Mod 5 WATER

Question 1

Why do we need to constantly replenish water in our bodies?

Answer 1

We do not store water.

Question 2

Two types of water in the body:

Answer 2

intracellular (within cells, doesn’t fluctuate much in healthy people) and extracellular- it is the extracellular water that is used for the body’s functions and must be regularly replenished.

Question 3

Where is most extracellular water found?

Answer 3

The blood (+~90%)

Question 4

One important function of protein in the blood is

Answer 4

Protein is a charged polar substance: in the blood it helps to maintain fluid balance, drawing water in from the extracellular space (this ensures too much water doesn’t collect there)

Question 5

Describe the molecular structure of water:

Answer 5

1 Oxygen (negative) and TWO hydrogen (positive) = water is Polar.

Question 6

Why is it important that water is polar?

Answer 6

This allows it to attract other polar molecules like itself -hydrophilic molecules, and repel non polar molecules, -like lipids- that are hydrophobic.

Question 7

The main force that pushes water out of blood into capillaries (extracellular spaces)

Answer 7

Blood Pressure!

Question 8

Functions of Water (6)

Answer 8

1. Structure
2. Solvent
3. Hydrolysis
4. Defense from Infection
5. Protection from Injury
6. Temperature Regulation

Question 9

Functions of Water- 1. Structure

Answer 9

Water helps body structure maintain their form - i.e. allows organelles in cells to keep their shape for proper functioning and allows structures like the eye to keep their shape

Question 10

Functions of Water- 2. Solvent

Answer 10

Water is the most important solvent because a variety of polar substances can dissolve –> this is important for moving things around the body

Question 11

Hydrolysis (definition)

Answer 11

The addition of water creating a reaction that splits larger molecules into smaller ones.

Question 12

An example of a hydrolysis reaction with sugar molecules

Answer 12

(Larger) Maltose —-> hydrolysis splits into 2 (smaller) glucose molecules

Question 13

Functions of Water- 3. Hydrolysis

Answer 13

Water is always in motion & allows substances to move around inside the cell, and brings reactants of chemical processes together

Question 14

Functions of Water- 4. Defense from Infection

Answer 14

Immune cells in the body are suspended in a water environment (the lymph), similarly, mucus is mostly water!

Question 15

Functions of Water- 5. Protection from Injury!

Answer 15

Water can reduce the amount of friction and damage from movement or trauma that can degrade our tissues.
ex. Helps protect bones, line the digestive tract (mucus). cerebrospinal fluid (spinal cord)

Question 16

Functions of water-6. Temperature regulation

Answer 16

Body temperature needs to be kept within a narrow range (~37C) to function properly

• sweating
• opening blood vessels close to the skin

Question 17

What is heat stroke (and Temp it occurs at)

Answer 17

Severe heat illness occurs when body temp rises about 40C, accompanied by neurological symptoms (delirium, convulsions, can lead to coma or death)

Question 18

What are the three ways we gain water in our bodies?

Answer 18

• certain metabolic processes—water is a byproduct of cellular respiration
• eating foods; plants and animals (water is in the cytoplasm of their cells)
• drinking (most of our water)

Question 19

When blood volume decreases, what Two mechanisms regulate water levels?

Answer 19

• thirst increases

- kidneys decrease production of urine (when blood volume/ blood pressure is low)

Question 20

hypovolemic shock

Answer 20

Too little water:::the body looses a lot of blood or extracellular fluid –compromises oxygen and nutrient delivery

Question 21

Water Intoxication definition

Answer 21

Too much water, dilution of electrolytes

Question 22

What can cause water intoxication

Answer 22

• person consumes too much water in a short time frame
• Lots of water is lost (due to excessive sweating, dialarhoea or vomiting) and only water is replaced (need to replace electrolytes)

Question 23

hyponatremia

Answer 23

low sodium content in the blood (can occur due to water intoxication)

Question 24

Diuretics

Answer 24

Promote water loss through urination

Question 25

What other two substances are diruretics?

Answer 25

Alcohol and Caffeine

Question 26

Why are alcohol and caffeine not considered nutrients? (They are psychoactive drugs)

Answer 26

They don't contribute to the 
-growth
-maintenance
-survival 
of the body

Question 27

Typical safe dose of caffeine per day

Answer 27

300 mg

Question 28

How many calories kcal/g does alcohol provide ?

Answer 28

7 kcal/g

Question 29

Why do moderate drinkers (1-2 drinks/day) see a modest cardiovascular benefit ?

Answer 29

Because alcohol thins the blood, might reduce artery-blocking clots and increase HDL “good cholesterol”

Question 30

At what concentration is alcohol absorption the fastest?

Answer 30

30-40% alcohol

Question 31

90% of alcohol is metabolized in ____ by two enzymes

Answer 31

The Liver

1) alcohol dehydrogenase
2) aldehyde dehydrogenase

Question 32

2 liver enzymes turn alcohol into

Answer 32

acetate

Question 33

4 proposed mechanisms for hangovers:

Answer 33

1. acetalhyde build up
2. Direct effect of alcohol on the gastrointestinal tract
3. alcohol withdrawal
4. congeners (substances within alcohol added during fermentation)

Question 34

What is the RDA of water?

Answer 34

It hasn’t been determined.

Question 35

What is the AI (Adequate Intake) for water?

Answer 35

2.7 L/day for women and 3.7 L/ day for men.