essay note
Microglial cells are small glial cells in the brain that act as the primary immune defense in the central nervous system, responding to injury or disease. They are known for their phagocytic activity, clearing damaged neurons and plaques.
Macroglial cells include larger types of glial cells, such as astrocytes and oligodendrocytes. Astrocytes support and maintain the blood-brain barrier, provide nutritional support to neurons, and regulate blood flow. Oligodendrocytes are responsible for the formation of myelin, which insulates neuronal axons, enhancing the speed of electrical transmission.
In summary, the key difference lies in their size and function: microglia are involved in immune responses, while macroglia have supportive and nutrient-providing roles.
Differences between Tight Junctions and Desmosomes:
Structure:
Tight Junctions are formed by strands of transmembrane proteins that create a seal between adjacent epithelial cells.
Desmosomes consist of adhesive protein complexes that anchor intermediate filaments from adjacent cells.
Function:
Tight Junctions prevent the passage of molecules between cells, thereby regulating the permeability of epithelial layers and maintaining the barrier function.
Desmosomes provide mechanical strength and stability to tissues by anchoring cells together, especially in areas subject to shear stress.
Location:
Tight Junctions are commonly found in epithelial tissues lining organs, such as the intestines and blood-brain barrier.
Desmosomes are primarily located in tissues that experience mechanical stress, such as cardiac muscle and the epidermis.
Differences between Tight Junctions and Desmosomes:
Structure:
Tight Junctions are formed by strands of transmembrane proteins that create a seal between adjacent epithelial cells.
Desmosomes consist of adhesive protein complexes that anchor intermediate filaments from adjacent cells.
Function:
Tight Junctions prevent the passage of molecules between cells, thereby regulating the permeability of epithelial layers and maintaining the barrier function.
Desmosomes provide mechanical strength and stability to tissues by anchoring cells together, especially in areas subject to shear stress.
Location:
Tight Junctions are commonly found in epithelial tissues lining organs, such as the intestines and blood-brain barrier.
Desmosomes are primarily located in tissues that experience mechanical stress, such as cardiac muscle and the epidermis.
Differences between Tight Junctions and Desmosomes:
Structure:
Tight Junctions are formed by strands of transmembrane proteins that create a seal between adjacent epithelial cells.
Desmosomes consist of adhesive protein complexes that anchor intermediate filaments from adjacent cells.
Function:
Tight Junctions prevent the passage of molecules between cells, thereby regulating the permeability of epithelial layers and maintaining the barrier function.
Desmosomes provide mechanical strength and stability to tissues by anchoring cells together, especially in areas subject to shear stress.
Location:
Tight Junctions are commonly found in epithelial tissues lining organs, such as the intestines and blood-brain barrier.
Desmosomes are primarily located in tissues that experience mechanical stress, such as cardiac muscle and the epidermis.
Intercellular Junctions and Their Functions:
Tight Junctions:
Function: Prevent the passage of substances between epithelial cells, regulating the permeability of epithelial layers and maintaining a barrier function. Commonly found in tissues like the intestinal lining and blood-brain barrier.
Desmosomes:
Function: Provide mechanical strength and stability to tissues by anchoring adjacent cells together. They are essential in areas that undergo significant shear stress, such as cardiac muscle and the epidermis.
Gap Junctions:
Function: Allow direct communication between adjacent cells by permitting the passage of ions and small molecules. This is crucial for coordinating activities between cells, particularly in cardiac and smooth muscle tissues. 6 connexin make a connexon
Hemidesmosomes:
Function: Anchor epithelial cells to the underlying basement membrane, providing stability and resistance to mechanical stress. They play a significant role in maintaining the integrity of epithelial tissues.
Adherens Junctions:
Function: mechanical stability and tissue integrity, it is beneath tight junctions as tight junctions are most apical
productive cells - fibroblasts, osteoblasts and chondroblasts
protective cells - mast cell, plasma cell, macrophage
trophic cells - adipocytes, pigmentous cells
adipose tissue is from mesenchyme
embryonic is - mucous and mesenchyme
mature connective tissue splits into two categoried as with FIBROUS or RIGID intercellular substance
rigid - bone, dentin, cartilaginous
fibrous - loose, dense, collagenous, reticular, elastic, pigment, adipose
collagen fibres most numerous and formed by fibroblasts making collagen as the primary structural protein
elastic fibres are arranged in bundles to form a 3D network and are found in ligaments
reticular fibres made of type 3 collagen and found in lymphoid organs, lymph nodes, bone marrow and spleen
hyaline most common type of cartilage consisting of 3-5 isogenous groups with lots of chondrocytes found in the articular surfaces of joints, the costal cartilages of the ribs, and the respiratory tract, providing support and flexibility.
fibrocartilage made of thick bundles of collagen fibres found in intervertebral discs, joint capsules and cruciate ligament
bone is a CT because its matrix is mineralised by calcium phosphate
fibroblast
from mesenchyme
spindle shape
large nucleus
basophilic cytoplasm
well developed golgi and rough ER
macrophage
from monocytes
many lysosomes, golgi apparatus, mitochondria, SER, RER
plasma cell
from b-lymphocytes
nuclei is eccentrically placed with heterochromatin
many rough ER and golgi apparatus
mast cell
arise from basophil granulocytes
plasma cell
from b-lymphocytes
many rough ER and golgi apparatus like fibrocytes
nuclei is eccentrically placed with heterochromatin
pigment cell has melanin which is created in the melanocytes stores in the melanophores in skin iris, meninges of brain, chorid of eye
stratum basale - single layer of columnar cells and contains melanin
stratum spinosum - has polygonal cells, with tonofibrils attached to the desmosome
stratum granulosum - has 1-5 layers of flattened cells with basophilic and keratohyalin granules
stratum lucidum only present in thick, non-hairy skin and has pyknotic nuclei
stratum corneum - is the most superficial, the cells die and are without nuclei
basal cells in multistratified squamous non-keratinised epithelium are columnar while apical cells are cuboidal and polygonal