Examples of second-class lever in the following topics:
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- Classes of levers include:
- In a second-class lever, the force is
applied at one end with the pivot at the other and the load in between.
- Second-class
levers are also relatively uncommon in the body.
- All second-class levers in the
body act at a mechanical advantage since the force is always applied closer to the
load than to the pivot.
- In a third-class lever the force is applied
between the load and the pivot.
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- Nuclear receptors can be classified into two broad classes according to their mechanism of action and sub-cellular distribution in the absence of ligand.
- For lipophobic hormones which cannot pass the cellular membrane activity is mediated and amplified within a cell by the action of second messenger mechanisms (molecules which relay signals from receptors on the cell surface to target molecules inside the cell in the cytoplasm or nucleus).
- General schematic of second messenger generation following activation of membrane bound receptors.
- This figure depicts the mechanism of a class I nuclear receptor (NR) that, in the absence of ligand, is located in the cytosol.
- Distinguish between the hormone mechanisms of direct gene activation and second-messenger system
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- Water-soluble hormones such as Epinephrine, bind to a cell-surface localized receptor, initiating a signaling cascade using intracellular second messengers.
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- The Aδ fiber axons are myelinated and can allow an action potential to travel at a rate of about 20 meters/second towards the central nervous system.
- These only conduct at speeds of around 2 meters/second.
- The first phase is mediated by the fast-conducting Aδ fibers, and the second part is due to C fibers.
- The second phase is a more prolonged and slightly less intense feeling of pain as a result of the damage.
- Aδ fibers are thinly myelinated; therefore, they conduct signals more rapidly than unmyelinated C fibers, but more slowly than other, more thickly myelinated "A" class fibers.
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- After a second exposure later, the proliferated T cells can become activated, generating an immune reaction, producing the typical blisters of poison ivy exposure.
- This also appears to be the mechanism by which the anesthetic gas halothane can cause a life-threatening hepatitis, as well as the mechanism by which penicillin-class drugs cause autoimmune hemolytic anemia.
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- The antigen is processed by the APC and bound to MHC class II receptors and MHC class I receptors on the cell membrane of the APC.
- In this manner, the second and subsequent exposures to an antigen produce a stronger and faster immune response.
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- The adrenergic receptors (or adrenoceptors) are a class of metabotropic G protein-coupled receptors that are targets of the catecholamines, especially norepinephrine or noradrenaline, as seen in , and epinephrine (adrenaline) as shown in ).
- Agonist binding thus causes a rise in the intracellular concentration of the second messenger cAMP.
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- Production begins in the second month of fetal life.
- The resulting excessive or deficient production of these three classes of hormones produce the most important problems for people with CAH.
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- The first name describes the number of cell layers present and the second describes the shape of the cells.
- The four major classes of simple epithelium are: 1) simple squamous; 2) simple cuboidal; 3) simple columnar; and 4) pseudostratified.