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from article Swim bladder
Young trout (Salmo trutta), showing the swim bladder. The trout is one of the primitive teleosts which have the swim bladder connected to the gut.
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from article Swim bladder
Diagram showing the blood supply to the gas gland. Blood traveling away from the gland is stippled. There are far more capillaries in the rete than are shown in this diagram.
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from article Vacuole
Vacuoles are important membrane-bound intracellular compartments. (Left) Protozoan vacuoles serve a variety of functions. For example, contractile vacuoles are involved in osmoregulation, controlling the excretion of water from the cell. The food…
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from article Vacuole
A large lipid vacuole surrounded by a mantle of multinucleated giant cells. This type of vacuole occurs in exogenous lipid (lipoid) pneumonia, which is caused by inhalation or aspiration of a fatty substance. (Credit: Yale Rosen)
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from article Mycoplasmas
Mycoplasmas. (a) Mycoplasma hominis, phase contrast micrograph (courtesy of W. Bredt). (b) Spiroplasma citri, electron micrograph of negatively stained specimen (courtesy of R. M. Cole). (c) Mycoplasma colony on solid nutrient medium. (d) Ureaplasma…
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from article Fibrinogen
Fibrinogen models. (a) Computer image of the symmetrical molecule. (b) Model for end-to-end aggregation. (c) Half-staggered molecular overlap between side-to-side aggregated filaments in a clot network. (Parts a and b from C. Cohen et al., The…
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from article Fibrinogen
Physiological pathway for the clotting of fibrinogen in normal plasma. Clotting time is measured by forming the (fibrin)n network; this, however, is not the end product. Unless this clot undergoes ligation by γ-glutamyl-ε-lysine cross-links,…
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from article Fibrinogen
Formation of γ-glutamyl-ε-lysine peptide bridges between fibrin molecules is the last enzyme-catalyzed reaction in blood clotting.
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from article Plant hormone
Plant hormones, such as gibberellins, are chemical messengers synthesized within plants, where they help to regulate a variety of physiological processes, including growth, differentiation, and development. The stunted plant on the left lacks…
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from article Plant hormone
Five of the most important plant hormones: auxin (indoleacetic acid; IAA), gibberellin (gibberellic acid; GA3), cytokinin (zeatin), abscisic acid, and ethylene. (Copyright © McGraw-Hill Education)
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from article Plant hormone
A simplified view of the interaction of three branching hormones. (Left) Auxin promotes production of strigolactones (SL), while limiting that of cytokinins (CK) at bud nodes. This blocks bud outgrowth in intact plants. (Right) After decapitation,…
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from article Plant hormone
The plant hormone ethylene initiates a signal transduction cascade that activates the transcription of a suite of genes needed for fully developed, ripe fruits and vegetables. The top illustration shows a normal path of ethylene synthesis leading to…
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from article Plant hormone
Auxin transport within a plant takes place in a cell-to-cell fashion, mainly in the vascular cambium and the procambial strands, but probably also in epidermal cells. Transport to the root probably involves the phloem. The transport mechanism…
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from article Endocrinology
The main endocrine glands in a human male. (Copyright © McGraw Hill)
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from article DNA microarray
An example of microarray data presentation is shown. In this experiment, five to seven different samples of a series of tissues are organized by column. Each column is one tissue. Tissue names are indicated across the top. The level of expression of…
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from article Nitrogen fixation
A mechanism for the functioning of the two components of nitrogenase. The box signifies that a complex of Fe and Mo-Fe proteins forms the active enzyme.
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from article Temperature adaptation in animals
Body temperature (°C) versus ambient temperature (°C) for (left) endotherm and (right) ectotherm animals. Temperature adaptation is one of the key characteristics necessary to ensure that an animal can live and exist in its environment over a…
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from article Temperature adaptation in animals
A collared lizard basking on a dried lava rock. The body temperature of this ectotherm is determined by sources of heat external to the body. (Credit: David Parsons/iStockphoto/Getty Images)
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from article Temperature adaptation in animals
The Arctic wolf is an endotherm with a thick pelage that reduces the cost of thermoregulation in cold environments. (Credit: Cultura Creative/Alamy Stock Photo)
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from article Hippo pathway (developmental biology)
Illustration depicting Hippo pathway components in (a) Drosophila and (b) mammals, with arrows and blunt lines indicating activation and inhibition, respectively. Expression of the pro-proliferative genes occurs when the Hippo pathway is “OFF.”…
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from article Spinal cord
Spinal cord and brain (ventral aspect). Nerve roots and chief autonomic ganglia are shown. (Credit: Based on an original illustration by H. V. Neal and H. W. Rand)
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from article Spinal cord
Human spinal cord sectioned to show the white matter and gray matter. (Credit: Based on an original illustration by G. M. Wyburn)
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from article Oligosaccharide
Blood group antigens. Five antigens are formed from a single glycolipid or glycoprotein precursor by adding various monosaccharide residues to different places in the oligosaccharide chain (where R can be protein or lipid). The monosaccharide…
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from article Death
Structural changes of cells undergoing the two processes of cell death—necrosis and apoptosis. Necrosis refers to the death of a cell or group of cells as a result of injury, disease, or some other pathologic state. Apoptosis (programmed cell death)…
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from article Death
Changes that can occur in living systems following an injury. In the case of a lethal or fatal injury, the system can be assumed to pass a point, shown as the zero level of homeostatic ability, beyond which the system is unable to restore a normal…
