Download Why does eating salty popcorn or baked ham make you thirsty

Name __________________________________________________________________ Class Period _____________
Why does eating salty popcorn
or baked ham make you thirsty,
sometimes a few hours after
you've eaten it?
Why Salt Makes You Thirsty
Let’s follow salt into the digestive system and see what happens. In the wall of the small intestine, the salt is absorbed
into your bloodstream, making your blood saltier than it was before.
Salty Circulation
As the saltier blood circulates through the body, it makes the fluid outside of our body cells saltier than the fluid inside
the cells.
The cells notice the change right away. That’s because the extra salt outside acts like a magnet, pulling water out of the
cells. The cells try to hold in the water and they send chemical messengers to the brain, protesting the saltiness of the
fluid around them.
Thirst Center
There are also sensors in the thirst center in the brain that keep tabs on the saltiness of the blood. When the thirst
center goes on alert because things are too salty and the body needs water to dilute the salt, that’s when you start to
feel thirsty.
The kidneys help dilute the salt too by slowing down urine production and conserving water. The constant balancing of
salt and water in the body helps maintain the right amount of water in our cells and in the bloodstream. That controls
our blood pressure.
Breau, A. (2011, December 13). Why salt makes you thirsty. Retrieved from http://indianapublicmedia.org/amomentofscience/why-salt-makes-you-thirsty/
Osmosis
os·mo·sis noun \äz-ˈmō-səs, äs-\
biology : the process that causes a liquid (especially water) to pass through the wall of a living cell
http://www.merriam-webster.com/dictionary/osmosis
Mini Osmosis Lab Day 1
1. Write the number of your cups. ________________
2. Test the crispness of your vegetable by bending then breaking one sample.
3. Write your observation.
4. Check the Water Content of Fruits and Vegetables table.
What is your vegetable? ___________________. What is the percent of water in your vegetable? _______
5. Label one cup “Fresh Water” and the second cup “Salt Water”
6. Fill each cup ½ full with water. Add salt to the “Salt Water” cup. Place one vegetable sample in each cup.
7. Place the cups on the counter to soak overnight.
8. What do your predict will happen?
9. Justify your prediction by quoting the text of the introductory article that supports your prediction.
Name __________________________________________________________________ Class Period _____________
Mini Osmosis Lab Day 2
1. Remove the vegetable from the “Fresh Water” cup. Test the crispness of your vegetable by bending it.
2. Write your observation.
3. Remove the vegetable from the “Salt Water” cup. Test the crispness of your vegetable by bending it.
4. Write your observation.
5. What has happened to the vegetables?
Plant cells have an organelle called a vacuole. Those vacuoles gain and lose water depending on how much water is
available to the plant. A drooping plant has lost much of its water and the vacuoles are shrinking. It still maintains its
basic structure because of the cell walls. When the plant finds a new source of water, the vacuoles are refilled and the
plant regains its structure.
6. Predict what will happen if we put the vegetable that we soaked in salt water into a cup of fresh water
overnight.
7. Put the vegetable soaked in salt water into the cup labeled “Fresh Water” and leave on the counter to soak
overnight.
8. Write your observations.