Pharmacology Topic 4

central nervous system

responsible for controlling bodily functions, and it is the center for

behavioral and intellectual abilities.

brain and spinal cord

The CNS can be grossly divided into

cerebral cortex

highest order of conscious function and integration in the CNS.

indirectly

Most CNS therapeutic medications tend to affect cortical function…

directly

An exception is the group of drugs used to treat epilepsy, which are often targeted…

caudate nucleus, putamen, globus pallidus, lentiform nucleus,

and substantia nigra.

components of basal ganglia

thalamus

contains distinct nuclei that are crucial

in the integration of certain types of sensations and

their relay to other areas of the brain

hypothalamus

involved in the control of diverse body functions, including temperature control, appetite, water balance, and certain emotional reactions. also significant in its control over the function of hormonal release from the pituitary gland.

midbrain and brainstem

are the locations of centers responsible for controlling respiration and cardiovascular function

cerebellum

lies posterior to the brainstem, helps plan and coordinate motor activity and is

responsible for comparing the actual movement with the

intended motor pattern.

limbic system

These structures are involved in

the control of emotional and behavioral activity.

grey matter

serves as an area for synaptic connections between various neurons in the spinal cord

white matter

consists of

the myelinated axons of neurons, which are grouped

into tracts ascending or descending between the brain

and specific levels of the cord.

blood-brain barrier

refers to the unique structure

and function of CNS capillaries, which act as a selective

filter and protects the CNS by limiting the substances

that enter the brain and spinal cord.

Astrocyte

glial cells that make up the majority of cells in the human central nervous system

passive diffusion

nonpolar, lipid-soluble drugs are able to cross the blood-brain barrier by

facilitated diffusion

Some substances (such as glucose) are transported via…

active transport or by endocytosis.

other compounds (including some drugs) may be able

to enter the brain by

neurotransmitters

Neurons often release a specific chemical to transmit a

signal to another neuron in the CNS.

Acetylcholine

abundant in the cerebral cortex and seems to play a critical role

in cognition and memory.

dopamine, norepinephrine, serotonin

Group of Monoamines

gamma-aminobutyric acid

Definition of GABA

GABA

the primary neurotransmiter used to cause inhibition at presynaptic and postsyn-

aptic neurons in the brain and spinal cord.

substance P

excitatory transmitter that is involved in spinal cord pathways transmitting

pain impulses.

Neurotransmitter release is blocked, preventing synaptic transmission. Local anesthetics work this way.

What happens when an action potential fails to reach the presynaptic terminal?

It's when reduced depolarization at the presynaptic terminal leads to less neurotransmitter release. GABA uses this mechanism.

What is presynaptic inhibition?

It depletes neurotransmitter levels, impairing signal transmission. Example: metyrosine blocks catecholamine synthesis.

How does blocking neurotransmitter synthesis affect synaptic activity?

Less transmitter is available for release, weakening synaptic signaling. Example: reserpine blocks norepinephrine storage.

What is the effect of impaired neurotransmitter storage?

They increase the release of neurotransmitters like norepinephrine, enhancing synaptic activity.

How do drugs like amphetamines affect neurotransmitter release?

It inhibits the release of acetylcholine, leading to muscle relaxation.

What does botulinum toxin do at the synapse?

It increases synaptic activity by allowing the neurotransmitter to stay longer in the cleft. Example: tricyclic antidepressants.

What is the effect of blocking neurotransmitter reuptake?

It prevents neurotransmitter breakdown, prolonging its effect. Example: neostigmine inhibits cholinesterase in myasthenia gravis.

How does enzyme inhibition affect synaptic transmission?

They block receptor activation, reducing synaptic transmission (e.g., in treating hypertension).

What is the role of postsynaptic receptor blockers like beta blockers?

They boost the effect of GABA at the postsynaptic receptor, increasing inhibitory activity.

How do benzodiazepines enhance synaptic transmission?

They detect excess neurotransmitter and reduce further release. Example: clonidine acts on these receptors to lower blood pressure.

What do presynaptic autoreceptors do?

By altering membrane fluidity, they can impact neurotransmitter release and receptor function. Example: alcohol and anesthetics.

How can drugs affect synaptic transmission through the membrane?