endo system regulates activities that require _____ rather than _____.
where do endo glands act in relation to where they are secreted?
located a long distance from the endocrine gland
how do cells most commonly communicate with one another?
indirectly thru extracellular chemical messengers or signal molecules
4 types of chemical messengers or signal molecules?
rapidly inactivated, diffuses to local cell area (ex histamine)
describe neurotransmitter secretion:
short term chemical messengers in response to electrical activity
describe hormone secretion:
Long range chemical messengers travel via blood to specific target cell
Endocrine hormone molecules are secreted directly into:
the bloodstream, typically into fenestrated capillaries
describe neurohormone secretion:
neurohormone goes into the blood and acts on a distant target cell (ex vasopressin (ADH))
signal transduction functions like a:
occurs when an:
extracellular signaling molecule activates a receptor
what are protein kinases?
enzymes that transfer a phosphate group from ATP to a particular intracellular protein
what does this phosphorylation do?
alters protein shape and function and it becomes “activated”
Protein kinase is activated on binding of the signal molecule to the surface receptor in one of two ways:
The Tyrosine Kinase Pathway
The Second Messenger Pathway
describe how receptor becomes activated in the tyrosine kinase pathway:
the simplest of the 2 pathways
the receptor itself functions as an enzyme aka " receptor enzyme"
An enzyme site on the cytoplasmic side of a receptor enzyme is activated when an extracellular messenger binds to the side facing outside the cell
The activated receptor bound enzyme ultimately leads to the cellular response
what occurs upon activation in the tyrosine kinase pathway
2 extracellular messengers bind with2 receptors & receptors pair, activating receptor's protein kinase site
protein kinase sire self-phosphorylates receptors tyrosines
inactive designated protein binds to receptor, which phos's it- activating it
active designated protein brings about desired response
Most extracellular chemical messengers activate second messenger pathways via:
describe what occurs upon binding and activation of the G protein:
-Activated G protein serves as a membrane bound intermediary that shuttles along the membrane to alter the activity of a nearby membrane protein called the effector protein
-Once altered, the effector protein leads to an increased concentration of an intracellular messenger, known as the second messenger
what does the second messenger do?
•Second messenger via cascade of reactions activates designated proteins which accomplish the cellular response dictated by the first messenger
•Most commonly, the second messenger activates an intracellular protein kinase, which leads to Phosphorylation and thereby altered function of designated proteins
what are G proteins?
also known as guanosine nucleotide-binding proteins,
are a family of proteins involved in transmitting signals from a variety of different stimuli outside a cell into the inside of the cell
what do G proteins do?
•G protein-coupled receptor and G proteins working together, transmit signals from many hormones, neurotransmitters, and other signaling factors
•G proteins regulate metabolic enzymes, ion channels, transporter, and other parts of the cell machinery, controlling transcription, motility, contractility, and secretion, which in turn regulate diverse system functions