2.2 human biology

• What are hormones?

  Chemical messengers in the bloodstream
• How do hormones bring about a response?

  They travel to target cells in the bloodstream
• Where are hormones produced?

  By endocrine glands

  
• What is the role of hormones in puberty?

  They control the onset of puberty and reproductive processes

  
• What triggers puberty?

  A releaser hormone from the hypothalamus

  
• What does the releaser hormone stimulate?

  The pituitary gland to release hormones

  
• What hormones are released by the pituitary gland during puberty?

  FSH, LH, and ICSH

  
• What is the function of follicle stimulating hormone (FSH)?

  Promotes sperm production in males

  
• What does interstitial cell stimulating hormone (ICSH) do?

  Stimulates testosterone production in males

  
• How does testosterone affect sperm production?

  It stimulates sperm production and gland secretions
• What happens as testosterone concentration increases?

  It inhibits FSH and ICSH production

  
• What is negative feedback control in hormonal regulation?

  It regulates hormone levels by inhibiting production

  
• How long does the menstrual cycle typically last?

  Approximately 28 days

  
• What marks the first day of the menstrual cycle?

  The first day of menstruation (bleeding)
• What are the two phases of the menstrual cycle?

  Follicular Phase and Luteal Phase
• When does ovulation occur in the menstrual cycle?

  Around day 14

  
• What does FSH do during the follicular phase?

  Stimulates the development of a follicle in the ovary
• What hormone does the developing follicle produce?

  Oestrogen
• What effect does oestrogen have on the endometrium?

  Stimulates proliferation to prepare for implantation
• How does oestrogen affect cervical mucus?

  Makes it more easily penetrated by sperm
• What triggers ovulation?

  A surge in LH secretion from the pituitary gland

  
• What develops after ovulation?

  The corpus luteum

  
• What hormone does the corpus luteum secrete?

  Progesterone
• What does progesterone do to the endometrium?

  Promotes further development and vascularisation
• What is the effect of combined ovarian hormones on the pituitary gland?

  They inhibit the secretion of FSH and LH

  
• What happens if fertilisation does not occur?

  The corpus luteum degenerates and progesterone drops
• What happens if fertilisation occurs?

  The corpus luteum does not degenerate