Introduction to Drugs of the CNS Flashcards
What pharmacological and psychological effects can drugs have on the CNS?
Relief of Pain Induction to Anesthesia Prevention of Epileptic Seizures Treatment of Depression Reduction of Anxiety
Why is there special importance attached to CNS drugs? What are examples to this?
Special importance (humans): recreational uses -> addiction/overdose
(alcohol, tea and coffee, nicotine, cannabis, ecstasy, opioids, cocaine, amphetamines)
What are CNS agents?
CNS agents are medicines that affect the CNS
CNS drugs affect the brain’s use and output of ____________.
CNS drugs affect the brain’s use and output of neurotransmitters (NT)
Drugs can speed up and slow down the productions of _________.
- Neurotransmitters
What are analgesics?
- Narcotic (pain relievers)
- NonNarcotic (acetaminophen and NSAIDs)
What are components of the PNS?
Nerves
What are components of the CNS?
Brain, Spinal Cord
What is the afferent nervous system?
Sensory system that conveys information from the receptors to the CNS
What is the efferent nervous system?
Motor system that conveys information from CNS to the muscles and glands.
The CNS Has routes of incoming stimuli and outgoing stimuli/ actions. What are they called? What are they a part of?
Afferent -> sensory -> input
Efferent -> motor > output
Part of the PNS
What are components of the efferent system?
SNS -> Somatic Nervous system -> information from CNS to skeletal muscle
ANS-> autonomic nervous system -> CNS to 1.) smooth muscle. 2.) cardiac muscle, 3.) glands.
What are components of the autonomic nervous system (categories)?
- Enteric nervous system
- Sympathetic NS
- Parasympathetic NS
What is Sympathetic and parasympathetic stimuli?
- Parasympathetic -> Feed or breed, rest and digest, counteracts sympathetic, lower heartrate.
- Sympathetic -> Emergency/ stress, fight or flight, allows body to function under stress. Increased heartrate, counteracts parasympathetic
What are the differences between human and dog brains?
Lots of similarities, dog brains are smaller, have less surface area, less folds
What is the composition of a nerve?
A Nerve is formed of nervous tissue (neurons plus blood vessels)
What is an efferent nerve?
- Efferent nerve: nerves that conduct signals from the CNS along motor neurons to their target muscles and glands
What are afferent nerves?
Afferent nerve: carries nerve impulses from sensory receptors or sense organs toward
the CNS
What are mixed nerves?
Mixed nerve: nerves that contain both afferent and efferent axons, and thus conduct both incoming sensory information and outgoing muscle commands in the same bundle
What are spinal nerves?
Spinal nerve: mixed nerve that carries motor, sensory, and autonomic signals between the spinal cord and the body
What cells are the building blocks of the CNS?
The building blocks of the CNS are two types of cells: Neurons and Glial cells
What are neurons?
Neurons are specialized nerve cells that can receive and transmit chemical and electrical signals
What are glial cells/ neuroglia?
Glial cells or neuroglia: (support functions) Astrocytes
Oligodendrocytes (provide myelin for many axons)
Microglial cells
Ependymal cells
What is the structure of a neuron ?
A.) Dendrite
B.) Soma
C.) Axon
D.) Axon Terminal
How do neurons communicate?
The process is occurring via orchestrated chemical (release of neurotransmitters) and electrical (alteration of neuronal membrane potential) actions
What is the arrow pointing at?
What are action potentials?
Action potentials are electrical signals carried along neurons. (nerve impulse): the change in electrical potential associated with the passage of an impulse along the membrane of a neuron
- All or nothing (on off switch) , one directional ( from body to axon terminal)
What are neurotransmitters?
Neurotransmitters: the chemical messengers released from presynaptic neurons so they can “talk” to neighboring cells
What are neuron receptors?
The Receptor on the neighboring cell is for “hearing” the message
What are synapses? What are the kinds of synapses?
Synapses are junctions that allow signals to pass.
Chemical synapse:
* Ionotropic receptors (Ligand-gated ion proteins)
* Metabotropic receptors (G-protein coupled proteins)
Electrical synapse:
* Gap junction proteins
What causes electrical signals? What is the membrane potential?
Electrical signal happens when the polarity across their plasma membrane changes Membrane potential: the differences between inside and outside of the cell
What is the composition of a cell with resting potential?
Inside Negative, outside +, channels are closed.
What is the composition of a cell with action potential?
inside positive, negative outside, channels are open
Which ion channel is open, closed, and inactivated? What does each mean?
What causes changes in polarization?
Changes in polarization occur when ion channels in the membrane open or close,
altering the ability of particular types of ions to enter or exit the neuron
What is depolarization? What does this cause? What kind of potential is present?
Positive potential: Depolarization – the opening of channels that let Na+ rush into a neuron
The neuron sends electrical signal
What is hyperpolarization? What does this cause? What kind of potential is present?
Negative potential: Hyperpolarization – the opening of channels that let negative ions flow in
Prevents the neuron from receiving another stimulus
What kind of synapse is seen here? What is an example of this?
What kind of synapse is seen here? What is an example of this?
What are the steps of neuonal communication?
What are examples of amino acid neurotransmitters? What is their location?
Neurotransmitters: Glycine, Glutamate, Amino acid, Aspartate, γ aminobutyric acid (GABA)
Location: CNS
Why are neurotransmitters secreted?
A NT is a signaling molecule secreted by a neuron to affect another cell (neuron, gland, muscle cell) across a synapse
What are exampled of biogenic amines? Where are they found?
Neurotransmitter: Dopamine, Serotonin, Norepinephrine
Location: CNS and /or PNS
Related to Amino acids: i.e :
dopamine, norepinephrine, and epinephrine to tyrosine
serotonin to tryptophan histamine to histidine
What are exampled of Neuromuscular transmitters? Where are they found?
Neurotransmitter: Acetylcholine
Location: CNS and/or PNS
What are exampled of Purinergic transmitters? Where are they found?
Neurotransmitters: Adenosine, ATP
Location: CNS/ PNS
What are exampled of Neuropeptide transmitters? Where are they found?
Neurotransmitters: Substance P, Endorphins
Location: CNS and or PNS
What is the key neurotransmitters found at neuromuscular junctions/ synapses?
Acetylcholine
What are neuropeptides made of?
3 or more amino acids
What is/ what does substance P do?
Substance P (11 aa): carries pain signals and stimulates vomiting (high in VC)
What is neuropeptide Y?
Neuropeptide Y: stimulates eating
What do endorphins and enkephalins do?
inhibit pain
What is the amino acid composition of enkephalin?
Tyr-Gly-Gly-Phe-Met
What are types of steroids?
Androgens and estrogens
What is dopamine? What does it contribute to?
Dopamine: important in addiction and pleasure-seeking; over-eating, movements, attention and learning, low in Parkinson’s disease
What is serotonin effects? What is it linked to?
Serotonin: (5-hydroxytryptamine, 5HT). Important for sleep, appetite, temperature regulation, mood, anxiety, pain, memory, aggression, and perception. Linked with depression.
What is acetylcholine effects? What is it linked to?
Acetylcholine: muscle and heart contractions; blockage causes paralysis, low in Alzheimer’s
What is norepinephrines involvement? When is it released? How does it help us?
Norepinephrine: involved in body’s emergency response and behavioral processes. Released in (Noradrenalin) stress, excitement. Helps brain work faster, lift our mood, makes us feel alert and focused
What is gaba / glycine? What can occur if it is disrupted? What increases the action of gaba and what is its effect?
GABA/ Glycine: are inhibitors that keeps neural communication under control. If disrupted:
* seizure, epilepsy. Alcohol and valium boost the action of GABA, make you calm.
What is glutamate? What is it important for? What can low levels cause?
- Glutamate: major excitatory NT in the CNS, normal brain functioning, linked to many other pathways, learning and memory. Anxiety, PTS, OCD, mania, depression, psychosis, schizop
What is histamine? What is it important for?
- Histamine: (brain and spinal cord), arousal, attention, feeding behavior, and memory
What is substance P important for?
Substance P: implicated in reproduction, social behaviors, appetite, arousal, pain,
reward, and learning and memory
What is orexin? What can happen in patients that are lacking it?
Orexin: (like glutamate): energy homeostasis. Animals lacking orexin system have narcolepsy and disrupted
sleep-wake pattern
How does NT receptor complexes regulate membrane potential?
The NT-receptor complex may directly regulate the membrane potential by altering permeability of the cell membrane through opening or closing specific ion channels
What can the NT receptor complex initiate?
The NT-receptor complex may initiate a sequence of chemical reactions that alter ion transport across the membrane.
What are second messengers?
Specific intracellular signal molecules are called second messenger.
What are receptor the site of?
Receptors are the site of action for exogenous DRUGS (usually G protein-coupled receptors, GPCRs)
The second messenger system _____ and _____ the cellular response to ____ -_____ binding
The second messenger system sustains and amplifies the cellular response to DRUG-RECEPTOR binding
What are the neurotransmitter receptor functions?
EPSPs: depolarization leading to action potentials
IPSP: hyper-polarization leading to resting potentials.
What is the main excitatory transmitter in the CNS?
Glutamate is the main excitatory transmitter in the CNS
What is the main inhibitory NT in the Adult Vertebrate Brain?
GABA is the main inhibitory NT in the adult vertebrate brain
What is the main inhibitory NT in the spinal cord?
Glycine is the main inhibitory NT in the spinal cord
What are EPSPs? IPSPs?
EPSP: Excitatory PostSynaptic Potentials
IPSP: Inhibitory PostSynaptic Potentials
What determines the effect a certain NT will have at a given synapse ?
Whether the effect of a certain NT is excitatory or inhibitory at a given synapse depends on which of its receptor(s) are present on the postsynaptic (target) cell.
What are excitatory neurotransmitters?
- Glutamate
- Aspartate
What are inhibitory neurotransmitters?
- GABA
- Glycine
What are mixed neurotransmitters?
Mixed
* Acetylcholine (Ach)
* Norepinephrine (NE)
* Epinephrine (EP)
* Dopamine(D)
* Serotonin (5-HT)
When a ligand gated receptor opens, what happens to the membrane potential? G coupled receptor?
- Depolarizes
- Depolarizes
What are excitatory skeletal muscle receptors of acetylocholine?What kind of recptor is this?
- Nicotinic Ach receptors. This causes depolarization. This is a ligand gated ion channel.
What are excitatory skeletal muscle receptors of acetylcholine?What kind of receptor is this?
- Nicotinic Ach receptors. This causes depolarization. This is a ligand gated ion channel.
What is the action of acetylcholine on nicotinic receptors?
Promotion of muscle contractions
What is the action of muscarinic on nicotinic receptors?
Inhibition of muscle contraction
What are Gpcrs? What do they do?
G Protein - Coupled Receptors (GPCRs)
- CPCRs are main targets of existing drugs (30-50-% drugs bind to them)
- GPCRs detect molecules outside the cells and activate cellular responses GPCRs regulate sensory (taste, light, smell) and non-sensory (neurological and endocrine) signals
- GPCRs comprise the largest family of transmembrane receptors (~ 1000 in humans)
- GPCRs are 7 transmembrane helixes (7-transmembrane receptors, 7TM- R)
What is the structure of GPCRs?
Structure: 7 transmembrane alpha helixes receptors interact (coupled) with trimetic signal-transducing G-proteins
G-proteins consist of α, β, and γ subunits
1) Each receptor binds to its ligand,
2) conformational changes
3) α separates from β and γ,
4) they interact with other proteins
What does 2nd messengers (cAMP) act on?
5) 2nd messengers (cAMP) act on heart, muscle, vessels
Where does adrenalin bind?
Adrenalin (Epinephrine) binds β-adrenergic receptor (GPCR)
What occurs after Epinephrine Binds to B-adrenergic receptors?
- ATP cAMP -2nd messenger
- muscle, heart, dilate blood vessels
