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Results for: 'natural selection'

How Broken Bones Repair Themselves

By: Administrator, Views: 335

Bone healing, or fracture healing, is a proliferative physiological process in which the body facilitates the repair of a bone fracture. Generally bone fracture treatment consists of a doctor reducing (pushing) displaced bones back into place via relocation with or without anaesthetic, stabili...

Primary and secondary response to infection

By: HWC, Views: 6335

• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...

B cells and antibodies

By: HWC, Views: 7408

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...

The primary factors that affect circulation - MABP, CO and SVR

By: HWC, Views: 6887

Introduction Blood flow is determined by the relative intensities of factors that drive and resist moving blood. • Cardiac output (CO) equals the mean arterial blood pressure (MABP, a driving force) divided by systemic vascular resistance (SVR, a resisting force). • Hormones and the cen...

Helper T cell receptors, activation, proliferation, differentiation & action

By: HWC, Views: 6705

• Most cells which have CD4 on their surface become Helper T cells (TN cells). • The CD4 1 cells only recognize a foreign antigen when it is presented with an antigen presenting immune cell (APC) that includes MHC-II protein. • The Helper T cell antigen receptor must match the presented...

Coaductile pathway, Timing of contraction signal & Conduction system and ECG

By: HWC, Views: 6829

• When the system is healthy, the signal to contract the entire conduction system originates in the SA node - known as the heart's pacemaker. • The SA node triggers contraction because it depolarizes at a faster rate than other parts of the conduction system. • The wave of excitation fr...

Predator- prey competition and symbiosis

By: HWC, Views: 6423

Predator-prey relationships occur when one species, the predator, kills and eats an organism of another species, the prey. This graph shows the cyclical nature of predator-prey relationships, in this case among populations of Canada lynx and snowshoe rabbits. If predation is without some li...

Bipolar Disorder

By: Administrator, Views: 9871

Bipolar disorder, previously known as manic depression, is a mental disorder that causes periods of depression and periods of abnormally elevated mood. The elevated mood is significant and is known as mania or hypomania, depending on its severity, or whether symptoms of psychosis are present. Dur...

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