Physio chapter 4

Drug effects

the observable changes in a person’s physiological processes and behavior due to a drug

Sites of action

where molecules of drugs interact with cells of the body

the steps of Pharmakinetics

1. drugs are absorbed

2. drugs are distributed throughout the body

3. drugs are metabolized

4. drugs are excreted

Ways drugs can be absorbed

1. IV injection

2. IP injection

3. IM injection

4. SC injection

5. Oral

6. Sublingual administration

7. inhalation

8. topical

9. ICV administration

What is drug absorbtion?

The drug is put into the body and absorbed though tissues

What is drug distribution?

Drug is distributed throughout body and blood

What is drug metabolism?

When the drug is changed to an inactive form by the enzymes, usually in the liver

What is drug excretion?

When the drug is excreted by the kidneys

What determines how fast the drug reaches the site of action?

How soluble the lipid is and can pass through cell membranes

How can drug effectiveness be measured?

Using a dose response curve to map the effects of the drug based on the dose

Why do drugs vary in their effectiveness?

1. Different drugs have different sites of action

2. Vary in how well they bind to binding sites

What happens when drugs are used repeatedly?

1. Tolerance (effects are diminished, need a higher dose)

2. Sensitization (effects increase)

3. Withdrawal (opposite effect of the drug, physical dependence)

What is a placebo?

An inactive substance that can effect patients. When patients expect it to have an effect and it does that is the placebo effect

Antagonists

block postsynaptic effects by preventing neurotransmitters from being released

agonists

facilitate postsynaptic effects by increasing the amount of neurotransmitter being released

Glutamate

In the CNS, excitatory

GABA

CNS, inhibitory

Acetylcholine (ACh)

In the CNS: learning, memory, REM sleep

In the PNS: Muscle contraction

Dopamine

CNS, voluntary movement, attention, learning, reinforcement, planning, problem solving

Norepinephrine/Epinephrine

CNS: vigilance

PNS: ANS regulation (heart rate, blood pressure, etc)

Serotonin

CNS: mood regulation, eating, sleeping, dreaming, arousal, impulse control

PNS: digestive system

Histamine

CNS: wakefulness

PNS: Immune response

Opioids

CNS: reinforcement, pain modulation

PNS: pain modulation

Endocannabinoids

CNS: appetite regulation

PNS: immune response

Describe the system of glutamate transport

1. Glutamate is put into vesicles by the vesicle glutamate transporter

2. binds to AMPA, NMDA, kainate, and metabotropic glutamate receptors

3. Metabolized by the enzyme glutamate synthase

4. Transported into the presynaptic cell by excitatory amino acid transporter

Describe the system of GABA transport

1. GABA is packaged into vesicles by the vesicle transporter

2. binds to GABA receptors like the GABAa receptor

3. metabolized by GABA aminotransferase

4. Transported into the presynaptic cell by GABA transporters

Describe the ACh system

1. ACh neurons are organized into three pathways in the brain

2. Synthesized by choline acetyltransferase

3. Packaged into vesicles by ACh transporter

4. Metabolized by acetylcholinestrase

5. Transported by choline transporters to the presynaptic cell

What are the monoamines?

Classic neurotransmitters such as dopamine, norepinephrine, epinephrine, serotonin, and histamine

Describe the system of monoamine transport

1. Sythesized from amino acid precursors

2. loaded onto vesicles by vesicle monoamine transporters

3. released after an action potential

4. Bind to ionotropic and metabotropic receptors

5. Metabolized by enzymes

6. Reuptake transporters remove monoamines from the synapse

What is special about peptide neurotransmitters?

Synthisized from large polypeptides, can be either neurotransmitters or neuromodulators depending on the sensitivity of the receptors to the neurotransmitters released at the same time

What is the lipid neurotransmitter system?

1. Synthesized on demand and not stored in vesicles

2. Endocannabinoids bind to CB1 and CB2 receptors

3. Anandamide is deactivated by FAAH in the presynaptic neuron and its transporter does reuptake in the presynaptic cell