Life Lines by Dr. Dolittle

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Tag Archive for ‘American Journal of Physiology’

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Migratory birds create their own water to prevent dehydration

Migratory birds are amazingly adapted for long-distance flights and can switch the fuels they rely on to support their endurance activities. Unlike humans that burn mainly carbohydrates for endurance exercise, avian flight is fueled mainly by fats and some proteins. In a recent study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology researchers examined how white-throated sparrows (Zonotrichia albicollis) prepared for migration. By altering the […]

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One reason why fish and mammals lose their appetite during stress

I don’t know about you, but sometimes I lose my appetite when I am really stressed. The endocrine system is responsible for controlling our stress responses and involves three main endocrine glands – the hypothalamus, pituitary, and adrenal gland. Hence, the stress pathway is often referred to as the “HPA axis”. When we are stressed, the hypothalamus releases a hormone called corticotropin releasing factor (CRF), which triggers the release of […]

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Heat may activate muscle growth and prevent atrophy

Skeletal muscle is not only important for our ability to move, it also plays a major role in metabolism. Under normal conditions, the routine processes of muscle growth (hypertrophy) and breakdown (atrophy) are in balance. While many of us are aware that exercise and healthy diets promote muscle growth, diseases and sedentary lifestyles can promote muscle atrophy. Studies examining the effects of heat on muscle – from environmental heat, direct […]

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Chronic stress during pregnancy increases risk of stillbirth and preterm delivery

At the end of pregnancy, levels of the hormone oxytocin increase to stimulate parturition, or childbirth. The stress hormone cortisol is also important for normal fetal development and, like oxytocin, cortisol increases at the end of pregnancy. This may help explain why chronic stress during pregnancy increases the risk of complications such as stillbirth.   A new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative […]

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Understanding genetic factors contributing to COPD

According to a study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, we have a lot in common with fruit flies when it comes to the layer of cells that line our airways. So much so, that researchers claim Drosophila melanogaster are important models for lung diseases such as chronic obstructive pulmonary disease (COPD). COPD is a debilitating disease that claimed the lives of over […]

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Surviving environmental challenges

Red tides happen when dinoflagellate algae populations increase and turn the water a shade of red due their red pigments. These algae consume oxygen in the water and release carbon dioxide and other acidic products that make the surrounding water acidic and hypoxic. These events are becoming more common with climate change. In fact, the most recent event off the coast of Sothern California occurred in 2020 and resulted in […]

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Combating kidney stones

If you have ever had a pet with kidney stones, you know that diet can be a major contributing factor to their formation. This is why veterinarians often recommend providing animals with foods higher in water content and switching to a diet that promotes a healthy urine pH (not too basic, not too acidic).   Did you know that bottlenose dolphins can develop kidney stones too? The particular kind of […]

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Tenrecs may shed light on the evolution of body temperature regulation

The common tenrec (Tenrec ecaudatus) just may be a living representative of ancestral placental mammals and they are very interesting when it comes to body temperature regulation and torpor. Torpor is a complex series of physiological changes that reduce an animal’s physical activity as well as heart, breathing and metabolic rates, which also results in decreases in body temperature than can be as low as their surrounding environment. Many mammalian […]

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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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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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