L9 Flashcards
What 4 reasons must the cell coordinate behaviour?
Comms with neighbouring cells
Adapt metabolism+nutritional requirements to nutritional state of body
Induce/decease division
Respond to danger signals
What can bone marrow stem cells differentiate to?
Erythrocytes B Lymphocytes Macrophages Neutrophils Eosinophils Blood platelets T lymphocytes Dendritic cells basophils Natural killer cells
IC signalling involves?
Synthesis/release of signal molecule Transport to target Detection by receptor Change in cell behaviour Removal of signal, removing response, sometimes req removal of receptor.
What 4 types of molecules can be used as IC signals and give examples of each.
Protein e.g. interferon, insulin
Peptides e.g. glucagon, GH(produced by cleavage of proteins)
Small chemicals e.g. steroids (from cholesterol), estradiol, cortisol, adrenaline, histamine
Dissolved gases (NO)
What is the signalling molecule that binds to a receptor?
Ligand
What must a cell have to respond to a signal?
Ligand present
Receptor + must be coupled to an IC signalling pathway
How can exposure to a signal affect receptor activity?
Temp/perm unavailable
Physically present but not function
Inactivated by signalling system
What are the 3 main categories of membrane receptors?
Ion channel
GPCR
Enzyme
What are the 2 ways receptor activation affects a cell?
Altered protein function to altered cytoplasmic machinery, to altered cell behaviour
DNA translates to RNA, altering protein synthesis, this then alter cytoplasmic machinery and cell behaviour
What molecules can cross directly across the membrane and bind to IC receptors?
Small molecules(NO), and hydrophobic molecules (steroids)
How can the same signal bring about diff responses?
Opp actions due to diff adrenergic receptors.
E.g. Adreniline
alpha = contract smooth muscle in gut
beta = relax smooth muscle in muscle
Give an example of a signalling molecule which can activate diff types of receptors and what receptors these are
Acetylcholine activate M1, and M2 receptors (Muscarinic-type GPCR). M1 cause secretion in salivary gland. M2 causes decrease force/rate contract in the heart.
It also activates Nicotinic-type Ion channels in skeletal muscle for the Na/K pump.
What are the 5 types of signals?
Which one is long range and which are short?
Endocrine - Long range Paracrine Neuronal Autocrine Juxtacrine
In endocrine signalling, how are reactions brought about?
Hormones released by an endocrine gland into the blood, act on a target cell which expresses correct receptor.
Hormones regulate cell reaction by affecting gene expression
In diabetes, describe what a-cells and b-cells do
B-cells release insulin when blood sugar is high recognised by islets of Langerhans, glucose can then be taken up from blood .
stream by adipocytes
a-cells release glucagon when blood sugar is low detected by islets of Langerhans, the liver then releases glucose
What can a glucocorticoid receptors do?
Activate/supressgene expressing producing both metabolic and anti inflammatory effects
How do paracrine signals work?
Signalling molecule released from 1 cell and diffuse to neighbouring cells.
Name 3 types of paracrine signals and an example of each
Proteins - Cytokines which generate an immune response
AA derivative - Histamine promotes local inflammation
Dissolved gas - nitrix oxide relaxes smooth muscles, dilates blood vessels
How does NO convert GTP to GMP
NO binds to guanylyl cyclase activates to cGMP from GTP.
cGMP relaxes smooth muscle increasing vasodialation
Short-lived cGMP hydrolysed to GMP by phosphodiesterase
How does neuronal signalling work?
NT travel across synaptic gap to adjacent target cell only
Name 4 NT and there derivative
Acetylcholine - derivative of choline, released by motor neurons innervating muscle cells
Serotonin - derivative of AA trp, mood modulation
Dopamine - derivative of AA tyrosine, fune-tuning motion
Endorphins - Peptide, released in pain
How do autocrine signals work?
Give an example
Secrete signalling molecules bind to own receptors to generate a change
Uncontrolled release of growth favotrs by cancel cells
How do juxtacrine signals work?
Contact-dependent signalling
Gap junctions channels form allowing small molecules to diffuse formed by connexons w 6 protein subunits w 20 types
Contact-dependent receptor ligand binding, direct cell to cell with the ECM
