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Attribution Theory

JoVE 11052

Behavior is a product of both the situation (e.g., cultural influences, social roles, and the presence of bystanders) and of the person (e.g., personality characteristics). Subfields of psychology tend to focus on one influence or behavior over others. Situationism is the view that our behavior and actions are determined by our immediate environment and…

 Core: Psychology

Animal Diversity - Student Protocol

JoVE 10600

Form and Function of Crickets and Crayfish
NOTE: To observe the relationship between form and function in animals, you will be examining and dissecting a cricket and a crayfish. Each pair of students will receive one of each of these organisms. When dissecting, be sure to wear gloves, closed-toed shoes, and safety goggles. Take care when handling…

 Lab Bio

Osmoregulation in Fishes

JoVE 10989

When cells are placed in a hypotonic (low-salt) fluid, they can swell and burst. Meanwhile, cells in a hypertonic solution—with a higher salt concentration—can shrivel and die. How do fish cells avoid these gruesome fates in hypotonic freshwater or hypertonic seawater environments?

Fish employ osmoregulatory strategies to balance bodily levels of water and dissolved ions (i.e., solutes), such as sodium and chloride. Imagine two solutions separated by a membrane that is permeable to water. Although water crosses the membrane in both directions, more water flows (i.e., there is net water movement) into the solution with a higher solute concentration; this is the essential part of osmosis. Osmoconformers maintain an internal solute concentration—or osmolarity—equal to that of their surroundings, and so they thrive in environments without frequent fluctuations. All osmoconformers are marine animals, although many marine animals are not osmoconformers. Most fish are osmoregulators. Osmoregulators maintain internal osmolarity independent of the environment, making them adaptable to changing environments and equipped for migration. Osmosis tends to equalize ion concentrations. Since fish require ion levels different from environmental concentrations, they need energy to maintain a solute gradient that optimizes

 Core: Biology

Central Venous Catheter Insertion: Subclavian Vein

JoVE 10241

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 for hemodynamic monitoring, medication delivery, and blood sampling. There are three veins in the body that are accessed for central venous cannulation: the internal…

 Emergency Medicine and Critical Care

What are Membranes?

JoVE 10971

A key characteristic of life is the ability to separate the external environment from the internal space. To do this, cells have evolved semi-permeable membranes that regulate the passage of biological molecules. Additionally, the cell membrane defines a cell’s shape and interactions with the external environment. Eukaryotic cell membranes also serve to compartmentalize the internal space into organelles, including the endomembrane structures of the nucleus, endoplasmic reticulum and Golgi apparatus. Membranes are primarily composed of phospholipids composed of hydrophilic heads and two hydrophobic tails. These phospholipids self-assemble into bilayers, with tails oriented toward the center of the membrane and heads positioned outward. This arrangement allows polar molecules to interact with the heads of the phospholipids both inside and outside of the membrane but prevents them from moving through the hydrophobic core of the membrane. Proteins and carbohydrates contribute to the unique properties of a cell’s membrane. Integral proteins are embedded in the membrane, while peripheral proteins are attached to either the internal or external surface of the membrane. Transmembrane proteins are integral proteins that span the entire cell membrane. Transmembrane receptor proteins are important for communicating messages from the outside to the ins

 Core: Biology

Solubility- Concept

JoVE 11159


Solubility describes how much of a solute can dissolve in a given volume of a specific solvent. Solubility is usually reported in terms of solute mass per solvent volume or solute mass per solvent mass. For example, the solubility of sodium chloride in water at room temperature is reported as 36 g per 100 mL of water. If solubility is reported in solute …

 Lab: Chemistry

Tonicity in Animals

JoVE 10702

The tonicity of a solution determines if a cell gains or loses water in that solution. The tonicity depends on the permeability of the cell membrane for different solutes and the concentration of nonpenetrating solutes in the solution within and outside of the cell. If a semipermeable membrane hinders the passage of some solutes but allows water to follow its concentration gradient, water moves from the side with low osmolarity (i.e., less solute) to the side with higher osmolarity (i.e., higher solute concentration). Tonicity of the extracellular fluid determines the magnitude and direction of osmosis and results in three possible conditions: hypertonicity, hypotonicity, and isotonicity. In biology, the prefix “iso” means equal or being of equal measurements. When extracellular and intracellular fluid have an equal concentration of nonpenetrating solute inside and outside, the solution is isotonic. Isotonic solutions have no net movement of water. Water will still move in and out, just in equal proportions. Therefore, no change in cell volume occurs. The prefix “hypo” means lower or below. Whenever there is a low concentration of nonpenetrating solute and a high concentration of water outside relative to inside, the environment is hypotonic. Water will move into the cell, causing it to swell. In animal cells, the swelling ul

 Core: Biology

Piping Networks and Pressure Losses

JoVE 10389

Source: Alexander S Rattner, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA

This experiment introduces the measurement and modeling of pressure losses in piping networks and internal flow systems. In such systems, frictional flow resistance from channel walls, fittings, and…

 Mechanical Engineering

Pelvic Exam I: Assessment of the External Genitalia

JoVE 10144

Alexandra Duncan, GTA, Praxis Clinical, New Haven, CT
Tiffany Cook, GTA, Praxis Clinical, New Haven, CT
Jaideep S. Talwalkar, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT

The pelvic exam can feel invasive to patients, so it is important to do everything possible to…

 Physical Examinations II

What is a Nervous System?

JoVE 10838

The nervous system is the collection of specialized cells responsible for maintaining an organism’s internal environment and coordinating the interaction of an organism with the external world—from the control of essential functions such as heart rate and breathing to the movement needed to escape danger.

The vertebrate nervous system is divided into two major parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain, spinal cord, and retina—the sensory tissue of the visual system. The PNS contains the sensory receptor cells for all of the other sensory systems—such as the touch receptors in the skin—as well as the nerves that carry information between the CNS and the rest of the body. Additionally, part of both the CNS and PNS contribute to the autonomic nervous system (also known as the visceral motor system). The autonomic nervous system controls smooth muscles, cardiac muscles, and glands that govern involuntary actions, such as digestion. The vertebrate brain is primarily divided into the cerebrum, cerebellum, and brainstem. The cerebrum is the largest, most anterior part of the brain that is divided into left and right hemispheres. Each hemisphere is further divided into four lobes: frontal, parietal, occipital, and temporal. The outermost layer of the cerebrum is called

 Core: Biology
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