Tuesday May 29, 2012

Hi everybody!

Today we started out finishing our Respiration notes. Here are the notes (know the terms in blue):

• When the diaphragm contracts air is "pulled" into the lungs due to increase in volume and decrease in pressure (negative pressure breathing)
• When the diaphragm relaxes air is "pushed" out of the lungs due to decrease in volume and increase in pressure
• Automatic control centers in the brain regulate breathing
• Nerves tell the diaphragm when to contract
• The normal respiratory rate is 10-14 inhalations per minute, but this changes depending on the level of carbon dioxide in the blood (more carbon dioxide = faster respiration rate)
• Hyperventilation - purges the blood of so much carbon dioxide that the brain stops sending messages to the diaphragm (breathing in a paper bag increases the amount of carbon dioxide in the body and restores normal breathing)
• Oxygen does not dissolve into the blood
• Oxygen will be carried through the blood by hemoglobin molecules in red blood cells
• Hemoglobin = 4 polypeptide chains, heme (chemical group), and iron - it is a big protein
• Every iron atom can bind to 1 oxygen molecule (therefore, hemoglobin can carry up to 4 oxygen molecules)
• Iron deficiency causes anemia
• Hemoglobin also binds to carbon monoxide
• Carbon monoxide interferes with the delivery of oxygen to the body cells, since hemoglobin binds to carbon monoxide VERY QUICKLY, and cellular respiration (it basically causes death - this is called carbon monoxide poisoning)
• Air pollutants can cause respiratory problems
• Tobacco smoke is one of the worst forms of air pollution, and contains over 4000 chemicals
• These damage mucus and cilia, making it difficult to remove foreign particles (think of smokers cough)
• Emphysema - disease that causes alveoli to disintegrate (it reduces the lungs' ability to exchange gases)

Next in class, we did a lab about lung capacity and breathing (UP 57-61). Make sure you know:

• Vital capacity - the largest possible amount of air which can be exhaled after drawing in a deep breath
• Expiratory reserve - the amount of air that remains in the lungs after exhaling normally but which can be expelled
• Tidal volume - the amount of air taken in or expelled during normal breathing
• Residual volume - the amount of air in the lungs that cannot be expelled

For this lab, we took a balloon and found the vital capacity (5 trials), the expiratory reserve (5 trials), and the tidal volume (5 trials). To do this, we had to blow up the balloon, expelling the amount of air required for each type of volume measurement. Then, we had to measure the diameter of the balloon, and record it. To find the lung volume in cubic centimeters, we had to refer to the chart on UP 59, going across for the balloon diameter and up to see where it hit the solid line. We also used a spirometer to measure vital capacity, expiratory reserve, and tidal volume (a spirometer measures the pressure).

Finally, we started the nervous system notes, so here they are:

• Neuron - nerve cell specialized for carrying signals from one part of the body to another
• Nerve - communication line made from bundles of neuron fibers wrapped in connective tissue
• CNS - central nervous system (brain and spinal cord)
• PNS - peripheral nervous system (nerves that carry impulses in and out of the CNS)
• 3 functions of the N.S. (nervous system)
• Sensory input - sensory neurons carrying impulses from sense organs to CNS
• Integration - association neurons or interneurons, found only in the CNS, interpreting the sensory signals and creating a response
• Motor output - motor neurons, conducting signals from integration to effector cells (muscle cells - perform body's response)
• In a motor neuron...cell body - nucleus and other organelles
• Dendrites - branched, short, and receive incoming messages from other cells or the environment
• Axon - long, single fiber, conducts signal toward another neuron or effector
• Supporting cells - protect, insulate, and reinforce neurons
• Myelin sheath - chain of beadlike supporting cells
• Node of Ranvier - spaces in myelin, only points where the impulse can be transmitte (signals = about 150 m/sec - 330 mi/hr)
• Synaptic knob - relays signals to another neuron or effector

• Resting potential - voltage (potential difference) across the plasma membrane of a resting neuron (negative charge inside, positive charge outside)
• Stimulus - anything that causes a nerve signal to start
• Action potential - self-propagating change in the voltage across the plasma membrane

That's it for what we did in class today!! Here is the homework:

1. Finish the lab (UP 57-61)
2. Crossword puzzle (due 6/1)
3. UP 47-54 (do/read/study)
4. TEST ON MONDAY 6/4
5. Study for finals

NEXT SCRIBE: Xavier