DIGESTIVE* CH 25 Flashcards by Gilberto Talamantes

Identify and describe the five stages of digestion

Ingestion - Intake of food

Digestion - Mechanical and chemical breakdown

Absorption - Uptake of nutrients into cells and blood

Compaction - Absorbing water and building up waste

Defacation - Elimination of feces

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Mechanical vs Chemical Breakdown of Food

Mechanical - Physical
Chemical - Hydrolysis of macromolecules into monomers

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Identify the 6 structures of the digestive tract

Mouth
Pharynx
Esophagus
Stomach
Small Intestine
Large Intestine

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Identify the 5(/6) accessory structures/organs of the digestive tract

Teeth
Tongue
Salivary Gland
Liver
Gallbladder
Pancreas

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Identify the layers of the digestive tract wall:

A - Mucosa
B - Stratified Squamous Epithelium
C - Lamina Propria
D - Muscularis Mucosae
E - Submucosa
F - Muscularis Externa
G - Inner Circular Layer
H - Outer Circular Layer
I - Serosa

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What is the enteric plexus? Identify and describe the two networks

The nervous network in the digestive tract that regulates motilitiy, secretion, and blood flow

Submucosal Plexus - Controls glandular secretions and movements of the muscularis mucosae
Myenteric Plexus - Controls peristalsis and contractions of muscularis externa

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What is the peritoneum? Which portion connects the greater curvature, which to the lesser curvature of the stomach?

Serous membrane that lines the abdominal cavity and most of the organs within it

Greater Omentum
Lesser Omentum

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Identify and describe the two reflexes regulate the digestive tract

Short Reflexes - Triggers peristalsis as we stretch organs in swallowing, MYENTERIC

Long Reflexes - Parasympathetic stimulation, VAGOVAGAL

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What type of tissue lines the mouth

(nonkeratinized AND keratinized)
Stratified Squamous Epithelium. provides protection against abrasion

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Identify and describe the three primary components of the tooth

Dentin - Hard yellow tissue that makes up most of the tooth

Enamel - White, visible part of the tooth

Cement - Covering the root

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Identify the follwing:

A - Enamel
B - Dentin
C - Cement

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Describe Gingivitis. What can it progress to?

Gingivitis: Bacterial invasion of the area between the tooth and the gums that causes gum inflammation

Periodontal Disease: Progresses from gingivitisand may begin to affect the bone

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What is the first step in mechanical digestion. Why is this important?

Mastication (chewing) - Breaks food into smaller pieces and increases the surface area for digestive enzymes

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Identify and describe the function of the components of saliva

IgA - Antimicrobial antibody found in secretions

Mucus - Lubricates Food

Salivary Amylase - Enzymatic Starch Digestion

Electrolytes - Salty Environment

Lingual Lipase - Enzymatic Fat Digestion

Lysozyme - Enzyme Kills Bacteria

IM SELL

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What are the three pairs of salivary glands?

Sublingual Gland
Submandibular Gland
Parotid Gland

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Describe Heartburn and the adjacent structure that plays a role

The lower esophageal sphincter (LES) that allows the movements of the bolus from the esophagus to the stomach

Heartburn is when the stomach acid goes back up into the esophagus

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Identify and describe the three phases of swallowing

Oral Phase - Voluntary, collects food and forms the bolus

Pharyngeal Phase - Involuntary, Bolus is driven down the pharynx and into the esophagus. Prevents the bolus from reentering the mouth

Esophageal Phase - Involuntary, Peristalsis movement down the esophagus getting the bolus to the stomach

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What is the term used to decribe chewed up food theat moves down the esophagus?

BOLUS

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Does the stomach do mechanical or chemical digestion, or both?

Both, rugae moves and breaks down the food inside the stomach

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Define Chyme

An acidic mixture of semidigested food formed by the stomach and enters the small intestine (at the duodenum)

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Identify the tissue type found in the stomach, small intestine and (MOST OF THE) large intestine

Simple Columnar Epithelium

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Identify and describe the function of the cells found in the stomach mucosa

Parietal Cells - Secrete HCl, Intrinsic Factor, Ghrelin

Enteroendocrine Cells - Secrete hormones that regulate digestion

Chief Cells - Most Numerous, Secrete Gastric Lipase and Pepsinogen

Mucous Cells - Secrete Mucus

People Eat Cow Meat

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Identify each of the following as acidic or basic:
- Gastric Juice
- Pancreatic Juice
- Intestinal Juice

Gastric Juice - Acidic
Pancreatic Juice - Basic
Intestinal Juice - Slightly Basic

What are the functions of HCl in Gastric Juice

Activate Pepsin + Lingual Lipase
Breaks up connective tissue + plant CW
Destroys ingested pathogens
Converts Fe3+ to Fe2+ to use for hemoglobin synthesis

What is the function of Pepsin? What is its inactive form and what stomach cell secretes it?

Pepsin digests protein PEPSINOGEN: Secreted by Chief Cells

What is the function of gastric lipase and what stomach cell secretes it?

Gastric lipase digests fats - Secreted by Chief Cells

What is the function of intrinsic factor and what stomach cell secretes it?

Intrinsic factor absorbs vitamin B12 which is necessary to synthesize hemoglobin - Secreted by Parietal Cells

Describe a gastrectomy. Can you survive this?

The surgical removal of the stomach. You can survive with the supplementation fo vitamin B12, necessary for hemoglobin synthesis

What cells of the stomach control the rhythm of peristaltic contractions

Enteric Pacemaker Cells

What is the name of the center in the medulla oblongata that controls vomitting

Emetic Center

Where does most digestion and absorption of food occur in the digestive system?

Small intestine (Mainly Jejunum)

What is gastritis and what can it lead to?

Inflammation of the stomach. Can lead to a peptic ulcer where pepsin and HCl erode the stomach wall

Identify and describe the three phases of gastric acitivity. Know the molecules or hormones it works on

Cephalic Phase - Sight, smell, taste or thought of food stimulating gastric secretion Gastric Phase - Ingested food stretches and increases the pH in the stomach, *ACh and GASTRIN* Intestinal Phase - Small intestine has a basic pH that responds to the acidic chyme as it enters. This, initially, enhances gastric secretion but is inhibited by the enterogastric reflex and releases *SECRETIN and 9CCK*

What chemicals of the intestinal phase suppress gastric secretion?

Secretin and 9CCK

What is the liver's role in digestion? What cells make up the liver?

In digestion, the liver functions in the secretion of bile in the DUODENUM. Hepatocytes

Where is bile made and stored, and what is its function in digestion?

Bile is made in the liver, stored in the gallbladder and works by digesting fats

What is the main pigment in bile, what is converted into?

Bilirubin > Urobilinogen - makes our urine yellow and our feces brown

What are Biliary Calculi? What is the term for the presence of these?

Gall Stones. Choleolithiasis

What is the exocrine function of the pancreas? What are the associated structures?

Excreting pancreatic juice into the duodenum

Identify the enzymes the pancreas provides to the small intestines and what they digest

Pancreatic Amylase - Starch Pancreatic Lipase - Fats Ribonuclease - RNA Deoxyribonuclease - DNA

What is the role of trypsin? What is its inactive form and what organ releases it?

Trypsin - Protein digestion Trypsinogen released by the pancreas

What molecules stimulate the release of pancreatic juice and bile?

ACh, CCK, Secretin

Identify the three portions of the small intestine in order down the digestive tract and describe their primary functions

Duodenum - Receives stomach content, pancreatic juice, and bile. Neutralizes stomach acid and pancreatic enzymes take over digestion Jejunum - Most digestion and nutrient reabsorption occurs here Ileum - Contains ileal papilla, lymphoid nodules, and links the small and large intestine at the ileocecal junction

What three structures increase the surface area within the small intestine? Which includes capillaries and lacteals? What is the function of lacteals?

Circular Folds Villi - Capillaries and lacteals (absorb lipids) Microvilli

Where are paneth cells found and what do they do?

They are found at the base of each crypt and secrete lysozyme and other ezymes to kill bacteria and protect the mucosa

What enzymes breaks down starch? Where are they found?

Salivary amylase breaks down most of the starch in the mouth but is continues again in the small intestine by pancreatic amylase

What enzymes digest proteins? Where are they found? Where are they absent

Proteases, peptidases, carboxypeptidase, aminopeptidase, and dipeptidase found in the stomach and small intestine not in saliva

What enzymes digest fats? Where are they found and what else happes in the stomach?

Lingual Lipase - MOUTH Pancreatic Lipase - Duodenum Gastric Lipase - antral pumping in the stomach breaks down clumps of fat

What enzymes break down nucleic acids

Deoxyribonuclease Ribonuclease Nucleosidase Phosphatase

What is unique about the digestion of vitamins?

They are digested without the need of being broken down, readily absorbed into the body

Diarrhea vs Constipation

Diarrhea - Food causes irritation and passes too quickly, not allowing enough time for the large intestine to absorb water Constipation - Fecal movement is too slow and large intestine absorbs too much water

What are hemorrhoids?

Veins that protrude into the anal canal or outside the anus

Internal vs External Anal Aphincters. Intrinsic and Parasympathetic Defacation Reflexes control which sphincter?

Internal - Involuntary, smooth muscle External - Voluntary, skeletal muscle INTERNAL is controlled by the intrinsic and parasympathetic defacation reflexes

What tissue type lines the lower half of the anal canal

Nonkeratinized, stratified squamous epithelium; resists abrasion with the passage of feces

What is the second most common cause of cancer deaths in the US?

Colorectal Cancer