Physiology
 The
cell is the basic unit of structure and
function of all living things
 The
cell is considered to be the smallest
structure in biology that has all the properties
of living things and an understanding of cells
and the basics of cell structure and function is
critical to making sense out of biology.
 Cell
membrane.
 Cytoplasm.
 DNA.

All cells have a
phospholipid based cell
membrane. The cell
membrane is selectively
permeable in that it
allows some materials to
pass into or out of the
cell but not others.

Cells are filled with a
complex collection of
substances in a water
based solution. This
substance is called
cytoplasm. Across all
cells there are a number
of common features to all
cell cytoplasm. For
example all cells have
ribosomes. Also, in all
cells the first steps in
cellular respiration take
place in the cytoplasm.

All cells contain DNA(2).
In the simplest cells, the
DNA is in one loop more
loop like structures free
in the cytoplasm. In some
cells such as those
making up our body the
DNA is isolated from the
cytoplasm in a special
structure called a
nucleus. Remember not
all cells have a nucleus!
This image shows a cell in an aquatic plant, Elodea. The
clear strand at the tip of the arrow represents a 'conveyor
belt' made of proteins that helps to move some of the
cell's parts around the cell.
 Plasma, the
liquid
portion of the blood
without the blood
cells, makes up about
7 percent of body
fluid.
The intracellular compartment, the
fluid located inside cells, makes up
about 65 percent of body fluid.

Intercellular fluid is the
fluid in the potential
spaces between cells in
the various organs and
tissues.
Since the human body is mostly water, proper fluid
balance is needed to sustain proper functions for
kidneys and other organs as well as help flush waste
from body.
Electrolytes are
minerals in your body
that have an electric
charge. They are in
your blood, urine and
body fluids.
Maintaining the right
balance of electrolytes
helps your body's
blood chemistry,
muscle action and
other processes.
Sodium, calcium,
potassium,
chlorine, phosphate
and magnesium are
all electrolytes.
You get them from
the foods you eat
and the fluids you
drink.
Levels of electrolytes in your body can become too low or too
high. That can happen when the amount of water in your body
changes. Causes include some medicines, vomiting, diarrhea,
sweating or kidney problems. Problems most often occur with
levels of sodium, potassium or calcium.
Water intoxication, also known as
hyper-hydration, water poisoning, or
overhydration, is a potentially fatal
disturbance in brain functions that
results when the normal balance of
electrolytes in the body is pushed
outside of safe limits by overconsumption of water.
First observable symptoms
of water intoxication:
headache, personality
changes, changes in
behavior, confusion,
irritability, and drowsiness.
These are sometimes
followed by difficulty
breathing during exertion,
muscle weakness,
twitching, or cramping,
nausea, vomiting, thirst, and
a dulled ability to perceive
and interpret sensory
information.
Nearly all deaths related
to water intoxication in
normal individuals have
resulted either from
water drinking contests
in which individuals
attempt to consume
large amounts of water,
or long bouts of
intensive exercise
during which
electrolytes are not
properly replenished,
yet excessive amounts
of fluid are still
consumed.
Normal, physically, nutritionally and mentally healthy
individuals have little reason to worry about
accidentally consuming too much water.
The two types of dehydration, chronic dehydration and
acute dehydration, can be caused by many things. The most
common are: flu, vomiting, diarrhea, blood loss,
malnutrition, and plain old failure to replenish liquids lost
from sweating and urination (Not drinking enough water).
Many illnesses and diseases can trigger acute
dehydration due to the increased body temperature and
sweating that usually occur. This is why your doctor tells
you to drink plenty of fluids when you are ill. Your body
uses fluids to expel toxins as well as to keep your system
flexible, lubricated and running smoothly.
The initial signs and symptoms of mild dehydration in adults
appear when the body has lost about 2% of it's total fluid.
These mild dehydration symptoms are often (but not limited
to):
Thirst
Loss of Appetite
Dry Skin
Skin Flushing
Dark Colored Urine
Dry Mouth
fatigue or Weakness
Chills
Head Rushes
Human homeostasis is derived from the Greek, homeo
or "same", and stasis or "stable" and means remaining
stable or remaining the same.
The human body manages a multitude of highly
complex interactions to maintain balance or return
systems to functioning within a normal range.
The kidneys are
responsible for
regulating blood water
levels, re-absorption of
substances into the
blood, maintenance of
salt and ion levels in
the blood, regulation of
blood pH, and
excretion of urea and
other wastes.
When we talk about acid-base
balance, we are referring to the
pH balance (degree of acidity or
alkalinity) of substances of the
body. The symbol pH is used
after numbers that measure the
degree of the acidity or
alkalinity of solutions. The
acidity or the alkalinity of a
solution is determined by the
number of hydrogen ions (H + )
it contains.
The blood is slightly alkaline, with a pH of 7.35 to 7.4.
Any abnormality in the acid-base balance in the human
body may lead to acidosis, which means the blood pH
level is more acidic or a pH level less than 7.35. A second
condition that may arise is called alkalosis, which means
the pH level of the blood has too little acid or a pH level
greater than 7.45. The normal average for pH balanced
blood is 7.4. Either one of the acid-base imbalances may
result in serious organ disorders.
Symptoms of
acidosis are not
typically
differentiated from
diseases from
which the body
may be suffering.
However, it may
result in weakness,
nausea or
vomiting.
Symptoms of
alkalosis are more
noticeable and
include dizziness,
light-headedness or
a sense of numbing
in feet or hands.
Most people are not aware of the
symptoms of either of these
conditions; regular health checkups
are necessary to avoid the
complications associated with
irregular acid-base balance of blood
chemistry.