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Questions and Answers
What is the primary function of the sympathetic nervous system?
What is the primary function of the sympathetic nervous system?
To prepare the body for 'fight or flight' responses.
What effect does the sympathetic nervous system have on heart rate?
What effect does the sympathetic nervous system have on heart rate?
It increases heart rate.
What type of receptors respond to epinephrine and norepinephrine?
What type of receptors respond to epinephrine and norepinephrine?
Adrenergic receptors.
What specific effect do beta-2 receptors have on the bronchioles?
What specific effect do beta-2 receptors have on the bronchioles?
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What neurotransmitter do cholinergic receptors respond to?
What neurotransmitter do cholinergic receptors respond to?
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What effect do M2 muscarinic receptors have on heart rate?
What effect do M2 muscarinic receptors have on heart rate?
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From what region of the spinal cord do the sympathetic nerves originate from?
From what region of the spinal cord do the sympathetic nerves originate from?
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Study Notes
Sympathetic Nervous System (SNS)
- Function: Prepares the body for "fight or flight" responses, activated during stress, danger, or vigorous activity.
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Effects:
- Increases heart rate and force of contraction.
- Dilates bronchioles (in the lungs).
- Dilates pupils.
- Inhibits digestion.
- Stimulates glucose release from the liver.
- Constricts blood vessels in non-essential organs, dilating them in muscles.
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Receptors: Adrenergic receptors, which respond to adrenaline (epinephrine) and noradrenaline (norepinephrine).
- Alpha Receptors:
- Alpha-1: Causes vasoconstriction (in blood vessels).
- Alpha-2: Found in the central nervous system (CNS) and presynaptic nerve terminals, modulating neurotransmitter release.
- Beta Receptors:
- Beta-1: Found in the heart, increasing heart rate and force of contraction.
- Beta-2: Found in the lungs and skeletal muscle blood vessels, causing bronchodilation & vasodilation.
- Alpha Receptors:
Parasympathetic Nervous System (PNS)
- Function: Promotes "rest and digest" activities, activated during restful periods and promoting energy conservation.
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Effects:
- Decreases heart rate.
- Constricts bronchioles (in the lungs).
- Constricts pupils.
- Stimulates digestion and peristalsis.
- Promotes glucose storage in the liver.
- Dilates blood vessels in the gastrointestinal tract.
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Receptors: Cholinergic receptors which respond to acetylcholine.
- Muscarinic Receptors:
- M1: Found in the CNS and gastric parietal cells, involved in cognitive function and gastric acid secretion.
- M2: Found in the heart, decreasing heart rate.
- M3: Found in smooth muscles and glands, causing smooth muscle contraction and glandular secretion.
- M4 and M5: Found in the CNS, involved in various central nervous system functions.
- Nicotinic Receptors: Found in the autonomic ganglia (both SNS and PNS) and the neuromuscular junction, transmitting nerve impulses to muscles.
- Muscarinic Receptors:
Key Differences
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Origin:
- Sympathetic: Thoracic and lumbar regions of the spinal cord (T1-L2).
- Parasympathetic: Cranial nerves (III, VII, IX, X) and sacral spinal cord segments (S2-S4).
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Neurotransmitters:
- Sympathetic: Primarily norepinephrine.
- Parasympathetic: Primarily acetylcholine.
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Responses:
- Sympathetic: Widespread, longer-lasting effects, due to adrenaline release from the adrenal medulla, in the bloodstream
- Parasympathetic: More localized and shorter-lasting effects.
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Description
Explore the functions and effects of the Sympathetic Nervous System (SNS) in this quiz. Learn how it prepares the body for 'fight or flight' responses, including the role of adrenergic receptors and their subtypes. Test your understanding of the physiological changes that occur during stress and vigorous activity.
