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
The stress response
- Thalamus part of 3rd ventricle
- Hypothalamus converts concious knowledge into an endocrine signal
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.
1. Hypothalamus releases Corticotrophic releasing hormone (CRH)
2. CRH travels down to anterior pituitary gland, stimulating Adrenocortico Trophic Hormone (ACTH)
3. ACTH goes to adrenal cortex signalling release of cortisol.
4. Cortisol has a negative feedback on the hypothalamus and pituitary, preventing more CRH and ACTH.
5. Cortisol breaks down fats and proteins for energy.
