GI 1 Flashcards by Michael McMahan

Mouth to anus
Lumen Contents considered outside body
30 feet in length

Alimentary Canal (GI Tract)

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Not part of GI tract
Produce substances secreted into tract
  –Salivary glands
  –Exocrine pancreas
  –Liver and Gall Bladder

Accessory organs

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Function of GI:
Breakdown ingested molecules into building blocks
Two Types
  A. Mechanical
  B. Chemical

Digestion

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Function of GI:
Digestive enzymes
Acid/Base
Bile

Secretion

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Function of GI:
Passive and Active transport processes
Moves substances from lumen of gut to blood

Absorption

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Function of GI:
Mixing
Mechanical Digestion
Move material through tract

Motility

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Function of GI:
Removal of Metabolic waste
Very little true waste in Feces (Bile pigments)

Excretion

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Function of GI:

Gut Associated Lymphoid Tissue

Defense

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What are the 4 layers of structure of GI tract wall from outermost to innermost?

Mucosa
Submucosa
Muscularis externa
Serosa

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Simple Columnar Epithelium
Lamina Propria
Muscularis Mucosa
-Movement of Villi

Mucosa

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CT Layer
Blood and lymph vessels
Submucosal Plexus
-Network of neurons-Projections to luminal surface cells, muscularis mucosa, and to Myenteric plexus

Submucosa

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-Network of neurons-Projections to luminal surface cells, muscularis mucosa, and to Myenteric plexus

Submucosal Plexus

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Circular Muscle-Contraction narrows lumen
Longitudinal muscle-Contraction shortens tube
Myenteric Plexus
-Network of neurons-Input from Autonomic NS-
Projections to Submucosal Plexus, Circular, and
Longitudinal muscle

Muscularis Externa

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Network of neurons
Input from Autonomic NS
Projections to Submucosal Plexus, Circular, and Longitudinal muscle

Myenteric Plexus

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CT covering

Support GI tract in abdominal cavity

Serosa

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What 2 things make up the enteric NS?

Submucosal and Myenteric Plexus

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\_\_\_\_\_\_ layer:
Simple Columnar (microvilli)
Goblet Cells
Enteroendocrine cells (base of villi)
Stem cells

Epithelial

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Tremendous surface area available for absorption of materials from lumen via what 3 things?

Circular Folds
Villi
Microvilli (Brush Border)

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Circular Folds, Villi, and Microvilli (Brush Border)Increases SA ____ times over flat surface

600x

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The following are Inside the ______:
Lacteals (lymph vessels)
Capillary network

Villus

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Control Systems regulate conditions in ____ of tract

lumen

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Control mechanisms are governed by ______ and ______ of luminal contents

volume and composition

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ECL cells in the GI system secrete ______

histamine

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D cells in the GI system secrete ______

Somatostatin

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_____ innervation: Responds to stretch, inflammation, nutrients, endocrine factors. Synapses in enteric nervous system, prevertebral ganglia, spinal cord, brainstem. Vagal nerves mainly afferent to brainstem.

Afferent (sensory)

_____ innervation– CN XII (tongue), V (chewing), IX, X (swallowing); Pudendal n. – ext. anal sphincter

Somatic

_____innervation post-ganglionicfibers (NEpi) to enteric nervous system, vasculature, ducts, parenchyma; usually inhibitory.

Sympathetic –

_____ innervation: ENS functions as post-ganglionic fibers, actions are stimulatory or inhibitory, depending on final neurotransmitter receptor.

Parasympathetic (vagus, pelvic)

____ is the neurotransmitter that is released from symp postganglionic neurons

____ is the neurotransmitter that is released from parasymp preganglionic neurons

ACh

Linear chain of neurons that extend the entire length of GI Tract Control muscle of muscularis externa When stimulated 1.Increase tone of gut wall 2.Increase intensity of rhythmic contractions 3.Slight increase in rate of rhythmic contractions 4.Increase conduction velocity of electrical waves along gut wall 5.Inhibition of sphincter contraction

Enteric nervous system (ENS)

``` _______: Controls function of each minute segment of tract Local control of -Intestinal secretions -Absorption -Contraction of mucosal muscle ```

Enteric Nervous System (ENS)

What are the 3 receptors that respond to GI lumen stimulus?

Chemoreceptors, osmoreceptors, and mechanoreceptors

Are there long or short feedback loops in GI?

Both

____ cells are scattered in gut mucosa

Endocrine cells

Specialized cells: one cell – one hormone (mostly). Specific cell types localized to regions of gut. Cells “taste” luminal contents.

Endocrine regulation of digestive function

Cells similar to endocrine. Released into interstitial fluid, diffuses to target (may “overflow” into the circulation). Two established gut paracrine factors: histamine (ECL cell), somatostatin (D cell).

Paracrine factors

____ is mainly released by gastrin

Histamine

_____ is mainly released by luminal H+

Somatostatin

``` Patterns of ______ include: Chewing Swallowing Esophageal transport Gastric storage, trituration, emptying Vomiting Gallbladder storage, emptying Small intestinal mixing & transport Colonic storage, defecation ```

Motility

_____ muscle of the GI tract: | -mouth, oropharynx, upper esophageal sphincter, upper 1/3 of esophagus, external anal sphincter.

Skeletal (voluntary, striated) –

_____ muscle of the GI tract: | - lower 2/3 of esophagus, stomach, small intestine, large intestine, gallbladder, biliary and pancreatic ducts.

Smooth (involuntary)

Collects all venous outflow from most GI organs.

Portal vein

All portal outflow goes to ____ before entering vena cava.

liver

Nutrients, hormones, drugs, toxins are “scanned” by _____ before going to IVC.

liver

_______ saliva: Watery secretion containing ptyalin (α amylase) Moisten and dissolve food Small amount of chemical digestion

Serous saliva

______ saliva: Thick secretions containing mucin Lubrication and protection of surfaces

Mucous saliva

What type of saliva is secreted by parotid?

Serous

What type of saliva is secreted by submandibular?

Mixed

What type of saliva is secreted by sublingual?

Mixed

What type of saliva is secreted by the many tiny buccal salivary glands?

Mucous

_____ is made up of the following things: - Water - Bicarb - Mucins - Amylase - Lysozyme, Lactoferrin, and IgA - Epidermal and nerve growth factors

Saliva

Up to _____ L/day of saliva is produced

1.5 L/day

Secretion of saliva is strictly under ______ reflex control

Neural reflex control

_____ (constituent of saliva): | -Facilitates taste and dissolution of nutrients, aids in swallowing

Water

_____ (constituent of saliva): Neutralizes refluxed gastric acid

Bicarbonate

_____ (constituent of saliva): Lubrication

Mucins

_____ (constituent of saliva):Starch Digestion

Amylase

_____ (constituent of saliva): Innate and acquired immunity

Lysozyme, Lactoferrin, IgA

_____ (constituent of saliva): ? Mucosal growth and protection

Epidermal and nerve growth factors

Does parasymp activity or symp activity increase saliva?

Parasymp

Predominate regulator of saliva production Critical for initiation of saliva secretion Critical for sustaining high levels of saliva secretion Vasodilation of blood vessels supplying salivary glands22 Causes:-Up to 20x increase in saliva production by acinar cells

Parasymp NS

What neurotransmitter binds to what receptors for the parasymp NS?

Ach/Muscarinic

As flow rate increases, the saliva becomes more closely resembles the ______

Plasma

As flow rate increases, the saliva becomes more basic or acidic?

Basic

As flow rate increases, the saliva becomes less hyper or hypotonic?

Hypotonic

Reflex Activation of ______ Stimulated Saliva Production: Taste (especially sour) and tactile stimuli (presence of smooth objects) on tongue surface Smell of food (especially if it is a food that is not liked) Ingestion of irritating foods Nausea

Parasympathetic

_____ NS plays a minor role in control of saliva and potentiates parasympathetic effects

SNS

What neurotransmitters bind to what receptors for SNS?

NE/adrenergic

At low flow rates, saliva is ______

hypotonic

What percentage of saliva in unstimulated salivation is secreted by parotid gland?

69%

What percentage of saliva in unstimulated salivation is secreted by submandibular gland?

26%

What percentage of saliva in unstimulated salivation is secreted by sublingual gland?

What percentage of saliva in stimulated salivation is secreted by parotid gland?

26%

What percentage of saliva in stimulated salivation is secreted by submandibular gland?

69%

What percentage of saliva in stimulated salivation is secreted by sublingual gland?

______ salivation is inhibited by the following: 1. Fear 2. Sleep 3. Fatigue 4. Dehydration

Unstimulated salivation

_____ salivation is stimulated by the following: 1. Autonomic (primarily parasympathetic) 2. Thinking/seeing/smelling food 3. Conditioned salivation 4. Chewing 5. Nausea

Stimulated salivation

T/F: Rates of saliva production are not dependent on age, flow rates remain constant in spite of acinar degeneration.

True

``` Subjective feeling of a dry mouth. Most common causes -Polypharmacy (>4 drugs/day) -Anxiety and depression (and medications used for treatment) -Insufficient hydration -Radiation to the head and neck -Sjogren syndrome ```

Xerostomia

What are the 5 common causes of xerostomia?

- Polypharmacy (>4 drugs/day) - Anxiety and depression (and medications used for treatment) - Insufficient hydration - Radiation to the head and neck - Sjogren syndrome

Autoimmune destruction of mucous membranes and moisture-secreting glands Decreased production of tears and saliva Dry eyes and mouth

Sjogren's syndrome

Consequences of _______: Increased caries due to reduced oral clearance of sugars, dietary acids, oral bacteria Halitosis Disrupted sleep due to dry mouth; wake up to sip water and moisten mouth Difficulty lubricating and swallowing food Dry mouth (feel thirsty, dry, cracked lips) –Burning mouth sensation –Dry/sore oral mucosa Impaired sense of tastes Heartburn –Low saliva; decreased buffering –Loss of protective growth factors in saliva –Lengthened healing time for ulcers

Xerostomia

Management of ______: •Avoid acidic, spicy, crunchy and coarse foods. •Alcohol-free toothpastes and rinses. •Oral moisturizers, sips of water, sugarless chewing gum. •Sialogogues such as pilocarpine and cevimeline before meals (cholinergic agonists)

Xerostomia

Rhythmic opening and closing of mandible that is coordinated with tongue movements

Mastication

Functions of ______ include: 1. Prepare food bolus for swallowing Mechanical digestion – Reduce particle size -Break up cells -Break up indigestible cellulose -Increase surface area/decrease particle size for mixing with digestive enzymes Mix food with saliva (serous and mucous) -Chemical digestion (mainly carbohydrates) -Sufficient plasticity-Surface lubrication -Cohesive structure 2. Initiate digestive and metabolic activities Digestion of carbohydrates in mouth Initiate reflexes to prepare digestive tract for incoming food

Mastication

What are the 3 stages of deglutition?

Voluntary stage Pharyngeal stage Esophageal stage

_____ stage of deglutition: Initiate swallowing process Bolus of food moved into pharynx by tongue Stimulates epithelial swallowing receptor area

Voluntary Stage

_____ stage of deglutition: Involuntary Mediated by swallowing center in brainstemSoft palate pulled upward and closes off nasopharynx Epiglottis closes off trachea (Respiration inhibited for < 2 sec.) Upper Esophageal Sphincter (UES; Pharyngoesophageal Sphincter) relaxes

Pharyngeal Stage

_____ stage of deglutition: Coordinated muscle contractions to move bolus through esophagus into stomach (aborally). ≈ 10 sec.

Esophageal Stage

What are the 3 functions of the esophagus?

1. Transport of solids and liquids from Pharynx to stomach 2. Prevents air intake - UES 3. Prevents reflux (stomach to esophagus) -LES

Which esophageal sphincter prevents air intake?

UES

Which esophageal sphincter prevents reflux?

LES

wave of contraction that moves bolus through esophagus

Peristalsis =

_____ peristalsis: | -continuation of peristaltic wave initiated during pharyngeal phase of swallowing (8-10 sec)

A. Primary Peristalsis

_____ peristalsis: | -activated by esophageal distension from retained food in esophagus

Secondary Peristalsis

Is the upper portion or lower portion of esophagus under voluntary control?

Upper

_____ peristalsis occurs as a wave of relaxation in front of bolus and a wave of contraction behind bolus

Primary peristalsis

_____ is the term used for the wave of relaxation in front of bolus

Caudad

_____ is the term used for the wave of contraction behind bolus

Orad

Which neurotransmitter carries out orad?

Ach

Which neurotransmitter carries out caudad?

______ peristalsis Function Clearing a bolus that was not wholly expelled by primary wave Removing any gastric contents that reflux back into the lower esophagus

Secondary peristalsis

Upper and lower esophageal sphincters remain _______ between swallows

closed

________ sphincter relaxes during swallow.

Upper esophageal sphincter

______ sphincter relaxes as peristaltic wave approaches.

Lower esophageal sphincter

Reflux of gastric contents into esophagus Common and potentially disabling Treated by inhibiting gastric acid secretion

Gastro-Esophageal Reflux Disease

GI 1 Flashcards

(107 cards)