1.During her weightlifting workout, her muscles generate energy (ATP) primarily through a process called aerobic respiration, where oxygen is used to break down glucose into ATP molecules, providing the necessary energy for muscle contraction. Additionally, muscles could use stored energy in the form of creatine phosphate (CP). Another way that uses energy stored within carbohydrates from the blood or from muscle cell reserves to generate ATP. 

2.During her workout, her nervous system sends signals to her muscle cells through neurons, triggering action potentials that result in muscle contraction. The frequency and intensity of these signals are adjusted by her nervous system to match the demands of the exercise.

However, this contraction isn't usually strong enough to fully shorten the muscle cell and it's more like a partial contraction.

To fully shorten the muscle cell and keep it contracted, it needs to receive multiple signals, one after the other, from the neuron. The more signals it gets in a row, the more the muscle cell shortens, and the longer it stays contracted.

When she workout, the pulling of actin by myosin provides force in her muscle, therefore adding more actin and myosin will get more force. That will also make your muscles thicker and appear more muscle when she continues lifting heavier weights.

   I would explained my friend that during weight lifting, muscle contraction requires energy, and when ATP is broken down

oxygen need to breakdown produce energy in the form ATP (adenosine triphosphate) to contract and perform work. 

 When the muscle cell is at rest, it uses some of its ATP to add a phosphate group to creatine, forming CP. When ATP levels drop during intense exercise, CP steps in. It’s rapidly broken down to generate more ATP, providing a burst of energy for about 8–10 seconds. Motor neurons transmit electrical signals from the brain , spinal cord to the muscle. When lifting weights, the nervous system coordinates the firing of motor neurons, which stimulate muscle fibers to contract.The frequency and intensity of these signals determine the force and duration of muscle contractions.Consistent work out perform training, muscle fibers increase in size due to increased protein synthesis and the addition of contractile proteins actin and myosin. Aerobic exercise promotes mitochondrial growth within muscle cells. More mitochondria mean better ATP production through aerobic respiration.

four forms of energy important in human functioning

 four forms of energy important in human functioning

Decompression sickness (DCS)

 Decompression sickness (DCS) is a condition in which gases dissolved in the blood or in other body tissues are no longer dissolved following a reduction in pressure on the body. This condition affects underwater divers who surface from a deep dive too quickly, and it can affect pilots flying at high altitudes in planes with unpressurized cabins. Divers often call this condition “the bends,” a reference to joint pain that is a symptom of DCS.

 In all cases, DCS is brought about by a reduction in barometric pressure. At high altitude, barometric pressure is much less than on Earth’s surface because pressure is produced by the weight of the column of air above the body pressing down on the body. The very great pressures on divers in deep water are likewise from the weight of a column of water pressing down on the body. For divers, DCS occurs at normal barometric pressure (at sea level), but it is brought on by the relatively rapid decrease of pressure as divers rise from the high pressure conditions of deep water to the now low, by comparison, pressure at sea level. Not surprisingly, diving in deep mountain lakes, where barometric pressure at the surface of the lake is less than that at sea level is more likely to result in DCS than diving in water at sea level.

 

 n DCS, gases dissolved in the blood (primarily nitrogen) come rapidly out of solution, forming bubbles in the blood and in other body tissues. This occurs because when pressure of a gas over a liquid is decreased, the amount of gas that can remain dissolved in the liquid also is decreased. It is air pressure that keeps your normal blood gases dissolved in the blood. When pressure is reduced, less gas remains dissolved. You have seen this in effect when you open a carbonated drink.

 Removing the seal of the bottle reduces the pressure of the gas over the liquid. This in turn causes bubbles as dissolved gases (in this case, carbon dioxide) come out of solution in the liquid.

The most common symptoms of DCS are pain in the joints, with headache and disturbances of vision occurring in 10 percent to 15 percent of cases. Left untreated, very severe DCS can result in death. Immediate treatment is with pure oxygen. The affected person is then moved into a hyperbaric chamber. A hyperbaric chamber is a reinforced, closed chamber that is pressurized to greater than atmospheric pressure. It treats DCS by repressurizing the body so that pressure can then be removed much more gradually. Because the hyperbaric chamber introduces oxygen to the body at high pressure, it increases the concentration of oxygen in the blood. This has the effect of replacing some of the nitrogen in the blood with oxygen, which is easier to tolerate out of solution.

The dynamic pressure of body fluids is also important to human survival. For example, blood pressure, which is the pressure exerted by blood as it flows within blood vessels, must be great enough to enable blood to reach all body tissues, and yet low enough to ensure that the delicate blood vessels can withstand the friction and force of the pulsating flow of pressurized blood.

 

 definitive of human life: organization, metabolism, responsiveness, movement, development, and reproduction.

Every cell in your body makes use of a chemical compound, adenosine triphosphate (ATP), to store and release energy.

 The cell stores energy in the synthesis (anabolism) of ATP, then moves the ATP molecules to the location where energy is needed to fuel cellular activities.

Then the ATP is broken down (catabolism) and a controlled amount of energy is released, which is used by the cell to perform a particular job.

Metabolic processes 

anabolic reactions- involve bulding require energy to proceed 

catabolic reaction- breakdown suger to release energy

ATP adenosene tri phosphate contain phosphate ion is release 

ADP cellular repiration