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Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.

Lipid Digestion

JoVE 10832

Lipids are large molecules that are generally not water-soluble. Since most of the digestive enzymes in the human body are water-based, there are specific steps the body must take to break down lipids and make them available for use.

Lingual lipase is an enzyme secreted by the acinar cells of the sublingual gland that aids lipid digestion. Although found in saliva, it plays only a minimal role in breaking down lipids in the mouth. Interestingly, lingual lipase has a pH optimum of 3.5-6.0 and is not activated until chewed food enters the acidic environment of the stomach. Gastric lipase is an acidic lipase that is secreted by the gastric chief cells in the lining of the stomach. Lingual lipase and gastric lipase comprise the two acidic lipases found in the human digestive system. These lipases are active in the stomach but rapidly inactivated by bile acids in the duodenum. Together, gastric lipase and lingual lipase account for 10-30% of lipid hydrolysis that occurs in human adults, with gastric lipase contributing the most. Given the low concentrations of pancreatic lipase and bile salts in the neonatal phase, the acidic lipases are critical for lipid digestion and account for 50% of lipid hydrolysis in neonates. Bile contains bile salts, lecithin, and cholesterol-derived substances, so it acts as an emulsifier in the duodenum of the small i

 Core: Biology

Cardiac Exam I: Inspection and Palpation

JoVE 10071

Source: Suneel Dhand, MD, Attending Physician, Internal Medicine, Beth Israel Deaconess Medical Center


The cardiac assessment is one of the core examinations performed by almost every physician whenever encountering a patient. Disorders of the cardiac system are among the most common reasons for hospital admission, with conditions ranging…

 Physical Examinations I

The Fluid Mosaic Model

JoVE 10698

The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function. The most abundant component of the fluid mosaic model is lipids. Lipids include both phospholipids and cholesterols. Phospholipids are amphipathic, having both hydrophobic and hydrophilic parts. They consist of a hydrophilic—water-loving—head, and two hydrophobic—water-fearing—fatty acid tails. Phospholipids spontaneously form a lipid bilayer that separates the inside of the cell from the outside. The lipid bilayer consists of the hydrophobic tails facing inward and the hydrophilic heads facing the aqueous environment inside and outside the cell. Cholesterols are a class of steroids that play a role in regulating membrane fluidity and flexibility. Membrane fluidity facilitates the transport of specific molecules and ions across the plasma membrane. The second major component of the mosaic is proteins. Proteins can differentially associate with the li

 Core: Biology

Preclinical Model of Hind Limb Ischemia in Diabetic Rabbits

1Department of Biomedical Engineering, University of Texas at Austin, 2Division of Cardiology, University of Texas McGovern Medical School, 3Center for Laboratory Animal Medicine and Care, UT Health Science Center at Houston, 4Memorial Herman Heart and Vascular Center, Texas Medical Center, 5Institute for Cellular and Molecular Biology, University of Texas at Austin, 6The Institute for Computational Engineering and Sciences, University of Texas at Austin, 7Institute for Biomaterials, Drug Delivery and Regenerative Medicine, University of Texas at Austin

JoVE 58964

 Medicine

Enrichment of Native Lipoprotein Particles with microRNA and Subsequent Determination of Their Absolute/Relative microRNA Content and Their Cellular Transfer Rate

1Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry and Pathobiochemistry, Medical University Vienna, 2School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria

JoVE 59573

 Biochemistry

A Familial Hypercholesterolemia Human Liver Chimeric Mouse Model Using Induced Pluripotent Stem Cell-derived Hepatocytes

1Department of Medicine, University of Hong Kong-Shenzhen Hospital, 2The Cardiology Division, Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, 3School of Biomedical Sciences, Institute of Vascular Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, 4Key Laboratory of Regenerative Biology of the Chinese Academy of Sciences, Joint School of Life Sciences, Guangzhou Institutes of Biomedicine and Health and Guangzhou Medical University, 5Laboratory of RNA, Chromatin, and Human Disease, CAS Key Laboratory of Regenerative Biology and Guangdong Provincial Key Laboratory of Stem Cells and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 6Research Centre of Heart, Brain, Hormone, and Healthy Ageing, Li Ka Shing Faculty of Medicine, University of Hong Kong, 7Hong Kong-Guangdong Stem Cell and Regenerative Medicine Research Centre, University of Hong Kong and Guangzhou Institutes of Biomedicine and Health

JoVE 57556

 Developmental Biology
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