Neurophysiology Flashcards

Vocabulary flashcards related to neurophysiology and the enteric nervous system.

Enteric Nervous System

The nervous system specific to the gastrointestinal tract; it has as many neurons as the entire spinal cord.

Mucosa

The innermost layer of the alimentary canal, consisting of epithelium, lamina propria, and muscularis mucosa.

Submucosa

A layer of areolar and dense connective tissue containing glands and the submucosal plexus (Meissner’s plexus).

Muscularis Externa

Layer containing inner circular and outer longitudinal muscle layers, along with the myenteric plexus (Auerbach’s plexus).

Serosa

The outermost layer; if present, the structure is intraperitoneal, and if absent, the structure is retroperitoneal and called adventitia.

Submucosal Plexus

Plexus located in the submucosa; also known as Meissner’s plexus.

Myenteric Plexus

Plexus located between the inner circular and outer longitudinal muscle layers of the muscularis externa; also known as Auerbach’s plexus.

Descending Fibers

Activated by stretch receptors in the muscular layer when food bolus stretches the alimentary wall.

Circular Muscle Layer (Ascending Fibers)

Fibers that release acetylcholine and substance P to the circular muscle layer, causing it to contract.

Longitudinal Muscle Layer (Ascending Fibers)

Fibers that release vasoactive intestinal peptide (VIP) and nitric oxide to the longitudinal muscle layer, causing it to relax.

Function of Descending Fibers

Area needs to relax to allow food to pass through the use of VIP + NO, potassium ions leaving the cell (hyperpolarization)

Stimulation of Submucosal Plexus

Stimulated by chemoreceptors that release chemicals depending on the food eaten and activates submucosal plexus

Secretin function

Stimulate hepatocytes to produce more bile that emulsifies fats.

CCK Function

Gall bladder contractions, potentiate secretin’s action on liver, pancreas ductal cells producing proteases, lipases and amylase

K Cells release

Glucose insulinotropic Peptide (GIP) stimulates pancreas to produce insulin.

Sympathetic Nervous System

Inhibits GI tract, motility, blood flow, secretions and absorption constricts sphincters (exception)

Parasympathetic Nervous System

Activates GI Tract, motility, secretions and absorption and relaxes sphincters (exception)

Short Reflexes

Short reflexes are completely peripheral and involve the local integration of sensory input with motor output.

Long Reflexes

Long reflexes have afferent branches that enter the spinal cord or brain and involve efferent branches.

Vagovagal Reflex

Chemoreceptor/stretch receptor transmit GVA fibers of vagus nerve (afferent fibers) to the Dorsal Nucleus of Vagus.

Entero-gastric Reflex

Chemoreceptor/stretch receptor -> prevertebral ganglion (sympathetic nervous system) -> inhibits secretions, dilation, etc.

Defecation reflex

Distention of the colon Chemoreceptor/stretch receptors activated sacral plexus (S2-S4) -> pelvic splanchnic nerves.

Function of Saliva

Hydrate oral cavity, lubricate food increases taste, chemical digestion

Serous cells

Watery secretions (enzymes, electrolytes)

Mucous cells

Viscous secretions (glycoproteins, mucins)

Pathway for Submandibular & Sublingual gland

Superior salivatory nucleus (CN VII - PSNS)

Pathway for Parotid gland

Inferior salivary nucleus (part of glossopharyngeal nerve CN IX - PSNS)

Afferent Stimuli

Special receptors (on tongue, in cheeks, around tonsils, in pharyngeal area, etc)

Acinus

Sac-like region lined by acinar cells

Duct

Lined by ductal cells

Effect of PSNS

ACh binds on muscarinic receptor M3 and Electrolyte, water secretion Increase

Effect of SNS

NE stimulates beta-receptor on acinar cells causes Mucins, salivary amylase secretion Increase

Extrinsic / Major

Parotid, submandibular, sublingual gland, Have ducts, Secrete after stimulus, Produce 90% of saliva, Serous and mucous

Intrinsic / Minor

Buccal, labial, palatal, etc, No ducts, Secrete constantly, Produce 10% of saliva, Mucous

Parotid Duct

Stensen duct

Submandibular Duct

Warthon’s duct

Sublingual Duct

Many ducts of Rivinus

Parotid Histology

Serous

Submandibular Histology

Mixed

Sublingual Histology

Mucous

Parotid Innervation

CN IX

SubManibular Innervation

CN VII

Swallowing = Deglutition

Bring food oral cavity to stomach.

Mandibular depressors

Lateral pterygoid m. (CN V3 - mandibular nerve) , Digastric m. (anterior belly) (CN V3) , Mylohyoid m. (CN V3) , Geniohyoid (cervical plexus, mainly C1)

Mandibular elevators

Masseter m. (most powerful) (CN V3) , Temporalis m. (CN V3) , Medial pterygoid m. (CN V3)

Muscles of mastication

Lateral pterygoid m, Medial pterygoid m, Masseter m, Temporalis m

Intrinsic muscles

Form central trough around food bolusBy: superior longitudinal, inferior longitudinal, vertical, transverse mm

Extrinsic muscles

Elevate tongue so that tip touches palate -> creates downward slope towards pharynx , By: styloglossus m, genioglossus m, mylohyoid m

Pharyngeal Phase

In back of oral cavity we find: Palatopharyngeal arch, Palatoglossal arch, Tonsillar fossa

CN X

Contracts uvula —> elevates uvula, Closes nasopharynx

Approximate/adducts vocal cords

Lateral cricoarytenoid m, Transverse / oblique arytenoid mm

Retroversion of epiglottis:

Aryepiglottic m, Elevates Anteriorly

Outer longitudinal layer of muscles contracts

Stylopharyngeus m. (CN IX, this is the only motor component of this cranial nerve.) , Salpingopharyngeus m. (CN X), Palatopharngeus m. (CN X)

Inner circular layer of muscles contracts

Superior, middle, inferior pharyngeal constrictors. Do pharyngeal peristalsis to push bolus down

Suprahyoid muscles

Digastric m, ant. + post. Belly, Stylohyoid m, geniohyoid m, mylohyoid m. Contraction —> pull hyoid bone up —> pulls larynx up and anteriorly

UES to receive Bolus Esophagus

at the lowest part of the inferior pharyngeal constrictor is: cricopharyngeus m. acts as UES (upper oesophageal sphincter) (CN X)

Primary peristalsis

Continuation of pharyngeal peristalsis going all the way down the esophagus (CN X)

Stimulates circular layer of muscles (2nd peristalsis)

Stimulates circular layer of muscles and Inhibits longitudinal layer of muscles

Sodium-potassium ATPase

Sodium pumped out and Potassium into the cell

Omeprazole

Competitive inhibitor of proton potassium pump, inhibits gastric acid secretion

Mucosal barrier

Protects the stomach from being digested by a very acidic environment and prevents corrosion of the stomach

Gastric stimuli influence gastric secretion

Occipital-> hypothalamus-> medulla

Vagovagal reflex

Stretch receptors are coupled with afferent fibers of cranial nerve 10 (vagus nerve) which is a sensory nerve.

Submucosal plexus

Are neurons in submucosa.

Myenteric Plexus

Concerns with the contractility and motility of the stomach

Intestinal phase the Secretin function

S-cells will release secretin in response to acidic or fatty concentration.

Function of CCK

Also helps increase bile synthesis, gall bladder contractions and relaxes the sphincter of Oddi

Gastric inhibitory peptide (GIP) chemical

Also known as glucose-dependent insulinotropic peptide.Released by enteroendocrine K-cells which responds to high concentrations of oligosaccharides/polysaccharides and fats.

Mucus gel layer (Figure 7)

Composed of: Water , Electrolytes, Phospholipids, Mucin proteins.

Space of Disse

Also called perisinusoidal space, found between sinusoidal capillaries and basolateral membrane of hepatocytes

Ligamentum venosum

Remnant of ductus venosus

Ligamentum teres

Remnant of umbilical vein in fetal life

Hepatic nerve plexus

From Vagus nerve and sympathetic nerves from celiac trunk

Superior mesenteric artery

branch of abdominal Aorta, supplies from duodenum to 2/3 of transverse colon

Inferior mesenteric artery

branch of abdominal Aorta, supplies from final 1/3 of transverse colon to superior aspect of rectum

Caput medusa

enlargement of the superficial periumbilical veins

TIPS (Transjugular Intrahepatic Portosystemic Shunt) procedure

Enter jugular vein — > right brachiocephalic vein -> SVC — > IVC -> hepatic veins -> portal vein tributaries

Shunt between portal vein and IVC (portacaval shunt)

A catheter is inserted from jugular vein

Portal tract

Enter and leaving the liver; hepatic artery proper, portal vein, hepatic plexus lymphatic vessels and bile duct

Hepatic lobule

Functional and structural unit of the liver

Hepatic arteriole

Carries highly oxygenated blood

Portal venule

Tributary of the portal vein

Sinusoidal capillaries

Fenestrated capillaries, found in the liver, spleen and bone marrow

Kupffer cells

Macrophages, found inside the sinusoidal capillaries which controls immunotolerance: old erythrocytes

Stellate cells

Store vitamin A + fat, Usually quiescent

Apoprotein

Apo A/B/C/E

Stellate cells

Store vitamin A + fat, Usually quiescent

Pancreas

Two types of cells, Alpha & Beta, contain Islets of Langerhans that are sensitive to glucose

Liver hormones

The site of RBC production in the fetus

Activates some clotting proteins

Vitamink

Mucus gel layer

Located at the top, contains Water (95%), Phospholipids, Mucin Proteins

Sodium and Potassium Pump

2K+ in, 3Na+ out

Biliary System

The bile produced by the liver

Mucus gel layer

Located at the top, contains Water (95%), Phospholipids, Mucin Proteins. and Prevent the proton from damaging the epithelial layer

Classic Lobule Model

From the hepatic artery and the portal venule to the internal vein.

Portal Lobule Model

Considers the direction of the bile flow.

Acinus lobule

It is a rhomboid structure where each zone performs a different function: Zone 1 is close to the portal triad that is 02 resistance

Stored In Fat

Vitamins A/D/B12

Transported with Transcobalamin

Vitamin B'S

Vitamin D.

Skin, Skin Cells is where the Vitamin 7 dehydrocholesterol is turned into active vitamins