The real purposes is to increase the awareness between men and women, and to help them set aside issues that are not personal but are merely manifestations of nature. To my way of thinking, it is important to honor and rejoice in both our nature and our individuality. As the goal of equality between men and women now grows closer we are also losing our awareness of important differences. In some circles of society, politically correct thinking is obliterating important discussion as well as our awareness of the similarities and differences between men and women.
Seven species infect humans Box. Plasmodium, as the causative agent of malaria, has the greatest impact on human health. Babesia is a relatively rare zoonotic infection. The other five species are all classified as coccidia. However, recent molecular data indicates that Cryptosporidium is more closely related to the gregarines than to the coccidia.
The coccidia are generally considered opportunistic pathogens and are often associated with AIDS. Several apicomplexan parasites are also important in terms of veterinary medicine and agriculture. Most notable are Babesia and Theileria in cattle and Eimeria in poultry.
Algal Origins of the Apicomplexa Historically the apicomplexa have been described as a group with only parasitic forms. This and their unique apical organelles bring up questions in regards to the origin of the group.
Phylogenetic analysis indicates that members or the genus Copodella form a sister group with the apicomplexa 1. The colpodellids are predatory flagellates that feed on unicellular algae by a process called myzocytosis.
Myzocytosis involves the predator or parasite attaching to the prey or host and literally sucking out the cytoplasm of the prey cell via specialized structures.
This attachment and interaction with the prey cell is mediated by organelles similar to those that the apicomplexa utilize for attachment to or invasion of host cells. Thus the evolution of the apicomplexa likely evolved from this myzocytoic predation to myzocytoic parasitism, as exhibited by gregarines and Cryptosporidiumto intracellular parasitism.
Other myzocytoic organisms with apicomplexa like apical organelles include Perkinsus, parasites of oysters and clams, and Parvilucifera, a predator of dinoflagellates. These perkinsids, however, form a sister group with the dinoflagellates and not the apicomplexa Figure.
This suggests that the progenitor of dinoflagellate and apicomplexan clades may have been a predatory flagellate and that the apical organelles were retained in the apicomplexan clade, but lost in most of the dinoflagellate clade.
The other connection between algae and the apicomplexa is a chloroplast remnant, called the apicoplast, found in most apicomplexans 2. The apicoplast is likely the result of a secondary endosymbiosis of a red algae and is likely the same endosymbiotic event giving rise to the plastids of dinoflagellates.
The apicoplast is nonphotosynthetic but exhibits activities associated with type II fatty acid biosynthesis, isoprenoid biosynthesis, and possibly heme synthesis.
These pathways are essentially prokaryotic and represent excellent drug targets. A photosynthetic alveolate, Chromera velia, that appears to be the earliest branching apicomplexan has also been identified 3.
Simdyanov The phylogeny of colpodellids Alveolata using small subunit rRNA gene sequeneces suggest they are the free-living sister group to Apicomplexans. Journal of Eukaryotic Microbiology Journal of Molecular Biology A photosynthetic alveolate closely related to apicomplexan parasites.
Some coccidia Cryptosporidium, Cyclospora, Isospora carry out their entire life cycle within the intestinal epithelial cells of the host and are transmitted by the fecal-oral route.
Other coccidia Sarcocystis, Toxoplasma have a more complicated life cycle involving tissue cysts and multiple hosts ie, heteroxenous. Cryptosporidium Since its initial identification in several Cryptosporidium species have been identified in a wide variety of animals ranging from fish to humans.
The first human cases of cryptosporidiosis were reported in and were characterized as a diarrheal disease associated with immune suppression.
Initially it was believed to be a rare and exotic disease. However, it is now recognized that Cryptosporidium is a common cause of diarrhea in immunocompetent persons and has probably been a human pathogen since the beginning of humanity.
Two species infecting humans have been identified: However, Cryptosporidium is more closely related to the gregarines and this is reflected in some aspects of its life cycle. The infection is acquired through the ingestion of sporulated oocysts Figure.
Sporozoites Sz emerge from the oocyst and attach to intestinal epithelial cells. In contrast to other coccidia, Cryptosporidium sporozoites do not invade the enterocytes. Instead they induce the fusion and expansion of the microvilli resulting in the parasite becoming surrounded by a double membrane of host origin.The sexual response cycle refers to the sequence of physical and emotional changes that occur as a person becomes sexually aroused and participates in sexually stimulating activities, including.
Evolution: Evolution, theory in biology postulating that the various types of plants, animals, and other living things on Earth have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations.
It is one of the keystones of modern biological theory. Pearson, as an active contributor to the biology learning community, is pleased to provide free access to the Classic edition of The Biology Place to all educators and their students.
Women's string-figure depicting "menstrual blood of three women", illustrating the Yolngu people's tribal mythology of menstrual synchrony Arnhem Land R "We Yolungu are a jealous people and have been since the days we lived in the bush in clans.
The sexual response cycle has four phases: desire (libido), arousal (excitement), orgasm and resolution.
Both men and women experience these phases, although the timing usually is different. For example, it is unlikely that both partners will reach orgasm at the same time. Orgasm (from Greek ὀργασμός orgasmos "excitement, swelling"; also sexual climax) is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic muscular contractions in the pelvic region characterized by sexual pleasure.
Experienced by males and females, orgasms are controlled by the .