Connective Tissue Flashcards
Ground substances
- Made up of many substances including Hyaluronic acid which is capable of binding water which is responsible for changes in the permeability and viscosity of the CT.
- Ground substance plays a role in preventing or retarding the spread of microorganisms and toxic materials at sites of infections.
Fibres in the CT
The fibres in CT are collagen, reticular and elastic produced by fibroblasts.
Fibroblasts
Fibroblasts (most common CT cells) are flattened cells with elliptical nuclei that contain 1 or 2 nucleoli.
Mast cells
Mast cells are large, ovoid cells with large granules in the cytoplasm and can control vasodilation - increases permeability of capillaries so that excess plasma enters the CT spaces, causing swelling.
Plasma
Plasma cells appear ovoid in shape with eccentrically placed nuclei in which the chromatin may be distributed along the nuclear envelope forming the “clockface” nucleus. Plasma cells produce the immunoglobulins (antibodies) that form a defence against infections.
Lymphocytes
Lymphocytes are cells that have come from the blood into the CT and are responsible for initiating the cell-mediated immune response (T cells). They have a small dark nucleus and little cytoplasm.
Macrophages
Macrophages are phagocytosing cells of the CT responsible for removing particulate matter and assisting in the immune response. They originate in bone marrow, circulate in the blood as monocytes, and migrate into the CT where they perform their functions.
Loose CT (areolar)
Characterized by much ground substance and tissue fluid housing the CT cells: fibroblasts, adipose cells, macrophages, and mast cells, as well as some undifferentiated cells.
- also loosely woven collagen, reticular, and elastic fibers
- found below the skin, adventitia of blood vessels and resp. tract
- binds organs and organ components
- Because this tissue lies immediately beneath the epithelia of the digestive and respiratory tracts, it is where the body first attacks antigens and bacteria.
Functions of connective tissue
Transport: CT carry blood vessels and lymphatics, mediate the exchange of metabolites
(nutrients, wastes, gases) between tissues and the blood
Repair: scar tissue formation after injury
Defense: phagocytes (macrophages), antibodies (plasma cells)
Packing: space between epithelium, muscle, and glands.
White fat
flat peripherally located nucleus and a thin ring of cytoplasm, the rest of the cell is filled by a single, large droplet of lipid (unilocular)
-Function: storage depot, production of energy, insulation, packing material and shockabsorbing pads in the palms of the hands, soles of the feet, around the eyeball and kidneys.
Brown Fat
Cells are smaller than white fat but show centrally placed round nuclei with a cytoplasm filled with numerous small droplets of lipid (multilocular).
Location: in the fetus and newborn mammals and some hibernating animals
Function: thermoregulation.
Periochondrium
The inner region is cellular (chondrogenic) composed of cells, which differentiate into chondroblasts, and begin to make matrix.
The outer region is fibrous (elastic, collagen, fibroblasts, blood vessels) and also contains chondroblasts, which have been pushed out as a result of inner growth.
In areas where the cartilage has no perichondrium e.g. the articular surfaces of a synovial joint, the cartilage cells receive their nutrients from the synovial fluid that flows in joint surfaces.
Cartilage formation
Starts with the differentiation of embryonic mesenchymal cells to form chondroblasts. Secretion of extracellular
material traps each chondroblast in a space or lacuna within the cartilaginous matrix. Each
chondroblast then undergoes mitotic divisions to form a small group of mature cells(chondrocytes) separated by extracellular material.
Hyaline Cartilage
- The most common type has ground substance, type II collagen fibres (40% of matrix) and small groups of chondrocytes.
- Location: nasal septum, larynx, tracheal rings, bronchi
Elastic Cartilage
Is a variety of hyaline cartilage except it also contains elastic fibers between type II collagen fiber bundles. It has a perichondrium whose outer fibrous layer is rich in elastic fiber. It grows by apposition.
Location: where support with flexibility is required, e.g. the ear pinna, auditory tube, epiglottis
Fibrocartilage
Serves as a transition between dense CT and hyaline cartilage.Unlike the other 2 types of cartilage,
fibrocartilage does not possess a perichondrium. Location: where support and tensile strength is needed, e.g. intervertebral discs, menisci, and pubic symphysis.
