Unit 1 Student Guided Notes
Introduction
HOMEOSTASIS: ______
Examples:
1.Blood Glucose Concentration remains about 0.01%
2.PH of blood is always near 7.4 (slightly basic)
3. Blood pressure in the brachial artery averages near 120/80
4.Blood temperature averages ~ 37C
- Pancreatic Juice (pH 8.5) neutralizes stomach acids so that
food entering the small intestine is basic.
- CO2 concentration in our blood stimulates our breathing.
NEGATIVE FEEDBACK : ______
Control centers in the ______release ______that cause specific body reactions.
Once normalcy is reached, the ______is NO LONGER stimulated. (This is why the process is called ______
______).
POSITIVE FEEDBACK: ______
Instead of achieving normalcy, ______
______
Negative Feedback tends to ______a system.
Positive Feedback leads to ______
Water
Water The Universal Solvent
Because water is the substance that makes life possible as we know it on Earth, astronomers hope to find evidence of water on newly discovered plants orbiting distant stars.
Life on Earth began in the water and evolved there for 3 billion years before spreading onto land.
Terrestrial organisms are still tied to water. In fact, most cells are surrounded by water and cells themselves are about 70-95% water.
Background Information:
Life as we know it, is based on the ______
______. To be "organic" a molecule must have a carbon atom in it. Eg. Vinegar (CH3CH2OH) is organic, whereas ______is not.
The organic molecules in living things are easily grouped into four types. Understanding these four biochemicals is the purpose of the next unit.
So if it's not organic, why is water so incredibly Important?
What happens to the quality of life if the chemical conditions of living things change?
In the formation of ______, atoms must bond together to form ______. In order to do this,the______ around the various nuclei in the compound must also be stable. This stability can be achieved through some degree of ______ between the atoms.
If the atoms share the electrons reasonably equally, their association is termed ______ bond.
Ionic Bonds
The alternative is a very unequal sharing of electrons. This is called an ______where it seems as though one atom actually gives ______. Neutral atoms become ______ when they lose electrons and ______ when they gain electrons.
In between these two extremes is what is termed ______. Polar covalent molecules have ______ (regions with slight positive and negative natures). A water molecule is an example of this kind of molecule.
Structure of water
In a covalent bond atoms ______to become stable. If the electrons in a covalent bond are not shared equally by the two atoms, the molecule is then called a ______.
Polar Molecules
Any molecule that ends with a different charge is called a ______. Hence it would be a ______. One end being the negative dipole and the other being the positive dipole.
Therefore, water molecules behave as______with ______one another. ______causes water to have some degree of structure that extends beyond the individual molecules and cause a community water effect. The overall property is called ______, i.e. the attraction of the ______.
This means that water molecules are ______ to one another. The negative charge on the oxygen attracts the positively charged hydrogen some distance away to produce a weak bond called a ______.
Hydrogen Bonding
Although hydrogen bonds are weak, the vast number of these bonds gives water its unique properties. Each water molecule can form hydrogen bonds with up to ______neighbors.
Water is the Solvent of Life
A ______ is a mixture of one or more soluble substances, called ______, dissolved in a liquid called the ______.
A sugar cube in a glass of water will eventually dissolve to form a uniform mixture of sugar and water. The dissolving agent is the ______ and the substance that is dissolved is the ______. In our example, water is the solvent and sugar the solute.
Can you identify the solvent in each of the following solutions?
(Which one is the solute?)
Example #1: 15g baking soda and 100 mL water
Example #2: Nail polish removed by acetone
Example #3: 1.00 L ethylene glycol and 875 mL water
Example #4: Chromium dissolved in hydrochloric acid
Water as a Solvent
The Properties of Water:
1)Solvent: Water ______ and is able to dissolve many chemical substances especially other ______. Since blood is mainly water, the ability of water to dissolve and transport substances greatly aids in bringing about necessary ______
______.
2)Temperature Moderator: Moderates temperature and Climate (both internal and external climates). Water can absorb a great deal of ______
______. Water also releases heat slowly. This property is referred to as a ______.
As a liquid evaporates the most energetic molecules are carried away leaving the lower kinetic energy molecules behind which cools the surface of the liquid that remains -______.
______.
External example - Oceans keep surrounding land masses cool in summer and warmer in winter.
3) Density:Liquid water is ______
______than ice (very rare for compounds). Most materials contract as they solidify, but water expands. Therefore, ice forms on top of water ______ levels. This oddity has important consequences for life. If ice sank, eventually all ponds, lakes, and even oceans would freeze solid. During the summer, only the upper few inches of the ocean would thaw. Instead, the surface layer of ice insulates liquid water below, preventing it from freezing and allowing life to exist under the frozen surface.
4) Transparent:Light ______ of water to the organisms below.
5) Cohesive/Adhesive: Water molecules ______
______. This keeps surfaces ______
______. Diffusion of gases occurs much more efficiently ______moist surfaces. ______ (sticking to each other) amoung water molecules plays a key role in the transport of water against gravity in plants. ______, is a measure of the force necessary to stretch or break the surface of a liquid and is related to cohesion. Water has a ______
______ than most other liquids because hydrogen bonds among surface water molecules ______the surface. Water behaves as if covered by an invisible film. Some animals can ______on water without breaking the surface.
______(clinging of one substance to another) contributes too, as water adheres to the walls of the blood vessels.
****Note: Focus on the properties of water that apply to the human body.****
What are 4 important functions of water in the human body?
Example #1:
Example #2:
Example #3:
Example #4:
pH
Acids
Organisms are sensitive to changes in pH (______
______). An ______is a substance that ______in a solution.
For example when hydrochloric acid is added to water, hydrochloric acid dissociates to form hydrogen ions and chloride ions:
HCL —> H+ + Cl-
The addition of H+ makes a solution more acidic.
A base is a substance that increases the hydroxide ion concentration in a solution.
For example when sodium hydroxide is added to water, sodium hydroxide dissociates to form sodium ions and hydroxide ions:
NaOH —> Na+ + OH-
Solution with more ______are basic solutions.
The pH scale is used to describe how ______(the opposite of acidic) a solution is.
pH Scale
The pH scale, ranging from 1 to 14, compresses the range of concentrations by employing logarithms. In other words every number on the pH scale is a multiple of 10. pH = -log [H+] or [H+] = 10 -pH
A pH of 7 is a neutral pH where the - ______
______. [H+] = [OH-]
A pH that ranges between 7 and 14 has more hydroxide ions than hydrogen ions making it a basic solution and a pH that ranges between 1 and 7 has more hydrogen ions than hydroxide ions making it an acidic solution. We can calculate the the difference in hydrogen ion concentrations at different pH levels by multiplying or dividing by 10.
For example a pH 6 has ______ more H+ than at pH 7. A pH of 3 has ______ more H+ than pH 5 and so on.
Try the following:
Example #1: pH of 12 has ______more H+ than a pH of 15
Example #2: Ph of 6 has ______more H+ than a pH of 11
The pH scale is just a comparison between the [H+] and [OH-].
Buffers
Most ______which control the ______ in your body, can only operate at certain ______ levels. If pH levels change too drastically these biochemicals will denature (lose their shape) and no longer function properly.
Example:
- Blood must be at a pH close to ______ or else we may become ill.
- At the wrong pH the blood cannot transport ______as efficiently.
As you can see then the ______ can be disrupted by changes to the H+ and OH- concentrations away from their ______
______.
To maintain cellular pH values at a constant level,______
______.
The function of Buffers is to______
______when H+ or OH- is added to the solution.
Buffers are______
______.
Buffers accept hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted.
Note: The buffer keeps pH constant ______
______.
Acids are molecules that dissociate to release ______ ions. In this respectwater acts as a ______. HCI on the other hand is a ______ because it dissociates to a much greater extent. Systems with HCI in them have a lot of free ______ floating around.
Bases are molecules that release ______. Molecules like ______
______. Bases have a ______ because the H+ in an acidic environment will combine with OH- from a base and form ______.
Note: The first graph shows pH change without a buffer, while the second graph shows pH change with a buffer.