Respiration

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Respiration

• Your body does it millions of times at once!

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What is respiration?

• Physiological definition The act of exchanging
  gasses with the environment
• mammals inhale air, exhale CO2
• Biochemical definition aka cellular respiration
  The release of energy from glucose or other
  organic substances inside living cells.

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Respiration in mammals

1. Air is inhaled through the lungs (breathing)
2. Hemoglobin molecules inside red blood cells
   capture O2
3. Blood with O2 is pumped through the body to all
   tissues
4. In capillaries, cells release CO2 into the blood
   and pick up fresh O2
5. O2 diffuses into the cell, and is used in the
   mitochondria to break down glucose molecules and
   make ATP

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How does O2 get into the blood?

• Lungs are mostly a collection of tiny hollow sacs
  called alveoli, and they are surrounded by tiny
  blood vessels called capillaries
• As you inhale, the alveoli fill up with air,
  which contains O2
• Because there is more O2 in the lungs than in the
  blood, O2 diffuses down its concentration
  gradient from the alveoli into red blood cells
• Blood coming from the lungs is red because it is
  filled with O2

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How does O2 get into cells?

• Cells and tissues receive all nutrients (food,
  O2, water) in capillary beds
• When blood from the lungs reaches cells, there
  are many more O2 molecules in the blood than in
  the cell, and O2 (green) diffuses into cells down
  its concentration gradient
• At the same time, waste CO2 (blue) travels out of
  those cells and into the blood where there is
  almost no CO2

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How do animal cells use O2?

• Cells break down glucose molecules to create ATP,
  the energy storing molecule
• O2 is a crucial molecule in this process
• Aerobic respiration
• Takes place in the mitochondria of animal cells
• Making energy from glucose with the use of O2
• What our bodies do 95 of the time

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What happens without O2

• Anaerobic respiration
• Making energy by breaking down glucose without O2
• Much less efficient, takes place during
  emergencies when not enough O2 is available
• Produces alcohol in yeasts
• Produces lactic acid in mammals
• EX When running away from a tiger, your muscles
  need lots of ATP FAST, but your heart cant pump
  enough O2 for aerobic respiration to produce
  enough ATP. Your muscles switch to anaerobic
  respiration, and the next day, all that lactic
  acid makes that tissue sore.

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How does your body use ATP?

• ATP is the most important energy provider for
  cells in all tissues
• Breaking a phosphate group off of ATP releases
  energy used in other reactions in the cell
• ATP ? ADP Pi
• ADP is recycled and the Pi group is put back on
  during cellular respiration

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Using ATP during active transport

• ATP is hydrolyzed (broken) into ADP Pi by the
  Na/K pump
• Energy released during ATP hydrolysis is used to
  make Na and K ions move against their
  concentration gradients
• ADP is transported back to the mitochondria to be
  recycled into ATP during cellular respiration