Search results for: 'El'

Watch Later 1:36

By: HWC, Views: 3542

Overview of interactions in antibody-mediated and cell-mediated immunity Animation The antibody mediated immune response begins when a naive B cell encounters antigens from a pathogen, such as a bacterium. The B cell binds, processes, and displays this antigen. It is now an antigen-presenti...

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What are Taste Receptors? How Does it Work? Animation

By: HWC, Views: 3504

Do you ever wonder how you can taste the foods you eat? It all starts with taste receptors in your muscular tongue. Taste receptor neurons are found in your taste buds but you are not looking at the taste buds. The raised bumps on the surface of the tongue that you see are specialized epith...

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Complement Proteins Animation

By: HWC, Views: 3480

Formation of membrane attack complexes. Complement proteins can activate when they bind to antibodies that are bound to a pathogen. Complement proteins also activate when they bind directly to bacterial surfaces. Cascading reactions yield huge numbers of different types of complement protei...

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Chemical Synapse Animation

By: HWC, Views: 4017

A neuromuscular junction is a chemical synapse between the axon endings of a motor neuron and a muscle cell. A narrow synaptic cleft separates the presynaptic cell (the motor neuron) from the postsynaptic cell (the muscle cell). The presynaptic cell contains vesicles filled with neurotransmitt...

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Genetic distance between human groups

By: HWC, Views: 3544

One proposed family tree for modern humans. This family tree is based on nucleic-add hybridization studies of many genes and immuno-logical comparisons. Branch points show presumed genetic divergences. This data indicates that the greatest genetic distance separates humans native to Afri...

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Hormones and the menstrual cycle Animation

By: HWC, Views: 3576

Feedback loops to the hypothalamus and pituitary gland from the ovaries during the menstrual cycle Animation for a step-by-step explanation. Production of a releasing hormone (GnRH) by the hypothalamus prods the pituitary's anterior lobe to release FSH and LH. In the ovary, FSH and LH stimula...

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Structure of a Ribosome

By: HWC, Views: 3582

The structure and function of the mammalian ribosome. The mammalian ribosome consists of two subunits, one small and one large. Each subunit is assembled in the nucleus from rRNA and structural proteins. Once assembled, the ribosomal subunits are shipped separately to the cytoplasm. ...

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Mutations and translation

By: HWC, Views: 3209

A mutation, which may arise during replication and/or recombination, is a permanent change in the nucleotide sequence of DNA. Damaged DNA can be mutated either by substitution, deletion or insertion of base pairs. Mutations, for the most part, are harmless except when they lead to cell death or t...

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Inflammatory response Animation

By: HWC, Views: 3210

Any tissue damage or bacterial invasion can bring about inflammation. The inflammatory response can be triggered by an invasion of bacteria, or by a cut or other physical damage to cells. Chemicals, such as histamine, released by the bacteria or damaged cells. accumulate in the tissue. Thes...

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