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The exocrine pancreas is one of two compartments that include digestive-acting acinar cells and duct cells.They represent an extension of the intercalated duct into each pancreatic acinus. [1] These cells are commonly known as duct cells, and secrete an aqueous bicarbonate solution under stimulation by the hormone secretin. They also secrete ...
Acinar exocrine glands are found in many organs, including: the stomach [1] the sebaceous gland of the scalp; the salivary glands of the tongue [2] the liver; the lacrimal glands; the mammary glands; the pancreas [3] the bulbourethral (Cowper's) glands
Merocrine – the cells of the gland excrete their substances by exocytosis into a duct; for example, pancreatic acinar cells, eccrine sweat glands [dubious – discuss], salivary glands, goblet cells, intestinal glands, tear glands, etc. Apocrine – the apical portion of the cytoplasm in the cell membrane, which contains the excretion, buds off.
These cells produce an electrical impulse known as a cardiac action potential that travels through the electrical conduction system of the heart, causing it to contract. In a healthy heart, the SA node continuously produces action potentials, setting the rhythm of the heart (sinus rhythm), and so is known as the heart's natural pacemaker.
Ductal cells comprise about 10% of the pancreas by number and about 4% in volume. Its function is to secrete bicarbonate and mucins and to form the tubule network that transfers enzymes made by acinar cells to the duodenum. Ductal cells have a proliferation rate of about 0.5% in normal adults, but mitotic activity goes up when the pancreas is ...
Cells of the ventricles contract nearly simultaneously. The action potentials of cardiac muscle are unusually sustained. This prevents premature relaxation, maintaining initial contraction until the entire myocardium has had time to depolarize and contract. Absence of tetany. After contracting, the heart must relax to fill up again.
The cells that make up the SA node are specialized cardiomyocytes known as pacemaker cells that can spontaneously generate cardiac action potentials. These signals are propagated through the heart's electrical conduction system. [1] [2] Only one percent of the heart muscle cells are conductive, the rest of the cardiomyocytes are contractile.
Purkinje fibers take up stain differently from the surrounding muscle cells because of having relatively fewer myofibrils than other cardiac cells. The presence of glycogen around the nucleus causes Purkinje fibers to appear, on a slide, lighter and larger than their neighbors, being arranged along the longitudinal direction (parallel to the ...