Diffusion and Osmosis in the Human Body

1
Diffusion and Osmosis in the Human Body

• Circulation, excretion, respiration, and hormone
  production.

2
Homeostasis

• Defined as one of the fundamental characteristics
  of all living systems
• It is the tendency of an organism to maintain a
  stable, constant internal environment
• Maintained by various organ systems in the body
• An organ system is a group of organs that works
  together to perform a common function

3
Circulatory System

• Made up of heart and various blood vessels filled
  with different types of blood cells and platelets
• Flow of blood goes from right side of heart to
  left side of hear in the following path
• right atrium receives deoxygenated blood from the
  superior and inferior vena cava ? right ventricle
  ?pulmonary artery ?lungs (capillaries in the
  lungs allow for diffusion of CO2 out of blood
  stream and O2 into bloodstream) ? pulmonary vein
  ?left atrium ? left ventricle ? oxygenated blood
  pumped to body from aorta to other arteries
• http//www.stjosephaspirin.com/images/stjoseph/pum
  pblood/

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Circulatory System

• Arteries are blood vessels that flow away from
  the heart and typically carry oxygenated blood
  the only deoxygenated artery is the pulmonary
  artery
• Veins are blood vessels that flow towards the
  heart and typically carry deoxygenated blood and
  CO2 waste the only oxygenated vein is the
  pulmonary vein

• Blood vessels get smaller as they get to areas in
  the body where gas exchanges must be made (lungs,
  body tissues, etc.) arteries branch into
  arterioles and veins branch into venules.
  Arterioles connect to venules through
  capillaries, the thinnest of all blood vessels.
  Through the walls of the capillaries, gasses are
  exchanged through the process of diffusion.
  Capillary beds have a total surface area in each
  human of about 6300 square meters!

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Flow of blood in heart and body
6
Respiration and Diffusion

• As you saw with your dissections, respiration
  depends heavily on both the circulatory system
  and the process of diffusion.
• The passage of air into your lungs comes in
  through the nasal cavity ? trachea ? branching
  system of bronchial tubes in each lung ? alveoli
• The alveoli are lined with capillaries so that O2
  you breathe in can enter the bloodstream and CO2
  waste can leave the blood stream.
• Like most animals, your lungs are lined with
  moist mucus providing a wet environment for gas
  exchange

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Diffusion and Osmosis a review

• Why does the CO2 leave the blood stream and O2
  enter?... Diffusion
• Diffusion is a form of passive transport (no
  energy required) in which substances flow from an
  area of high concentration to an area of low
  concentration. Substances such as O2 and CO2,
  are small enough to pass through the walls of the
  capillaries.
• A specific type of diffusion is osmosis, or the
  movement of water from high to low concentration
  due to a change in conditions (think of the
  eggs-periment)

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Diffusion and Osmosis

• Three types of environments can exist outside
  cells to effect the internal environment
• Isotonic concentration of solute is the same
  both in and out of cell, water movement is equal
• Hypertonic concentration of solute is greater
  outside the cell, water moves to the outside of
  cell to balance out (possibly resulting in cell
  shriveling)
• Hypotonic - concentration of solute is lower
  outside the cell, water moves into the cell to
  balance out (possibly resulting in cell explosion)

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Cells in the three environments
10
Diffusion and osmosis in the kidney

• The main function of the kidneys is to filter our
  blood and remove waste as urine. Both kidneys do
  the same job. Blood is taken to the kidneys by
  the renal artery and when it is cleaned, it is
  returned to the heart by the renal vein. The
  urine is taken to the bladder by the ureters.

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Diffusion and osmosis in the kidney

• The functional unit of the kidney is the nephron.
  They are long coiled tubes that act as filtering
  units in the kidney. Each nephron has a capsule
  (bowmans capsule) that is in direct contact with
  a capillary bed known as the glomerulus. The
  glomerulus is the site of filtration. The
  capillaries in the glomerulus drain into more
  arterioles that continue to help blood get
  filtered along the nephron before returning to
  the renal vein. Reabsorption takes place between
  the nephron tubule and the second capillary bed.
  
• http//www.youtube.com/watch?vglu0dzK4dbUfeature
  related

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Diffusion and Osmosis in the kidney

• Maintaining water balance in the kidney can be
  inhibited by a diuretic, a substance that causes
  the kidneys to allow excess water loss. A very
  common diuretic is caffeine.
• Diuretics block the production of the hormone
  vasopressin, an anti-diuretic hormone (ADH).
  When the blood has a high concentration of sodium
  ions, the hypothalamus and pituitary gland (both
  in the brain) triggers the release of ADH which
  would tell the kidneys to reabsorb more water to
  help rehydrate the body. This is an example of
  maintaining homeostasis with the endocrine
  system. The endocrine system is made up of
  glands and cells that release chemical messengers
  called hormones, directly into the blood stream.

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Hormones and Homeostasis

• The endocrine system helps maintain homeostasis
  with positive and negative feedback.(p235)
• Negative feedback involves constantly adjusting
  to correct and abnormal situation.
• Example production of ADH returns water balance
  to normal, ADH production stops
• Positive feedback involves processes that must be
  completed quickly and the production of some
  hormone triggers the production of more
• Example production of chemical clotting agents
  at the site of a cut will trigger the production
  of more clotting agents to rapidly clot and
  minimize blood loss