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Internal Standards

JoVE 10225

Source: Laboratory of Dr. B. Jill Venton - University of Virginia



The goal of many chemical analyses is a quantitative analysis, where the amount of a substance in a sample is determined. In order to accurately calculate the concentration of an unknown from a sample, careful sample preparation is key. Every time a sample is…

 Analytical Chemistry

Central Venous Catheter Insertion: Internal Jugular

JoVE 10237

Source: James W Bonz, MD, Emergency Medicine, Yale School of Medicine, New Haven, Connecticut, USA


Central venous access is necessary in a multitude of clinical situations, including vascular access, vasopressor and caustic medication delivery, central venous pressure monitoring, intravascular device delivery (pacing wires, Swann-Ganz…

 Emergency Medicine and Critical Care

Internal Receptors

JoVE 11011

Many cellular signals are hydrophilic and therefore cannot pass through the plasma membrane. However, small or hydrophobic signaling molecules can cross the hydrophobic core of the plasma membrane and bind to internal, or intracellular, receptors that reside within the cell. Many mammalian steroid hormones use this mechanism of cell signaling, as does nitric oxide (NO) gas.

Similar to membrane-bound receptors, binding of a ligand to a receptor located in the cytoplasm or nucleus of a cell causes a conformational change in the receptor. Like transcription factors, the active receptor can bind to receptor-specific DNA binding sites to increase or decrease the transcription of target genes. In the case of an intracellular receptor located in the cytoplasm, the receptor-ligand complex must first cross the nuclear membrane. Many steroid hormones, including estrogen and testosterone, use intracellular receptors to induce specific effects. As an example, estrogen can diffuse across the membrane; binding of estrogen to its receptor results in dimerization of the receptors and transport of the ligand-receptor complex to the nucleus. Once in the nucleus, the complex can bind to DNA sequences called Estrogen-Response Elements (EREs). Depending on the other transcription factors and co-activators, binding of activated estrogen receptors (ERs) to EREs may cause an incre

 Core: Biology

Fundamental Attribution Error

JoVE 11053

According to some social psychologists, people tend to overemphasize internal factors as explanations—or attributions—for the behavior of other people. They tend to assume that the behavior of another person is a trait of that person, and to underestimate the power of the situation on the behavior of others. They tend to fail to recognize…

 Core: Psychology

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

Enthalpy of Reaction - Student Protocol

JoVE 11157

Source: Smaa Koraym at Johns Hopkins University, MD, USA



Collecting Data for Calculating the Heat Capacity of a Calorimeter

This experiment will use a constant-pressure calorimeter made of two stacked polystyrene cups, a cardboard lid, and a probe measuring the temperature of a solution in real-time. Polystyrene is a good…

 Lab: Chemistry
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