GI Flashcards by Spencer Martin

What two groups of organs make up the digestive system

Gastrointestinal tract (alimentary)
Accessory digestive organs

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The gastrointestinal tract extends from the __________ to the _________

Mouth to the anus

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What anatomy is considered the GI tract

Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine

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What are the accessory digestive organs

Teeth
tongue
salivary gland
liver
gallbladder
Pancreas

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What is the function of accessory digestive organs

Aid in digestion

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What are the three regions of the abdomen

Intrathoracic
True abdomen
Retroperitoneal

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What defines an organ as intrathoracic

Enclosed by the lower ribs and immediately distal to the diaphragm

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Intrathoracic organs

Liver
Gallbladder
Spleen
Stomach
Transverse

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What is contained in the true abdomen

Large and small intestines, portion of the liver, and the bladder

Females: uterus, Fallopian tubes, ovaries

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How is retroperitoneal defined

Lies behind the thoracic and true portions, separated by the retroperitoneal membrane

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Retroperitoneal organs

Kidneys
Urters
Pancreas
Posterior duodenum
Ascending and descending colon
Inferior vena cava

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What are the six basic functions of digestion

Ingestion
Secretion
Mixing and propulsion
Digestion
Absorption
Defecation

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What is ingestion

Taking in food and liquid through the mouth

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What is secretion

Cells lining the GI tract produce water, acid, buffers and enzymes to aid digestion

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What is Mixing and propulsion

Continuous contraction and relaxation moving food along the tract.

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What is digestion

Mechanical and chemical process that breaks down food

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What is absorption

Small molecules produced in digestion move into spaces to be used by cells

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What is defecation

Elimination of materials not absorbed by our body

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What are the layers of the GI tract

Mucosa
Submucosa
Muscularis
Serosa

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Mucosa in the GI tract is the ________

Innermost lining in direct contact with the substances passing through

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What is the submucosa within the GI tract

Areolar connective tissue that connects the mucosa and the muscularis. Contains blood and lymph vessels

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What does the muscularis contain within the GI tract

Skeletal and smooth muscles

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What are the layers of the serosa

Visceral peritoneum
Parietal peritoneum

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What is the visceral peritoneum

Outmost layer around the organs

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What is the parietal peritoneum

Lines the walls of the abdominal cavity

Define the greater omentum

Fatty apron that drapes over transverse colon and small intestine

What is mesentery

Binds the small intestine to the posterior abdominal wall

Name the salivary glands

Parotid Submandibular Sublingual

What is the function of salivary glands

Dissolve food and begin digestion Contain lysosomes that kill bacteria Mucous produced to lubricate food Amylase begins digestion of starches in mouth

What percentage of saliva is water

99.5% water 0.5% solutes

The tongue is what type of organ

Accessory digestive organ

Define the frenulum

Fold of mucous membrane in the midline underneath tongue that limits posterior movement

What is the function of teeth

Perform mechanical digestion (chewing and breaking down food)

What is the pharynx

Funnel shape tube, located posterior end of oral cavity and comprised of skeletal muscle

Name the branches of the pharynx

Nasopharynx Oropharynx Laryngopharynx

Where is the esophagus located

Posterior to the trachea

Where the esophagus begins and ends

Begins at the end of the pharynx Ends at the superior aspect of the stomach

What are the sphincters of the esophagus

Upper esophageal - skeletal muscle Lower esophageal - smooth muscle

Define the function of esophagus

Transport food along its path, mixing it with mucous

Phases of swallowing

Voluntary Pharyngeal Esophageal

What is voluntary swallowing

Bolus forced into oropharynx from upward movement of tongue against palate

What is pharyngeal swallowing

Breathing is temporarily stopped, soft palate and uvula move up to close of nasopharynx, epiglottis closes off larynx and UES relaxes to allow bolus to move into esophagus

What is esophageal swallowing

Good is pushed through esophagus via peristalsis, LES relaxes and bolus moves to stomach

Describe the stomach

J shaped organ which serves as a mixing chamber for food. Aids in digestion

What is the pH of stomach

2 (acidic, < 7)

The stomach can accommodate up to _____ liters of food

6.4 liters

The stomachs extends from where and ends where

Extends from end of esophagus and ends at the top of the duodenum

Four main regions of stomach

Cardia Fundus Body Pylorus

What are gastric gland cells

Exocrine cells that combine to make gastric juices

What are the 3 types of gastric exocrine cells

Mucous neck cells Chief cells Parietal cells

Function of mucous neck cells

Secrete mucous

Function of chief cells

Secrete pepsinogen

Function of parietal cells

Secrete hydrochloride acid and intrinsic factor

What converts Pepsinogen into pepsin

Hydrochloride acid

Why is intrinsic factor needed

Absorption of B12 in small intestines

What is the function of G cells

Secrete gastrin into the bloodstream

What is gastrin

The major hormone regulator of hydrochloride acid secretion

Define Chyme

Thick liquid with pea soup consistency made up up gastric juices and macerated food

What type of functions does the pancreas have

Endocrine and exocrine

Specialized areas within the pancreas are called?

Islets of Langerhans

Islets of langerhans are made up of different cells that make what?

Hormones

The most common cells within the islet of langerhans

Beta cells

Insulin is produced by what cell?

Beta cells

Alpha cells are found where

Islet of langerhans

Alpha cells produce

Glucagon

What role does glucagon play within the body

Prevent blood glucose levels dropping too low

Is the pancreas Retroperitoneal or intra abdominal

Retroperitoneal behind the stomach

Secretions within the pancreas pass through what duct

Pancreatic duct

The hepatopancreatic duct is formed by

The common bile duct and the pancreatic duct

From the hepatopancreatic duct, secretions pass through the

Sphincter of Oddi

What are pancreatic juices

Clear colorless liquid made up of three enzymes

Enzymes in pancreatic juices

Trypsin and chymotrypsin Pancreatic amylase Pancreatic lipase Ribonuclease

Trypsin and chymotrypsin help digest what

Protein, broken down into amino acids, dipeptides and tripeptides

Pancreatic amylase helps digest what

Starch (carbs), absorbed as monosaccharides

Pancreatic lipase breaks down what

Triglyceride (fat), absorbed as monoglycerides and fatty acids

Ribonuclease break down what

Nucleic acid

Second largest organ in the body

Liver

The liver is responsible for what

Carbohydrate metabolism Lipid metabolism Protein metabolism Processing drugs and hormones Excretion of bilirubin Storage of vitamins and minerals Activation of vitamin D

What makes poop brown

Stercobilin

What is the major functional cell of the liver

Hepatocyte

Hepatocytes have what functions

Metabolic Secretory Endocrine

Describe the gallbladder

Pear shaped sac that hangs from inferior margin of the liver

Function of the gallbladder

Stores bile Aids in chemical digestion especially fats

Bile and waste created in the liver are passed into what ducts

Left and right hepatic duct

Bile produced in the gallbladder secreted through what duct

Cystic duct

Muscular valve that controls the passage of contents from the hepatopancreatic duct to the duodenum

Sphincter of Oddi

Segment of GI system that comes after the stomach

Small intestine

Length of the small intestine

Approx 3m (10ft), 6.5 (21ft) cadaver

What are intestinal glands

Contain three types of endocrine cells that secrete hormones into the bloodstream

Types of intestinal gland cells

S cells CCK cells K cells

Purpose of S cells

Secrete secretin, stimulates release of pancreatic juices

Purpose of CCK cells

Secrete cholecystokinin, regulates gastric emptying

How do CCK cells stimulate gastric emptying

Stimulates bile and pancreatic juice secretion which causes relaxation of the sphincter of Oddi, and feeling of satiety

Segments of the small intestine

Duodenum Jejunum Ileum

Significant landmark of the duodenum

Ligament of Trietz, connects at the duodenal-Jejunal flexure

Ligament of Trietz denotes what

Upper/lower GI bleed

What is the middle section of the small intestine

Jejunum

Primary function of the Jejunum

Absorption of sugars, amino acids, and fatty acids

What attaches to the large intestine at the ileocecal sphincter/valve

Ileum

Function of the ileum

Absorb remaining nutrients, B12, and bile salts

Types of digestion

Mechanical and chemical

What is mechanical digestion

Segmentation and peristalsis

What is chemical digestion

Pancreatic enzymes, bile and intestinal juice

Define absorption

Nutrients are broken down into their simplest form to be absorbed

Last part of the GI tract

Large intestine

Regions of the large intestine

Cecum Colon Rectum Anal canal

The appendix attaches to what

The cecum

Portions of the colon

Ascending/descending Transverse Sigmoid

Purpose of the rectum

Connects the sigmoid colon to the anus

What consists of the anal canal

Last 2-3cm of the rectum. Internal (involuntary) sphincter External (voluntary) sphincter

Function of the large intestine

Finishes absorption of water, electrolytes and vitamins Forms and holds feces

What are the phases of digestion

Cephalic Gastric Intestinal

What is cephalic digestion

Smell, sight, sound or thought of food stimulates salivary glands and gastric glands

What is gastric digestion

When food enters the stomach, gastrin is released

What is intestinal digestion

Food enters the small intestines, pancreatic juices promote absorption