The Endocrine System

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The Endocrine System

• What is the function of the endocrine system?
• How does the endocrine system maintain
  homeostasis?

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Whats it all about?

• The endocrine system is made up of glands that
  release their products into the bloodstream.
  These products broadcast messages throughout the
  body.

Video Clip
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Hormones

• Hormones are chemicals that travel through the
  bloodstream and affect the activities of other
  cells. Hormones do this by binding to specific
  chemical receptors on those cells.
• Cells that have receptors for a particular
  hormone are called target cells.

Lock and key
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Glands

• A gland is an organ that produces and releases a
  substance or a secretion.
• Exocrine glands release their secretions through
  tubelike structures called ducts directly to the
  organs that need them.
• Sweat glands
• Tear glands
• Digestive glands
• Endocrine glands release their hormones directly
  into the blood stream.
• There are 10 major endocrine glands in the body

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Control of the Endocrine System

• Like most systems of the body the endocrine
  system is regulated by feedback mechanisms that
  function to maintain homeostasis.

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Feedback

• Feedback mechanisms are best described as a
  process that helps keep body conditions near a
  normal, steady state.
• Example An increase in the level of insulin in
  the blood would result in a decrease in the
  amount of glucose in the blood.

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Actions of Insulin and Glucagon
Beta cells release insulin into the blood
Body cells absorb glucose
Blood glucose level decreases
Blood glucose level increases
Liver converts glycogen to glucose
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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https//www.youtube.com/watch?vCLv3SkF_Eag
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Endocrine Glands

• Hypothalamus
• Pituitary gland
• Parathyroid glands
• Thymus
• Adrenal Glands
• Pineal Gland
• Thyroid
• Pancreas
• Ovary
• Testis

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The Endocrine System
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The Pituitary Gland Master Gland

• The pituitary gland secretes nine hormones that
  directly regulate many body functions and
  controls the actions of several other endocrine
  glands.
• Releases a hormone that causes the release of
  estrogen.

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The Pituitary Gland
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Hypothalamus

• The hypothalamus controls the secretions of the
  pituitary gland.

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• https//www.youtube.com/watch?vnNLsXKkLSTs

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Thyroid gland

• The thyroid gland has the major role in
  regulating the bodys metabolism.

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Parathyroid Glands

• Hormones from the thyroid gland and the
  parathyroid glands maintain homeostasis in blood
  calcium levels.

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Adrenal Glands

• The adrenal glands help the body prepare for and
  deal with stress.
• Also regulates the glucose levels in blood.

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Pancreas

• Insulin and glucagon released from the pancreas
  help to keep the level of glucose in the blood
  stable.
• Insulin decreases blood sugar
• Glucagon increases sugar level

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Hormone Action

• Hormones may be classified as belonging to two
  general groups
• Steroid hormones produced from a lipid called
  cholesterol, can pass through cell membranes
  easily (target cells)
• Non-steroid hormones include proteins, small
  peptides, and modified amino acids cannot pass
  through cell membranes of target cells

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Feedback Mechanism

• Recall that feedback inhibition occurs when an
  increase in any substance feeds back to inhibit
  the process that produced the substance in the
  first place.

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• https//www.youtube.com/watch?vWVrlHH14q3o

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The Reproductive System
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Sexual reproduction (Review)

• Meiosis -process of reduction division in which
  the number of chromosomes per cell is cut in half
  
• Haploid- a cell that contains only a single set
  of chromosomes. (single set of genes)
• Gamete- Sex cell, sperm or egg
• Gonads- ovaries or testes
• Hormones-
• Estrogen (female)
• Testosterone (male)

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Hormones

• Puberty begins when the hypothalamus signals the
  pituitary to produce increased levels of two
  hormones that affect the gonads.
• These hormones are follicle-stimulating hormone
  (FSH) and luteinizing hormone (LH)
• FSH LH in males stimulates the production of
  testosterone
• FSH LH in females stimulates the production of
  estrogen

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The Female Reproductive System

• The main function of the female reproductive
  system is to produce ova (egg). In addition, the
  female reproductive system prepares the females
  body to nourish a developing embryo.
• Ovaries produce and release the egg
• Follicles are clusters of cells that surround a
  cell egg.
• Female hormone is estrogen has direct effect on
  the changes within the uterus.

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Egg Development

• Each ovary contains about 400,000 primary
  follicles.
• The function of a follicle is to help an egg
  mature for release into the reproductive tract,
  where it can be fertilized. Eggs develop within
  their follicles.
• Approximately every 28 days, under the influence
  of FSH, a follicle gets larger and completes the
  first meiotic cell division.

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Menstrual Cycle

• Menstrual in Latin means month
• About a 28 day cycle
• Regulated by hormones
• During the menstrual cycle, an egg develops and
  is released from an ovary. The uterus is prepared
  to receive a fertilized egg.
• If fertilized then the egg is implanted in the
  uterus.
• If an egg is not fertilized then it is discharged
  along with the uterus lining.

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Phases

• Follicular phase- Starts with low levels of
  estrogen. Body reacts releases FSH and LH which
  cause a follicle to develop.
• Ovulation- shortest phase 3-4 days sudden rush of
  FSH LH causes follicle to rupture and a mature
  egg is released into one of the fallopian tubes

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• Luteal Phase- Starts after the egg is released
  and moves through fallopian tube. The cells of
  the ruptured follicle undergo a change, turn
  yellow and is called corpus luteum. This
  continues to release estrogen and progesterone.
• Menstruation- If no fertilization within 2-3 days
  of ovulation the egg will pass through the uterus
  without implantation. Corpus luteum will begin
  to disintegrate. Estrogen levels drop and the
  uterus lining will detach and be discharged along
  with the egg and blood. Lasts 3-7 days

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Figure 3915 The FemaleReproductive System
Section 39-3
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• Fetus usually develops in the uterus
• Egg is fertilized in the fallopian tube.

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The Male Reproductive System

• The main function of the male reproductive system
  is to produce and deliver sperm (internal
  fertilization)
• Testes are adapted to produce sperm cells.
• Sperm (male gamete) transports genetic
  information
• Haploid
• Testosterone

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The MaleReproductive System
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Fertilization

• Fertilization occurs in the fallopian tube
• After fertilization the zygote begins to undergo
  mitosis
• Four days after it is a solid ball of about 64
  cells.
• 7 days after implantation occurs.

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Placenta

• The placenta is a vital organ that connects the
  mother and the embryo.
• It is the embryos organ of respiration,
  nourishment and excretion. (diffusion)
• It is also a means of getting rid of metabolic
  wastes (excretion). CO2 passes from fetus to
  parent is the greatest amount.
• Wastes diffuse into the mothers blood from the
  embryos blood.
• Their blood does not mix!

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Figure 3920 The Placenta
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Fetus

• After 8 weeks of development the embryo is called
  a fetus.

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Embryonic Stem Cells

• Cells that are capable of differentiating into
  any type of cell.