biology unit2 HIGHER

• gametes are haploid cells produced from diploid germline cells
• male gametes are sperm and female gametes are ova
• in males sperm is produced in the testes, which have specialised structures called seminiferous tubules
• the male hormone testosterone is produced in the interstitial cells, found between the seminiferous tubules
• the prostate gland and seminal vesicles secrete fluids which maintain the mobility and viability of sperm
• this liquid allows sperm to swim and contains enzymes, to maintain the viscosity of the liquid, and sugars, to provide energy for the sperm
• label side view of male genitals

  A) seminal vesicle

  B) prostate gland

  C) testis

  
• label front view of male genitals

  A) seminal vesicle

  B) prostate gland

  C) testis

  
• label structure of testes

  A) seminiferous tubules

  
• label structure of seminiferous tubules

  A) interstitial cells

  B) sperm

  C) gamete mother cell/ germline cell

  
• in females gametes are produced in the ovaries
• the ovaries contain immature ova, in various stages of development these ova are produced from germline cells within the ovaries
• each ovum is surrounded by a follicle that protects the developing ovum and secretes hormones (oestrogen)
• mature ova are released into the oviduct in a process known as ovulation, where they are then fertilised by sperm and form a diploid zygote
• label the front view of female reproductive system

  A) oviducts

  B) ovary

  C) endometrium

  
• label side view of female reproductive system

  A) ovary

  B) uterus

  
• label structure of ovary

  A) ovary

  B) immature ova

  C) follicle

  D) mature ova

  
• hormones control the onset of puberty, sperm production and the mentrual cycle
• the pituitary gland is a key endocrine gland, located in the brain, which secretes many hormones
• label the brains hormones

  A) hypothalamus

  B) pituitary gland

  
• the hypothalamus produces a releaser hormone which stimulates the pituitary gland to release three hormones:

  • follicle stimulating hormone (FSH)
  • luteinising hormone (LH)
  • interstitial cell stimulating hormone (ICSH)
• in males the pituitary gland releases FSH and ICSH, in females the pituitary gland releases FSH and LH
• the production of sperm is controlled by two hormones, which act on the testes:

  • FSH - promotes sperm production in seminiferous tubules
  • ICSH - stimulates production of testosterone by the interstitial cells
• testosterone stimulates sperm production and activates the prostate gland and seminal vesicles, which will produce the liquid which maintains the sperm
• rising levels of testosterone will inhibit the production of FSH and ICSH through negative feedback, this decreases testosterone levels being produced
• when testosterone levels drop, this stimulates the pituitary gland to secrete more FSH and ICSH which result in the interstitial cells secreting more testosterone
• the menstrual cycle takes approximately 28 days with the first day of menstruation regarded as day one of the cycle
• menstruation is the shedding on the endometrium lining of the uterus
• the menstrual cycle is controlled by two hormones produced by the pituitary gland, which act on the ovaries:

  • FSH - stimulate development of the follicle
  • LH - stimulates ovulation
• in addition to FSH and LH, oestrogen and progesterone are involved in the menstrual cycle and are produced within the ovaries
• the menstrual cycle consists of two stages:

  • follicular phase
  • luteal phase
• days 1 to 14 of the menstrual cycle are known as the follicular phase and involve the development of the follicle
• FSH stimulates the development of a follicle within the ovary and also stimulates the production of oestrogen by the follicle during the follicular phase
• oestrogen stimulates proliferation (rapid growth) of the endometrium layer, preparing it for implantation
• oestrogen also affects the consistency of the cervical mucus. making it thinner and more easily penetrated by sperm
• when levels of oestrogen peak this stimulates a surge in secretion of LH which will trigger ovulation
• ovulation is where the mature follicle ruptures and releases the ovum
• ovulation normally occurs around day 14 of the menstrual cycle
• at ovulation the body temperatures of a woman rises by around 0.5 degrees and will remain higher during the luteal phase
• label the LH and FSH levels during ovulation

  A) LH

  B) FSH