L3&4. Cells And Tissues Flashcards
Define tissue
Groupings of cells with similar morphology that perform a particular function
Define organ
Group of tissues that perform a particular function
Define system
Group of organs that work together to perform a specific function
Name the 4 components of blood
Plasma
Erythrocytes = RBC
Leukocytes = WBC
Platelets
4 Functions of connective tissue
Binds cells an organs together
Provides structural support
Contains blood vessels and tissue defence mechanisms
Important in tissue repair
What is the ECM
Major component of connective tissue
Made of protein fibres in a hydrated carbohydrate rich gel
In vivo all cells are in contact with it
Carries a machanicak load
What is the difference between plant and animal ECM composition
Plant comtains cellulose
Describe the structure of collagen
Triple helices
Rich in proline and glycine
Synthesised as pro alpha chains
Can associate outside of the cell forming fibrils and fibres (covalent cross links between molecules)
What is the function of collagen
Tensile strength
Structural support
What is the structure of elastin
Contains proline and glycine
Molecules form cross links = fibres
Microfibrils cover the elastin core
What is the function of elastin
Allows cells to reform their dhape after being stretched
What is the structure of fibronectin
Large non collagenous glycoprotein
2 subunits linked by disulfide bonds
Binds to the cell surface by the Arg-Gly-Asp tripeptide
What is the function of fibronectin
Bind to the ECM to the cell surface
What is the structure of GAGs
Unbranched polysaccharide
High negative charge from S and OH groups
Repeat units of amino sugar and Uronic acid
How is the ECM synthesised
By the cell in it
Eg. Cartalige contain chondoblasts that secrete the ECM
How is the ECM degraded
Locally by extra cellular proteases
Give 2 examples of proteases that degrade the ECM
Metalloproteases and serine proteases
How is ecm degradation controlled
Proteases are secreted as inactive precursors and tvhen activated by protein modification
Protease inhibitors can block secretion
How do cells binds to other cells
Integrins
What are integrins
Cell surface receptors
Transmembrane glycoprotein that link cytoskeleton to the ECM
Located in cell-matrix junctions
What is the structure of integrins
2 non covalently bonded sub units
What are syndecans
Co receptors
Cell surface proteoglycans
What are the functions of the ECM
- Provide structural support
- Aid cell migration (basement membrane)
- Bind peptide growth factors
- Integrins inform the cell about their environment
Function of epithelial tissue
Protect lower surfaces from physical damage and UV radiation
Absorption and secretion
Define simple epithelia
1 layer
Define stratified epithelia
1+ layer of cells
Define pseudostratified epithelia
Mono layer but cells have nuclei at different heights
Define squamous epithelia
Fiat
Define cuboidal epithelia
Square shaped
Define columnar epithelia
Rectangular (height>width)
Define translational epithelia
Change height depending on if it’s stretched or relaxed
Function of simple epithelia
Diffusion and absorbance
Example of where simple epithelia is found
Alveoli
Intestine
What is the function of stratified epithelia
Protection
Where is stratified epithelia found
Skin
What is an occluding junction
Seals spaces Between cells
Prevent leakage of water soluble substances
Maintain cell polarity
What proteins are used in occluding junctions
Occluding and Claudin
What are communicating junctions
Allow communication between cells
Intercellular channels
Allow diffusion of ions
What are anchoring junctions
Connect cytoskeleton of adjacent cells
Give mechanical strength
What are the 2 types of anchoring junctions
Adherens and desmosomes
What are the 3 types of muscle
Skeletal, smooth and cardiac
Function of skeletal muscles
Body movement
Type of cells in skeletal muscle
Elongated
Multinucleated
Myofibrils
Function of smooth muscle
Apply pressure to vessels and organs
What type of cells are in smooth muscle
Mononucleated
Small cells
Branched and irregular fibre bundles
No cross striations
What types of cell is in cardiac muscle
Long
1/2 nuclei per cell
Striations
A little branched
What does PNS stand for
Pereipheral nervous system
What does somatic stand for
Voluntary
What does autonomic mean
Involuntary
What are glial cells
Support and protection cells
Receive no electrical impulses
What is grey matter
Neurone cell body + axons
What is white matter
Myelinated nerve fibres
