lecture 3 Flashcards
Rate of reaction depends on?
Conc of substrates
Rates are more sensitive to conc at cones near or below their kM
Rate is insensitive as enzyme becomes saturated
If livers km is the highest for glucose , what does this mean
More able to respond to increases in glucose than any other tissue
In fed state, liver and pancreas are able to take up glucose more quickly than other tissues §
Endocrine system features
Used alongside nervous system to control organ systems and maintain homeostasis
Uses hormones in bood stream
How are the endocrine and nervous system connected
Directly via the hypothalamus and pituitary gland
Signal transduction
Converting one type of signal to anotherS
Neuronal signalling
Action potentials transmitted along axon
When signal reaches nerve terminal, causes release of neurotransmitters onto adjacent cells
Contact dependent signalling
Cell surface bound molecule binds to a protein receptor on an adjacent cell
No molecules released
paracrine signalling
released by cells into extracellular fluid in their neighbourhood as local mediators
Endocrine signalling
Secreted into the blood stream and distributed WIDELY
Cell surface receptors
Most extracellular signal molecules are large and hydrophilic - can’t cross membrane
Generate intracellular second messagner signalling molecules
Intracellular receptors
Some small hydrophobic extracellular molecules pass through membrane and bind to intracellular receptors that regulate eg gene transcription
How does AcH effect heart peacemaker cell, salivary gland cell and skeletal muscle cell
Heart = decreased rate of firing Salivary = secretion Skeletal = contraction
Processes that rely on altered protein function - eg movement secretion and metabolism are ..
fast
Processes that rely on altered protein synthesis e.g. differentiation, growth and division are …
slow
explain the pathway from extracellular signalling molecule
Signalling molecule receptor protein Intracellular signalling molecules Effector proteins Target cell responses
