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Flashcards in Cells Into Tissues Deck (31):

Name three times of cell that exist in single form.

Red blood cells


How do you store single cells?

Cryopreservation/ Freezing
- Also can be used for early embryos
- Packed red cells can be stored at 6oC for 42 days or frozen for 10 years (rarely)


Describe what is meant by cell attachment in the lateral domain.

Cells attached, side to side.
Epithelial cells form barricade with no gaps between cells
Cell junctions (tight, desmosomes,gap junctions)


What is a tight junction?

- Tightly connect adjacent epithelial cells.
- Fused plasmalemma forms a seal, preventing molecules move between the cells, must move through the cells (Selective barrier).
- Found in intestine epithelium.


What is a desmosomes?

- Strengthen adjacent epithelial cells & tight junctions.
- Found under/ next to tight junctions
- Between epithelial cells that need to withstand physical stress e.g. Skin (twisting and stretching).
- Consists of proteins and intermediate filaments that link the cells


What is a gap junction?

- Allow cell to cell communication
- Have connexons (protein channels) that allow movement of ions and molecules


How do cells attach to the basement membrane?

Focal adhesions or hemidesmosomes


What is a hemidesmosome and where do you find them?

- Hemidesmosomes attach one cell to the extracellular matrix using integrins.
- Hemidesmosomes are asymmetrical
- Found in epithelial cells connecting the basal face of the cell to basal lamina.
- Found in tissues subject to abrasion, such as skin, epithelium of oral cavity


What is a focal adhesion?

- Anchor intracellular actin filaments to the basement membrane.
- Play a prominent role in cell movement such as migration of epithelial cells in wound repair


What are integrins?

- Integrins are transmembrane proteins
- Attach the cell cytoskeleton to the extracellular matrix (ECM)
- Sense whether adhesion has occurred


What is the function of an integrin?

– Attachment of the cell to the ECM
– Signal transduction from the ECM to the cell
- Also involved in a wide range of other biological activities, including immune patrolling and cell migration


How do you culture cells?

- Separate cells from tissues using collagenase or microdissection.
- The cells can then be cultured in Petri dishes or flasks.
- Need to provide nutrients, control pH, temperature (incubator) and oxygen
- Prevent bacterial contamination using Class 2 microbiology safety cabinet


How does separating a cell from its tissue causes it to act in a different way ?

- Cultured cells behave differently and look different to the same cells in tissues
1. They demonstrate contact inhibition (stop growing once they touch)
2. Cultured cells have a limited life span. They demonstrate senescence


How do cells communicate through gap junctions?

Via connexons


What is autocrine communication?

Autocrine signaling is a form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell.


What is paracrine communication?

Paracrine signaling is a form of cell-to-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behavior or differentiation of those cells.


What is endocrine communication?

Endocrine communication is carried out by endocrine cells releasing chemicals called hormones into the bloodstream, which alters the metabolic activities of many tissues and organs simultaneously


What is synaptic communication?

In a chemical synapse, electrical activity in the presynaptic neuron is converted (via the activation of voltage-gated calcium channels) into the release of a chemical called a neurotransmitter that binds to receptors located in the plasma membrane of the postsynaptic cell.


What is neurocrine communication?

A type of cell signaling similar to paracrine, but involving neurons


What are the four types of tissue?

– Epithelial
– Muscle
– Nerve
– Connective tissue (general connective tissue)


What is the 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.
- Epithelium also forms the secretory portion of glands and lines their ducts.
- In addition, specialised epithelium functions as receptors for the special senses (smell, taste, hearing and vision)


What is an epithelioid cell cell? Give an example.

- An epithelial cell that does not have a free surface
• Leydig cells in the testis, lutein cells of the ovary
• Islets of Langerhans in the pancreas
• Parenchyma of the adrenal gland


What are microvilli?

Cytoplasmic processes that extend from the cell surface. Examples are intestine and kidney tubule


What are cilia?

Motile cytoplasmic processes that can beat in synchrony with a rapid forward movement called the effective stroke and a slower return recovery stroke.
Examples are the tracheobronchial tree and the oviduct


What are stereovilli?

Particularly long microvilli limited to epididymis and sensory hair cells of the ear


Describe the process of endocytosis.

- Bulk transport of particles into the cell

1. Membrane forms a pouch surrounding particles outside of the cell
2. Buds off to form vesicle inside the cell
3. Contents released to the cytoplasm


Describe the process of endocytosis

Bulk transport of particles out of the cell

1. Vesicle containing waste products fuses to membrane
2. Contents released out of cell
3. Membrane smooths out


What is apoptosis?

- Programmed cell death
- Molecular signals promote or continually inhibit apoptosis


What is necrosis?

- Physical disruption to the cell through injury, toxins or nutrient deprivation


How can bacteria cause cell necrosis?

- Bacteria release toxins
- Toxins disrupt cell structure and function
- Induces tissue damage and inflammation
- Cell bursts
- Cellular components spill from membrane


How does the Bcl-2 protein, on the outer mitochondrial membrane, inhibit apoptosis?

- Deactivating bcl-2 initiates apoptosis through a chain of enzyme reactions
- Catabolic processes begin through the cell
- Enzymes digest cytosolic components and fragment the DNA
- Specialised cysteine proteases (capases) target specific proteins in the nuclear lamina and cytoskeleton
- The cell is re-packaged for safe removal
- Chromatin condenses/ aggregates
- Cell shrinks and fragments into small membrane- bound apoptotic bodies
- Compacted cell is engulfed by phagocyte