S2) Integrating Cells into Tissues Flashcards
How are cells held together in a tissue?
- Cells are held together in a tissue through their attachment to each other (lateral domain)
- This involves tight junctions, desmosomes and gap junctions
What is the basement membrane?
The basement membrane is the structural site for overlying cells and underlying connective tissue
How do cells attach to the basement membrane?
- Hemidesmosomes – found in tissues subject to abrasion, such as skin, epithelium of oral cavity
- Focal adhesions – that anchor intracellular actin filaments to the basement membrane
What are integrins?
Integrins are transmembrane proteins that function mechanically, by attaching the cell cytoskeleton to the extracellular matrix (ECM), and biochemically, by sensing whether adhesion has occurred.
What are the two main functions of integrins?
- Attachment of the cell to the ECM
- Signal transduction from the ECM to the cell
Outline the 3 forms of cell renewal in living body and where it occurs
- Static – CNS, cardiac and skeletal muscle cells
- Stable – fibroblasts, endothelium, smooth muscle cells
- Renewing – blood, skin epithelium, gut epithelium
Why is cell renewal significant?
There is a relationship between cell renewal rate and the propensity to develop cancer
Outline the endosymbiotic theory
- Ancestral eukaryotes lived symbiotically with prokaryotes
- These eukaryotes engulfed the prokaryotes which then evolved to become intracellular mitochondria
- The mitochondria share DNA, replication patterns, rRNA, RNA with prokaryotes
What are the four basic tissue types?
- Epithelial
- Muscle
- Nerve
- Connective tissue
What are the 6 specialised connective tissues?
- Cartilage
- Haemopoietic
- Lymphatic
- Adipose
- Bone
- Blood
What is epithelium?
Epithelium: a tissue composed of cells that covers the exterior body surface and lines internal closed cavities and body tubes that communicate with the exterior
Identify the 3 different types of apical domain of epithelial cells
- Microvilli
- Cilia
- Stereovilli
What are microvilli?
Microvilli are cytoplasmic processes that extend from the cell surface e.g. intestine and kidney tubule
What are cilia?
Cilia are motile cytoplasmic processes that can beat in synchrony e.g. tracheobronchial tree and the oviducts
What are stereovilli?
Stereovilli are particularly long microvilli limited to epididymis and sensory hair cells of the ear
What is necrosis?
Necrosis is a form of cell injury which results in the premature death of cells in living tissue by autolysis
What is apoptosis?
Apoptosis is a naturally occurring programmed and targeted cause of cellular death
Why is necrosis worse than apoptosis?
- Necrosis is always detrimental and can be fatal
- Necrosis does not follow the apoptotic signal transduction pathway
- Necrosis results in the loss of cell membrane integrity and an uncontrolled release of cell contents into the extracellular space
Why do necrotic cells swell and burst?
Necrotic cells swell and burst because of failure of action of Na, K ATPase
Define osmosis
Osmosis is the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration until dynamic equilibrium is reached
What is oncotic pressure?
Oncotic pressure is a form of osmotic pressure exerted by proteins (albumin) in a blood vessel’s plasma that usually tends to pull water into the circulatory system
