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Introduction to Human Immunodeficiency Virus (HIV)

By: Administrator, Views: 9554

Human immunodeficiency virus gains entry into helper T cells, uses the cell DNA to replicate, interferes with normal function of the T cells, and destroys the normal cells. 1 in 10 persons with AIDS: age 50 or older. 4% of all AIDS cases: age 65 or older. AIDS’ main form of treatment: an...

Molecules, Membrane Permeability and Structure

By: HWC, Views: 6134

Organisms are not isolated system at equilibrium and need to intake nutrients and electrolytes as remove wastes. Similarly Cells within an organism must also exchange compound by passing them through membrane. The permeability of a membrane is the rate of passive diffusion of molecules th...

Apicomplexan life cycle Animation

By: HWC, Views: 972

Malaria is caused by the sporozoan, Plasmodium. It is transferred to humans by mosquitoes. When an infected mosquito feeds, infective sporozoites move from her salivary glands into the human body. The bloodstream carries the sporozoites to the liver. Here, they reproduce asexually and...

Ciliate conjugation Animation

By: HWC, Views: 1005

Protozoan conjugation is an unusual form of sexual reproduction Prospective partners join together, usually at the surface of their oral depressions. The cells undergo cytoplasmic fusion. Meiosis II produces four haploid micronuclei. Now the macronucleus of each cell begins to bre...

Red Blood Cells - Erythropoietin (EPO)

By: HWC, Views: 6656

• 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...

Neurosynapse Animation

By: Administrator, Views: 9601

In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Synapses are essential to neuronal function: neurons are cells that are specialized to pass signals to individual tar...

Secondary Active Transport

By: HWC, Views: 7166

Energy stored (in a hydrogen or sodium concentration gradient) is used to drive other substances against their own concentration gradients Secondary active transport, is transport of molecules across the cell membrane utilizing energy in other forms than ATP. In many cells, antiporters mov...

Optic Nerve and Optic Disk Animation (Part 2 of 2)

By: Administrator, Views: 9622

The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the optic nerve after they leave the eye. The optic disc ...

Phases of an Action Potential - Resting Potential, Threshold, Rising, Falling, & Recovery Phases

By: HWC, Views: 6081

In this tutorial, we will review the phases of an action potential measured from a small area of a neuron's membrane. The action potential can be divided into five phases: the resting potential, threshold, the rising phase, the falling phase, and the recovery phase. When the neuron is at rest,...