The large intestine, sometimes collectively referred to as the colon or large bowel, is the final sequence of segments in the gastrointestinal tract. After you swallow food, It takes the bolus about eight to nine hours to reach, in the form of chyme residue, the large intestine, where it is further broken down for excretion.
Read MoreThe Gastrointestinal System: The Large IntestineANATOMY & PHYSIOLOGY
The CrossFit stimulus—constantly varied high-intensity functional movement coupled with meat and vegetables, nuts and seeds, some fruit, little starch, and no sugar—prepares you for the demands of a healthy, functional, independent life and provides a hedge against chronic disease and incapacity. This stimulus is elegant in the mathematical sense of being marked by simplicity and efficacy. The proven elements of this broad, general, and inclusive fitness, in terms of both movement and nutrition, are what we term our CrossFit Essentials.
The digestive processes within the small intestines are affected by influences outside the anatomical boundaries of the alimentary canal itself. One such influence is the pancreas, which has both exocrine and endocrine roles in digestive and metabolic functions.
Read MoreThe Gastrointestinal System: The PancreasA great deal of enzymatic digestion occurs in the small intestine, the products of which are very small nutrient molecules, small enough to be absorbed through the intestinal wall and into the bloodstream. For carbohydrates this means monosaccharides (simple, single-unit sugars like glucose). For proteins this means individual amino acids. For lipids this means fatty acids.
Read MoreThe Gastrointestinal System: Small IntestineEver wonder what happens in the two to four hours after you take a bite of that apple? Lon Kilgore delves into the sophisticated mechanical and chemical processes that take place in the stomach during digestion.
Read MoreThe Gastrointestinal System: Stomach PeristalsisThe stomach receives ingested and masticated food and drink from the esophagus. This material is then subjected to further mechanical and chemical degradative processes. New contents of the stomach spend about two to four hours being digested before they pass out of the stomach and into the small intestines.
Read MoreThe Gastrointestinal System: Stomach StructureThe esophagus is a muscular tube composed of four layers: the mucosa, submucosa, muscularis, and adventitia. This 7- to 10-inch tube helps carry food and drink downstream to the stomach. Additionally, sphincters at either end of the esophagus keep air from entering the digestive tract and digestive acid from escaping the stomach.
Read MoreThe Gastrointestinal System: The EsophagusWe don't often think about what happens when we swallow because the process is mostly reflexive, but here's why the feat is an anatomical wonder worth pausing over.
Read MoreThe Gastrointestinal System: SwallowingThe tongue has roughly 10,000 taste buds, with receptor types specific to each of the five basic tastes regionally distributed. Taste buds also exist elsewhere. Chemoreceptors in the nose and sinuses help sommeliers, cicerones, and gourmands assess taste more fully. And although we associate taste with deriving pleasure from the foods we eat, it also has a more fundamental biological function: survival.
Read MoreThe Gastrointestinal System: Anatomy of TasteThe lips, mouth, and tongue are the gateway to the body’s gastrointestinal system. As soon as you put food or a drink into your mouth, you begin the process of deriving nutrition and energy from it.
Read MoreThe Gastrointestinal System: The Mouth and TongueUnderstanding the anatomy and physiology of the gastrointestinal system allows us to know how eating supports exercise adaptation. It also provides us with an essential critical skill: the ability to determine which dietary approaches may actually work and which are baseless marketing claims that ignore how the body actually functions.
Read MoreThe Gastrointestinal System: An IntroductionAsthma is a chronic inflammatory disease of the airway. During an asthma attack, the respiratory tract becomes narrowed. This may be a survival mechanism — a reduction in airflow to limit lung injury from harmful airborne materials — that has gone awry in some individuals. Lon Kilgore, Ph.D., explains what happens to the body’s respiratory system during an asthma attack and why coaches must become cognizant of how to safeguard athletes in the case of an episode.
Read MoreLung Anatomy and Physiology: AsthmaThrough breathing and gas exchange, our bodies manage to get oxygen into the blood and carbon dioxide out of the blood. How this is accomplished is conceptually simple but also exquisitely intricate and complex when considered in detail. Lon Kilgore, Ph.D., explains.
Read MoreThe Lungs: Gas ExchangeEver wonder what's going on in your body when your plan to complete a WOD unbroken comes crashing down mid-workout? Lon Kilgore, Ph.D., explains how lung volume and breathing frequency change as the body moves from rest to work.
Read MoreLung Physiology: BreathingThe lungs are less like balloons and more like giant warm marshmallows. They contain 1,000 miles of air-conducting tubes. The surface area of the tiny air sacs that make up the lungs is roughly the size of a tennis court. Here, Lon Kilgore, Ph.D., describes the anatomy of the lungs and explains how the respiratory system works to move oxygen from the atmosphere into the bloodstream.
Read MoreLung Anatomy: The Airway and AlveoliAs a key part of the respiratory system, the lungs help process a critical element of life and exercise: oxygen. The circulatory system then helps distribute oxygen throughout the body. To maintain this elegant system of supply and demand during sustained aerobic exercise, our ventilation rate increases by about 300 to 400%. If we push our exercise intensity, that rate can exceed baseline by more than 500%.
Read MoreAnatomy of the LungsWhat happens during a heart attack? How long is the window before permanent damage begins to occur in the heart’s tissues? Here, Lon Kilgore, Ph.D., describes the series of events that follow a complete or partial blockage. He also discusses innovative research into how high-intensity exercise might harness the body’s healing processes to create an infarction-resistant heart.
Read MoreThe Heart, Part 11: Myocardial Remodeling and SalvageHeart attack: Words no one wants to hear from a physician. Here's what happens when a person suffers a myocardial infarction.
Read MoreThe Heart, Part 10: Myocardial InfarctionBlood is made up of a solution of water and mineral ions and bioactive molecules called plasma. The solid portion of blood is made of cells, platelets, cell fragments, and very large molecules. The ratio of these two components, solid and liquid, is expressed as a percentage and is called the hematocrit. A higher hematocrit is associated with better endurance performance, but efforts to artificially elevate hematocrit can sometimes prove fatal.
Read MoreThe Heart, Part 9: BloodWhen we teach about the heart, we differentiate between the structures and functions of its right and left sides. The major functional difference is that the right side of the heart delivers blood to the lungs and the left side delivers blood to the rest of the body. The right side’s purpose is pulmonary circulation, and the left side is responsible for systemic circulation.
Read MoreThe Heart, Part 8: Pulmonary and Systemic CirculationCoronary circulation includes important arteries and veins that perfuse the heart. The blood inside the atria and ventricles does not directly support the heart muscle; the heart has to deliver and drain blood as it does for any other muscle.
Read MoreThe Heart, Part 7: Coronary Circulation