Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

Diet and Exercise

Oddity of mammalian red blood cells

Mammalian red blood cells do not have a nucleus, which is different from birds, amphibians, reptiles, and fish (see image above). Many textbooks report that the absence of a nucleus provides room for more hemoglobin within the cells, which is important to fuel the relatively high metabolic rates of mammals. Hemoglobin is an important oxygen-binding molecule that allows the red blood cells to transport oxygen to tissues throughout the body […]

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Extreme Physiology of Diving

Can you imagine what would happen to your body if you dove up to 1700 meters deep in the ocean for an hour and a half, or experienced months of food deprivation? In the case of deep diving, the high pressure causes the collapse of the lungs of terrestrial mammals (including humans!) and depletion of body oxygen stores, whereas long fasting periods compromise health and induce muscle wasting. Northern elephant […]

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Day 1: Experimental Biology 2021

I attended a really great session this afternoon on the Evolutionary Physiology of Locomotor Behavior: Causes, Consequences, and Mechanisms.   The session started with a talk by Dr. David Raichlin from the University of Southern California who spoke about locomotion from a human perspective. He described how locomotion is not only essential for the survival of species, but also provides benefits for the aging brain. It was fascinating to learn […]

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Surviving the cold

The ability to regulate body temperature is critical for animals. This is especially true for small mammals as they have a larger surface area resulting in more heat loss to the environment than larger animals. Animals that stay active during the winter likewise have to spend more energy to stay warm. To do this well, they need to balance heat loss with heat generation through shivering as well as non-shivering […]

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Scientists discover gene that may protect from hypertension

Giraffes are extreme. Given their long necks, their blood pressure is 2.5 times higher than ours, which ensures that oxygenated blood makes it all the way up to their head. Having high blood pressure, however, is simply a normal characteristic of being a giraffe. A new study published in Science Advances explored the giraffe genome to identify genes that might help protect the cardiovascular system of giraffes by comparing their […]

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Anoxia tolerance in goldfish

The reason mammals are not very good at tolerating hypoxic (i.e. low oxygen) environments, is because the brain relies heavily on oxygen for metabolism. It is so stingy, it uses about 20% of the oxygen in the body to make ATP. Without oxygen, the brain has to rely on glycolysis to make ATP and this process is not good at meeting the energy requirements of the neurons, ultimately resulting in […]

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How exercise training and diet may impact exercise performance

Both diet and exercise training are associated with muscle performance and endurance. Migratory birds undergo intense endurance exercise. In fact, a recent review indicated that flapping flight costs more energy (9 x increase from basal metabolic rate) than required by elite athletes competing in the Tour de France (4.3 x increase from basal metabolic rate) (Butler, 2016). Unlike running animals, migratory birds fuel endurance exercise with fats as opposed to […]

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Take Time for Activity Snacks

There went another day spent sitting at my computer in virtual meetings with easily accessible snacks in the kitchen nearby. Okay, granted this is not a comparative physiology topic. But it is something many of us can relate to in this age of Covid-19. In a new study published in the Journal of Applied Physiology, researchers explored what happens when people seek out so-called “activity snacks” instead of the salty […]

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Extreme Fasting

While giant pandas roll in horse manure to stay warm in the winter (that’s a different story), other animals spend up to 8 months hibernating to conserve energy during times of reduced food availability and freezing temperatures. During their long winter’s nap, animals such as the Arctic ground squirrel and 13-lined ground squirrel go without food or water while at the same time avoiding muscle wasting – a rather impressive […]

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The evolution of sugar addiction

I have been opening Christmas cards and pondering the science of sugar addiction, admittedly while snacking on sugar cookies – ‘tis the season after all! Excess consumption of highly palatable (i.e. quite tasty) foods as well as sedentary lifestyles are thought to be at the root of the current obesity epidemic. In fact, it is thought that as many as 30% of people living in developed countries are either overweight […]

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