Basic Science Concepts Flashcards
What is a substrate (ligand)?
A substance that creates a signal or produces an effect by binding to a receptor, enzyme or transporter
What is the definition of endogenous?
A substance that is produced by the body (such as naturally-produced substrate)
What is the definition of exogenous?
A substance that is produced outside of the body (such as a drug or other chemical)
What is an agonist?
A substance that combines with a receptor to initiate a reaction. Can be endogenous or exogenous (mimicking an endogenous substrate)
What is an antagonist?
A substance that reduces or blocks a reaction. Can be endogenous or exogenous
What is the definition of induction?
When a substance increases the activity of an enzyme
What is the definition of inhibition?
When a substance decreases or blocks the activity of an enzyme
What does the central nervous system include?
The central nervous system (CNS) includes the brain and the spinal cord
What is the function of the CNS?
The CNS controls the functions of the rest of the body by sending signals to the peripheral nervous system (PNS)
What are the two main systems of the PNS?
Somatic and autonamic
What does the somatic nervous system control?
The somatic nervous system (voluntary) controls muscle movement
What does the autonomic nervous system control?
The autonomic (involuntary) controls other bodily functions, such as digestion, cardiac output and blood pressure
What are neurotransmitters?
The body’s chemical messenger
How is signal transmission in the CNS and PNS accomplished?
NTs are released from presynaptic neurons into the synaptic cleft, then they travel to postsynaptic neurons or other parts of the body to exert their effect
What are some examples of common NTs?
Acetylcholine (Ach), epinephrine (Epi), norepinephrine (NE), dopamine (DA) and serotonin (5-HT)
What is the primary NT involved in the somatic nervous system?
Ach
Describe the mechanism of action of ACh in the somatic nervous system.
It is released in response to neuron signals and binds to nicotinic receptors (Nn) in skeletal muscles to affect muscle movement
What are the two main divisions of the autonomic nervous system?
Parasympathetic and sympathetic
Describe the parasympathetic nervous system (PSNS) and how it works.
The PSNS is known as the “rest and digest” system. The PSNS works by releasing ACh, which binds to muscarinic receptors located throughout the body, including the GI tract, the bladder and the eyes. This results in a physiologic response known as SLUDD (salivation, lacrimation, urination, defecation and digestion)
Describe the sympathetic nervous system (SNS) and how it works.
The SNS is known as the “fight or flight” system. The SNS works by releasing Epi and NE, which act on adrenergic receptors (alpha-1, beta-1 and beta-2) in the CV and respiratory system. Activation of this system results in increased BP, HR and bronchodilation. Stimulation of beta-2 receptors in the GI tract increases glucose production to provide muscles with oxygen and energy. When the SNS is activate, functions like digestion and urination are minimized to focus on the more important bodily functions for “fight or flight”
What is the mechanism by which cells communicate and send signals?
The substrate binds to receptors on the receiving cell to cause a signal or change. Substrates can be endogenous or exogenous. Once bound, the receptor substrate complex causes some change that results in a biological effect (e.g. secretion of hormone, contraction of muscle)
What is competitive inhibition?
Competitive inhibition occurs when an antagonist binds to the same active site of a receptor as the endogenous substrate, preventing the activity
What is non-competitive inhibition?
In non-competitive inhibition, the antagonist binds to the receptor at a site other than the active site (called the allosteric site) which changes the shape of the active site and prevents the endogenous substrate from binding
What is an example of a beta-2 agonist?
Albuterol
What is the MOA of albuterol?
Albuterol, a beta-2 agonist that behaves similarly to epinephrine. It binds to beta-2 receptors in the lungs, which activate several steps and results in bronchial smooth muscle relaxation
What is the MOA of beta-1 blockers?
Beta-1 blockers prevent adrenergic neurotransmitters from binding to beta-1 receptors in the heart. By blocking the receptor, beta-1 blockers decrease heart rate and contractility
What is the endogenous substrate for the muscarinic receptor?
Acetylcholine
What are some examples of drug agonists of muscarinic receptors and what is the agonist action?
Pilocarpine and betanechol increases SLUDD
What are some examples of drug antagonists of muscarinic receptors and what is the antagonist action?
Atropine, oxybutynin decreases SLUDD
What is the endogenous substrate of nicotinic receptors?
Acetylcholine
What is an example of a drug agonist of nicotinic receptors and what is the agonist action?
Nicotine increases HR, BP
What is an example of a drug antagonist of nicotinic receptors and what is the antagonist action?
Neuromuscular blockers (e.g. rocuronium) causes neuromuscular blockade