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Anatomy and Chemical Makeup of a Single Hair (Animation)

By: HWC, Views: 5949

The hair's outer cuticle surrounds hair cells filled with tough keratin macrofibrils. Each macrofibril consists of smaller microfibrils. A microfibril is made up of three keratin polypeptide chains. The chains are linked together by disulfide bonds. A hair consists of keratin chains held...

Digestion Animation

By: Administrator, Views: 11370

The mouth or oral cavity is formed by: - The hard and soft palates at the top or roof - the cheeks - the tongue - the lips Contains the teeth and salivary glands. The gingivae (gums) surround the necks of the teeth. The lingual frenulum is a thin fold of mucous membrane that connects...

Chemical Messengers Animation

By: Administrator, Views: 11326

Three types of chemical messengers.

Green alga life cycle Animation

By: HWC, Views: 2371

Chlamydomonas zoospores are haploid flagellated cells. As long as conditions are favorable, these cells reproduce asexually. As many as sixteen cells may form by mitosis within a parent cell. Daughter cells escape when the cell wall ruptures. When conditions become less favorable, the...

DNA close up Animation

By: HWC, Views: 1681

A section from a DNA double helix The backbone of each DNA strand consists of alternating deoxyribose sugars and phosphate groups. The two strands run in opposite directions. One runs from the 5' to 3' direction, the other in the 3' to 5' direction. Think of the deoxyribose units o...

Virtual Tour of the Heart

By: Administrator, Views: 10554

Everything you need to know about your heart

Neuron Type Animation

By: Administrator, Views: 10727

Interneurons: - Are called central or associative neurons. - Located entirely within the central nervous system. - They function to mediate impulses between sensory and motor neurons.

Inflammatory response Animation

By: HWC, Views: 4295

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...

Frequency of stimulation and force (Recruitment of motor units and force)

By: HWC, Views: 8074

• Muscle tension depends on the frequency of stimulation. • Muscle twitch: First stimulus. • Wave summation: When a second stimulus excites a partially relaxed muscle, producing a stronger contraction. • Unfused tetanus: Successive stimulations at the same frequency, producing a se...