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What is the primary effect of sympathetic mass discharge?
What is the primary effect of sympathetic mass discharge?
Which of the following conditions could trigger sympathetic stimulation?
Which of the following conditions could trigger sympathetic stimulation?
How do parasympathetic cardiovascular reflexes primarily function?
How do parasympathetic cardiovascular reflexes primarily function?
What is a consequence of parasympathetic mass stimulation?
What is a consequence of parasympathetic mass stimulation?
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Which scenario would most likely cause prolonged GIT atony?
Which scenario would most likely cause prolonged GIT atony?
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What effect does the sympathetic nervous system have on muscle activity during stress?
What effect does the sympathetic nervous system have on muscle activity during stress?
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What initiates the bladder emptying reflex?
What initiates the bladder emptying reflex?
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Which of the following is NOT associated with sympathetic stimulation?
Which of the following is NOT associated with sympathetic stimulation?
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What is the role of sympathetic tone at rest?
What is the role of sympathetic tone at rest?
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What happens to the heart rate when parasympathetic activity is increased?
What happens to the heart rate when parasympathetic activity is increased?
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What effect does cutting sympathetic nerves (sympathectomy) have on blood vessels?
What effect does cutting sympathetic nerves (sympathectomy) have on blood vessels?
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Which of the following statements about parasympathetic tone is correct?
Which of the following statements about parasympathetic tone is correct?
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During which state does sympathetic tone maintain arterial blood pressure?
During which state does sympathetic tone maintain arterial blood pressure?
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What is a consequence of vagotomy in the heart?
What is a consequence of vagotomy in the heart?
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What influences gastrointestinal motility when sympathetic activity is heightened?
What influences gastrointestinal motility when sympathetic activity is heightened?
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How does cutting the parasympathetic nerve affect gastrointestinal activity?
How does cutting the parasympathetic nerve affect gastrointestinal activity?
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What effect does sympathetic mass stimulation have on the pupils during stress?
What effect does sympathetic mass stimulation have on the pupils during stress?
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How does sympathetic stimulation affect heart function?
How does sympathetic stimulation affect heart function?
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What physiological change occurs in the bronchioles during sympathetic activation?
What physiological change occurs in the bronchioles during sympathetic activation?
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Which effect relates to the blood vessels during sympathetic mass stimulation?
Which effect relates to the blood vessels during sympathetic mass stimulation?
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What is the effect of sympathetic stimulation on skeletal muscle contraction?
What is the effect of sympathetic stimulation on skeletal muscle contraction?
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What role does the spleen play during sympathetic mass stimulation?
What role does the spleen play during sympathetic mass stimulation?
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What effect does adrenaline have on blood glucose levels during stress?
What effect does adrenaline have on blood glucose levels during stress?
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During sympathetic activation, what happens to sweat secretion?
During sympathetic activation, what happens to sweat secretion?
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What is a defining characteristic of sympathetic stimulation in isolated portions of the system?
What is a defining characteristic of sympathetic stimulation in isolated portions of the system?
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Which reflex serves as an example of parasympathetic influence on gastrointestinal functions?
Which reflex serves as an example of parasympathetic influence on gastrointestinal functions?
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In which scenario would a state of sympathetic mass discharge most likely occur?
In which scenario would a state of sympathetic mass discharge most likely occur?
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What is the primary consequence of parasympathetic mass stimulation?
What is the primary consequence of parasympathetic mass stimulation?
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What is a result of sympathetic mass stimulation during stress responses?
What is a result of sympathetic mass stimulation during stress responses?
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Which statement accurately describes the association between parasympathetic functions?
Which statement accurately describes the association between parasympathetic functions?
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How does the body react to the sympathetic response during emergency situations?
How does the body react to the sympathetic response during emergency situations?
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What physiological change takes place in the sweat glands due to sympathetic stimulation during stress?
What physiological change takes place in the sweat glands due to sympathetic stimulation during stress?
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What is the primary physiological role of sympathetic tone at rest?
What is the primary physiological role of sympathetic tone at rest?
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What happens to the heart rate when parasympathetic activity decreases?
What happens to the heart rate when parasympathetic activity decreases?
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What is the initial effect of symapathectomy on blood vessels?
What is the initial effect of symapathectomy on blood vessels?
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What physiological change occurs in the gastrointestinal tract with increased parasympathetic activity?
What physiological change occurs in the gastrointestinal tract with increased parasympathetic activity?
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What effect does cutting parasympathetic nerves (vagotomy) have on heart rate?
What effect does cutting parasympathetic nerves (vagotomy) have on heart rate?
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What long-term effect does cutting the sympathetic nerve have on arterial blood pressure?
What long-term effect does cutting the sympathetic nerve have on arterial blood pressure?
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What physiological response is most associated with the constriction of blood vessels in the skin during sympathetic mass stimulation?
What physiological response is most associated with the constriction of blood vessels in the skin during sympathetic mass stimulation?
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Which process is increased in the liver during sympathetic mass stimulation to provide more energy?
Which process is increased in the liver during sympathetic mass stimulation to provide more energy?
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How does sympathetic activity affect the diameter of blood vessels?
How does sympathetic activity affect the diameter of blood vessels?
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What is the primary effect of adrenaline secretion on metabolism during stress?
What is the primary effect of adrenaline secretion on metabolism during stress?
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What is a key factor involved in the regulation of sympathetic tone?
What is a key factor involved in the regulation of sympathetic tone?
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During sympathetic activation, what happens to the strength of skeletal muscle contraction?
During sympathetic activation, what happens to the strength of skeletal muscle contraction?
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What effect does sympathetic mass stimulation have on bronchioles to enhance respiratory function?
What effect does sympathetic mass stimulation have on bronchioles to enhance respiratory function?
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How does the contraction of the splenic capsule during sympathetic activation affect blood volume?
How does the contraction of the splenic capsule during sympathetic activation affect blood volume?
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In the context of sympathetic stimulation, what is the role of exophthalmos?
In the context of sympathetic stimulation, what is the role of exophthalmos?
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What is the overall effect of sympathetic mass stimulation on the cardiovascular system during stress?
What is the overall effect of sympathetic mass stimulation on the cardiovascular system during stress?
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Study Notes
Sympathetic and Parasympathetic Tone at Rest
-
Sympathetic Tone
- Continuous discharge of impulses to organs, leading to mild activity
- Causes:
- Continuous basal discharge of sympathetic impulses
- Continuous basal secretion of adrenaline and noradrenaline from the adrenal medulla
- Sympathetic supply to blood vessels causes partial vasoconstriction, maintaining normal arterial blood pressure
-
Parasympathetic Tone
- Continuous discharge of impulses to organs, leading to mild activity
- Causes:
- Continuous basal discharge of parasympathetic impulses
- Continuous afferent impulses from baroreceptors in the carotid sinus and aortic arch along sinus and aortic nerves to the cardioinhibitory center in the medulla oblongata
- Effects:
- Decreases heart rate from 120 to 70 beats per minute
- Maintains normal gastrointestinal motility
Cutting Nerves
-
Sympathectomy (Cutting Sympathetic Nerves)
- Leads to immediate maximal vasodilatation
- After some time, intrinsic tone of smooth muscle in blood vessels increases, restoring vasoconstriction and returning normal arterial blood pressure
-
Vagotomy (Cutting Parasympathetic Nerves)
- Effects:
- Increases heart rate from 70 to 120 beats per minute
- Leads to prolonged gastrointestinal atony
- Effects:
Sympathetic and Parasympathetic Stimulation in Specific Organs
-
Sympathetic Stimulation
- Affects isolated portions of the body, like skin blood vessels during hot weather or hand sweating during writing
-
Parasympathetic Stimulation
- Cardiovascular Reflexes: Act only on the heart
- Gastrointestinal Reflexes: Act only on the gastrointestinal tract
Sympathetic Mass Discharge (Stress Response)
-
Causes:
- Emergency or stress conditions like hemorrhage, hypoglycemia, severe cold, pain, severe exercise, fear, fight, flight, and emotions
-
Effects:
- Enables the body to face stressful situations
- Increases the body's capacity for vigorous muscular activity
-
Specific Effects:
- Eyes: Pupillary dilatation, exophthalmos, widening of the palpebral fissure
- Heart: Increased heart rate, force of contraction, and blood pressure, supplying blood to vital organs and muscles
- Thorax: Bronchodilation for increased lung ventilation and oxygen supply
- Somatic: Vasoconstriction in the skin to limit bleeding, vasodilation of skeletal and cardiac muscle blood vessels, increased muscle contraction strength, delayed fatigue
- Spleen: Contraction of the splenic capsule, ejecting red blood cells into circulation, increasing blood volume and oxygen carrying capacity
- Adrenal Medulla: Secretion of adrenaline and noradrenaline potentiates sympathetic stimulation
- Liver: Increases glycogenolysis and glycolysis
- Other: Increased sweat secretion for heat loss
Parasympathetic Mass Stimulation
- Fatal
- Causes: Association between closely related parasympathetic functions, where one reflex can initiate another
-
Effects:
- Rectal Emptying Reflex: Initiates bladder emptying reflex, leading to simultaneous emptying of the bladder and rectum
- Salivary Secretion: Activates gastric secretion
- Gastric Secretion: Activates pancreatic secretions
Sympathetic Mass Stimulation Effects During Stress
- Increased Mental Activity and Cellular Metabolism
- Orbelli Phenomenon: Delay in the onset of muscle fatigue during stress
- Sympatho-Adrenal System: Adrenaline and noradrenaline secretion potentiates sympathetic stimulation
- Energy Supply: Increased blood glucose and free fatty acid levels
- Glycogenolysis & Glycolysis: Increased glycogenolysis in the liver and glycolysis in the muscle
- Heat Loss: Increased sweat secretion for heat loss
Sympathetic & Parasympathetic Tone
- At rest, both the sympathetic and parasympathetic nervous systems have a continuous basal discharge, known as tone.
-
Sympathetic tone:
- Leads to mild activity in organs due to continuous sympathetic nerve discharge.
-
Causes:
- Continuous basal secretion of adrenaline & noradrenaline from the adrenal medulla.
- Vasoconstriction in blood vessels, maintaining normal arterial blood pressure.
-
Parasympathetic tone:
- Leads to mild activity in organs due to continuous parasympathetic nerve discharge.
-
Causes:
- Continuous afferent impulses from baroreceptors in the carotid sinus and aortic arch, transmitted via the sinus & aortic nerves to the cardioinhibitory center in the medulla oblongata.
-
Effects:
- Heart: Decreases heart rate from 120 beats/min to 70 beats/min.
- Gastrointestinal tract (GIT): Maintains normal motility.
Cutting of Nerves
-
Sympathectomy (Cutting sympathetic nerves):
- Leads to immediate maximal vasodilatation.
- After some time, intrinsic tone of smooth muscles in blood vessels increases, restoring vasoconstriction and returning arterial blood pressure to normal.
-
Vagotomy (Cutting parasympathetic nerves):
- Heart: Increases heart rate from 70 to 120 beats/min.
- GIT: Leads to prolonged GIT atony (loss of muscle tone).
Localized Effects
-
Sympathetic stimulation can occur in isolated portions of the body.
-
Examples:
- Hot weather: Affects only skin blood vessels and sweat glands, without affecting other organs.
- Handwriting: Sweat secretion occurs only in the hand for a better grip.
-
Examples:
-
Parasympathetic stimulation often acts on specific organ systems.
-
Examples:
- Cardiovascular reflexes: Act only on the heart.
- GIT reflexes: Act only on the gastrointestinal tract.
-
Examples:
Mass Actions (Generalized Effects)
-
Sympathetic mass discharge (stress response):
- Occurs in emergency or stress conditions such as hemorrhage, hypoglycemia, severe cold, pain, severe exercise, fear, fight, flight, and emotions.
-
Effects:
- Pupillary dilatation (widening of pupils)
- Exophthalmos (bulging eyes)
- Increased heart rate
- Increased force of myocardial contraction
- Increased blood pressure
- Bronchodilation (widening of airways)
- Vasoconstriction in the skin
- Vasodilation in skeletal muscles and cardiac muscle
- Increased skeletal muscle strength
- Splenic contraction, releasing red blood cells into circulation
- Secretion of adrenaline and noradrenaline, potentiating sympathetic system stimulation (sympatho-adrenal system)
- Increased blood glucose and free fatty acid levels
- Increased glycogenolysis in the liver
- Increased glycolysis in muscles
- Increased mental activity
- Increased cellular metabolism
- Increased sweat secretion
-
Parasympathetic mass stimulation:
- Fatal
- Associated with closely related functions: One parasympathetic reflex can initiate another.
-
Examples:
- Rectal emptying reflex initiates bladder emptying reflex, leading to simultaneous emptying of both.
- Salivary stimulation activates gastric secretion, which then activates pancreatic secretions.
Sympathetic Mass Stimulation During Stress
- Eye: Pupillary dilatation, exophthalmos, and widening of the palpebral fissure (eyelid opening) for an increased field of vision.
- Heart: Increased heart rate, increased force of myocardial contraction, and elevated blood pressure, directing increased blood flow to vital organs and active muscles.
- Thorax: Bronchodilation for better lung ventilation and oxygen supply.
- Somatic System: Vasoconstriction in the skin to limit bleeding, vasodilation in skeletal and cardiac muscles, shifting blood flow to active areas. Increased skeletal muscle strength and delayed fatigue (Orbelli Phenomenon).
- Spleen: Contraction of the splenic capsule, releasing red blood cells into circulation to increase blood volume and oxygen-carrying capacity.
- Adrenal Medulla: Secretion of adrenaline and noradrenaline, potentiating the stimulation of the sympathetic system (sympatho-adrenal system).
- Liver: Increased glycogenolysis and glycolysis, providing energy for active muscles.
- Other: Increased sweat secretion for heat loss through evaporation, increased mental activity and cellular metabolism throughout the body.
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