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Graded potentials - electrical characteristics and types

By: HWC, Views: 8000

• A graded potential occurs when a gated channel is opened or closed, altering ion flow through the membrane. • Changes in ion and charge distributions cause voltage changes to the resting membrane potential. • The strength of the stimulus determines the number of gated channels affect...

PET Scan Animation

By: Administrator, Views: 10918

Positron Emission Tomography (PET) Computer-based nuclear imaging procedure that can produce three-dimensional pictures of actual organ functioning. Ultrasonography, Brain Use of high-frequency sound waves to record echoes on an oscilloscope and film.

Ultrasound of a Fetus (Sonogram)

By: Administrator, Views: 10600

An ultrasound exam is a procedure that uses high-frequency sound waves to scan a woman's abdomen and pelvic cavity, creating a picture (sonogram) of the baby and placenta. Although the terms ultrasound and sonogram are technically different, they are used interchangeably and reference the same exam.

Stress and Immune System Animation

By: Administrator, Views: 10945

How stress and the immune system are linked. Immune response declines with age, limiting body's ability to identify and fight foreign substances. Loss of thymus cortex leads to reduced production of T lymphocytes, including T cells, NK cells, B lymphocytes. Frequency and severity of infectio...

Negative Feedback Regulation of Blood Pressure

By: HWC, Views: 7737

stimulus • Blood pressure determines the flow of blood to and from capillaries. • Low blood pressure results in reduced blood flow. • High blood pressure can cause blood vessels to break. Baroreceptors • The aortic arch carries blood to the body. • The common carotids ca...

Gastrin (protein digestion)

By: HWC, Views: 7749

The endocrine system maintains many body conditions within normal limits with feedback loops. Each endocrine feedback loop maintains homeostasis using the following components: • Stimulus - a change in a body condition. • Production cell - an endocrine cell that produces a hormone after b...

Lactation and Breast Feeding

By: HWC, Views: 8550

Regulation of lactation - breast preparation • Pregnancy hormones trigger breast changes to prepare for feeding the new baby. • The amount of the hormone prolactin, essential to the initiation of lactation, increases steadily throughout pregnancy. • However, high levels of both estroge...

Introduction to Photolithography - WC, BLF, PA, Hard and Soft baking

By: HWC, Views: 7342

Prior to use, wafers are chemically cleaned to remove particulate matter on the surface as well as any traces of organic, ionic, and metallic impurities. Barrier Layer Formation After cleaning, the silicon wafer is covered with the material which will serve as a barrier layer. The most commo...

Action potentials - electrical characteristics and generation

By: HWC, Views: 7586

• An action potential is the nervous impulse or signal for long distance communication. Each action potential is generated at the cell's trigger zone. • Action potentials are considered an all-or-nothing phenomena because they are either generated or not. • The generation of an action...