Cell Signaling Flashcards
What are the four reasons we need cell signalling?
- To process information
- For self preservation
- For voluntary movement
- For homeostasis
What is meant by self-preservation?
The activation of the reflex arc to protect ourself from danger
What are the two systems which provide the main lines of communication?
Nerve fibers of the central and peripheral nervous system
Blood vessels of the cardiovascular system
What line of communication is used for a rapid, instantaneous response?
The nerve fibres of the CNS and PNS
What line of communication is slower and more versatile?
The blood vessel system
What is meant by intercellular signalling?
Signalling between cells
What is meant by intracellular signalling?
Signalling within a cell
What are the four methods of signalling?
- Autocrine
- Endocrine
- Paracrine
- Communication between membrane attached proteins
What is meant by endocrine communication?
When the hormone travels in the blood vessel and acts on a distant target cell
How does glucagon act as an example of endocrine signalling?
Glucagon is released by the alpha cells of the Islets of Langerhans, and then transported in the blood to act on the liver, to stimulate glyconeogenesis and glycogenolysis to make more glycogen and glucose
How does insulin provide an example of endocrine communication?
Insulin produced by the pancreas acts on muscle and adipose tissue
How does adrenaline provide an example of endocrine communication?
Produced by the adrenal glands and travels in the blood to act on many body systems like the lungs and trachea
What type of communication is shown in response to hypoglycaemia?
Endocrine
What type of communication is shown in response to hyperglycemia? and why
Paracrine and Endocrine - when blood glucose levels are too high, insulin is released which inhibits the secretion of glucagon from the alpha islet cells
Endocrine effects on the liver ie reduced glycogenolysis
What is meant by paracrine communication?
When the home that is released acts on the adjacent cell
How does the pancreas show paracrine communication?
Insulin produced by the Beta cells acts on the ALpha cells of the islet of langerhans to inhibit glucagon production
Describe how nitric oxide acts in a paracrine manner
Nitric Oxide produced by the endothelium in blood vessels, acts on the smooth muscle to vasodilate the vessels
What is meant by membrane attached protein comunication?
When plasma proteins in the membrane of two different cells interact
Describe an immunological example of membrane-attached protein communication
An APC detects blood borne virus
Digests it and presents its antigens on MHC
A circulating T cell then interacts with the MHC through T cell receptors
What is meant by autocrine communicaiton?
When a hormone acts on the same cell that produced it
How do T cells display autocrine forms of communication?
When T cells become activated they express IL-2 receptors, as well as release IL-2 which mediates cytokine release
Describe how neurotransmission occurs?
- Acton potential arrives at the synapse due to an influx of sodium ions into the pre-synaptic bouton
- This triggers the opening of voltage gated calcium channels, allowing an influx of Ca2+ into the neurone
- Ca2+ binds to vesicles containing NT
- The NT vesicles then move to the cell membrane and are released into the synapse through exocytosis
- They then bind to receptors n the post-synaptic neurone
What are the four distinct categories of receptors which exist?
- Ligand Gated Ion channel receptors
- G Protein coupled receptors
- Enzyme-linked receptors
- Intracellular receptors
How do ionotrophic receptors work?
When an appropriate ligand binds to the ligand-binding domain on the external surface of the protein the pore opens due to a conformational change, allowing ions to move in or out