Exam 1 – Lecture 3: Dr. Langston Flashcards
What are neurotransmitters release by?
Axon terminals into the synaptic junctions and act locally to control nerve cell functions
What are endocrine hormones released by? What do they influence?
Glands or specialized cells into the circulating blood and influence the function of cells at another location in the body
What are neuroendocrine hormones secreted by? What do the influence?
Neurons into the circulating blood and influence the function of cells at another location in the body
What does endocrine imply?
That it is produced in one place and then release into the blood stream (insulin)
What is the fight or flight response due to?
Neuroendocrine hormones
What are cytokines?
Peptides secreted by cells into the extracellular fluid and can function as autocrines, paracrines, or endocrine hormones
What are paracrines secreted by? What do they affect?
Cells into the extracellular fluid and affect neighboring cells of a different type
What are autocrines secreted by? What do they affect?
Cells into the extracellular fluid and affect the function of the same cells that produced them by binding to cell surface receptors
What are eicosanoids?
A large group of molecules derived from polyunsaturated fatty acids, primarily arachidonic acid
What are the principal groups of hormones of eicosanoids?
Prostaglandins
Prostacyclins
Leukotrienes
Thromboxanes
How are eicasanoids inactivated? How long are they active?
By being metabolized
Only for a few seconds
What is an agonist?
A substance that induces a physiologic action
What do physiological antagonists do?
Oppose that of another agonist
What is an antagonist?
A substance that blocks the action of an agonist
Does an antagonist normally exist in the body?
No, it is a drug
How do competitive antagonists bind to a receptor?
They do not permanently bind to a receptor. There is a constant release and reattachment of both agonist and antagonist
What is the magnitude of effect of competitive antagonists dependent on?
The amount of drug present and the affinity constant of that drug for the receptor
When do you have the maximum effect on the dose-response curve?
When all the receptors that can be occupied are occupied
What are the pathways for mechanism of action for hormones and cytokines?
Interaction with cell surface receptors
Interaction with intracellular receptors
What are interactions with cell surface receptors often associated with?
Ion channels or enzyme activations-rapid onset is common
What do interactions with intracellular receptors require?
Synthesis of proteins-onset delayed several hours
What is an example of interaction with cell surface receptors?
Gated ion channel
Enzyme-linked receptors
What is a good example of enzyme-linked receptors?
Insulin receptor
What does the insulin receptor form?
Dimer
What does insulin do?
Increases the facilitated diffusion of cell membranes and allows for glucose to diffuse through
What does lipid soluble hormone do in interaction with intracellular receptors?
Diffuses through the cell membrane and combines with cytoplasmic receptor
Where does the hormone-receptor complex migrate?
To the nucleus where protein synthesis is triggered
What does new protein do in interaction with intracellular receptors?
Alters transcriptional activity of responsive genes
What is an examples of interaction with intracellular receptors?
Steroid hormones
What do interactions with intracellular receptors require?
Protein synthesis so onset effect is typically delayed a few hours
