Chapter 24 - Digestive System

Major organs in Alimentary Canal

Oral cavity

Pharynx 

Esophagus

Stomach

Small & Large Intestine

Anus 

Deglutition

Swallowing

What are the 4 phases of Deglutition

Buccal Phase

Pharyngeal Phase

Esophageal Phase

Bolus Entering Stomach

Buccal Phase

Tongue manipulates chewed food into a bolus, pushing it to back of mouth to be swallowed 

Pharyngeal Phase

Bolus enters the pharynx and ends as it passes through upper esophageal sphincter and into esophagus 

Esophageal Phase

Food bolus travels down esophagus, peristalsis occurs, enters stomach through esophageal sphincter 

Bolus entering stomach

Bolus triggers the opening, then bolus continues into stomach

Bolus

Collection of partial digested food

Peristalsis

Contraction of smooth muscle

How many stages of Peristalsis are there

4

What are the 4 stages of peristalsis

Initial state

Contraction of circular muscles behind bolus

Contraction of longitudinal muscles ahead of bolus 

A wave of contraction in circular muscle layer forces bolus forward 

What is the esophagus

Muscular tube connecting the oral cavity and stomach

Characteristics of the esophagus

Travels through the mediastinum and the hiatus of diaphragm

Ensures one way movement of food (exempt emesis)

What is the abdominopelvic cavity 

Space inferior to diaphragm and superior to pelvic bones

Characteristics of abdominopelvic cavity

Contains most digestive organs

Line by peritoneum (visceral/parietal) 

Contains mesenteries which secure organs, blood vessels and nerves in place

What is the stomach

Muscular hollow organ that mechanically and chemically digests food

Characteristics of stomach

Temporarily stores food bolus following meals

Found in left upper quadrant 

Secretes hydrochloric acid giving stomach low pH

What are the layers of stomach wall

Mucosa

Submucosa

Muscular 

Serosa 

What are the cells of the gastric glands

Mucus

Parietal

Gastric (G)

Chief 

Mucus cells

Make mucus to protect stomach lining

Chief cells

Makes pepsinogen to break down proteins

Gastric cells

Make gastrin to stimulate GI tract

Parietal cells

Make stomach acid

What factors control the stomach

Local and external factors

What affects the activity of stomach

Autonomic nervous system

Hormones 

Chemical and mechanical sensors and responses are included in what …

Gastric system

What are the phases of stomach digestion

Cephalic phase

Gastric phase

Intestinal phase 

What are the two central gastric reflexes

Gastroenteric

Gastroileal 

What is the gastroenteric reflex

Stimulates motility and secretion along the entire small intestine

What is the gastroileal reflex

Triggers opening of ilioceceal valve, allowing materials to pass from small intestine to large intestine

What is the specialization of small intestine

Absorption with large surface area

Two main characteristics of small intestine

Approx. 20ft of hollow muscular tubing

Has a smaller diameter than large intestine

What are the 3 sections of small intestine

Duodenum, jejunum, ileum

Where does the small intestine start

Starts at pyloric sphincter,

Where does the small intestine end

Ends at ileocecal valve

What are the surface area adaptations for small intestine

About a football field worth of surface area

Circular folds 

Villi 

Microvilli 

What are circular folds

Wrinkles on small intestine

What are Villi

Tiny fingerlike extensions

What are microvilli

Brush border; villi on individual cells

Aspects of control of small intestine

Hormonal and neural control like the stomach

Based on chemical and mechanical stimuli 

What are myentericreflexes

Muscles of intestine 

What are the digestive hormones

Gastrin

Secretin

Gastric inhibitory peptide (GIP) 

Cholecystokinin (CCK) 

Vasoactive intestinal peptide (VIP) 

Gastrin

Stimulates stomach

Secretin

Secretes more digestive juices

GIP

Inhibits stomach

CCK

Stimulates gallbladder

VIP

More blood flow

Importance of large intestion

Waste storage and water reabsorption

Also absorbs ions, vitamins, minerals 

Where does the large intestine start

Cecum 

Where does the large intestine end

Rectum

What shape does large intestine make

Upside down U

Defecation

Removal of stool from body

Characteristics of defecation

Combination of conscious and unconscious control

Requires relaxation of the internal and external sphincter muscles 

What are accessory organs in digestive system

Parts of the digestive system that aid in mechanical or
chemical digestion

Characteristics of accessory organs in digestive system

Food does not pass through them

Secretes enzymes to break down specific macronutrients

Accessory organs of digestive system

Teeth

Tongue 

Salivary glands

Liver

Gallbladder

Pancreas

How many types of teeth are there

6

What are the different types of teeth

Incisors

Canines/Cuspids 

Premolars/Bicuspids 

Molars

Deciduous/Baby 

Permanent/Adult 

Incisors

Shaped; good for cutting

Canines/Cuspids

Good for ripping and tearing meat

Premolars/Bicuspids

Hybrid between canines and molars

Molars

Good for crushing and grinding

Deciduous/Baby teeth

Lost during childhood/adolescence

Permanent/Adult

Sets of 32 teeth (including wisdom)

How many types of salivary glands are there

3

What are the 3 types o

Sublingual salivary glands

Submandibular salivary

Parotid salivary glands

In the cheeks

What is the liver

Solid organ in the right upper quadrant of abdomen 

Characteristics of Liver

Makes albumin, cholesterol, glucose, bile, coagulation factors

Filters blood from hepatic portal vein

Cirrhosis 

Scarring of liver

Hepatitis

Inflammation of the liver

Characteristics of gallbladder

Stored bile made by liver

Releases bile after a fatty meal 

Cholecystitis

Inflammation of the gallbladder

Cholelithiasis

Gallstones

Cholecystectomy

Removal of the gallbladder

What are enndocrine

Insulin and glucagon

What are exocrine

Digestive enzymes; amylase, lipase, trypsinogen 

What disease destroys pancreas

Type 1 diabetes

Pancreatitis

Inflammation of the pancreas

Where is the pancreas found in body

Found in retroperitoneal space

What does lipase do

Breaks

What does proteases do

Breaks down proteins 

Example of proteases enzyme 

Pepsin or Trypsin

What does carbohydrases do

Breaks down carbohydrates

Example of carbohydrases enzyme

Amylase

What absorbs carbs in digestive system

Capillaries 

What absorbs proteins in digestive system 

Capillaries

What absorbs lipids in digestive system

Lacteals