Autonomic Nervous System Flashcards
(40 cards)
What is the autonomic nervous system (ANS)?
The autonomic nervous system is a part of the peripheral nervous system (PNS) that provides involuntary information from the central nervous system (CNS) to peripheral organs.
What are the two main branches of the autonomic nervous system?
The two main branches of the autonomic nervous system are the sympathetic nervous system and the parasympathetic nervous system.
What functions does the ANS control?
The ANS innervates various cell types and regulates important functions such as heart rate, blood vessel contraction, glandular secretions, and smooth muscle contraction or relaxation in organs like the intestines and bladder.
How does the sympathetic nervous system affect the body?
The sympathetic nervous system increases heart rate and force, causes vascular smooth muscle contraction, dilates airways, dilates pupils, increases glucose metabolism, and triggers sweating (using acetylcholine in sweat glands).
What are the major effects of the parasympathetic nervous system?
The parasympathetic nervous system decreases heart rate and force, stimulates visceral smooth muscle contraction (in the bladder and gastrointestinal tract), promotes vascular dilation, causes pupil constriction, and increases secretions such as tears and saliva.
What neurotransmitters are released by the sympathetic and parasympathetic systems?
The parasympathetic system primarily releases acetylcholine, while the sympathetic system mainly releases noradrenaline. Notably, the sympathetic system also releases acetylcholine in the sweat glands.
Where are the nerve origins for the parasympathetic and sympathetic systems located?
The parasympathetic nerves originate in the cranial and sacral areas, while the sympathetic nerves originate in the thoracic and lumbar areas of the spinal cord.
What is an autonomic ganglion?
An autonomic ganglion is a cluster of nerve cell bodies, primarily associated with the parasympathetic nervous system.
What role do sino-atrial node cells play in the heart?
Sino-atrial node cells regulate the heart rate by generating electrical impulses that initiate each heartbeat.
How does the ANS affect smooth muscle cells?
The ANS can contract or relax smooth muscle cells in various organs, including blood vessels, airways, intestines, and the bladder, thus influencing functions like blood flow and digestion.
What is the significance of myelination in the autonomic nervous system?
In the parasympathetic system, the first nerve is lightly myelinated, which facilitates faster signal transmission. In contrast, the sympathetic system’s first nerve is mostly unmyelinated, affecting the speed and efficiency of its responses.
How does the sympathetic nervous system prepare the body for stress?
The sympathetic nervous system activates the “fight or flight” response, increasing heart rate, blood flow to muscles, and energy availability, while preparing the body to respond to perceived threats.
What is the effect of parasympathetic stimulation on digestion?
Parasympathetic stimulation enhances digestive processes by promoting visceral smooth muscle contraction and increasing secretions of digestive enzymes and acids.
How does the sympathetic nervous system affect pupil size?
The sympathetic nervous system causes pupil dilation (widening) to allow more light into the eye, which is beneficial in stressful situations.
What is the effect of the parasympathetic system on blood vessels?
The parasympathetic system primarily promotes vascular dilation through the endothelium, leading to increased blood flow in certain areas during restful states.
In what situations would the sympathetic nervous system use acetylcholine?
The sympathetic nervous system uses acetylcholine primarily in sweat glands to stimulate sweating, while other functions typically involve noradrenaline.
What is the relationship between the autonomic nervous system and glandular secretions?
The autonomic nervous system controls glandular secretions by stimulating glands to release substances such as saliva, sweat, gastric acid, insulin, and glucagon, depending on whether the sympathetic or parasympathetic system is activated.
How does the autonomic nervous system influence airway function?
The ANS regulates airway function by relaxing bronchial smooth muscles during sympathetic activation (to increase airflow) and promoting contraction during parasympathetic activation (which can narrow the airways).
What is the primary neurotransmitter involved in the parasympathetic response?
The primary neurotransmitter involved in the parasympathetic response is acetylcholine, which is released at various target organs to elicit responses such as decreased heart rate and increased glandular secretions.
How do the sympathetic and parasympathetic systems work together?
The sympathetic and parasympathetic systems work together to maintain homeostasis by balancing each other’s effects; for example, while the sympathetic system increases heart rate during stress, the parasympathetic system helps to slow it down and promote relaxation afterward.
What neurotransmitter is primarily associated with the sympathetic nervous system, and what receptors does it bind to?
Noradrenaline is primarily associated with the sympathetic nervous system. It binds to adrenoreceptors, specifically beta 1 G protein-coupled receptors, to produce various physiological effects.
How do noradrenaline and adrenaline affect heart function?
Noradrenaline and adrenaline increase the force of contraction (positive inotropy), the rate of contraction (positive chronotropy), and the rate of relaxation (positive lusitropy) of the heart by acting on beta 1 adrenoreceptors.
What role do alpha 1 adrenoreceptors play in the sympathetic nervous system?
Alpha 1 adrenoreceptors mediate vasoconstriction in blood vessels, leading to narrowed blood vessels when activated by noradrenaline or circulating adrenaline.
How does the sympathetic nervous system affect visceral smooth muscles?
The sympathetic nervous system can relax many types of visceral smooth muscles, allowing for decreased activity in organs such as the intestines and bladder, which is important during stress or “fight or flight” responses.
