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Muscle Twitch and Muscle Tension - Motor unit size and force

By: HWC, Views: 7987

• A motor unit is a group of muscle cells controlled by a single neuron. • A stimulus of sufficient intensity will cause all the cells in the motor unit to contract. • A single contraction, caused by a single action potential, is called a muscle twitch. • Latent period: A brief per...

Introduction to Mammography

By: Administrator, Views: 310

Mammography (also called mastography) is the process of using low-energy X-rays (usually around 30 kVp) to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses or microcalcificat...

Mechanics of Sound Animation

By: Administrator, Views: 11000

Process of Hearing Sound waves are directed to the eardrum, causing it to vibrate. These vibrations move the three small bones of the middle ear (malleus, incus, and stapes). Movement of stapes at oval window sets up pressure waves in the perilymph and endolymph. Process of Hearing The wav...

The Lac Operon in E. Coli

By: Administrator, Views: 11810

The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is no...

Pressure volume relationships - Normal inspiration and expiration

By: HWC, Views: 7654

• Changing the relative pressure in the compartments can control the direction of airflow between compartments. • In a closed compartment, pressure and volume are inversely related. • Reducing the volume will increase the pressure. • Increasing the volume will decrease the pressure. ...

Premenstrual Syndrome

By: Administrator, Views: 10955

Premenstrual syndrome (PMS) refers to physical and emotional symptoms that occur in the one to two weeks before a woman's period. Symptoms often vary between women and resolve around the start of bleeding. Common symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mo...

Interspecific Competition Relationship - Competitive & Niche Differentiation

By: HWC, Views: 7436

In an environment with limited resources, any organisms that utilize the same resources will be in competition with each other. For example, let's look at two competing species of paramecium, a single-celled organism that feeds on bacteria. If we raise each of these species in isolation, both...

Fetal development - Weeks 9 to 38

By: HWC, Views: 7887

Weeks 9-12 • Fetal development during the third month includes: • A large head, about 1/2 the length of the fetus. • Visible eyes and ears. • A detectable heartbeat. • Kidneys that form urine. • Gender identification. • Weak, undetectable body movements. • By the e...

Smoking Cessation

By: Administrator, Views: 10620

Smoking cessation (also known as quitting smoking or simply quitting) is the process of discontinuing tobacco smoking. Tobacco smoke contains nicotine, which is addictive and can cause dependence. Nicotine withdrawal makes the process of quitting often difficult. Seventy percent of smokers wou...