Valve Disease
Mary N. Sheppard in Practical Cardiovascular Pathology, 2022
An increasing number of patients are undergoing surgery or percutaneous procedures to replace valves affected by senile calcific degeneration, myxomatous degeneration, congenital disease and infective endocarditis. Like the aortic valve, the mitral has five similar layers. There is an endothelial-covered atrial and ventricular layer with a narrow layer of underlying loose connective tissue. Cardiac innervation shows significant differences in nerve density and distribution between and within cardiac valves. Age-related degenerative changes will alter the aortic valve and should be taken into account in any morphological evaluation. After the surgical specimen has been received, the clinical details should be obtained before gross morphological observations are recorded. The valvulitis of the acute phase is neither functionally important nor macroscopically striking. Calcification is a common age-related change in the aortic valve cusps and just below the insertion of the mitral valve cusp into the mitral annulus.
Cells, Tissues and Organs
David Sturgeon in Introduction to Anatomy and Physiology for Healthcare Students, 2018
Human cells vary greatly in sophistication and function from relatively simple skin cells to highly specialised nerve cells. There are over 200 different types of cell in the human body including skins cells, bone cells, blood cells and nerve cells. For the most part, human cells require three basic components: a cell membrane, cytoplasm and a nucleus. All cells need some form of plasma membrane in order to maintain structural integrity. Anyway, in human cells, amphipathic phospholipid molecules are arranged in a continuous bi-layer and provide a highly impermeable barrier. This chapter looks at the body on an atomic, molecular and a cellular level. In terms of size and complexity, the next functional unit of the body is tissue. There are four distinct categories of tissue: epithelial, connective, muscular and nervous. Loose connective tissue is typically found beneath epithelial membranes and glandular epithelium. It binds loose connective tissues to other tissues and contributes to the formation of organs.
Dermis
Neena Washington, Clive Washington, Clive Wilson in Physiological Pharmaceutics, 2001
The dermis is a fibrous layer which supports and strengthens the epidermis. It ranges from 2-3 mm thick and in man constitutes between 15% to 20% of the total body weight. The dermis consists of a matrix of loose connective tissue composed of fibrous protein collagen, embedded in an amorphous ground substance. The ground substance consists primarily of water, ions, and complex carbohydrates such as glycosaminoglycans that are attached to proteins (proteoglycans). The ground substance helps to hold the cells of the tissue together and allows oxygen and nutrients to diffuse through the tissue to cells.
Ultrastructural Organization of the Epithelial Lining in the Endolymphatic Duct and Sac in the Guinea Pig
Published in Acta Oto-Laryngologica, 1964
P. G. Lundquist, R. Kimura, J. Wersäll
The finer details of the epithelial lining of the endolymphatic duct and the proximal, intermediate and distal portions of the endolymphatic sac have been described. The most highly differentiated and active part of the entire areas was the intermediate portion where pinocytosis appeared to be a main function. These active cells demonstrated numerous microvilli, pedicels, concentration of mitochondria, many short endoplasmic reticuli and a rich vacuolar system. The infolding of the cytoplasmic membrane was noted near the base of the cell and particularly between adjacent cells. A rich network of the capillaries with fenestrated endothelium was observed in relation to the basement membrane of the sac proper. The epithelial organization and vascularization of this area seemed to be ideally suited for passing fluid from the lumen towards the loose connective tissue.
The Role Of The Perilymph In Semicircular Canal Stimulation
Published in Acta Oto-Laryngologica, 1973
The assumption of a mechanical function of the perilymph in vestibular reactions has been reiterated in the literature (Anliker, M. & v. Buskirk, W. 1971. The role of the perilymph in response of the semicircular canals to angular acceleration. Acta Otolaryng (Stockh.) 72, 93). This assumption is essentially based on three premises: that the perilymph should meet a lower resistance than the endolymph because of the larger perilymphatic space, that the ampulla blocks perilymph movement by presenting one wall perpendicularly placed at the end of the perilymphatic canal and that this ampullary wall and the perilymphatic meshwork of loose connective tissue offer no resistance to perilymph movement. This paper presents criticisms of each of these premises and maintains that the assumption of a mechanical function for the perilymph cannot be supported or sustained by reference to them.
The Morphological Basis for Development of Reinke's Oedema
Published in Acta Oto-Laryngologica, 1984
éva Remenár, János élö, Tibor Frint
Normal human vocal cords and surgically removed Reinke's oedema were studied by light and electron microscopy. The Reinke's space between the lamina propria and vocal ligament was filled with loose connective tissue sheets, which seemed to be an organic part of the vocal ligament. The structure suggested the possibility of the lamellae moving on each other. This could be important for the vibratory function of vocal cords. Inside the lamellae, masses of inmature young elastic fibres were found. Reinke's oedema develops in the superficial elastic sheets. Therefore in the case of surgical intervention the specially structured rubbery elastic vocal cord mucosa must be removed, which is essential to perfect vibratory function.
Related Knowledge Centers
- Epithelium
- Connective Tissue
- Blood Vessel
- Adipose Tissue
- Reticular Lamina
- Organ
- Nerve