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Premenstrual Syndrome

By: Administrator, Views: 10928

Premenstrual syndrome (PMS) refers to physical and emotional symptoms that occur in the one to two weeks before a woman's period. Symptoms often vary between women and resolve around the start of bleeding. Common symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mo...

Ciliate conjugation Animation

By: HWC, Views: 2110

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...

Fetal development - Weeks 9 to 38

By: HWC, Views: 7855

Weeks 9-12 • Fetal development during the third month includes: • A large head, about 1/2 the length of the fetus. • Visible eyes and ears. • A detectable heartbeat. • Kidneys that form urine. • Gender identification. • Weak, undetectable body movements. • By the e...

Endocrine System Animation

By: Administrator, Views: 1421

Vital function of endocrine system: Production and regulation of chemical substances called hormones. Hormones Chemical transmitters released in small amounts and transported via bloodstream to a target organ or other cells. Transfer information and instructions from one set of cells to anot...

Muscular System Animation

By: Administrator, Views: 10628

Three basic types of muscles: - Skeletal - Smooth - Cardiac Composed of striated or smooth muscle tissue and classified according to their functions and appearance. Skeletal Muscle: - Also known as voluntary or striated muscle. - Controlled by the conscious part of the brain and attach...

X chromosome inactivation in calico cats

By: HWC, Views: 4672

X chromosome inactivation causes a mosaic tissue effect in calico cats. what makes this female calico cat "calico." Like all mammals, this cat began her life as a single cell. That cell had two X chromosomes, one from each parent. One of the chromosomes carried a dominant allele for the ...

Hormones and the menstrual cycle Animation

By: HWC, Views: 4646

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...

Homologous chromosomes during prophase I - Animation

By: HWC, Views: 5595

The chromosomes were duplicated during interphase and the sister chromatids are now in thin threadlike form. Each chromosome becomes zippered to its homologue, so that all four chromatids are closely aligned. The chromosomes are tightly aligned, but we will show them as separate so that y...

Neuron Structure Animation

By: Administrator, Views: 11069

There are several types of neurons, three of which are: Motor neurons, Sensory neurons, Interneurons. The nervous system is usually described as having two interconnected divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). CNS: Includes the brain and spinal...