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Action potentials - electrical characteristics and generation

By: HWC, Views: 7568

• 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...

Contraction cycle of a sarcomere

By: HWC, Views: 8174

• A single nervous signal releases Ca2+ ions into the sarcoplasm and initiates the contraction cycle. step 1. ATP hydrolysis • ATP provides the to move myosin molecules back into the energized configuration necessary to perform the power stroke. Step 2. Crossbridge attachment • Myosin...

Rh blood type and complications during pregnancy & Fertilization

By: HWC, Views: 5080

Complications can arise if an Rh- woman is impregnated by an Rh+ man. The fetus maybe Rh+. During childbirth, some of the fetal Rh+ cells may leak into the maternal bloodstream. The woman's immune system views the Rh+ as foreign and makes antibodies against it. If the woman becomes pr...

Natural Selection, Species Isolation and Real World Example

By: HWC, Views: 7151

`Natural selection' is the process in which organisms with adaptive traits survive and breed in greater number than organisms without such traits. Eventually, almost all of the individuals in the population will have the same adaptive trait. This was the concept presented by Charles Darwin in ...

Male Reproductive System - Testosterone

By: HWC, Views: 8330

• Under the influence of FSH and testosterone, Sertoli cells produce androgen-binding protein (ABP) that binds to testosterone and maintains high levels of the hormone near spermatogenic cells. • Testosterone stimulates the final stages of spermatogenesis. • In addition, testosterone is...

B cells and antibodies

By: HWC, Views: 8513

What Are Antibodies? Antibodies, also known as immunoglobulins, are Y-shaped proteins that are produced by the immune system to help stop intruders from harming the body. When an intruder enters the body, the immune system springs into action. These invaders, which are called antigens, can be vi...

Upper Limb Arteries Animation

By: Administrator, Views: 700

Arteries A branching system of vessels that transports blood away from the heart to all body parts. All arteries have a pulse, reflecting the rhythmical beating of the heart. Arteries Certain points are commonly used to check rate, rhythm, and condition of the arterial wall. Most commonly ...

Lower Limb Arteries Animation

By: Administrator, Views: 10848

Arteries A branching system of vessels that transports blood away from the heart to all body parts. All arteries have a pulse, reflecting the rhythmical beating of the heart. Arteries Certain points are commonly used to check rate, rhythm, and condition of the arterial wall. Most commonly ...

Labor and Delivery - Placenta Cord

By: Administrator, Views: 350

Soon after a baby is conceived, a support system, comprised of the placenta and umbilical cord, begins to develop. These two structures are essential for sustaining a healthy pregnancy, explains Donald Davis, an obstetrician in Medicine Hat, Alta., and past president of the Society of Obstetricia...