L. 16 Cells, tissues and communication Flashcards
L.O.
- Explore the ways that cells aggregate with each other to form tissues
- Compare and contrast the four types of animal tissue.
- Explain how cells communicate and regulate cell growth in a healthy state (e.g. differentiation of stem cells)
- and what can go wrong to result in a pathophysiological state
(e.g. cancer).
4 major tissue types
- Epithelial
- Connective
- Muscle
- Nervous
Epithelial tissue
- Interface between animal and environment
- Allows for molecules to diffuse
- Basal Lamina anchors epithelial tissue
Connective tissue
Connects epithelial to muscle & nervous tissue
Non-living, ground substance & fibres = matrix
.
3 components:
- Fibres
- Cells
- Ground substance
Muslce tissue
3 subdivisions
- Cardiac
(branched fibres, striated, intercollated disks, involuntary, usually 1 nuclei)
- Smooth
(Spindle shaped, non-striated, involuntary)
- Skeletal
(long & non-branched fibres, striated, multinuclei, voluntary)
Classifying epithelial sheets
- Stratisfied
- Pseudostratisfied
- Simple Squamous
- Simple Cuboidal
- Simple Columnar
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- Some areas of body need multiple layers due to some cells breaking off (oesphegus)
- Microvilli on Pseudostratisfied epithelial cells allow for increased SA transport proteins.
- Squamous cells = flat/ squat
Epithelia cells
- anchored by basal lamina
- Have polarity (top = apical region bottom = basal region)
- Tight junctions create waterproofing by strings of proteins holding the cells together
.
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. - Actrive transport through apical membrane, but passive though basal mambrane
Desmosomes
- Form a structurally strong connection between epithelail cells
- Reinforce by intermediate filaments to hold structure together
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Desmosomes in cell
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- Plaque (portal that connects cadherins)
- Cadherins (Interlock to hold different cells together via plaque)
- Intermediate filaments (Inside cell connecting plaque)
- Hemidesmosomes (Bottom of cell anchoring to basal lamina/ basement membrane)
Cancer
- Often forms in epithelial tissue due to the rapid turnover in cell life. Consequently more chances for mistakes
- The basal lamina holds back the cancer from being malignant/ metastatic.
Nervous tissue
- Allows the animal to have coordinated movement and bahaviour
- Explains how cells are depolarized for muscle movement
How cells coordinate physiological processes
- Often via signals then have physiological output
- Cells can affect cytoplasm and nucleus
- Protein hormones require a receptor on outside of cell to get in
- Steroid hormones require receptor on inside of cell (can pass through membrane)
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Cells impact on nucleus and cytoplasm
- Protein hormone attaches to receptor on cell
- Signal entres the cell and can either go into nucleus or cytoplasm
Into Nucleus:
- Causes transcription and translation
- Slow process
Into Cytoplasm:
- alters enzymes and cytoskeleton
- Faster process
Different types of cell signals
Steroid Hormones:
- straight through membrane
- to receptor
- into nucleus
- turns on a gene
Neurotransmitters:
- To receptor on membrane
- Channel opened
- ions rush in
- cell depolarized
Protein Hormones:
- To receptor on membrane
- Triggers mesenger system
- message sent to nucleus or cytoplasm of cell
- Messanger = Cyclic AMP
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Cyclic AMP (CAMP)
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- Stimulates protein kinase
- Kinase phosphorylates a protein
