What Does the Term Metabolism Mean?
Each and every second of every day our cells are engaged in the oper-
ations that help keep them alive and well. At the same time the efforts
of each cell also contribute to the proper functioning of our body as a
whole. To do so each cell must perform an incredible number of chemical
reactions every second. The term metabolism refers to those chemical
reactions collectively.
The term metabolism is somewhat general. For instance, total body
metabolism refers to all the energy released from all the chemical reac-
tions and associated processes in our body. Said differently, total body metabolism is the total of all reactions taking place in each cell added
together. However, if we wanted to describe just those chemical reactions
within a specific tissue, such as muscle or bone, we would say "muscle
metabolism" or "bone metabolism." We can be even more focused and
use the term metabolism to describe only those reactions associated with
a single nutrient or nutrient class. For example, if we were discussing the
chemical reactions that involve only proteins or carbohydrates, we would
be discussing protein or carbohydrate metabolism, respectively.
In general, chemical reactions and/or pathways will release energy.
Ultimately, this extra energy will be converted to heat. Since body tem-
perature remains fairly constant, the heat produced in metabolism must
be removed from our body. Therefore, our total body metabolism can be
estimated by measuring how much heat is lost from our body.
Table Primary Functions of the Major Tissue and Organs in Our Body
Bone Provides structure and the basis of movement of limbs and
our entire body. Also serves as a mineral storage. Primarily
composed of minerals and protein and smaller amount of
cells, nerves and blood vessels.
Skeletal muscle We have three kinds of muscle (skeletal, cardiac (heart) and
smooth), which is largely water and protein and to a lesser
degree carbohydrate and fat. Contraction of muscle results in
movement of some type. Skeletal muscle is connected to bone
and provides movement of our limbs and body.
Heart and blood Our heart is mostly muscle (cardiac). Contraction of cardiac
muscle establishes the blood pressure in our heart, which
drives blood through our blood vessels. We have about
100,000 miles of blood vessels and our blood is, for the most
part, a delivery medium!
Smooth muscle Smooth muscle lines tubes in our body such as airways, blood
vessels, digestive tract, reproductive tract, etc.) Smooth
muscle is responsible for regulating the flow of content (gases,
fluids, semi-solids) through those tubes.
Lungs Serves as the site of oxygen and carbon dioxide exchange
between our body and the air around us.
Liver Perhaps the "hub" of nutrition. Our liver is involved in
maintain blood glucose, regulating blood lipid levels,
processing amino acids, making plasma proteins (e.g., clotting
factors, transport proteins), and bile and metabolizing and
storing many vitamins, minerals, and other nutrients.
Kidneys Regulate the composition of our body fluid. They do this by
filtering and regulating the composition of our blood, which
in turn regulates the composition of the fluid in-between our
cells and inside of our cells.
Adrenal glands Our adrenals are steroid hormone producing factories. They
produce cortisol (stress hormone), aldosterone, a lot of
DHEA and lesser amount of androstenedione, testosterone,
and estrogens.
Thyroid gland Produces the hormones thyroid hormone and calcitonin.
Thyroid hormone is one of the most influential hormones in
regulating our energy expenditure.
Brain and spinal Our brain is an information processing center and the spinal
cord cord is the conduit for signals to leave (or be carried to) our
brain to the rest of our body. Our brain initiates and regulates
muscle activity, processes sensory information and controls
body temperature and appetite.
Skin Site of heat removal and protective coating. Some vitamin D is
produced in our skin.
Pancreas Produces the hormones insulin and glucagon and digestive
enzymes.
Pituitary gland Produces a slew of hormones including thyroid stimulating
hormone (TSH) and adrenocorticotrophic hormone (ACTH).
Wednesday, June 9, 2010
Tuesday, June 8, 2010
Maintain an Optimal Working Environment?
Do Individual Cells and Our Body as a Whole Attempt to
Maintain an Optimal Working Environment?
Just as you clean your apartment or house and determine what kind of
stuff is found within your living area, so too will our cells clean and
regulate the contents in their intracellular fluid. This allows each cell to
maintain an optimal operating environment. Scientists often use the term
homeostasis to describe the efforts associated with the maintenance of
this optimal environment. Furthermore, just as it is the responsibility of
each cell to maintain its own ideal internal environment; at the same
time many of our organs work in concert to regulate the environment
within our body as a whole. These organs include the kidneys, lungs,
skin, and liver. Many of our most basic functions, such as breathing,
sweating, urinating, digesting, and the pumping of our heart, are actu-
ally functions dedicated to homeostasis . Therefore, homeo-
stasis is the housekeeping efforts of all our cells working individually as
well as together to provide an environment conducive to optimal function.
Maintain an Optimal Working Environment?
Just as you clean your apartment or house and determine what kind of
stuff is found within your living area, so too will our cells clean and
regulate the contents in their intracellular fluid. This allows each cell to
maintain an optimal operating environment. Scientists often use the term
homeostasis to describe the efforts associated with the maintenance of
this optimal environment. Furthermore, just as it is the responsibility of
each cell to maintain its own ideal internal environment; at the same
time many of our organs work in concert to regulate the environment
within our body as a whole. These organs include the kidneys, lungs,
skin, and liver. Many of our most basic functions, such as breathing,
sweating, urinating, digesting, and the pumping of our heart, are actu-
ally functions dedicated to homeostasis . Therefore, homeo-
stasis is the housekeeping efforts of all our cells working individually as
well as together to provide an environment conducive to optimal function.
Sunday, June 6, 2010
How Do We Measure Acidity or Alkalinity?
How Do We Measure Acidity or Alkalinity?
Acidity and alkalinity indicates the level of hydrogen ions in a water-
based fluid and we use the pH scale to assess a fluid. The pH scale ranges
from 0 to 14, with 0 being the most acidic and 14 being the most basic as
shown in Figure 1.9. Thus, a pH of 7 is said to be neutral because it splits
the two extremes. A pH lower that 7 means a higher hydrogen ion con-
centration and thus greater acidity. On the other hand, an alkaline solu-
tion has a pH greater than 7 and has a lower level of hydrogen ions.
The pH scale was conceived by Sören Sörensen who was a pretty good
biochemist and an excellent brewer of beer! Back in the days before
sophisticated pH meters, one could speculate as to whether a fluid was
acidic or basic based on taste. Acidic substances tend to have a sour taste
(lemon juice, orange juice), while more alkaline substances taste bitter.
So what is the big deal about pH? Our body has but a narrow pH range
at which it can function appropriately. As noted on the scale in Figure 1.9,
the pH of our blood is about 7.4. This means that the pH of our body is
slightly basic. If the pH falls below or above 7.4 these conditions are
referred to as acidosis and alkalosis, respectively. Nearly all chemical
reactions in our body are controlled by enzymes, most of which function
in our best interest at a pH around 7.4. Thus, when our pH falls or climbs,
the efficiency of many enzymes is significantly affected. Some enzymes
will work harder and others will work less hard, thus impacting key
chemical reactions in our body. This can compromise normal function
and possibly our vitality.
Inherent to our body are systems that help us maintain the pH of our
body fluid (for example, blood) around 7.4. These systems are called
buffering systems and they act either to soak up excessive hydrogen ions
or to release them when our body pH begins to change. Thus pH can be
maintained at the 7.4 ideal despite changing internal factors.
Acidity and alkalinity indicates the level of hydrogen ions in a water-
based fluid and we use the pH scale to assess a fluid. The pH scale ranges
from 0 to 14, with 0 being the most acidic and 14 being the most basic as
shown in Figure 1.9. Thus, a pH of 7 is said to be neutral because it splits
the two extremes. A pH lower that 7 means a higher hydrogen ion con-
centration and thus greater acidity. On the other hand, an alkaline solu-
tion has a pH greater than 7 and has a lower level of hydrogen ions.
The pH scale was conceived by Sören Sörensen who was a pretty good
biochemist and an excellent brewer of beer! Back in the days before
sophisticated pH meters, one could speculate as to whether a fluid was
acidic or basic based on taste. Acidic substances tend to have a sour taste
(lemon juice, orange juice), while more alkaline substances taste bitter.
So what is the big deal about pH? Our body has but a narrow pH range
at which it can function appropriately. As noted on the scale in Figure 1.9,
the pH of our blood is about 7.4. This means that the pH of our body is
slightly basic. If the pH falls below or above 7.4 these conditions are
referred to as acidosis and alkalosis, respectively. Nearly all chemical
reactions in our body are controlled by enzymes, most of which function
in our best interest at a pH around 7.4. Thus, when our pH falls or climbs,
the efficiency of many enzymes is significantly affected. Some enzymes
will work harder and others will work less hard, thus impacting key
chemical reactions in our body. This can compromise normal function
and possibly our vitality.
Inherent to our body are systems that help us maintain the pH of our
body fluid (for example, blood) around 7.4. These systems are called
buffering systems and they act either to soak up excessive hydrogen ions
or to release them when our body pH begins to change. Thus pH can be
maintained at the 7.4 ideal despite changing internal factors.
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