Related Concept Videos

SNAREs and Membrane Fusion01:43

SNAREs and Membrane Fusion

Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
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Factors Affecting Dissolution: Particle Size and Effective Surface Area01:23

Factors Affecting Dissolution: Particle Size and Effective Surface Area

Dissolution kinetics, an essential aspect of oral drug delivery, is significantly influenced by the drug's particle size. According to the Noyes-Whitney dissolution model, the dissolution rate correlates directly with the drug's surface area. The larger the surface area, the higher the drug's solubility in water, leading to a faster drug dissolution rate. Reducing particle size increases the effective surface area, enhancing the dissolution process. Micronization and nanosizing are...
1.7K
Gastric Emptying01:16

Gastric Emptying

Gastric emptying occurs when the stomach gradually releases chyme into the duodenum. When the stomach is distended, it triggers the release of gastrin, a hormone that promotes gastric acid secretion to aid in digestion. Additionally, stomach distension contributes to peristaltic waves that propel gastric contents toward the pyloric region. The gastroenteric reflex, on the other hand, primarily stimulates peristalsis in the intestines, facilitating the movement of contents further along the...
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Gastric Motility01:16

Gastric Motility

Gastric motility is the coordinated contraction and relaxation of stomach muscles that convert ingested food into chyme, a semi-liquid substance ready for further digestion in the intestines. The process begins with the vagus nerve inducing the relaxation of the smooth muscles in the fundus and body of the stomach, allowing these regions to expand and accommodate up to approximately 1.5 liters of food and liquid.
Peristaltic Waves and Chyme Formation
Upon food entry, the stomach initiates...
3.2K
Cell Size01:22

Cell Size

Cell sizes vary widely among and within organisms. Bacterial cells range between 1-10 micrometers (μm)and are considerably smaller than most eukaryotic cells. The smallest bacteria are 0.1 μm in diameter—about a thousand times smaller than eukaryotic cells, which typically range from 10-100 μm.
Surface Area
Cells can take in nutrients and water via diffusion through the plasma membrane itself or through specific channels in the membrane. The area of the membrane surrounding...
129.2K
Gastric Phase of Digestion01:26

Gastric Phase of Digestion

The gastric phase of digestion begins as soon as food enters the stomach. The incoming food bolus triggers neural and hormonal mechanisms, which last approximately 3 to 4 hours. During this phase, the stomach undergoes significant changes to prepare the food for further digestion and absorption.
When food enters the stomach, it stretches the stomach walls and activates stretch receptors. This triggers local reflexes of the enteric nervous system, mediated through the myenteric plexus. These...
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