Endocrine System

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Endocrine System

• Your endocrine (hormonal) system is the slow
  message system of your body. Its messages consist
  of chemicals released by glands into the
  bloodstream.

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The Endocrine Glands
Section 39-1
Pineal gland The pineal gland releases melatonin,
which is involved in rhythmic activities, such as
daily sleep-wake cycles.
Hypothalamus The hypothalamus makes hormones that
control the pituitary gland. In addition, it
makes hormones that are stored in the pituitary
gland.
Thyroid The thyroid produces thyroxine, which
regulates metabolism.
Pituitary gland The pituitary gland produces
hormones that regulate many of the other
endocrine glands.
Pancreas The pancreas produces insulin and
glucagon, which regulate the level of glucose in
the blood.
Parathyroid glands These four glands release
parathyroid hormone, which regulate the level of
calcium in the blood.
Ovary The ovaries produce estrogen and
progesterone. Estrogen is required for the
development of secondary sex characteristics and
for the development of eggs. Progesterone
prepares the uterus for a fertilized egg.
Thymus During childhood, the thymus releases
thymosin, which stimulates Tcell development.
Testis The testes produce testosterone, which is
responsible for sperm production and the
development of male secondary sex characteristics
Adrenal glands The adrenal glands release
epinephrine and nonepinephrine, which help the
body deal with stress.
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Concept Map
Section 39-2
The Endocrine System
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by meansof the
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by meansof the
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Actions of Insulin and Glucagon
Section 39-2
Beta cells release insulin into the blood
Body cells absorb glucose
Blood glucose level decreases
Blood glucose level increases
Liver converts glucose to glycogen
Homeostasis Normal blood glucose level
Blood glucose level decreases
Blood glucose level increases
Alpha cells release glucagon into blood
Liver converts glycogen to glucose
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Reproductive System

• The function of the human reproductive system is
  to produce, store, nourish and release sex cells
  (gametes eggs and sperm).
• In addition, the function of the female
  reproductive system is to nourish a developing
  embryo.
• The fusion of egg and sperm produces a zygote.

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• What would happen if you removed a persons
  circulatory system?
• What would happen if you removed a persons
  reproductive system?
• Why is the reproductive system important if a
  person can survive without it?
• Does every member of a species have to reproduce?

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The Male Reproductive System
Section 39-3
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The Female Reproductive System
Section 39-3
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Female reproductive system

• Contrary to males, who are able to produce about
  1000 sperm per minute, females produce one egg
  per month.
• All the eggs a woman will ever have are formed
  while she is in her mothers uterus (about 5
  million eggs) by the time she is a five month old
  fetus.
• Only about 400 eggs will be ovulated.

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• Your period starts a cycle that usually produces
  a single egg that can be fertilized.
• Cycle lengths are from 21 35 days, but usually
  are 28 days.
• FSH and LH reach the ovaries and signal them to
  produce estrogen. Estrogen causes the egg to
  ripen.
• The egg ripens in a sac called the follicle.
  When an egg is ripe, it is released from the
  follicle into the abdomen where it is picked up
  by the fimbria of the Fallopian tube.

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• Ovulation, which takes about 2 minutes to
  complete, usually occurs 14 days AFTER the onset
  of the period in a 28 day cycle.
• Ovulation always occurs 14 days BEFORE the onset
  of the period (bleeding).
• Therefore, if you have a 35 day cycle, you will
  ovulate on day 21 and if you have a 20 day cycle,
  you will ovulate on day 6.

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What happens next?

• After the egg is in the Fallopian tube, it
  continues to ripen and prepare itself for the
  sperm.
• The egg is capable of being fertilized for 24
  hours.
• Sperm can live in the vagina, cervix, uterus and
  Fallopian tubes for 3 - 5 days.

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How the gametes meet
During sexual intercourse a small amount of
seminal fluid containing millions of sperm cells
is expelled through the mans penis and deposited
below the womans uterus. Helped by the movements
of the womans vagina and uterus, some of the
sperm cells manage to swim through the cervix to
the uterus. Many get no further and either die
of exhaustion or the warmth of the uterus. Only
the strongest sperm pass through the uterus to
the Fallopian tubes. And only half of these
enter the correct tube where an egg may be
waiting. Eventually a few hundred sperm approach
the egg. An egg is fertilized when one sperm
enters it.
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If fertilization occurs

• Fertilization occurs in the Fallopian tube.
• One sperm penetrates the eggs protective outer
  layer. Once this happens, a chemical reaction
  occurs that makes it impossible for any other
  sperm to penetrate the egg.
• The fertilized egg becomes a dividing ball of
  cells which implants into the uterine wall.

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Fertilization and Implantation
Day 2
Day 3
Day 1
Day 4
Fertilization
Day 0
Day 7
Implantation of blastocyst
Egg released by ovary
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Embryo development

• Male and female embryos are identical for the
  first 6 weeks.
• After the 7th week of development, the embryos
  reproductive organs produce sex hormones that
  make it either male or female. The male testes
  produces androgens and the female ovaries produce
  estrogens.

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• What triggers a female to become female is not so
  much the presence of estrogen as the absence of
  testosterone. Without testosterone, both male
  and female embryos would develop as female.
• The mother produces so much estrogen that
  diffuses across the placenta, that the amount the
  embryo produces is insignificant.
• The testosterone produced by the male embryo is
  the essential difference between males and
  females. Male and female reproductive organs
  develop from the same embryonic tissue.

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• Testicular feminization syndrome Y chromosome
  present, but externally female due to either lack
  of testosterone production, or problem with
  testosterone receptor cells.
• Female androgenital syndrome Genetic female
  with male characteristics (enlarged clitoris).

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6 week old embryo
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7 week embryo
12 weeks 20 weeks Full term
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12 weeks
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Fetus

• After 8 weeks of development, the embryo is
  called a fetus.
• On average it takes 9 months (40 weeks after the
  last menstrual period) for a fetus to become full
  term. Babies born before 8 months (37 weeks
  after the last menstrual period) are premature.

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Fetuses older than 23 weeks can be viable
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20 weeks
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28 weeks
36 weeks
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40 weeks Full term
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• After birth, the testes and ovaries continue to
  produce hormones that influence the development
  of reproductive organs.
• Testes and ovaries produce gametes after puberty
  (starts between ages 9 15).

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Secondary sexual characteristics in females
development of breasts, widening of hips and an
increase in body fat.
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Secondary sexual characteristics in
males deepening of the voice, broadening of the
chest and shoulders and development of facial
and body hair
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If fertilization does not occur

• The egg dies and the lining of the uterus is
  shed, resulting in a period (menstruation/bleeding
  )

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Mythical Methods of Birth Control

• OR, THE ONES THAT DONT WORK
• Withdrawal (a small amount of semen can escape
  from the penis before ejaculation, plus you have
  to trust that he will pay attention and pull
  out)
• Rhythm (counting days and only having sex when it
  is safe you really need to have a regular
  cycle and know your body)
• Intercourse during menstruation (if you have a
  short or erratic cycle you can be ovulating
  during your period)
• The First Time (yes, virgins CAN get pregnant)
• Standing up immediately after sex
• Douching with Pepsi or Coke
• Praying