Sexual Hormones in the Human Body

• Hormones - a chemical substance produced by a gland and carried by the blood which alters the activity of one or more specific target organs
• Primary sexual characteristics are present during development in the uterus and are the differences in reproductive organs etc. between males and females
• Secondary sexual characteristics are the changes that occur during puberty as children become adolescents

  • controlled by the release of hormones - oestrogen in girls, testosterone in boys
• Female secondary sexual characteristics:

  A) breasts

  B) body hair

  C) menstrual cycle

  D) hips

  E) wider

  
• • Male secondary sexual characteristics:

  A) penis

  B) testes

  C) facial

  D) body hair

  E) muscles

  F) voice

  G) testes

  H) sperm

  
• Some changes occur to both boys and girls

  • growth of sexual organs and growth of body hair
• Emotional changes also occur due to the increased levels of hormones in the body

  • more interest in sex and increased mood swings
• Menstrual cycle starts in early adolescence in girls (around age 12) and is controlled by hormones

  • the average menstrual cycle is 28 days long
• Menstrual cycle process:

  • Ovulation (release of an egg) occurs about halfway through the menstrual cycle cycle (day 14) and the egg then travels down the oviduct to the uterus
  • Failure to fertilise the egg causes menstruation (commonly called a period) to occur - this is caused by the breakdown of the thickened lining of the uterus
  • Menstruation lasts around 5 - 7 days and signals the beginning of the next cycle
  • After menstruation finishes, the lining of the uterus starts to thicken again in preparation for possible implantation in the next cycle
• Menstrual cycle process

  A) uterus lining

  B) menstrual cycle

  C) menstruation

  D) lining

  E) lining

  F) build

  G) maintained

  H) new cycle

  I) lining breaks

  J) menstruation

  K) 7

  L) 14

  M) 28

  
• Menstruation - uterus lining is shed and blood and fragments of tissue leave the body through the vagina

  • triggered by a decrease in the concentrations of progesterone
  • blood is lost during menstruation and needs to be replaced during the repair phase
  • menstruating women have high requirements for iron because of the blood loss
• Repair phase - more blood vessels grow in the lining of the uterus and the lining thickens, becoming more stable

  • changes triggered by an increase in the concentration of oestrogen
• Ovulation - an ovum is released into the oviducts

  • occurs at the peak of oestrogen concentration and is triggered by a hormone from the pituitary gland
• Receptive phase - lining of the uterus and blood vessels are now well developed

  • if fertilisation occurs, the embryo can be implanted in the lining
  • this optimum set of conditions only happens for 6-7 days after ovulation
  • maintained by an increasing concentration of progesterone
• Premenstrual phase - uterus lining degenerates

  • progesterone concentration starts to fall unless embryo has been implanted where the progesterone keeps the lining intact to begin pregnancy
• The menstrual cycle is controlled by hormones released from the ovary and the pituitary gland in the brain
• • Roles of the FSH and LH and their changes in the menstrual cycle

  A) fsh

  B) lh

  C) ovulation

  D) egg released

  E) egg matuaration

  F) follicles

  G) ovary

  H) follicles

  I) ovaries

  J) oestrogen

  K) peak

  L) ovulation

  M) egg

  N) oviduct

  
• Pituitary gland - releases hormones which control activity of the ovary
• Brain - processes information from other parts of the body and instructs the pituitary gland
• FSH (follicle-stimulating hormone) - released by the pituitary gland and causes an egg to start maturing in the ovary

  • stimulates the ovaries to start releasing oestrogen
• Luteinising hormone (LH) - releases when the pituitary gland is stimulated when oestrogen levels have reached their peak

  • causes ovulation to occur and also stimulates the ovary to produce progesterone
  • stimulates the release of mature ovum from the ovary aka follicle
• • Roles of oestrogen and progesterone and their changes in the menstrual cycle

  A) oestrogen

  B) ovulation

  C) progesterone

  D) uterus

  E) lining

  F) replace

  G) lining

  H) menstruation

  I) post-ovulation

  J) fsh and lh

  K) pituitary gland

  L) maintains

  M) thickens

  N) lining

  O) uterus

  P) fsh and lh

  Q) fertilisation

  R) drop

  S) menstruation

  
• Oestrogen - repairs the lining of the uterus and stimulates development of female sexual characteristics

  • produced by ovary
  • supress production of FSH
  • stimulate production of LH
• Progesterone - keeps the linining of the uterus ready for implantation and pregnancy

  • inhibits release of FSH and LH
  • continues to be produced in pregnancy so the lining stays
  • from empty egg follicle
• Oestrogen levels rise from day 1 to peak just before day 14

  • causes the uterine wall to start thickening and the egg to mature
  • the peak in oestrogen occurs just before the egg is released
• Progesterone stays low from day 1 – 14 and starts to rise once ovulation has occurred

  • the increasing levels cause the uterine lining to thicken further
  • a fall in progesterone levels causes the uterine lining to break down (menstruation aka ‘period’)
• Interactions between four of the menstrual cycle hormones (1)

  • The pituitary gland produces FSH which stimulates the development of a follicle in the ovary
  • An egg develops inside the follicle and produces the hormone oestrogen
  • Oestrogen causes growth and repair of the lining of the uterus wall and inhibits production of FSH
  • When oestrogen rises to a high enough level it stimulates the release of LH from the pituitary gland which causes ovulation (usually around day 14 of the cycle)
  • The follicle becomes the corpus luteum and starts producing progesterone
  • Progesterone maintains the uterus lining
• Interactions between four of the menstrual cycle hormones (2)

  • If the ovum is not fertilised, the corpus luteum breaks down and progesterone levels drop
  • This causes menstruation, where the uterus lining breaks down and is removed through the vagina - commonly known as having a period
  • If pregnancy does occur the corpus luteum continues to produce progesterone, preventing the uterus lining from breaking down and aborting the pregnancy
  • It does this until the placenta has developed, at which point it starts secreting progesterone and continues to do so throughout the pregnancy
• Interactions between the four menstrual cycle hormones

  A) pituitary gland

  B) fsh

  C) lh

  D) oestrogen

  E) progesterone

  F) ovaries

  G) inhibts

  H) uterus

  I) oestrogen

  J) progesterone

  K) development

  L) maintenance

  M) lining

  N) uterus

  O) ovary

  P) oestrogen

  Q) progesterone

  R) fsh

  S) egg maturation

  T) lh

  U) ovulation

  V) hormones

  W) blood

  
• What day is the uterus lining the thickest?

  Day 14 which is when ovulation is, because the progesterone maintains the lining of the uterus in case an egg is fertilised for implantation
• Define hormone

  A chemical substance produced by a gland that is carried by the blood which alters the activity of specific target organs
• What are the functions of FSH and LH?

  FSH: egg maturation, stimulates the release of oestrogen

  LH: egg released, stimulates the production of progesterone
• What happens to the female body when they have PCOS?

  FSH levels are significantly reduced. This means that ovaries won't be stimulated to release oestrogen. If oestrogen is not released, the pituitary will not be stimulated to release LH. With no LH levels, ovulation will not occur. This means that progesterone will not be produced from the ovary.