Parasympathetic Nervous System Overview

The parasympathetic nervous system is a part of the autonomic nervous system responsible for "rest and digest" functions, promoting relaxation and energy conservation.

Acetylcholine is a neurotransmitter released by parasympathetic preganglionic and postganglionic neurons, responsible for transmitting signals in the parasympathetic nervous system.

Nicotinic receptors are a type of acetylcholine receptor found on postganglionic neurons in both the sympathetic and parasympathetic nervous systems.

Muscarinic receptors are a type of acetylcholine receptor found on target organs innervated by the parasympathetic nervous system.

Pre-ganglionic neurons in the parasympathetic nervous system originate in the brain and sacral region of the spinal cord.

Post-ganglionic neurons in the parasympathetic nervous system are located in ganglia near the target organs.

Cholinergic transmission refers to the process of signal transmission using acetylcholine as the neurotransmitter.

Acetylcholine binds to receptors on target cells, trigger a biological response, such as muscle contraction or gland secretion.

Choline is re-captured by neurons and recycled to create more acetylcholine.

Acetylcholine is broken down by the enzyme acetylcholinesterase, quickly terminating its action.

True cholinesterase is a specific type of acetylcholinesterase found in nerve endings, neuromuscular junctions, and red blood cells.

Pseudocholinesterase is a non-specific type of acetylcholinesterase found in plasma, intestines, liver, and skin.

Acetylcholine causes contraction of the ciliary muscle, making the lens more convex for near vision.

Atropine blocks the action of acetylcholine on the ciliary muscle, leading to loss of accommodation.

Acetylcholine causes muscle twitching due to depolarization of the motor end plate.

Acetylcholine causes a decrease in blood pressure by stimulating parasympathetic activity.

Nicotinic receptors are found on skeletal muscle, allowing acetylcholine to trigger muscle contraction.

M1 receptors are a subtype of muscarinic receptors found in the central nervous system and peripheral neurons.

M2 receptors are a subtype of muscarinic receptors primarily found in the heart.

M3 receptors are a subtype of muscarinic receptors found on smooth muscle and glands.

Atropine blocks the effects of acetylcholine at muscarinic receptors, inhibiting parasympathetic activity.

Hemicholinium blocks the uptake of choline into the presynaptic neuron, reducing acetylcholine synthesis.

Botulinum toxin blocks the release of acetylcholine from the presynaptic neuron, leading to paralysis.

Spider venom can also block the release of acetylcholine, causing paralysis.

The sympathetic nervous system is responsible for "fight or flight" responses, preparing the body for action.

Norepinephrine is a neurotransmitter released by sympathetic postganglionic neurons, responsible for transmitting sympathetic signals.

Adrenergic receptors are a type of receptor that bind to norepinephrine and epinephrine.

The central nervous system (CNS) is comprised of the brain and spinal cord, responsible for processing information and controlling bodily functions.

The peripheral nervous system (PNS) connects the CNS to the rest of the body, transmitting sensory and motor information.

The somatic nervous system is part of the PNS, responsible for voluntary control of skeletal muscles.

The autonomic nervous system is part of the PNS, responsible for involuntary control of smooth muscle, cardiac muscle, and glands.