Physiology (Autonomic Nervous System) Flashcards
Q: What is the general function of the sympathetic nervous system?
Catabolic and energy-consuming system (stress, fight, fear, and flight).
Q: What are the sympathetic effects on the eye?
Dilator pupillae muscle: Contraction → Mydriasis (pupil dilatation).
Smooth muscle of upper eyelid: Contraction → widening of palpebral fissure → increased field of vision.
Ciliary muscle: Relaxation → decreased lens power → far vision.
Müller’s muscle (animals): Contraction → eyeball protrusion → exophthalmos.
Conjunctival vessels: Vasoconstriction (VC).
Q: What are the sympathetic effects on the skin?
Sweat glands: Stimulates secretion.
Cutaneous blood vessels: Vasoconstriction.
Piloerector muscles: Contraction → hair erection
Q: What are the sympathetic effects on salivary glands?
Trophic secretion of saliva: Small amount, concentrated, and viscid
Q: What are the sympathetic effects on the brain and cerebral circulation?
Cerebral circulation: Increased blood flow (due to increased ABP) with mild vasoconstriction.
Brain: Increased mental alertness
Q: What are the sympathetic effects on the heart?
ncreases all cardiac properties:
Rate and force of contraction.
Excitability.
Rate of conduction.
Coronary blood vessels: Indirect vasodilatation.
Q: What are the sympathetic effects on the lungs?
Bronchodilatation.
Mild vasoconstriction of pulmonary blood vessels.
Q: What causes Horner’s Syndrome, and what are its manifestations?
Cause: Lesion on one side of the cervical sympathetic chain.
Manifestations (on the same side):
Miosis: Constricted pupil.
Ptosis: Drooping of the upper eyelid.
Anhidrosis: Absence of sweating.
Warm and red skin: Due to vasodilatation
Q: What is the origin and relay of the sympathetic fibers for head, neck, and thoracic viscera?
Head & Neck:
Origin: Lateral horn cells of T1-T2.
Relay: Cervical ganglia.
Thoracic Viscera:
Origin: Lateral horn cells of T1-T4.
Relay: Cervical and upper thoracic ganglia.
Q: What is the origin and relay of sympathetic fibers to the abdominal viscera?
Origin: LHCs of T5-T12.
Relay: Greater splanchnic nerve → coeliac & superior mesenteric ganglia.
Q: What are the sympathetic effects on the gastrointestinal tract?
Relaxation of smooth muscles (stomach, small intestine, proximal large intestine).
Contraction of sphincters (e.g., pyloric sphincter).
Q: What are the sympathetic effects on abdominal blood vessels?
Vasoconstriction of arterioles supplying abdominal viscera.
Vasodilatation in specific arterioles.
Q: What are the sympathetic effects on the liver, spleen, and adrenal medulla?
Liver: Stimulates glycogenolysis → increases blood glucose.
Spleen: Contraction of capsule → releases stored blood (RBCs).
Adrenal Medulla: Secretes adrenaline and noradrenaline into blood
Q: What is the origin and relay of sympathetic fibers to the pelvic viscera?
Origin: LHCs of T12-L2.
Relay: Lesser splanchnic nerve → inferior mesenteric ganglion.
Course: Postganglionic fibers run with blood vessels to pelvic organs
Q: What are the sympathetic effects on the gastrointestinal tract in the pelvis?
Relaxation of smooth muscles (distal large intestine & rectum).
Contraction of internal anal sphincter → fecal retention
Q: What are the sympathetic effects on the urinary bladder?
Relaxation of bladder wall.
Contraction of internal urethral sphincter → urine retention.
Q: What is the function of the sympathetic system on the adrenal medulla?
Stimulates secretion of adrenaline and noradrenaline directly into the bloodstream → enhances “fight or flight” response.
Q: What are the sympathetic effects on the spleen?
Contraction of the splenic capsule → releases stored blood (RBCs) into circulation.
Q: How does the sympathetic system affect gastrointestinal sphincters?
Causes contraction of sphincters (e.g., pyloric sphincter, internal anal sphincter) → retention of contents (food or feces).
Q: What is the sympathetic effect on blood glucose levels?
Stimulates glycogenolysis in the liver → increases blood glucose to provide energy for “fight or flight” situations.
Q: What happens to the urinary bladder under sympathetic control?
Relaxation of bladder wall muscles → prevents urination.
Contraction of the internal urethral sphincter → retains urine.
Q: How does the sympathetic system regulate blood vessels?
Vasoconstriction of arterioles in abdominal and pelvic viscera → redirects blood to vital organs (brain, heart, muscles).
Selective vasodilatation of certain arterioles when necessary.
Q: Summarize the sympathetic effects on abdominal GIT.
Abdominal GIT:
Relaxes smooth muscles (stomach, small intestine, proximal large intestine).
Contracts sphincters (pyloric sphincter).
Q: Summarize the sympathetic effects on pelvic GIT.
Pelvic GIT:
relaxes smooth muscles (distal large intestine, rectum).
Contracts internal anal sphincter → fecal retention.
Q: Summarize the pathway of sympathetic fibers for head, thorax, abdomen, and pelvis.
Head & Neck: LHCs T1-T2 → Cervical ganglia → Blood vessels.
Thoracic Viscera: LHCs T1-T4 → Paravertebral ganglia → Organs.
Abdominal Viscera: LHCs T5-T12 → Coeliac/Superior mesenteric ganglia → Organs.
Pelvic Viscera: LHCs T12-L2 → Inferior mesenteric ganglion → Organs.
Q: What are the sympathetic effects on female genital organs?
The effects are variable depending on the stage of the menstrual cycle.
Q: What are the sympathetic effects on male genital organs?
Vasoconstriction of blood vessels → shrinkage of the penis.
Contraction of:
Vas deferens
Seminal vesicles
Prostate gland
→ Leads to ejaculation of semen.
Q: What are the sympathetic effects on the urinary bladder?
Relaxation of the smooth muscles in the bladder wall → inhibits urination.
Contraction of the internal urethral sphincter → retention of urine.
Q: What is the general function of the parasympathetic nervous system?
Anabolic and energy-preserving system.
Controls activities during rest, digestion, and reading.
Q: What is the pathway of parasympathetic fibers of the oculomotor nerve?
Origin: Edinger-Westphal nucleus in the midbrain.
Relay: In the ciliary ganglion.
Course: Postganglionic fibers enter the eye as short ciliary nerves.
Q: Where do the preganglionic fibers of the oculomotor nerve originate?
A: From the Edinger-Westphal nucleus in the midbrain.
Q: In which ganglion do the oculomotor preganglionic fibers relay?
A: In the ciliary ganglion.
Q: What is the course of the postganglionic fibers of the oculomotor nerve?
A: They enter the eye as short ciliary nerves.
Q: Which muscle contracts to cause pupil constriction under parasympathetic control?
A: The constrictor pupillae muscle.
Q: What is the medical term for parasympathetic-induced pupil constriction?
Miosis
Q: What effect does the parasympathetic system have on the ciliary muscle?
A: It causes contraction of the ciliary muscle.
Q: How does contraction of the ciliary muscle affect the lens of the eye?
A: It increases the power of the lens, preparing the eye for near vision.
Q: What is the function of the short ciliary nerves in the parasympathetic pathway?
A: They carry postganglionic fibers to the eye.
Q: What is the origin, relay, and course of parasympathetic fibers in the oculomotor nerve?
Origin: Edinger-Westphal nucleus.
Relay: Ciliary ganglion.
Course: Short ciliary nerves enter the eye.
Q: What are the two main parasympathetic effects mediated by the oculomotor nerve?
Miosis: Contraction of constrictor pupillae muscle.
Accommodation for near vision: Contraction of the ciliary muscle
Q: Where do the preganglionic fibers of the facial nerve originate?
A: From the superior salivary nucleus in the lower pons.
Q: Where do the preganglionic fibers of the facial nerve relay?
Sphenopalatine ganglion (for lacrimal and nasal glands).
Submandibular ganglion (via chorda tympani) for submandibular and sublingual glands.
Q: What is the course of the postganglionic fibers from the sphenopalatine ganglion?
A: They supply the lacrimal glands and nasal glands.
Q: What is the role of the chorda tympani branch of the facial nerve?
A: It carries preganglionic fibers to relay in the submandibular ganglion.
Q: Which glands are supplied by postganglionic fibers from the submandibular ganglion?
Submandibular salivary gland
Sublingual salivary gland
Q: What are the main parasympathetic functions of the facial nerve?
secretomotor: Stimulates secretion of:
Lacrimal glands
Nasal glands
Submandibular and sublingual salivary glands
Vasodilation (VD): Increases blood flow to the glands
Q: Where do the preganglionic fibers of the glossopharyngeal nerve originate?
A: From the inferior salivary nucleus located between the pons and medulla.
Q: Where do the preganglionic fibers of the glossopharyngeal nerve relay?
A: In the otic ganglion.
Q: What is the course of postganglionic fibers of the glossopharyngeal nerve?
A: Postganglionic fibers travel from the otic ganglion to supply the parotid gland.
Q: What are the functions of the glossopharyngeal nerve parasympathetic fibers?
Secretomotor: Stimulates secretion of the parotid gland.
Vasodilation (VD): Increases blood flow to the parotid gland.
Q: Where do the preganglionic fibers of the vagus nerve originate?
A: From the vagal nucleus in the medulla oblongata.
Q: What is the course of the vagus nerve parasympathetic fibers?
A: Preganglionic fibers run in the vagus nerve to supply the thoracic and abdominal viscera.
Q: Where do the preganglionic fibers of the vagus nerve relay?
A: In terminal ganglia located inside or close to the organ.
Q: What are the parasympathetic effects of the vagus nerve on the heart?
The vagus nerve does not supply the ventricles.
Inhibits all properties of the atrial cardiac muscle only.
Decreases coronary blood flow and O₂ consumption.
Q: What are the parasympathetic effects of the vagus nerve on the lungs?
Bronchoconstriction.
Vasodilation of pulmonary blood vessels.
Stimulation of bronchial glands → increases secretion.
Q: What are the parasympathetic effects of the vagus nerve on the gastrointestinal tract?
Contraction of smooth muscles in:
Esophagus
Stomach
Small intestine
Proximal part of the large intestine.
Relaxation of GIT sphincters.
Stimulation of secretions from:
GIT glands
Liver
Pancreas.
