


  - top of testes ( coiled tube )

  - sperm mature and stored in epididymis for 6 weeks

  - if not released it's broken down

  - reabsorbed into blood stream
• sperm duct


  - aka vas deferens

  - carrie's sperm to the urethra

  - urethra carries urine, sperm out the body
• glands


  - seminal vesicle, prostate gland, cowpers glands produce seminal fluid

  - seminal fluid nourishes sperm

  - allows sperm to swim
• sperm


  - produced by meiosis

  - sperm - 23 chromosomes
• ejaculation


  - release of semen
• penis


  - used to introduce sperm into the female body

  - fold of skin , foreskin

  - more blood drops into penis causing to become erect
• male hormones


  - FSH - follicle stimulating hormone

  - causes testes to form new sperm

  
  

  - LH - leutinising hormone

  - stimulates testes to produce testosterone

  
  

  - both produced by pituitary gland
• testosterone


  - causes primary male sex characteristics to form

  - growth of penis and other male reproductive parts

  - descent testes into scrotum
• secondary sexual characteristics


  - testosterone causes secondary sexual characteristics

  - features that distinguish males from females apart from sex organ

  - pubic hair , facial hair

  - enlargement of larynx

  - broad shoulders
• male infertility


  - low sperm count
• cause of male infertility

  - smoking

  - alcohol

  - anabolic steroids
• corrective measure for male infertility

  - stop smoking

  - reduce alcohol intake

  - reduce stress
• ovaries

  - produce eggs and female hormone

  - puberty in females start age 11 or 12
• female reproductive system

  - potential egg divides by meiosis turns into haploid egg, 2 week turns to graffian follicle
• changes in the ovary

  - after ovulation griffin follicle fills with yellow cells become corpus luteum

  - corpus luteum releases progesterone ( maintains uterus wall )
• fallopian tube


  - aka oviduct

  - egg is moved by muscular peristalsis or cilia ( hairs )

  - egg and sperm meet at fallopian tube
• uterus ( womb )

  - muscular structure

  - inner lining endometrium ( blood thickens each month )

  - nourishes embryo in first 3 months in placenta
• vagina


  - muscular 10cm long

  - allows entry of sperm into female body

  - lined with mucous producing cells
• female infertility

  - failure to ovulate
• causes of female infertility

  - hormonal disorder ( FSH )

  - stress

  - problems with ovary ( tumor )
• corrective measures for female infertility

  - hormonal treatment

  - surgery
• female hormones


  - oestrogen and progesterone

  - both prevent egg from developing
• both cause secondary female characteristics

  - maturing and enlargement of the breast

  - widening of the pelvis

  - increased body fat

  - growth of body hair
• menstrual cycle


  - series of events every 28 days

  - if fertilisation has not taken place

  - begins at puberty ends at menopause
• menstrual cycle day 1 - 5

  - lining of endometrium break down ( menstruation )

  - meiosis occurs in ovary to make a new egg ( graffian follicle ) ( egg )
• menstrual cycle day 6 - 14

  - graffian follicle produce's oestrogen ( repairs endometrium )

  - oestrogen causes endometrium to thicken

  - prevents new egg developing ( only one graffian follicle develope )
• menstrual cycle day 14

  - ovulation occurs release egg ( graffian follicle bursts )

  - egg passes into fallopian tube

  - egg can normally fertilised for 48 hours after ovulation
• menstrual cycle day 14 - 28

  - graffian follicle develops into corpus luteum

  - corpus luteum makes progesterone causes endometrium to thicken

  - progesterone prevents new egg from forming

  - if not fertilised it dies

  - corpus luteum starts to degenerate by day 22 ( progesterone levels decrease )

  - lining of uterus begins to break down
• hormones


  - FHS , follicle stimulating hormone - made by pituitary

  - oestrogen , graffian follicle - made by ovary

  - LH , leutinising hormone - made by pituitary

  - progesterone , ovary , made by corpus luteum
• FSH

  - produces day 1 - 5

  - stimulates graffian follicle and to develop

  -FSH causes production of oestrogen ( graffian follicle)
• oestrogen

  - made by day 5 - 14

  - causes endometrium to thicken

  - inhibits production of FSH

  - prevents new egg to develop

  - stimulates release of LH before day 14
• LH


  - made day 14

  - causes ovulation

  - causes graffian follicle to develop into corpus luteum

  - makes progesterone
• progesterone


  - made by corpus luteum

  - made day 14 - 28

  - causes endometrium to thicken further

  - inhibits production of LH and FSH

  - prevent new egg developing

  - prevents contractions
• if pregnancy doesn't occur

  - corpus luteum degenerates on day 22

  - levels of progesterone are low

  
  

  effects

  - new egg develop , FSH allowed to be produced

  - uterus contracts , endometrium brakes down
• menstrual disorder


  - fibroids

  - heavy prolonged menstrual bleeding

  - causes pain, miscarriage or infertility
• causes of fibroids


  - abnormal response to oestrogen

  - taking contraceptive pill
• treatment of fibroids

  - no treatment if small

  - large fibroids removed by surgery

  - large number requires hysterectomy