Digestive Physiology Final

what are the 9 segments of the GI tract?

Mouth

Pharynx

Esophagus

Small intestine

Large intestine

Rectum

Anus

Sphincters between segments

What are the functions of the digestive system?

Ingestion

Digestion (mechanical, chemical)

Secretion

Absorption

Excretion

What are the layers of the GI tract?

Serosa

Longitudinal muscle

Myenteric (Auerbach’s) nerve plexus

Circular muscle (diameter)

Submucosa

Submucosa (Meissner’s) nerve plexus

Muscularis mucosae

Mucosa

Epithelial lining

What are the 2 major muscle layers of the muscularis externa?

Longitundial (outer, length)

Circular (inner, diameter)

What innervates the muscularis externa?

Myenteric plexus

What is the function of the muscularis externa?

Propel (move food) along the gut tube

What innervates the submucosa?

submucosal plexus

What can be found within the submucosa (3 things)?

increase in loose connective tissue

increase in blood vessels

mucus secreting glands

The mucosa contains what 3 things?

epithelial cells

lamina propina

muscularis mucosa

What is the extrinsic (SNS) innervation of the digestive system?

Decrease digestion

decrease contractility and secretion

vasoconstrict

sphincters contract (close)

What is the extrinsic (PSNS) innervation of the digestive system?

Increase in digestion

promote contractions and secretions

sphincters contract or relax

What is the intrinsic innervation of the digestive system (enteric NS)?

Submucosal plexus

Myenteric plexus

Interneurons

Where is the submucosal plexus located?

Esophagus to anus

What does the submucosal plexus regulate?

Secretions

What kind of neurons does the submucosal plexus contain?

Sensory neurons (mechano R, Chemo R, Thermo Rm Noci R)

Where is the myenteric plexus located?

Esophagus to anus

What does the myenteric plexus regulate?

Motility

What kind of neurons does the myenteric plexus contain?

motor neurons (contraction)

Where are the interneurons located?

Sensory and motor neurons

What does the interneurons connect?

Connect 2 plexuses

What is the location of the ENS?

Esophagus to anus

What is the composition of the ENS?

Sensory and motor neurons

What cells does the ENS innervate?

Gut cells

The ENS contains what kind of neurotransmitters?

Both excitatory and inhibitory

What are the 2 divisions within the PSNS innervation?

Cranial division (vagus nerve)

Sacral division (S2-S4)

What kind of neurons are found within PSNS innervation?

long preganglion and short post ganglion

Is the PSNS usually excitatory or inhibitory?

excitatory

What are satiety signals?

Hormones regulating food intake, telling you when you are full

What are the 2 major functions of the pancreas?

Exocrine (ducts for enzyme release)

Endocrine (bloodstream, hormones)

What are the 2 functions of the gallbladder?

store and concentrate bile

What is the function of the liver?

detox blood

Store excess nutrients

produce bile

What are the 3 stages of digestion?

Cephalic phase

Gastric phase

Intestinal phase

What occurs during the cephalic phase of digestion?

oral phase

begins due to sight, smell and taste

Psychogenic

What occurs during the gastric phase of digestion?

Occurs when food enters the stomach

What occurs during the intestinal phase of digestion?

Occurs when processed ‘food’ or ‘chyme’ enters the small intestine

What neural mechanisms are in place during the cephalic phase?

Salivary glands, will be innervated by the vagus nerve

stomach, will prepare stomach for food arrival, innervated by the PSNS

The submandibular and sublingual gland produce what?

mucus

The parotid gland produces what?

Mucus

Salivary amylase enzyme

What is the function of salivary amylase?

Digest carbs

What 5 components make up saliva?

Salivary amylase

Mucin

Muramidase

Lingual lipase

watery fluid

What is the function of mucin in the saliva?

Lubricant (sticky), to create bolus of food

What is the function of muramidase in the saliva?

bacteriostatic (kill bactera)

What is the funciton of lingual lipase in the saliva?

enzymes in babies, help with digestion of milk fat

What is the function of the watery fluid within saliva?

has a pH of 8

helps to stop acid from eroding teeth

How much saliva is secreted every day?

1 liter/day

What is the SNS stimulation of saliva?

Simulation secretion briefly

How is saliva secretion controlled by the PSNS?

Increases the rate and flow of saliva

What are the three phases of the swallowing reflex?

Oral

Pharyngeal

Esophageal