poniedziałek, 23 października 2017
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Chemia/Biochemia (847)

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! EN_90278326_0005 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Serotonin molecule. Computer model showing the structure of the neurotransmitter (nerve signalling chemical) serotonin (5-hydroxytryptamine). Atoms are colour-coded (carbon: dark grey, hydrogen: light grey, nitrogen: blue, and oxygen: red). Serotonin is an important brain signalling molecule and a lack of it has been shown to cause depression and other mood disorders.
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! EN_90279535_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Somatostatin hormone molecule. Computer model showing the structure of the hormone somatostatin, also known as growth hormone-inhibiting hormone (GHIH). Atoms are colour-coded spheres (carbon: dark grey, hydrogen: light grey, nitrogen: blue, sulphur:yellow, and oxygen: red). GHIH is released by the hypothalamus in the brain where it inhibits the release of somatotrophin, or growth hormone (GH), and thyroid-stimulating hormone (TSH). It is also produced in the stomach, intestine and pancreas where it supresses the release of gastrointestinal and pancreatic hormones.
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! EN_90279535_0002 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Somatostatin hormone molecule. Computer model showing the structure of the hormone somatostatin, also known as growth hormone-inhibiting hormone (GHIH). Atoms are colour-coded spheres (carbon: dark grey, hydrogen: light grey, nitrogen: blue, sulphur:yellow, and oxygen: red). GHIH is released by the hypothalamus in the brain where it inhibits the release of somatotrophin, or growth hormone (GH), and thyroid-stimulating hormone (TSH). It is also produced in the stomach, intestine and pancreas where it supresses the release of gastrointestinal and pancreatic hormones.
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! EN_90280357_0004 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Stem cells, computer artwork. A stem cell is an undifferentiated cell that can produce other types of cell when it divides. Medical researchers believe that eventually it will be possible to manufacture new tissues and organs from stem cells. There are three main types of mammalian stem cell: embryonic stem cells, derived from blastocysts; adult stem cells, which are found in adult tissues; and cord blood stem cells, which are found in the umbilical cord.
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! EN_90280357_0005 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Stem cells, computer artwork. A stem cell is an undifferentiated cell that can produce other types of cell when it divides. Medical researchers believe that eventually it will be possible to manufacture new tissues and organs from stem cells. There are three main types of mammalian stem cell: embryonic stem cells, derived from blastocysts; adult stem cells, which are found in adult tissues; and cord blood stem cells, which are found in the umbilical cord.
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! EN_90266055_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Leptin hormone molecule. Computer model showing the secondary structure of the hormone leptin. This hormone is produced by adipose (fat) tissue. It interacts with receptors in the brain's hypothalamus to signal when a person is full. It also circulates in the blood at levels proportionate to body fat, which allows the brain to regulate appetite and metabolism. Mutations in the ob gene that codes for leptin are thought to be responsible for some forms of obesity.
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! EN_90266124_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Leukotriene E4 molecule. Computer model showing the structure of the fatty acid leukotriene E4. Atoms are colour-coded spheres (carbon: dark grey, hydrogen: light grey, nitrogen: blue, sulphur: yellow, and oxygen: red). Leukotrienes are part of the immune system and are an important part in inflammatory response. They are involved in asthmatic and allergic reactions, where they act to sustain inflammatory reactions. Leukotrienes are produced within cells and send signals that either act on the cell producing them (autocrine signalling) or on neighbouring cells (paracrine signalling) to regulate the immune response.
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! EN_90266124_0002 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Leukotriene E4 molecule. Computer model showing the structure of the fatty acid leukotriene E4. Atoms are colour-coded (carbon: dark grey, hydrogen: light grey, nitrogen: blue, sulphur: yellow, and oxygen: red). Leukotrienes are part of the immune system and are an important part in inflammatory response. They are involved in asthmatic and allergic reactions, where they act to sustain inflammatory reactions. Leukotrienes are produced within cells and send signals that either act on the cell producing them (autocrine signalling) or on neighbouring cells (paracrine signalling) to regulate the immune response.
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! EN_90274300_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Prostacyclin molecule. Computer model showing the structure of the hormone prostacyclin, or prostaglandin I2 (PGI2). Atoms are colour-coded (carbon: dark grey, hydrogen: light grey, oxygen: red). Prostacyclin acts to widen blood vessels (thus lowering blood pressure) and to prevent aggregation of platelets (preventing blood clotting). These effects are the opposite of those of the related hormone thromboxane, and the balance between the two is important in regulating the functioning of the circulatory system. When taken as a drug it is known as epoprostenol.
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! EN_90274300_0002 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Prostacyclin molecule. Computer model showing the structure of the hormone prostacyclin, or prostaglandin I2 (PGI2). Atoms are colour-coded (carbon: dark grey, hydrogen: light grey, oxygen: red). Prostacyclin acts to widen blood vessels (thus lowering blood pressure) and to prevent aggregation of platelets (preventing blood clotting). These effects are the opposite of those of the related hormone thromboxane, and the balance between the two is important in regulating the functioning of the circulatory system. When taken as a drug it is known as epoprostenol.
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! EN_90258805_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Follicle stimulating hormone molecules. Computer artwork showing the secondary structure of two strands of follicle stimulating hormone (FSH). This hormone, which is produced in the brain's pituitary gland, is a gonadotrophin, that is it acts on the ovaries and testes. In women FSH stimulates the maturation and release of an egg from the ovaries every month, while in men it stimulates the cells that produce sperm.
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! EN_90258805_0002 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Follicle stimulating hormone molecules. Computer artwork showing the quaternary structure of two strands of follicle stimulating hormone (FSH). This hormone, which is produced in the brain's pituitary gland, is a gonadotrophin, that is it acts on the ovaries and testes. In women FSH stimulates the maturation and release of an egg from the ovaries every month, while in men it stimulates the cells that produce sperm.
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! EN_90263197_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Human placental lactogen hormone molecule. Computer model showing the secondary structure of human placental lactogen (hPL). Hydrogen bonding is shown by alpha helices (ribbons) and random coils (wires). HPL is a polypeptide hormone produced by the placenta during pregnancy. It breaks down fats from the mother to provide fuel for the growing foetus. It can lead to insulin resistance and carbohydrate intolerance in the mother. It also plays a role in stimulating lactation (milk production) in the mother.
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! EN_90274278_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Prolactin hormone molecule. Computer model showing the secondary structure of human prolactin (hPRL), or luteotropic hormone (LTH). Hydrogen bonding is shown by alpha helices (ribbons) and random coils (wires). PRL is primarily associated with lactation (milk production). It is synthesised and secreted by lactotrope cells in the anterior pituitary gland of the brain, as well as other tissues including the breast, and the central nervous system. During breastfeeding, suckling of the nipple stimulates the production of PRL, which triggers milk production. The breast then fills with milk via a process called lactogenesis.
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! EN_90279536_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Somatotrophin hormone molecule. Computer model showing the secondary structure of the human growth hormone somatotrophin (GH). Hydrogen bonding is shown by alpha helices (ribbons) and random coils (wires). GH stimulates growth and cell reproduction and regeneration in humans and other animals. It is synthesized, stored, and secreted by somatotroph cells within the anterior pituitary gland of the brain. Somatotrophin is also produced artificially by recombinant DNA technology, when it is termed somatropin.
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! EN_90250450_0005 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Carbon nanotube. Computer artwork showing the hexagonal carbon structure of a nanotube, or buckytube.
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! EN_90250450_0006 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Carbon nanotube. Computer artwork showing the hexagonal carbon structure of a nanotube, or buckytube.
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! EN_90260489_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Ghrelin hormone molecule. Computer model showing the crystal structure of the human hormone ghrelin. The crystal structure consists of both the secondary structure, represented by an alpha helix (ribbon), and primary structure, represented by colour-coded rods (carbon: grey, oxygen: red, nitrogen: blue). Ghrelin is responsible for stimulating the feeling of hunger. It is produced mainly by P/D1 cells lining the fundus of the human stomach, and epsilon cells in the pancreas. Ghrelin levels increase before meals and decrease after meals.
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! EN_90260087_0001 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Gastrin hormone molecule. Computer model showing the structure of the human hormone gastrin. Atoms are colour-coded spheres (carbon: grey, hydrogen: light grey, nitrogen: blue, sulphur: yellow, and oxygen: red). Gastrin stimulates secretion of gastric acid by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the stomach, duodenum and pancreas, in response to stimuli including stomach distension, the presence of partially digested proteins (especially amino acids), and elevated blood calcium levels (hypercalcemia).
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! EN_90260087_0002 SCI
PHOTO: EAST NEWS/SCIENCE PHOTO LIBRARY Gastrin hormone molecule. Computer model showing the structure of the human hormone gastrin. Atoms are colour-coded spheres (carbon: grey, hydrogen: light grey, nitrogen: blue, sulphur: yellow, and oxygen: red). Gastrin stimulates secretion of gastric acid by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the stomach, duodenum and pancreas, in response to stimuli including stomach distension, the presence of partially digested proteins (especially amino acids), and elevated blood calcium levels (hypercalcemia).
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