the autonomic nervous system Flashcards
central nervous system
brain, spinal cord
peripheral nervous system
all neurones outside the CNS it consists of 3 divisions
sensory nerves: travel to the spinal cord from the periphery (afferent fibres)
motor nerves: voluntary control of skeletal muscle travel away from the spinal cord to the muscle: somatic efferent system
Autonomic nerves: unconscious physiological control of organ systems
sympathetic nervous system
fight or flight
parasympathetic nervous system
rest and digest
-under normal condition they work together to co-ordinate organ function
the enteric nervous system
Local neuronal network co-ordinating the GI tract, with input from PNS and SNS
the 2 neurones used in the PN and SN pathway
the first neurone makes a synapse with the second. through a group of nerve cell bodies
pre-ganglionic: neurone from the CNS
post-ganglionic: neurone innervates the target tissue
somatic motor efferent
(somatic=voluntary) is a single neurone leading to the skeletal muscle
spinal cord divisions
Medullary
Cervical
Thoracic
Lumbar
Sacral
adrenaline release
A small group of nerve fibers from the sympathetic nervous system (SNS) bypass normal nerve connections and directly connect to the adrenal medulla (the inner part of the adrenal glands). When these nerve fibers activate the adrenal medulla, it releases adrenaline into the blood. this is much faster than using the sensory and motor neurone
Preganglionic sympathetic neurons originate in the thoracic and lumbar spinal cord.
They synapse in one of three locations:
Paired paravertebral ganglia (for controlling peripheral organs like blood vessels).
Unpaired prevertebral ganglia (for organs like the intestines and pelvic viscera).
Adrenal medulla (which releases adrenaline into the bloodstream for systemic effects).
PRE ARE SHORT
POST ARE LONG
right and left vagus nerves
parasympathetic nervous system, which controls “rest and digest” functions.
They help slow the heart rate by acting on the heart.
They control breathing by affecting the lungs, making the airways narrower when needed.
They promote digestion in the stomach and intestines by increasing acid production and muscle contractions to move food along.
both parasympathetic and sympathetic are active under normal conditions
-they have opposing actions (eg heart rate to balance bodily function)
-single system control (liver sympathetic, GI secretion (parasympathetic)
-co-ordinated effects
(salivary secretion of fluid is parasympathetic and enzymes is sympathetic and they work simultaneously)
autonomic nervous system transmitter and co-transmitter
Acetylcholine (ACh): Mainly used by parasympathetic neurons.
Noradrenaline (NA): Mainly used by sympathetic neurons.
However, neurons in the ANS also release other chemicals called co-transmitters alongside ACh or NA.
These co-transmitters help fine-tune the body’s responses and make them more specific.
Nicotinic receptors
are fast-acting ion channels that open when acetylcholine binds to them, allowing ions to flow and creating quick electrical signals. This helps in fast communication in the nervous system.
Muscarinic receptors (M receptors)
are G-protein coupled receptors that mediate slower, flexible responses in the body. Unlike nicotinic receptors (which have fast ion flow), muscarinic receptors can trigger a variety of effects depending on the type of G-protein involved, and their actions are slower and more complex. These receptors are involved in a range of functions, including heart rate, muscle contraction, and digestion.
Ionotropic receptors vs Metabotropic receptors
Ionotropic receptors: Fast signaling, used in situations requiring rapid communication (e.g., synaptic transmission, sensory processing, reflexes).
Metabotropic receptors: Slow signaling, used in contexts requiring longer-term changes (e.g., mood regulation, learning and memory, hormonal responses).
