Signalling between Cells 1 Flashcards

1
Q

Why do cells need to communicate?

A

Process Information - sensory stimuli

Self Preservation

  • spinal reflexes
  • Sympathetic nervous system

Voluntary Movement

Homeostasis

  • Thermoregulation
  • Glucose Homeostasis
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2
Q

What happens during Hypoglycaemia?

A

Glucagon - secreted by alpha cells in the IoL

Stimulates gluconeogenesis and glycogenolysis in the liver

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3
Q

What happens during Hyperglycaemia?

A

Insulin - secreted by beta cells in the IoL

  • it has paracrine effects
  • inhibits glucagon secretion by nearby alpha cells
  • has endocrine effects on liver cells.
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4
Q

Examples of Paracrine Signalling?

A

Nitric Oxide produced by endothelial cells in blood vessels

Osteoblast activating factors produced by adjacent osteoblasts

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5
Q

Describe signalling between membrane attached proteins?

A
  • blood borne virus detected in the blood stream by an APC
  • APC digests the pathogen and expressed MHC class II on the surface.
  • T-lymphocytes engages with the MHC molecule through TCR interaction
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6
Q

Describe Autocrine Signalling?

A
  • Activated T lymphocyte initiates cascade of reactions
  • Activated T lymphocyte IL-2 receptor on surface
  • Activated T lymphocyte secrete IL-2
  • IL2 binds to receptor on its own surface having an effect on its cell
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7
Q

Describe signalling at the Neuromuscular Junction?

A
  • VGSC opens –> membrane depolarisation
  • VGKC opens –> membrane repolarisation
  • VGCC -> Calcium influx -> vesicle exocytosis
  • Acetylcholine binds to sarcolemmal nicotinic receptors
  • ACh is metabolised by cholinesterase and recycled
  • Ca2+ is a second messenger
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8
Q

Identify Receptor Types?

A

Ionotropic Receptor - ligand binding opens an ion permeable pore
G-protein coupled receptor - ligand binding activates intracelllar G-protein
Enzyme-linked receptor - ligand binding leads to receptor clustering which activates internal enzymes.
Intracellular Receptor - a membrane permeable ligand binds to a receptor inside the cell.

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