Chapter 1
I. Definitions
A. Anatomy
B. Physiology
C. Microscopic vs. Gross Anatomy
1. Cytology
2. Histology
D. Cell
E. Tissue
F. Organ
G. Homeostasis- Every cell is made of, and
manipulates, chemicals. Every cell, tissue, organ and
various functional chemicals require a specific range
of environmental conditions to function properly (ex.,
pH, temp, ion concentration). Those ranges often risk
being disrupted, and cells constantly work to maintain
and restore them. See example in book: response to
rising heat during exercise.
II. Levels of organization in the body
Molecular/chemical- ex., proteins, DNA, calcium,
phospholipids, etc. --> Cellular --> Tissue --> Organ -->
Organ System (see pp. 9-10, fig 1-3 for organ systems of
the body) --> Organism
III. Homeostasis- General Overview
A. General Control Mechanisms
1. Autoregulation- localized group of cells/tissue
"fixes its own problem": examples:
-cells need more O2, release vasodilators causing
local blood vessels to expand and bring more blood
with O2
-injured cells release chemicals to start the
clotting process and attract immune cells
2. Extrinsic regulation- a broader, larger scale
response to maintain homeostasis. Hormones &/or
neurotransmitters are released in response to a change
in homeostasis. They are released by an organ and sent
throughout the body, not so localized. Often, hormones
released by one organ affects the activities of
distant organ/s, and may affect different organs in
different ways. Examples:
-blood sodium concentrations rise, a hormone
released by a gland in the brain causes kidneys to
retain water
-blood glucose concentrations rise, the pancreas
releases insulin. Insulin causes most body cells to
take in glucose and use it for energy, causes fat
cells to store fat (triglycerides), and causes liver &
muscle cells to store glucose.
B. Regulatory mechanisms employ 3 steps:
1. Sense the change via a receptor (ex:
hypothalamus in the brain monitors temperature, senses
change in temp)
2. A control center will process the information
and respond (ex.: hypothalamus directs the release of
some chemicals that will help restore temperature)
3. Effectors will respond to the chemical
commands of the control center (ex: surface blood
vessels relax [dilate], allowing more blood near the
surface to release heat)
C. Chemicals released to maintain/restore homeostasis
can work in one of two ways:
1. Negative feedback (most common): ex., blood
glucose rises, insulin causes changes that decrease
blood glucose levels
2. Positive feedback: ex., blood clotting. When
vessels are damaged, chemicals are released by local
cells to start the clotting process. As the process
starts, it induces cells to release more chemicals
that will accelerate the process, and so on, until the
vessel is patched.
IV. Anatomical Landmarks, Body Cavities & Slices- use Lab
Exercise 2 as a guideline.
Chapter 2
I. Atoms & Molecules
A. The number of electrons an element has determines
how reactive it will be. Some elements tend to give up
electrons, some tend to take them on. The one that lost the
electron carries a positive charge, the one that took it
carries a negative charge. Charged atoms are called ions.
Positive ion = cation, negative ion = anion. Some elements
give up or take on more than one electron. For example,
calcium tends to lose 2 electrons and exists as a Ca 2+
cation.
B. Molecules & Bonding
1. Ionic bonding: one atom gives up an electron
to another atom. Both become more stable, but also
become charged. Now they are attracted to each other
because of their opposing charges. Table salt, or
sodium chloride, is a classic example. Ionically
bonded substances can easily dissociate in water to
become their component ions.
2. Covalent bonding: atoms share electrons. The
electrons they share zip around both of their nuclei.
Covalent bonds are stronger than ionic bonds, and
covalently bonded molecules do not tend to dissociate
in water. Atoms that share 1 pair of electrons are
single-bonded; 2 pairs, double-bonded; 3 pairs,
triple-bonded.
Sometimes, the atoms share the electrons equally. But
sometimes, the atoms of a covalent bond have different
electron affinities, and the electrons spend more time
around one of the atoms than the other. If the
electrons in a molecule tend to spend more time around
certain atoms than others, then the atom/s with the
extra electron time take on a slight negative charge,
and the others a slight positive charge. We say that
they are polar, or have polarity.
3. Hydrogen bonding: weak associations between
polar molecules. The slightly negative end of one
polar molecule is attracted to the slightly positive
end of another. Important when many polar molecules
interact through hydrogen bonding. The surface tension
of water is a result of H-bonding: O hogs electrons
and takes on a slight negative charge, while H takes
on a slight positive charge. O and H of adjacent
molecules are attracted to one another.
H-bonding between base pairs in DNA holds the two
strands together.
Proteins are huge molecules that have polar sections.
The unique folding of each protein is, in part,
determined by H-bonding between sections of the
protein strand.
Ionically bonded ions tend to dissociate (separate) in
water, because the slightly positive H's of water
surround anions, and the slightly positive O's
surround cations. See the explanation of pH below for
an example of the dissociation of ionically bound
substances in water.
II. Reactions & Enzymes
A. Background: energy
1. Kinetic energy: the energy of movement.
Includes a ball flying through the air, or a
molecule bouncing around in space. Heat is a form
of kinetic energy: the random movement of
molecules/atoms (the faster they go, the hotter
it gets). Kinetic energy also includes a rubber
band flying through the air toward the back of
your little sister's head.
2. Potential energy: stored energy. When you
stretch the rubber band back and aim it at your
sister, you know that there is stored energy in
that rubber band, because when you let go it will
move, and will do work (startle your sister).
Energy is stored in chemical bonds, so when
chemical bonds are broken, energy is released.
Cells take advantage of the fact that chemical
bonds store energy. They purposefully break bonds
to use the released energy.
3. Energy conversions: energy is converted
between forms. When you pull the rubber band
back, you are converting kinetic energy (moving
your hand & the rubber band) to stored energy.
Whenever energy is converted between forms, some
of the energy is converted to heat, whether you
mean to do that or not. So, when cells break
chemical bonds to release energy to do work, some
heat is always produced.
Homeotherms (warm-blooded animals) take advantage
of that fact to maintain stable temperatures. We
"waste" tons of energy, just contracting &
releasing muscles constantly to break bonds &
release heat. Your pet boa constrictor can go
without food for much longer than your pet guinea
pig because the boa wastes much less energy on
heat production.
4. Ways that cells store energy: keep this in
mind, we will look at three specific modes of
energy storage used by cells. Come back here and
fill it in!
B. Types of reactions
1. Decomposition/catabolism- breaking molecules
down into smaller components. Overall, tends to
release energy.
Hydrolysis is a type of decomposition reaction,
where water is split into H and OH, which are
used to stabilize the 2 resulting molecules.
Cells break down glucose to release it's energy.
The cell then repackages that energy in smaller,
portable ATP. When this happens, glucose
(C6H12O6) is split into water (H20) and carbon
dioxide (CO2).
2. Synthesis-building larger molecules from
smaller components. Overall, tends to consume
energy. Dehydration synthesis (condensation) is a
type of synthesis reaction where one molecule
loses a H, the other loses a OH, and water is
formed.
C. Enzymes- Increase the rate of reactions by lowering
the activation energy, or energy required to get a reaction
going. Without enzymes, the reactions in our cells wouldn't
happen fast enough to sustain life. Each cell makes the
enzymes it needs for the reactions it needs to carry out.
III. Inorganic compounds
Go over in book: properties of water, aqueous solutions, H+
in body fluids, pH, acids, bases, salts & buffers. Here's
an explanation of acids and buffers:
First, a little bit about water and pH. Water, as you know,
is composed of two hydrogen atoms (H) bound to one oxygen
atom (O): H2O. A glass of water contains millions of
molecules of H2O. Being a liquid, these molecules are
constantly moving around, bumping into the sides of the
glass and each other. Occasionally, collisions cause a
molecule to dissociate, or break up. When this happens, the
H2O molecule is broken into a hydrogen ion (H+, which is
called a proton for convenience) and a hydroxide (OH-). The
hydroxide takes an electron (negative charge) from the
hydrogen, which is why they end up with charge. Now we say
these protons and hydroxides are "free" in solution, which
means they are floating around on their own, not bound to
any other particles.
In pure water, the number of free H+ must equal the number
of free OH-, because the dissociation of H2O always
produces one of each. In this situation, when free H+
equals free OH-, the solution is neutral. A neutral
solution has a pH of 7, which is a way of describing the
concentration of free H+ relative to the concentration of
free OH-. If we could drop extra H+ into the water without
adding extra OH-, we would end up with an acid solution.
Acid solutions have pH ranging from 0-7. Stronger acids
have a low pH (for example, vinegar or acetic acid is
around pH 5, while the stronger stomach or hydrochloric
acid is around pH 2). If we could drop extra OH- into
solution without adding H+, we would end up with a basic
solution, pH 7-14, with 14 being the strongest. The
remainder of the explanation will focus on acids since they
are what we will encounter most with living systems.
Acids are compounds that release H+ when dropped in water.
So, if you took a bunch of dry HCl (hydrochloric acid)
molecules, they'd probably look like a powder, and they'd
be bound together as HCl. When you drop those molecules in
water, however, most of them would immediately dissociate
into H+ and Cl- (chloride), completely separate, not really
giving a hoo-ha about what the other is doing.
Strong acids are compounds that tend to dissociate
immediately and almost completely. HCl is a strong acid, so
when dropped in water, practically all of the Climmediately drop their H+ s like a hot potato. What this
means is that strong acids throw LOTS of H+ into solution.
H+ tends to react with other stuff, which gives acidic
solutions their properties.
Weak acids are compounds that tend to dissociate a little
bit. H2CO3 (carbonic acid) dissociates into H+ and HCO3(bicarbonate) in water. Carbonic acid is a weak acid, so
when dropped in water, only some of the HCO3- drop their
H+. In addition, the other HCO3- are still on the fence
about H+; they will take them back sometimes to become
H2CO3 again. The H+ and anion of a weak acid kind of have
an "on again, off again" relationship. The anions of a weak
acid will bind to H+ again, if there are a lot of H+
around.
Buffers are generally weak acids. Buffers can maintain a
solution within a range of pH. That's because the anions of
weak acids will drop their H+ if there aren't many H+ in
solution, but will bind with H+ if there are lots of H+ in
solution. To say that another way, when H+ concentrations
rise, buffers bind them and take them out of solution. When
H+ concentrations fall, buffers release them and put them
back into solution. Buffers, therefore, keep the number of
free H+ relatively constant. Since it is the concentration
of free H+ in solution that determine acidity, buffers keep
pH relatively constant.
IV. Organic Compounds
A. Functional groups: hydroxide, carboxyl, amino,
phosphate. Carboxyls tend to lose H+ in water. Amino
groups can pick up an extra H+ (-NH3) if H+
concentration is high.
B. Carohydrates- typically end in "-ose"
1. Monosaccharides- The major ones we will
consider all have the formula C6H12O6. Tend to
form hexagon ("hexose") or pentagon ("pentose")
rings, and you will see them illustrated in this
way. The root "gly" refers to glucose (ex.
proteoglycans = protein linked to
polysaccharide). Glucose is the primary
monosaccharide we will consider, but we will also
talk about fructose and galactose when we get to
the digestive system.
2. Di- and polysaccharides- two or many
monosaccharides linked in branched chains. For
example, the disaccharide sucrose (table sugar)
is composed of one glucose attached to one
fructose. Starch and many fibers are
polysaccharides composed of thousands of glucose
attached in chains (like a pearl necklace). We
will talk a lot about the polysaccharide
glycogen, which is also made of chains of
glucose. Animals store glucose in certain cells
with glycogen.
Reference the pictures above under "types of
reactions" to see examples of mono- and disaccharides.
C. Lipids- nonpolar, hydrophobic, lipophilic
1. Fatty acids
a. Glycerides: storage of fatty acids
b. Phospholipids: using fatty acids as the
fat-soluble end of an amphipathic molecule
2. Eicosanoids- Used by cells to send LOCAL
chemical messages. Kind of a folded, modified
fatty acid.
3. Sterols
D. Proteins- root "pep" refers to proteins/bonded
amino acids
1. Long folded, convoluted chains of amino acids;
R-group determines amino acid; often carry an
overall negative charge (because of many of the
carboxyls losing their H+, plus many of the R
groups tend to lose H+).
2. Shape and function
-four levels, H-bonding and disulfide bonds,
denaturation
3. Enzymes- function, action, saturation, factors
that affect rate of activity.
E. Nucleic Acids- DNA and RNA
F. High Energy Compounds: Cells use the energy from
foods to do work. Glucose, fatty acids, and amino
acids can all be used by cells for energy; that is,
cells can break the bonds in those molecules and use
the energy released. Cells do not use that released
energy directly. Instead, they carefully move the
energy stored in "food" bonds to energy stored in the
bonds of ATP. Many ATPs can be produced from one
glucose, fatty acid or amino acid. ATP is composed of
one adenosine (an organic molecule) and 3 phosphates
(an inorganic side group, abbreviated Pi).
When a cell needs energy to do work, it breaks the
bonds between the 2nd or 3rd phosphate of ATP, and
uses the energy released to do work directly. ATP is
considered a "high energy compound," because it stores
energy that can be easily accessed. It is not the only
high-energy compound. We will talk about others when
their contributions are important to specific systems.
When a cell uses "food" energy to make ATP, it uses
the energy released from glucose, fatty acids or amino
acids to add phosphate/s to AMP (Adenosine
MonoPhosphate) or ADP (Adenosine DiPhosphate).
ATP is like the cell’s AA battery; it is portable, it
has just the right amount of energy to do one job, AND
it is rechargeable. When ATP is used to do a job, it
splits into ADP +Pi. The cell can then recharge it by
extracting some energy from glucose or fatty acids,
and using that energy to re-attach the phosphate.
Viola, now the cell can do another job!