C1 Tissues and Cells Flashcards
What do parietal cells do?
Secrete acid
What do G cells do?
Secrete gastrin
What do epithelial cells do?
Separate one compartment from another, may be specialised for secretion.
What does connective tissue do?
Structural role, main types of cells are fibroblasts. Fatty connective (adipose) tissue, blood vessels.
What does nervous tissue do?
Sensory and motor signals.
What does muscle tissue do?
Role in support and movement.
What is basement membrane?
Mesh-like fibrous protein, anchors epithelial and endothelial cells to connective tissue.
Barrier of particles and macromolecules
What is hyaluronan? (Extracellular matrix)
Glycan (polysaccharide). Medical use = osteoarthritis and subcutaneous injections.
What is collagen? (Extracellular matrix)
Most abundant protein in the body, triple helix.. Medical use = cosmetic and reconstructive surgery.
What are the three types of epithelial cells? Examples?
- Simple epithelium (single layer) e.g. stomach and intestine.
- Stratified epithelium (multiple layers of cells) can be keratinised e.g. skin or non-keratinised e.g. oesophagus and inside mouth.
- Specialised epithelial cells (secretion) e.g. goblet cells, (microvilli) e.g. enterocyte, (cillia) e.g. lung epithelium.
Describe the gastric pit
Mucus layer- glycosylated proteins protective gel layer with neutral pH
Mucous cell/Neck cell - produce mucus and line most of the surface in the stomach
Parietal cell - produce gastric acid
Other cell types e.g. G cells produce gastrin and Chief cells produce pepsin
Connective tissue - fibroblast cells, blood vessels.
What is the basolateral membrane?
Faces the epithelial cells/supporting tissue
What is the apical membrane?
Faces the lumen
What are the three types of junction between cells?
- Tight junction prevents passage of small molecules and fluid between cells
- Anchoring junctions linked to cytoskeletal structures and provide rigidity in a group of cells
- Gap junctions provide channels between cells thereby facilitating movement of small molecules between neighbouring cells.
What is mucus?
Network of proteins with sugar polymers attached. Formation of a viscous layer (gel) due to sugar chains retaining water.
Secretion of HCO3-
Maintains a neutral environment at cell surface.
What is glycosylation?
Post-translational modification of amino acid chain with sugar moieties
What are the two types of glycosylation and where do they take place?
N-glycosylation in the endoplasmic reticulum
N-acetylglucosamine linked to asparagine
O-glycosylation in the golgi complex
N-acetylglucosamine linked to serine
What are the three important roles of glycosylation?
- secreted proteins e.g. components of gastric mucus
- blood type antigens
- immunity (transplant rejection)
What are the four steps to protein sorting?
- Synthesis/translation in rough ER (N-linked glycosylation)
- Vesicle transport form rough ER to golgi complex (O-linked glycosylation)
- Transport vesicles move to membrane
- Membrane fusion a. delivery of membrane bound proteins to surface, b. secretion of extracellular proteins
What are the features of an active parietal cell?
Large surface area to volume ratio
Small number of internal vesicles
Proton pump on apical surface
What are the features of an inactive parietal cell?
(resting)
Small surface area to volume ratio
Large number of internal vesicles (tubulovesicles)
Proton pump internalised
What causes gastric ulceration? (Final diagram)
Cell and tissue dammage –> Histamine released by Mast Cell ; signalling, immune cells invade area and cause swelling.
Increased blood flow causes redness and bleeding
Loss of protective function and pain caused
