Week 1 Flashcards
(24 cards)
Autocrine Regulation
A cell communication mechanism in which the signalling molecules bind to receptors located on the cell secreting the signalling molecules
What is an example of autocrine regulation
The regulation of somatostatin in the stomach
Where is somastatin secreted from and what does it bind to
Secreted from D cells in the gastric glands.
Binds to SST2R receptors (on the D cells themselves)
What happens when somastatin binds to SST2R receptors
Inhibits adenylyl cyclase > decreases cAMP > decreases gastric acid secretion from parietal cells
What happens when somastatin binds to SST2R receptors on the D cells
A negative feedback loop is created and reduces somastatin receptors
What is paracrine regulation
A cell communication mechanism in which the signalling molecules are secreted into the extracellular space and bind to receptors located on the adjacent cells without passing through the circulatory system
What is an example of paracrine regulation
Histamine in the stomach
What is histamine secreted by, and what does it bind to?
Enterochromaffin-like cells in the gastric glands, in response to stimulation by acetylcholine.
Binds to H2 receptors with subsequent activation of adenyl cyclase
What does the action of histamine in the stomach via paracrine regulation cause?
An increase in cAMP, which increases the number of proton pumps, increasing gastric acid secretion from parietal cells
what are parietal cells
The largest cells in the stomach glands (in the fundas and the body)
What types of regulation are responsible for the release of gastric acid in the stomach?
Paracrine , endocrine and neural pathways (synaptic transmission)
Neurotransmitter
A chemical substance released from a neutron to bring about the transfer of an impulse to another neuron
Name some common neurotransmitters
Acetylcholine
Adrenaline
Dopamine
Glycine
Histamine
Noradrenaline
Serotonin
Glutamate
GAMA
What is endocrine regulation
A cell communication mechanism in which the signalling molecules are secreted from cells located in secretory glands into the circulatory system. Allowing for the signalling molecules to travel over a relatively large distance, eventually binding to receptors located on/in cells of a target organ/tissue
What is an example of endocrine communication
The hypophyseal portal system.
Hormones such as ACTH are secreted from the pituitary glands into the connected circulatory vasculature.
Actions of Cortisol
Maintains blood pressure
Facilitated stress response
Immune system suppression
Protein breakdown and liberation of fatty acids
Stimulates gluconeogenesis in the liver
Ligand-gated Ion Channels
Response occurs in miliseconds
Hyperpolarisation or depolarisation of ions
E.g. nicotinic or ACh receptor
G protein-coupled receptors
Response occurs in seconds
Ions go through change in excitability
E.g. Muscarinic, ACh receptor
Kinase-linked receptors
Response in hours
Ions go through protein phosphorylation > gene transcription > protein synthesis
E.g. cytokine receptors
Nuclear receptors
Response in hours
Receptor in the nucleus to then activate gene transcription > protein synthesis
E.g. Oestrogen receptor
Nicotinic acetylcholine receptors
Permeable to Na+, K+ and Ca2+
Non-specific cation channels
Modulate fast synaptic excitation
Intracellular receptors
Protein monomers located in the nucleus of the target cell and contain DNA-binding domains, allowing for the control for gene transcription.
Are steroid hormones hydrophilic/lipophilic or hydrophobic/lipophobic and can they pass through plasma membrane
Steroid hormones are lyophilic/lipophilic and can pass through the plasma membrane
When the steroid hormones pass through the plasma membrane what 2-step process occurs?
Activated hormone-receptor complex forms within the cell
The complex binds to DNA and activates specific genes
- gene activation leads to production of key proteins
