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Natural Selection, Species Isolation and Real World Example

By: HWC, Views: 8776

`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: 10009

• 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: 10135

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: 729

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: 12541

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: 380

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...

Red Blood Cells - Erythropoietin (EPO)

By: HWC, Views: 9264

• 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 aft...

Bond in biological molecules (Ionic, Covalent and Hydrogen bonds)/ How atoms bond?

By: HWC, Views: 6660

Sodium atoms and chloride atoms have unfilled orbitals in their outer shells. The lone electron in the outermost shell of a sodium atom can be pulled or knocked out. This ionizes the atom. It is now a positively charged sodium ion. A chlorine atom has an electron vacancy in its outer shell and...

Otitis Media

By: Administrator, Views: 12474

Otitis media is a group of inflammatory diseases of the middle ear. The two main types are acute otitis media (AOM) and otitis media with effusion (OME). AOM is an infection of rapid onset that usually presents with ear pain. In young children this may result in pulling at the ear, increased cryi...