Fat in human body

Fats are energy dense (37 kJ or 9 kcal per gram), which is more than double the energy content of protein or carbohydrate (4 kcal per gram) and more than quadruple the energy content of fiber (2 kcal per gram).

Fats provide the medium for the absorption of fat-soluble vitamins, are a primary contributor to the palatability of food, and are crucial to proper development and survival during the early stages of life – embryonic development and early growth after birth – on through infancy and childhood.

The two types of fat in the body are: essential fat and nonessential fat, or storage fat. Essential fat is needed for normal physiological and biological functioning. Essential fat is that

in bone marrow, heart, lungs, liver, kidneys, intestines, muscles and lipid-rich tissue of the central

nervous system with roles other than energy storage. The level of essential fat is approximately 3% of total body weight for men and 12% of total body weight for women

Storage fat is located around internal organs (internal storage fat) and directly beneath the skin (subcutaneous storage fat).

Nonessential fat, known as storage fat, is located around internal organs (internal storage fat) and directly beneath the skin and referred as subcutaneous storage fat. Storage fat is also found surrounding internal organs in the abdominal

cavity and this fat is referred to as visceral fat.

Nonessential fat provides bodily protection and serves as an insulator to conserve body heat. Also as an energy substrate during rest and exercise.

A number of techniques are currently available to assess body fat content. Indirect methods include: body-mass-index (BMI), skinfold anthropometry, bioelectrical impedance, underwater weighing, and body water dilution.

Direct methods for body-fat measurements: CT and MRI to measure adipose tissue content and distribution.
Fat in human body

ATP, ADP and biological energy

ATP - Adenosine Triphosphate
ADP - Adenosine Diphosphate

ATP can be used to store energy for future reactions or be withdrawn to pay for reactions when energy is required by the cell. Animals store the energy obtained from the breakdown of food as ATP.

Adenosine triphosphate is composed of the nitrogenous base adenine, the five-carbon sugar ribose, and three phosphate groups. These three phosphate groups are linked to one another by two high-energy bonds called phosphoanhydride bonds. When one phosphate group is removed by breaking a phosphoanhydride bond in a process called hydrolysis, energy is released, and ATP is converted to adenosine diphosphate (ADP). The energy can be harnessed for cellular work.

When the cell has extra energy (gained from breaking down food that has been consumed or, in the case of plants, made via photosynthesis), it stores that energy by reattaching a free phosphate molecule to ADP, turning it back into ATP.

Energy is stored in the covalent bonds between phosphates, with the greatest amount of energy (approximately 7 kcal/mole) in the bond between the second and third phosphate groups. This covalent bond is known as a pyrophosphate bond.

The energy released from the hydrolysis of ATP into ADP is used to perform cellular work, usually by coupling the exergonic reaction of ATP hydrolysis with endergonic reactions.

Sodium-potassium pumps use the energy derived from exergonic ATP hydrolysis to pump sodium and potassium ions across the cell membrane while phosphorylation drives the endergonic reaction.
ATP, ADP and biological energy

ATP - Adenosine Triphosphate 

What is adenosine triphosphate?

The energy released from food during respiration is used to create molecules of a chemical called adenosine triphosphate or ATP. It is a nucleotide identical to the molecule found in RNA.

ATP is a temporary store of energy, which can be released whenever required for a wide variety of jobs, such as contraction of muscle or synthesis of complex chemicals, such as synthesis of amino acids, protein synthesis, and active transport systems

It is uniquely situated in the middle of the standard of the energy of hydrolysis for phosphate compounds.

Usually only the outer phosphate is removed from ATP to yield energy; when ATP is hydrolyzed, a molecule of adenosine diphosphate (ADP) and one of inorganic phosphate ion are formed and energy is liberated.

ATP is able to power cellular processes by transferring a phosphate group to another molecule (a process called phosphorylation).

This ADP is used to make more ATP and the process repeats itself over and over again.
What is adenosine triphosphate?

Anaerobic exercise

With anaerobic exercise, ATP is needed quickly to perform an activity. It is defined as a physical motion intense in power and strength, yet short in duration. Anaerobic activities do not depend on oxygen metabolism at all because the exercise intensity is high and the duration is less than 2 or 3 minutes.

Theoretically, anaerobic activity is the type of movement or exercise used in the ‘fight’ response. Anaerobic exercise (e.g. resistance training, sprint training) increases and help maintain lean body mass, which is the most metabolically active tissue in the body.

Anaerobic energy systems are of two major types. The immediate energy system is used for high-intensity activities that last less than 30 seconds, such as running the 100-meter dash or lifting heavy weights. Here, the muscles use ATP and creatine phosphate (CP) supplies at are already stored in the muscles, which last only 1 to 10 seconds.

The lactic acid system is a second source of energy for anaerobic activities. This system generates ATP for high-intensity activities lasting from 30 seconds to 3 minutes, such as the 400-meter or 800 meter run, which continues after the ATP-CP system for approximately 5 to 6 minutes.

Lactic acid has an incredibly fatiguing effect on muscle contraction. Because the full redistribution of blood takes 4 to 6 minutes, depending on the condition of the individual, initial oxygen supply is minimal at best.
Anaerobic exercise

Resting metabolic rate

There are three components to daily human expenditure:
*basal metabolic rate (BMR) or resting metabolic rate (RMR)
*The thermic effect of food
*Daily physical activity

Resting metabolic rate also known as resting energy expenditure is the energy that is required by the body to sustain basic life processes such as respiration, heartbeat, renal function and blood circulation.

It also includes the energy needed to remain in an awake state, because the measurements are usually made shortly after the person wakes.

Two third of an individual’s daily energy expenditure can be accounted for from the resting metabolic rate. Resting metabolic rate can be measured by direct calorimetry or indirect calorimetry. Direct calorimetry measures the amount of heat lost by the body through radiative, convective and evaporative mechanisms.

Indirect calorimetry can be measured through total collection systems, open circuit systems, confinement systems or close circuit systems.

Resting metabolic rate is measured when the person is at rest in a comfortable environment. The fasting is only for 2 to 4 hours.

Factors that can influence a person’s resting metabolic rate:
*Ingesting food, especially a meal mixed with carbohydrates, fats and protein raises resting metabolic rate by approximately 5-10%

*Resting metabolic rate is a subject to changes in hormonal concentration. Two major hormones linked are epinephrine and thyroid hormone.

*The amount of lean body mass

*Body size and shape affect resting metabolic rate with stout and heavier individuals having lower rates than those that are tall and thin with the same body weight.

*Age. It has been reported that the resting metabolic rate per kilogram body weight in young children may be two times greater than in adults.

*Gender

*Climate changes, especially temperature changes can also raise resting metabolic expenditure.
Resting metabolic rate

Cycling for your muscles

Riding a bike is great for toning and building the muscles, especially in the lower half of the body –calves, thighs, and the rear end.

The average bicyclist burns at least 400 calories an hour and requires calories just to keep pedaling.

The exercise of cycling supplies blood and nutrients to the muscles, discs and ligaments of the back. But, as with all exercise, it must be performed properly and in moderation.

Flexibility is important for cyclists because flexible muscles and connective tissue facilitates the ability to generate and transmit power to the pedals while maintaining an aerodynamic position on the bike.

Although the muscle of the back may not be directly involved in pedaling, they help stabilize human body on the bike and increase the energy transfer from the hip and leg muscles to the pedals.

Bicycling strengthens the hearts, helps reduce blood pressure, increases lung efficiency and keeps cyclist energy level up all day.

In cycling, as in any other athletic endeavor, the athlete’s body must have a strong, solid base.

To obtain peak performance, all human systems must be operating in concert and as a single coordinated unit.
Cycling for your muscles

What is Basal Metabolic Rate?

Basal metabolite rate or BMR is the rate at which the body expends energy for these life-sustaining activities.

It is the rate in which the energy uses for metabolism under specified conditions. It is usually expressed as kcalories per kilogram body weight per hour.

The basal metabolic rate of most people requires more energy than their voluntary muscular activity. Much of this energy is used to keep the body temperature constant.

The rate may vary from person to person and may vary for the same individual with a change in circumstances or physical condition.

Several factors affect an individual’s basal metabolic rate, including age, gender, height and weight.

The more a person weighs, the more total energy is expended in basal metabolism, but the amount of energy per pound of body weight may be lower.

Gender correlates roughly with body composition. Men generally have a faster metabolic rate than women, and researchers believe that this is because of men’s greater percentage of lean tissue.
What is Basal Metabolic Rate?