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Waste Products: Debris resulting from a process that is of no further use to the system producing it. The concept includes materials discharged from or stored in a system in inert form as a by-product of vital activities. (From Webster's New Collegiate Dictionary, 1981)

Physiology of the Circulatory System- Concept

JoVE 10625

Homeostasis

Conditions in the external environment of an organism can change rapidly and drastically. To survive, organisms must maintain a fairly constant internal environment, which involves continuous regulation of temperature, pH, and other factors. This balanced state is known as homeostasis, which describes the processes by which organisms maintain their optimal internal…

 Lab Bio

First Law of Thermodynamics

JoVE 10726

The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed. This can be demonstrated within a classic food web where light energy from the sun is harnessed as radiant energy by plants, converted into chemical energy, and stored as complex carbohydrates. The vegetation is then consumed by animals and during the digestion process, the sugars release energy as heat. The sugars also produce chemical energy that either gets used up doing work, stored in macromolecules like glycogen and fatty acids or are consumed by a predator. The waste products and dead organic matter from animals are then decomposed by bacteria and fungi and returned to the soil to provide food for plants to grow and the cycle continues. During the process of photosynthesis, the photons are used to make complex carbohydrates that the plants use to live and grow, and oxygen is released into the atmosphere. The plants eventually become food for animals—herbivores—and during the digestion process, the sugars are broken down and energy is released—either as heat or to provide chemical energy from glucose, to drive cellular processes that allow the animal to survive and reproduce. It can also be stored in macromolecules as chemical energy. For example, glycogen can be stored in the liver or muscles and can be quickly accessed in tim

 Core: Metabolism

The Nitrogen Cycle

JoVE 10934

Nitrogen atoms, present in all proteins and DNA, are recycled between abiotic and biotic components of the ecosystem. However, the primary form of nitrogen on Earth is nitrogen gas, which cannot be used by most animals and plants. Thus, nitrogen gas must first be converted into a usable form by nitrogen-fixing bacteria before it can be cycled through other living organisms. The use of nitrogen-containing fertilizers and animal waste products in human agriculture has greatly influenced the natural nitrogen cycle. About 78% of the air we breathe is nitrogen gas. However, in this form, N2, few organisms are able to use it. Nitrogen makes up essential molecules in all organisms, like proteins and DNA. Unable to use the atmospheric form of nitrogen, most organisms use the byproducts of nitrogen-fixing and nitrifying prokaryotes. Nitrogen fixation converts nitrogen gas (N2) into ammonia (NH3), whereas nitrification converts NH3 into nitrites (NO2-) and nitrates (NO3-). Plants can directly use the ammonia and nitrates, and plant-eating organisms obtain nitrogen by ingesting plants. When these organisms die, bacteria in the soil are able to convert the organic nitrogen into ammonia in a process called ammonification. Through denitrification, aerobic bacteria can then convert a

 Core: Ecosystems

Filtration

JoVE 10891

The function of the kidneys is to filter, reabsorb, secrete, and excrete. Every day the kidneys filter nearly 180 liters of blood, initially removing water and solutes but ultimately returning nearly all filtrates into circulation with the help of osmoregulatory hormones. This process removes wastes and toxins but is also crucial to maintain water and electrolyte levels. Most of these functions are performed by the tiny but numerous nephrons contained within the kidneys. Blood enters the renal corpuscle of the nephron through a glomerulus of capillaries. The capillaries are surrounded by a structure called the Bowman’s capsule which absorbs water and most solutes from the blood. The blood pressure from capillaries pushes these into the capsules. If the blood pressure is too high, as seen in hypertension, the capillaries can weaken and harden, reducing the ability of the kidney to filter the blood. The filtrate from the corpuscles empty into the proximal convoluted tubules and the descending portions of the Loop of Henle. Here nearly 70% of solutes—salt, glucose, amino acids, and bicarbonates—are reabsorbed into the surrounding capillaries. Circulating blood hormones involved in osmoregulation induce reabsorption of sodium, calcium, or more water if needed to increase or decrease blood pressure and regulate electrolytes. Sec

 Core: Regulation and Excretion

What is Metabolism?

JoVE 10725

Metabolism represents all of the chemical activity in a cell, including reactions that build molecules (anabolism) and those that break molecules down (catabolism). Anabolic reactions require energy, whereas catabolic reactions provide it. Thus, metabolism describes how cells transform energy through a variety of chemical reactions, which are often made more efficient with the help of enzymes. Metabolism is the management of energy in cells and provides three key functions: converting food into energy to run various cellular processes, producing energy to build cell components, and removing waste products. To produce energy, macromolecules from food must be broken down into smaller molecules—through a catabolic pathway. This, in turn, provides energy to construct larger molecules from smaller building blocks—through an anabolic pathway. In other words, the potential energy in food—comprised of the chemical energy stored in the bonds between atoms—can be converted into kinetic energy that can be used for cellular reactions. Enzymes are essential molecular tools in metabolic pathways, as they greatly speed up many chemical reactions by reducing the amount of required energy. Catabolism is the breakdown of macromolecules for any purpose. This inc

 Core: Metabolism

Osmoregulation in Insects

JoVE 10990

Malpighian tubules are specialized structures found in the digestive systems of many arthropods, including most insects, which handle excretion and osmoregulation. The tubules are typically arranged in pairs and have a convoluted structure that increases their surface area.

Malpighian tubules extend from the digestive tract, typically the area between the midgut and hindgut, into the hemolymph—a mixture of blood and interstitial fluid found in insects and other arthropods, as well as most mollusks. Unlike other excretory systems, the excretory processes of Malpighian tubules lack a filtration step. Metabolic wastes, like uric acid, diffuse into the tubules from the hemolymph. The tubules are lined with a layer of transport epithelia. These specialized epithelial cells contain pumps that actively transport ions, like sodium (Na+) and potassium (K+), from the hemolymph into the interior of the tubule, called the lumen. Osmosis allows water to follow ions into the tubules passively. From the tubule lumen, water, ions, and waste travel from the intestine to the rectum. Tiny, protruding microvilli lining the inside of the tubules help maximize solute-water coupling and the propulsion of uric acid crystals through the tubules. In the rectum, specialized glands pump many of the ions back into the hemolymph. Osmosis

 Core: Regulation and Excretion

Dietary Connections

JoVE 10746

Metabolic pathways are interconnected. The cellular respiration processes that convert glucose to ATP—such as glycolysis, pyruvate oxidation, and the citric acid cycle—tie into those that break down other organic compounds. As a result, various foods—from apples to cheese to guacamole—end up as ATP. In addition to carbohydrates, food also contains proteins and lipids—such as cholesterol and of these organic compounds are used as energy sources (i.e., to produce ATP). The human body possesses several enzymes that break down carbohydrates into simple sugars. While glucose can enter glycolysis directly, some simple sugars, such as fructose and galactose, are first converted into sugars that are intermediates of the glycolytic pathway. Proteins are broken down by enzymes into their constituent amino acids, which are usually recycled to create new proteins. However, if the body is starving or there is a surplus of amino acids, some amino acids can lose their amino groups and subsequently enter cellular respiration. The lost amino groups are converted into ammonia and incorporated into waste products. Different amino acids enter cellular respiration at different stages, including glycolysis, pyruvate oxidation, and the citric acid cycle. Amino acids can also be produced from intermediates in cellular respiration processes. Lipids, such as choleste

 Core: Cellular Respiration

Tissues

JoVE 10696

Cells with similar structure and function are grouped into tissues. A group of tissues with a specialized function is called an organ. There are four main types of tissue in vertebrates: epithelial, connective, muscle, and nervous.

Epithelial tissue consists of thin sheets of cells and includes the skin and the linings of internal organs and body cavities. Epithelial cells are tightly packed, providing a barrier against injury, infection, and water loss. Epithelial tissue can be a single layer called simple epithelium, or multiple layers called stratified epithelium. In stratified epithelium, such as the skin, the outer cells—which are subject to damage—are replaced through the division of cells underneath. Epithelial cells have a variety of shapes, including squamous (flattened), cuboid, and columnar. Some epithelial tissues absorb or secrete substances, such as the lining of the intestines. Connective tissue is composed of cells within an extracellular matrix and includes loose connective tissue, fibrous connective tissue, adipose (fat) tissue, cartilage, bone, and blood. Although the characteristics of connective tissue vary greatly, their general function is to support and attach multiple tissues. For example, tendons are made of fibrous connective tissue and attach muscle to bone. Blood transports oxygen, nutrients and waste produ

 Core: Cell Structure and Function

Levels of Organization

JoVE 10648

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth’s biosphere. Each level of the hierarchy represents an increase in complexity that builds upon the previous level.

The most basic levels include atoms, molecules, and biomolecules. Atoms, the smallest unit of ordinary matter, are composed of a nucleus and electrons. Molecules comprise two or more atoms held together by chemical bonds, most commonly covalent, ionic, or metallic bonds. Biomolecules are molecules found in living organisms, including proteins, nucleic acids, lipids, and carbohydrates. Biomolecules are often polymers—large molecules that are created from smaller, repeating units. For instance, proteins are composed of amino acids, and nucleic acids are composed of nucleotides. Biomolecules can be endogenous or exogenous. Endogenous means that the biomolecule is produced inside a living organism. Biomolecules can also be consumed; for example, a cow gets carbohydrates from digesting grass (exogenous), but the grass must produce the carbohydrates through photosynthesis (endogenous). The next hierarchical level comprises subcellular structures called organelles. Organelles are made up of biomolecules and compartmentalize eukaryotic cells. Organelle means “little organ” as

 Core: Scientific Inquiry

Energy Dynamics- Concept

JoVE 10577

The Food Chain

Energy is one of the most important abiotic factors in an ecosystem and organisms in an ecosystem are connected by the flow of energy and matter among one another. Since energy can be neither created nor destroyed, it can only change form or be transferred to the next organism in a food chain. For example, every time a cow grazes on grass or an osprey hunts and…

 Lab Bio

Bacterial Growth Curve Analysis and its Environmental Applications

JoVE 10100

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Luisa Ikner


Bacteria are among the most abundant life forms on Earth. They are found in every ecosystem and are vital for everyday life. For example, bacteria affect what people eat, drink, and breathe, and there are actually more…

 Environmental Microbiology

Physiology of the Circulatory System - Prep Student

JoVE 10569

Measuring Blood Pressure
To prepare for the blood pressure exercise, simply place the appropriate number of alcohol swabs, sphygmomanometers, and stethoscopes at the front of the classroom.
Be sure to check over each of the component parts of the sphygmomanometers, including the tubing, cuff, manometer, and bulb to ensure they are undamaged.…

 Lab Bio

Anatomy of the Circulatory System

JoVE 10885

The human circulatory system consists of blood, blood vessels that carry blood away from the heart, around the body, and back to the heart, and the heart itself, which acts as a central pump. The systemic circuit supplies blood to the whole body, the coronary circuit supplies blood to the heart, and the pulmonary circuit supplies blood flow between the heart and lungs.

Blood travels from the right atrium to the right ventricle of the heart through the tricuspid valve, then from the right ventricle to the pulmonary artery through the pulmonary valve. Pulmonary veins then carry the blood to the left atrium of the heart, from which it is carried to the left ventricle through the mitral valve. Finally, the left ventricle pumps blood to the aorta (the largest artery in the body) through the aortic valve. Arteries, which carry blood away from the heart, split and get progressively smaller, becoming arterioles and eventually a series of capillaries, the sites of gas exchange. Capillaries converge to become larger venules, and eventually merge into veins, which bring blood back to the heart. Humans have a double circulatory system, in which blood travels through the heart twice via the pulmonary and systemic circuits. First, the heart receives deoxygenated blood in its right side and then pumps it to the nearby pulmonary circuit, the capillaries that ar

 Core: Circulatory and Pulmonary Systems

Isolation of Human Endothelial Cells from Normal Colon and Colorectal Carcinoma - An Improved Protocol

1Division of Molecular and Experimental Surgery, Department of Surgery, University Medical Center Erlangen, Friedrich-Alexander University of Erlangen-Nuremberg, 2Department of Surgery, University Medical Center Erlangen, Friedrich-Alexander University of Erlangen-Nuremberg, 3Division of Nephropathology, Department of Pathology, University Medical Center Erlangen, Friedrich-Alexander University of Erlangen-Nuremberg, 4Department of Pathology, University Medical Center Erlangen, Friedrich-Alexander University of Erlangen-Nuremberg

JoVE 57400

 Cancer Research

Using In Vivo and Tissue and Cell Explant Approaches to Study the Morphogenesis and Pathogenesis of the Embryonic and Perinatal Aorta

1Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 2Department of Neurology, Yale University School of Medicine, 3Department of Neurology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine

JoVE 56039

 Developmental Biology

The Arteriovenous (AV) Loop in a Small Animal Model to Study Angiogenesis and Vascularized Tissue Engineering

1Department of Plastic and Hand Surgery and Laboratory for Tissue Engineering and Regenerative Medicine, University Hospital of Erlangen, Friedrich-Alexander University of Erlangen-Nürnberg (FAU), 2Genetic Engineering and Biotechnology Institute for Postgraduate Studies, Baghdad University, 3Department of Plastic, Hand and Microsurgery, Sana Klinikum Hof GmbH

JoVE 54676

 Bioengineering

Hollow Fiber Bioreactors for In Vivo-like Mammalian Tissue Culture

1Department of Chemical Engineering and Centre for Regenerative Medicine, University of Bath, 2MRC Centre for Drug Safety Science and Institute of Translational Medicine, University of Liverpool, 3Mechanical Engineering, University College London, 4Department of Applied Mathematics, Liverpool John Moores University

JoVE 53431

 Bioengineering

Functional Human Liver Preservation and Recovery by Means of Subnormothermic Machine Perfusion

1Center for Engineering in Medicine, Dept. of Surgery, Massachusetts General Hospital, Harvard Medical School, 2Transplant Center, Dept. of Surgery, Massachusetts General Hospital, Harvard Medical School, 3Section of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, University Medical Center Groningen, University of Groningen

JoVE 52777

 Medicine

Detecting Glycogen in Peripheral Blood Mononuclear Cells with Periodic Acid Schiff Staining

1Department of Biology, Centre for Structural and Functional Genomics, PERFORM Centre, Concordia University, 2Department of Chemistry and Biochemistry, Centre for Structural and Functional Genomics, PERFORM Centre, Concordia University, 3Department of Exercise Science, Centre for Structural and Functional Genomics, PERFORM Centre, Concordia University

JoVE 52199

 Immunology and Infection

Fundus Photography as a Convenient Tool to Study Microvascular Responses to Cardiovascular Disease Risk Factors in Epidemiological Studies

1Environmental Risk and Health, Flemish Institute for Technological Research (VITO), 2Centre for Environmental Sciences, Hasselt University, 3Transportation Research Institute, Hasselt University, 4Department of Public Health, Occupational and Environmental Medicine, Leuven University

JoVE 51904

 Medicine

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

1Department of Obstetrics, Perinatal Pharmacology, University Hospital Zurich, 2Laboratory for Materials - Biology Interactions, EMPA Swiss Federal Laboratories for Materials Testing and Research, 3Graduate School for Cellular and Biomedical Sciences, University of Bern

JoVE 50401

 Bioengineering

The Use of Cystometry in Small Rodents: A Study of Bladder Chemosensation

1Laboratory of Experimental Urology, Department of Development and Regeneration, KU Leuven, Belgium, 2Laboratory for Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven, Belgium, 3TRP Research Platform Leuven (TRPLe), KU Leuven, Belgium

JoVE 3869

 Medicine
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