Mesenchymal Tissues Flashcards
What is mesenchymal tissue?
Tissue forms from the mesoderm. It is the tissue below the epithelia - it is connective tissues e.g. muscle, bone, cartilage, Fat, blood and lymph.
Connective tissue is important as it holds the human body together and supports the epithelial structure.
What makes up connective tissue?
Connective tissue is made up of an extracellular matrix and cells.
What are the functions of connective tissue?
- Metabolic functions - e.g. blood vessels
- Defence e.g. immune cells
- Storage e.g. fat
- Repair e.g. scarring
What are the components of extracellular matrix?
Extracellular matrix is made up of:
- A gel known as Around substance which contains glycosaminoglycans (GAGs), proteins and glycoproteins.
- Fibres run through this matrix e.g. elastic and collagen
- An percolating tissue fluid i.e. a fluid that moves through the fenestrations of cells
What are the roles of fibroblasts and adipocytes”?
- Fibroblast: cells that make collagen, elastin and glycosaminoglycans
- Adipocytes - Cells that cells fat
Give the roles and structures of different mononuclear leucocytes.
Lymphocytes - dense nuclei. Poorly stained cytoplasm
Plasma cells - Granular nuclei and basophilic cytoplasm. Clock-faced nuclei. Antibody production
What is the role of macrophages? What is the role of mast cells?
Macrophages: phagocytosis of debris and pathogens
Mast cells: Anti-allergy, secrete vasoactive substances such as histamine.
Give the roles and structures of granulocytes.
Neutrophills: Most abundant, phagocytic. Multi-lobed nuclei.
Eosinophis: ‘Tomato wearing sunglasses’. Bilobed nuclei. Pink cytoplasmic granules (small lysosomes). Made in red bone marrow. Role is to respond to and destroy parasitic worms.
Basophils: Active in the inflammatory response.. Mostly found in the skin and mucosa lining (lining exposed to the external environment)
What is found in blood?
Red blood cells Platelets non-nucleated cells from megakaryocytes Proteins Immunoglobulins - immune Albumin – oncotic pressure/transport Fibrinogen - clotting Hormones Nutrients/metabolic waste Gases Plasma
What is the organisation of blood vessels?
Tunica intima - endothelium Tunica media - made up of smooth muscle cells, elastic tissue and collagen Tunica externa (adventita) - tough layer consisting mainly of collagen fibres that act as a supportive element. The large arteries differ structurally from the medium-sized arteries in that they have a much thicker tunica media and a somewhat thicker tunica adventitia.
What is lymph?
Since the lymph is derived from the interstitial fluid, its composition continually changes as the blood and the surrounding cells continually exchange substances with the interstitial fluid. It is generally similar to blood plasma, which is the fluid component of blood. Lymph returns proteins and excess interstitial fluid to the bloodstream. Lymph also transports fats from the digestive system (beginning in the lacteals) to the blood via chylomicrons (lipoproteins). Lymph is drained into the blood at the subclavian vein.
What are the functions of bone?
Movement Protection Haematopoieis Structure Calcium homeostasis
What are osteocytes?
Cells inside osteoid (bone) also made form osteoblasts.
What are osteoblasts?
Cells that make osteoid (extracelluar matrix). Osteoid can then be mineralised using calcium phosphate to make bone. When immature it is woven, when mature it is lamellar. Osteoblasts become tapped in osteocytes which maintain the bone.
What are osteoclasts?
Cells that resorb bone in repose to stress/growth/calcium status. They are formed from two or more cells that fuse together, so the osteoclasts usually have more than one nucleus.
