Physiology Flashcards by Garrett Gilbert

Enteric nervous system comprises what

Myenteric and submucosal plexuses

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Vagal-Vagal reflex: afferents go where

Nodose ganglion

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Vagal vagal reflex: Efferents come from where?

NTS: Nucleus Tractus Solitarius

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Gastrin: Source?

Stimuli of secretion

-G cells of stomach

small peptides and aa
Distention
vagal stimulation (via GRP)

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CCK: source?

Stimuli of secretion?

I cell of duodenum and jejunum

Small peptides and a.a.
Fatty acids

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Secretin: source?

Stimuli of secretion?

S cell of the duodenum

H+ in duodenum
Fatty acids in duodenum

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GIP: source?

stimuli of secretion?

What does it do?

Duodenum and jejunum

Glucose
stimulates insulin

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What does the NT VIP do?

relaxation of smooth muscle

- increase intestinal and pancreatic secretion

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what does the NT GRP do?

-increases Gastrin secretion

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What 2 NTs are used for food intake regulation

Neuropeptide Y

- Substance P

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What is it called when the GI smooth muscle, even subthreshold depolarizes and can produce weak contraction

Basal Contractions

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Sub thrshold depolarization and repolarization of the GI membrane potential

slow waves

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What 3 things stimulate depolarization of the slow waves?

what stimulates hyper polarization?

stretch
ACh
Parasympathetics
Norepinephrine
Sympathetics

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pacemaker for GI smooth muscle

Interstitial cells of Cajal (ICC)

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slow waves occur spontaneously in the ICC and spread how

gap junctions

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Smooth muscle cells response to slow wave depolarization with increased what?

Ca2+ channel open probability

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3 phases of swallowing

Oral phase
pharyngeal phase
Esophageal phase

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involuntary swallowing reflex is controlled by what?

the medulla

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What nerve sends afferent sensory input due to food in the pharynx to the swallowing center in the medulla?

Glossopharyngeal N.

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Esophageal phase of swallowing contains what 2 types of peristaltic waves?

primary and secondary

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Which wave of the esophageal phases can still occur after a vagotomy

secondary

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Receptive relaxation occurs in what region of the stomach

orad

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What does CCK do to the contractions and distensibility of orad region upon reception of food

decreases contractions

- increases distensibility

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how long does gastric emptying take

3 hours

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What secretion from the duodenum inhibits gastric emptying

CCK

Large particles of undigested residue remaining in the stomach are emptied by what

Migrating myoelectric complexes (MMC)

- intervals for MMCs - when do they occur? - what mediateds them? - when are they inhibited?

- 90 min - during fasting - Motilin-mediated - inhibited by feeding

What type of contractions: - back and forth movements - No forward propulsive movement

segmentation

What type of contrations: | -Circular and longitudinal muscles work in opposition and are reciprocally innervated

peristaltic

what does the myenteric plexus do?

regulates relaxation/contraction of intestinal wall

What does submucosal plexus (Meissner) plexus do?

sense the lumen environment

what inhibits contraction in small intestine via and interneuron and causes relaxation DISTAL (caudad) to the signal of distention

VIP and NO

what excites and stimulates contraction in the small intestine via and interneuron and causes relaxation PROXIMAL (Orad) to the signal of distention

ACh and substance P

What is released by ECCs and binds to receptors in IPANs, initiating peristaltic reflex

serotonin

Colon Absorbs what?

water and vitamins

What 2 things can cause achalasia

- Lack of VIP | - enteric system has been knocked out

LES stays closed during swallowing and elevation of LES resting pressure

Achalasia

- slow emptying of stomach/paralysis of stomach | - 20% of type 1diabetics have this

gastroparesis

Causes of Gastroparesis

Damage to vagus nerve from: - idiopathic - high blood glucose (diabetic gastroparesis)

Ganglion cells absent from segment of colon

Hirschsprung disease

Failure to pass meconium

Hirschprung

what levels are low in Hirschsprung

VIP

What is saliva composed of

- H2O - electrolytes - a amylase - lingual lipase - Kallikrein - mucus

Tonicity of saliva

HYPOtonic compared to plasma

- K+ and HCO3 in saliva | - Na and Cl?

- increased | - decreased

What cells form isotonic plasma like solution in the first step of salivary secretion

Acinar cells

What cells modify the isotonic solution that was created by Acinar cells to make it hypotonic

Ductas cells

How do vasopressin and aldosterone modify the composition of saliva

- decreases its Na | - increases its K

Parasympathetics to acinar and ductal cells for salivary secretions

- Vagus and Glossopharyngeal | - IP3 and Ca

Sympathetic to Acinar and ductal cells for salivary secretions

- T1-T3 | - cAMP

What are the 2 unusual features in the regulation of salivary secretion

- EXCLUSIVELY under control of ANS | - increase by BOTH parasympathetics and sympathetics

What is required for absorption of vitamin B12 in the ileum

intrinsic factor

What kind of gland is in the proximal 80% (body and fundus) of the stomach and secretes acid

Oxyntic gland

What kind of gland has chief cells? | These secrete what?

Oxyntic | pepsinogen

What kind of gland is in the distal 20% (antrum) and synthesizes and releases gastrin

pyloric gland

What kind of gland has D cells? | These secrete what?

pyloric gland | somatostatin

What are the 2 Gq pathways leading to increase in IP3/Ca2 and H+ secretion in gastric parietal cells

- G cells -->Gastrin --> CCKB receptor | - Vagus -->Ach -->M3 receptor

What is the Gs pathway leading to increased cAMP and H+ secretion in gastric parietal cells

-ECL cells--> Histamine --> H2 receptor

What are the 2 Gi inhibitory pathways that decrease cAMP and inhibit secretion of H+ in gastric parietal cells

- D cells --> somatostatin | - Prostaglandins

Falling pH inhibits what?

gastrin release so decreases HCl secretion

what are the 2 pathways that the vagus nerve uses to stimulate HCl secretion from parietal cells

- Directly on parietal cells | - indirectly through GRP and G cells --> gastrin --> to parietal cells (atropine doesn't block this pathway)

What is in the protective layer of the mucosa to protect stomach from H+ and pepsin? What secretes each?

mucus .. . mucous neck cells | HCO3- . . . Gastric epithelial cells

Unconjugated Jaundice diseases

- Gilbert's | - Crigler-Najjar syndrome

Conjugated Jaundice diseases

- Dubin-Johnson | - Rotor syndrome

transporter for fructose from lumen to cell? cell to blood?

GLUT5 GLUT2

transporter for Glucose and Galactose from lumen to cell? -cell to blood?

- SGLT 1 | - GLUT2