Module 2: Introduction to the Nervous System Flashcards
The parasympathetic and sympathetic nervous system are sub-divisions of what other nervous systems?
Autonomic nervous system, which is a division of the motor (efferent) NS, which is a division of the Peripheral NS.
What is the parasympathetic nervous system (PSNS) responsible for?
“rest and digest” responses. Is activated under non-stressful conditions.
Effects are pupil constriction, decreased HR, increased digestive intestinal activity
What is the sympathetic (SNS) nervous system responsible for?
“Fight or flight” responses activated upon stressful conditions
Effects include pupil dilation, increased sweating, HR and BP.
The PSNS preganglionic fibres release ____ that bind to _____ receptors in the ganglia
Acetylcholine; nicotinic
The PSNS has ___ preganglionic fibres and ____ postganglionic fibres
Long; short
The PSNS postganglionic fibres release ____ that bind to ____ receptors on the target organ
Acetylcholine; muscarinic
What kind of receptor is a muscarinic recepto?
A G-protein coupled receptor
What kind of receptor is a nicotinic receptor?
A ligand-gated ion chanel
What enzyme breaks down acetylcholine in the synaptic cleft?
Acetylcholinesterase (AchE)
T/F - Drugs that stimulate the PSNS are called adrenergic drugs
False - they are called cholinergic drugs (adrenergic is for SNS)
Drugs can activate the parasympathetic nervous system through what 3 main actions?
Binding and activating nicotinic receptors
Binding and activating muscarinic receptors
Blocking the metabolism of acetylcholine (inhibiting AchE)
Cholinergic drugs are used to activate the PSNS in what medical conditions?
Glaucoma, poor muscle tone in the bladder
Anti-cholinergic drugs are used in what medical conditions?
Respiratory disorders, GI disorders, Urinary disorders
What are two main side affect of cholinergic drugs?
Slowing of the heart rate and constriction of the respiratory passages
The SNS has ____ preganglionic neurons and ____ postganglionic neurons
Short; long
The SNS preganglionic neurons release ___ at the ganglia, activating ____ receptors
Acetylcholine; nicotinic
What is the main side affect of anticholinergic drugs?
Tachycardia
The SNS postganglionic neurons release ____ or _____ at the target organ, activating ____, ____, _____ and ____ receptors, depending on the tissue
norepinephrine or acetylcholine (in sweat glands and smooth muscle); alpha and beta receptors, M receptors (sweat glands), dopamine (smooth muscle),
Describe how the adrenal medulla gets activated
Long SNS preganglionic fibres release acetylcholine, which bind to nicotinic receptors on the adrenal medulla, ultimately releasing epinephrine and norepinephrine from the adrenal medulla
Describe the location and response of Alpha1 receptors
Smooth muscle (blood vessels, GI muscle, uterus)
Contracts smooth muscle in BV and uterus, decreases motility and tone in GI tract
Describe the location and response of Alpha2 receptors
Post-synaptically on smooth muscle, pre-synaptically on the neuronal membrane.
Contracts smooth muscle and decreases release of norepinephrine from the presynaptic neurons (decreasing sympathetic activation)
Describe the location and response of Beta1 receptors
Heart, GI muscle
Increases HR and force of contraction
Relaxes GI smooth muscle
Describe the location and response of Beta2 receptors
Lungs, blood vessels, GI muscle, uterus
Relaxes smooth muscle
What are the common adverse effects of adrenergic activators?
Headache, restlessness, tremors, nervousness, dizziness, excitement, insomnia, eurphoria, heart palpitations, tachycardia, vasoconstriction, hypertension, dry mouth, nausea, vomitting, muscle cramps
