It’s not exactly a secret that many humans derive pleasure from massages, and previous research has shown other primates enjoy it as well. And now, we’ve found the first non-primate to use massages to relieve stress: the surgeonfish.

Surgeonfish are one of a number of fish species that enlist tiny cleaner wrasse fish to clean it, scraping off dead skin and potential parasites. Previous observations have also suggested that the wrasse rubbing on the pelvic and pectoral fins of the surgeonfish might serve to calm it down, in much the same way a masseur can relieve stress in a human.

To put this idea to the test, Marta Soares of Portugal’s ISPA University Institute ran an experiment featuring two groups of eight surgeonfish. The fish were first exposed to all the stresses they would naturally experience in the wild, which included everything from predators to competition over food. They were then place in tanks that had models of cleaner wrasse. One set of models stayed completely stationary, while the other could move back and forth, which would allow them to simulate rubbing on the surgeonfish’s fins.

While all the surgeonfish tried to get some use out of these fake cleaner fish, only those in the tanks with the moving models had any success. By positioning themselves below the model’s “fins”, the surgeonfish could get their equivalent of a backrub. It wasn’t cleaning them, but it apparently still had an effect – these fish had significantly lower levels of the stress hormone cortisol than the fish in the tanks with stationary models. It seems this fishy back rub relaxed the surgeonfish just as a human massage might.

San Diego State researcher Todd Anderson comments on the research:

“Normally I would think that physical contact would elevate stress in fish, as it should, for example, in prey experiencing attempted capture by a predator. However, the contact [in this study] is initiated by the client fish for an often beneficial relationship [that includes] removing parasites.”

For her part, Soares says that this apparent pleasure and stress relief indicates a previously unconsidered benefit for the surgeonfish in their relationship with the cleaner wrasse. It also might well mean that fish experience tactile sensations in a way that’s far more similar to humans than previously thought.

Does fish enjoy a good massage as much as humans ? is a post from: getanswer

Heart

Your heart is an incredibly powerful organ. It works constantly without ever pausing to rest. It is made of cardiac muscle, which only exists in the heart. Unlike other types of muscle, cardiac muscle never gets tired.

Four chambers

Your heart is divided into four hollow chambers. The upper two chambers are called atria. They are joined to two lower chambers called ventricles. These are the pumps of your heart.

One-way valves between the chambers keep blood flowing through your heart in the right direction. As blood flows through a valve from one chamber into another the valve closes, preventing blood flowing backwards. As the valves snap shut, they make a thumping, ‘heart beat’ noise.

Double pump

Blood carries oxygen and many other substances around your body. Oxygen from your blood reacts with sugar in your cells to make energy. The waste product of this process, carbon dioxide, is carried away from your cells in your blood.

Your heart is a single organ, but it acts as a double pump. The first pump carries oxygen-poor blood to your lungs, where it unloads carbon dioxide and picks up oxygen. It then delivers oxygen-rich blood back to your heart. The second pump delivers oxygen-rich blood to every part of your body. Blood needing more oxygen is sent back to the heart to begin the cycle again. In one day your heart transports all your blood around your body about 1000 times.

Your right ventricle pumps blood to your lungs and your left ventricle pumps blood all around your body. The muscular walls of the left ventricle are thicker than those of the right ventricle, making it a much more powerful pump. For this reason, it is easiest to feel your heart beating on the left side of your chest.

Pacemaker

Unlike skeletal muscle cells that need to be stimulated by nerve impulses to contract, cardiac muscle cells can contract all by themselves. However, if left to their own devices, cardiac muscle cells in different areas of your heart would beat at different rates. Muscle cells in your ventricles would beat more slowly than those in your atria. Without some kind of unifying function, your heart would be an inefficient, uncoordinated pump. So, your heart has a tiny group of cells known as the sinoatrial node that is responsible for coordinating heart beat rate across your heart. It starts each heartbeat and sets the heartbeat pace for the whole heart.

Damage to the sinoatrial node can result in a slower heart rate. When this is a problem, an operation is often performed to install an artificial pacemaker, which takes over the role of the sinoatrial node.

Heart rate

Without nervous system control, your heart would beat around 100 times per minute. However, when you are relaxed, your parasympathetic nervous system sets a resting heart beat rate of about 70 beats per minute, (resting heart rate is usually between 72-80 beats per minute in women and 64-72 beats per minute in men).

When you exercise or feel anxious your heart beats more quickly, increasing the flow of oxygenated blood to your muscles. This is triggered by your sympathetic nervous system. Your heart rate also increases in response to hormones like adrenalin.

On average, your maximum heart rate is 220 beats per minute minus your age. So a 40 year old would have a maximum heart rate of 180 beats per minute.

Oxygen supply to your heart

Although your heart is continually filled with blood, this blood doesn’t provide your heart with oxygen. The blood supply that provides oxygen and nutrients to your heart is provided by blood vessels that wrap around the outside of your heart.

What is Heart and How does it work ? is a post from: getanswer

The secret to ‘mega-dinosaurs’  impressive sizes may be that the reptiles used more of their energy for growing and less for keeping their bodies warm compared with some creatures.

A new model could help explain how some dinosaurs, such as long-necked sauropods, could have achieved masses of around 60 tons — about eight times the mass of an African elephant, the largest land animal alive today.

The two main factors that determine vertebrate size are the amount of available food and how the creature expends its energy, said researcher Brian K. McNab, a paleontologist at the University of Florida. For example, elephants can be quite large because they feed off grasses, a relatively abundant food supply as opposed to say, the nectar that hummingbirds and bees consume, McNab said.

Energy expenditure depends in part on how an organism controls its body temperature. Mammals and birds, which are warm-blooded, must expend energy to keep their internal body temperatures constant, and so they have a high metabolic rate. But cold-blooded creatures such as reptiles rely on their environment for body heat, and their internal temperature fluctuates depending on the surrounding conditions.

Warm-blooded animals must eat a lot more than cold-blooded animals to produce their own body heat.

Whether dinosaurs were warm-blooded or cold-blooded has been a hotly debate issue among paleontologists. McNab attempted to answer this question by looking at what food resources were available to dinosaurs, and included this factor in his model that describes how vertebrate size, energy expenditure and food resources tie together.

If resources were much more abundant in the Mesozoic Era — the time period when the dinosaurs lived — than today, it may have been possible for dinosaurs to be warm-blooded, even though they would need to eat a lot to maintain their body temperature. Indeed, blue whales, the largest creatures thought to have ever lived on Earth, are warm-blooded. They fuel their 160-ton bodies by feeding off of the plentiful resources in marine environments.

What were some dinosaurs so huge? is a post from: getanswer

Our Earth feels like all there is, but we know that it’s just a tiny planet in a vast Solar System. And our Solar System is just one member of a vast Milky Way galaxy. But how many galaxies are there in the entire Universe?

Astronomers think that there are hundreds of billions galaxies in the universe, however the exact number is not known. But astronomers should know how many galaxies we’ve actually seen and discovered, right? Well, not necessarily. “We don’t know,” says Ed Churchwell, professor of astronomy at the University of Wisconsin-Madison. “We know it’s a very large number.” In just one image for example, the Hubble Ultra Deep Field, above, there are about 10,000 galaxies visible.

In our own galaxy, There are between 100-300 billion stars in the MilkyWay. At most, 8,479 of them are visible from Earth. Roughly 2,500 stars are available to the unaided eye in ideal conditions from a single spot at a given time.

But the number of galaxies will keep growing as our telescopes get better and can look out and back farther in time.

“To count them all, you have to be able to look far enough back in time or deep enough inspace to see when galaxies were formed,” Churchwell says. “We haven’t reached that point yet. It’s not a well-determined number, but at some point we’re going to reach it.”

Most of the galaxies in the Universe are probably tiny dwarf galaxies. For example, in our Local Group of galaxies there are only 3 large spiral galaxies: the Milky Way, Andromeda, and the Triangulum Galaxy. The rest are dwarf and irregular galaxies.

The estimate of how many galaxies there are in the universe is done by counting how many galaxies we can see in a small area of the sky. This number is then used to guess how many galaxies there are in the entire sky.

For the time being, the hundreds of billions in the tally are extrapolated from the Hubble Ultra Deep Field, taken over a time period in 2003 and 2004. Pointed at a single piece of space for several months — a spot covering less than one-tenth of one-millionth of the sky — Hubble returned an image of galaxies 13 billion light years away.

How many Galaxies are there in the Universe? is a post from: getanswer

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