A&P 2-3

Gallbladder Function

Concentrates and stores liver secretion

Ingestion Definition

Introduction of solid and liquid nutrients into the oral cavity

Motility Definition

Voluntary and involuntary muscular contractions that moves materials through the GI tract

Secretion Definition

Process of producing and releasing fluid products facilitating digestion (digestive enzymes, acid, bile)

Mechanical Digestion Definition

Material physically broken down by chewing and mixing

Chemical Digestion Definition

Involves specific enzymes to break chemical bonds. Change large complex molecules into smaller ones

Absorption Defintion

Transport of digested molecules, electrolytes, vitamins, water from GI tract into blood or lymph

4 Gastrointestinal Tract Wall Layers (inner to outer)

1. Mucosa

2. Submucosa

3. Muscularis

4. Serosa/Adventitia

Mucosa membrane has lamina propria which allows for __ and __

secretion, absorption

__ __ contractions facilitate release of secretion into GI Tract lumen

Muscularis mucosae

Submucosa GI Tract Layer Function

Houses mucosa-associated lymphatic tissue

(MALT). MALT prevents ingested microbes from

crossing GI tract wall

Muscularis Layer: 2 types of motility movement

1. Mixing: Backward and forward movement, no direction, blends ingested materials with secretion

2. Propulsion: Directional movement of materials through GI tract

Peritoneum Definition

The largest serous membrane associated with the abdominal cavity

Peritonitis Definition

Inflammation of peritoneum, causes abdominal pain, commonly caused by GI tract perforation that allows contents to contact peritoneum

Receptors Initiate Reflexes Function

Monitor changes associated with GI tract and contents. Found throughout mucosa and submucosa layer

2 Parts of Digestive Nervous Control

1. Enteric Nervous System (ENS)

2. Autonomic Nervous System (ANS)

Enteric Nervous System Function

Coordinates mixing and propulsion reflex

Autonomic Nervous System Function

Parasympathetic: promotes GI tract activity

Sympathetic: opposes GI tract activity

3 Digestive Hormones and where they are located

1. Gastrin - Stomach

2. Secretin - Small Intestine

3. Cholecystokinin - Small Intestine

Saliva contains __ __ that initiates chemical digestion of starch

salivary amylase

Mass of food mixed with saliva in mouth is called

Bolus

Bolus mixed with gastric secretions by smooth muscle contractions and form

__

chyme

5 parts of Upper GI Tract Organs

1. Oral cavity/salivary glands

2. Pharynx

3. Esophagus

4. Stomach

5. Duodenum

Intrinsic Salivary Glands Definition

Within oral cavity, continuously releases saliva regardless of presence of food

Intrinsic Salivary Gland contains what enzyme to start digestion

lingual lipase

3 Extrinsic Salivary Glands

1. Parotid

2. Submandibular

3. Sublingual

Parotid Salivary Gland Description

Largest salivary gland, 20-30% of saliva

Submandibular Salivary Gland Description

60-70% of saliva, Submandibular duct opens from each gland to floor of cavity

Sublingual Salivary Gland Description

3-5% of saliva, Extends tiny sublingual ducts opening into inferior surface of cavit

Infection or parotid glands causes __

mumps

Two types of secretory cells within salivary glands

1. Mucous cells: secrete mucin

2. Serous cells: secrete watery fluid containing electrolytes and salivary amylase

__-__L secreted daily by salivary glands

1, 1.5

Superior Esophageal Sphincter Description

Area where esophagus and pharynx meet, closed during inhalation of air

Inferior Esophageal Sphincter Description

Not strong enough by itself to stop stomach contents from regurgitating, diaphragm helps

3 Swallowing Phases

1. Voluntary: controlled by cerebral cortex, bolus formed

2. Pharyngeal: involuntary reflex, tactile sensory receptors stimulated, sensory input to swallowing center in medulla oblongata

3. Esophageal: involuntary, bolus passes through esophagus

Stomach releases __ __ needed for absorption of Vitamin __ in small intestine

intrisic factor, B12

Cardia and Cardiac Orfice

entry into stomach lumen from esophagus, where cardia meets esophagus

Fundus Definition

dome shaped region at the top of stomach

Stomach Body Definition

Largest part of the stomach

Pylorus Definition

Funnel-shaped located at end of stomach consists of a ring of circular smooth muscle surrounding orifice

Pyloric Sphincter Function

Regulates entry of material into small intestine

Gastric Folds Definition and Function

Also called Rugae, found on internal stomach lining when stomach empty. Allows stomach to expand greatly when it fills with food

3 Smooth muscle Layers of Muscularis Layer (inner to outer)

1. Inner Oblique

2. Middle Circular

3. Outer Longitudinal

Gastric Secretions are produced by 5 types of secretory cells:

1. Surface mucous cell

2. Mucous neck cell

3. Parietal cell

4. Chief cell

5. G cell

Surface Mucous Cell Function

Continuously secrete alkaline product, protects stomach lining

Mucous Neck Cell Function

Produces acidic mucin, protects stomach lining

Parietal Cell Function (2)

Intrinsic Factor: Required for absorption of B12 (B12 essential for normal erythrocyte production)

Hydrochloric Acid: For low pH of stomach, converts inactive enzyme pepsinogen into active pepsin, kills microorganisms entering stomach

Chief Cells Function

Primarily contains pepsinogen, produces gastric lipase which plays a limiting role in fat digestion

G Cells Function

Secrete gastrin which stimulate stomach secretions and motility (also produces somatostatin hormone)

5 Steps of Gastric Mixing and Emptying

1. Contractions of smooth muscle mix bolus with gastric secretions, forms chyme

2. Peristaltic waves result in pressure gradient that moves stomach content towards pylorus

3. Pressure gradient increases force in pylorus against pyloric sphincter

4. Pyloric Sphincter opens and a small amount of chyme enters duodenum

5. Pyloric Sphincter closes and retropulsion occurs

Peptic ulcers in stomach are called __, in duodenum __

gastric ulcers, duodenal ulcers

Symptoms of Peptic Ulcers

Gnawing or burning pain in epigastric region, nausea, vomiting, bleeding

Peptic Ulcer may erode portion of stomach or duodenum and

cause __, medical emergency

perforation

__ __ causes erosion of gastric

lining

Helicobacter pylori

3 Parts of Small Intestine (beginning to end)

1. Duodenum

2. Jejunum

3. Ileum

Most chemical digestion and absorption happens in the

Small intestine

Bile is secreted by __ and stored by __

liver, gallbladder

Pacreatic juice with digestive enzyme secreted by __

pancreas

Large Intestine Function

Continues absorption of water, electrolytes, and vitamins. Feces produced

Ingested nutrients stay in small intestine for at least

12 hours

Duodenum Primary Function

Recieves accessory gland secretions from liver, gallbladder, pancreas; chyme from stomach

Jujunem Primary Function

The primary region for chemical digestionand nutrient absorption

Ileum Primary Function

Distal end terminates at ileocecal valve, sphincter controlling entry of materials into large intestine

Segmentation Definition

The type of motility that occurs in the small intestine: smooth muscle of small intestine mixes chyme with gland secretions, then propels contents through small intestine by peristalsis

4 Parts of Small Intestine Wall

1. Circular Folds

2. Villi

3. Lacteal

4. Microvilli

Circular Folds Function

Slows movement of chyme

Villi Function

Fingerlike projections of mucosa, increase absorption and secretion

Lacteal Function

Lymphatic capillary within villus. Responsible for absorbing lipids and lipid-soluble vitamins

Microvilli Function

Increases surface area of small intestine. Responsible for complete chemical digestion of most nutrients

Intestinal Glands Location

In the villus, invaginations of mucosa between intestinal villi

Intestinal Glands Function

Secrete intestinal juice

4 Intestinal Villus Cells

1. Goblet

2. Paneth

3. Enteroendocrine

4. Duodenal Submucosal

Goblet Cells Function

Produce mucin, protects lining

Paneth Cells Function

Secrete lysozyme and other antimicrobial agents

Enteroedncorine Cells Function

Releases hormones such as cholestokinin CKK and secretin (regulates digestion)

Duodenal Submucosal Gland Function

Produces alkaline mucus secretion protecting duodenum from chyme

5 Accessory Ducts of Digestive System

1. Biliary Aparatus

2. Hepatopancreatic Ampulla

3. Hepatopancreatic Sphincter

4. Major Duodenal Papilla

5. Accessory Pancratic Duct

Biliary Apparatus includes which ducts

L and R Hepatic Ducts, merge to form common Hepatic Duct

Biliary Apparatus Function and Location

Drains left and right lobes of liver, merges with cystic duct from gallbladder to form common bile duct

Hepatopancreatic Ampulla Function and Location

Allows bile and digestive enzymes to enter the duodenum together, where common bile duct and main pancreatic duct pierce duodenal wall

Hepatopancreatic Sphincter Function and Location

Regulates movement of bile and pancreatic juice into duodenum, where the hepatopancreatic ampulla (ampulla of Vater) enters the small intestine

Major Duodenal Papilla Function and Location

Bile and pancreatic juice enter here, on wall of duodenum

Accessory Pancreatic Duct Function and Location

Allows small amount of pancreatic juice to enter duodenum, connects head of pancreas to duodenum

Liver Bile Function

Helps mechanically digest lipids

Hepatic Lobules are

the structural and functional units of the liver

Within Hepatic Lobules are liver cells known as

Hepatocytes

Central Vein Function

Located at the center of each lobule, drains blood from lobule, merges to form hepatic veins

Bile Caniculus Function

Conducts bile produced by hepatocytes to hepatic duct in portal triad

Liver Cirrhosis Causes

Caused by chronic injury to hepatocytes (alcoholism, liver disease, drugs, toxins, viral infections like hepatitis B/C)

Gallbladder is connection to common hepatic duct by the

cystic duct

Gallstones in gallbladder are caused by

condensation of cholesterol or calcium and bile salts

Cholecystectomy Definition

The surgical removal of gallbladder, used to treat gallstones

Gallstones are asymptomatic until lodged in neck of cystic duct which causes gallbladder inflammation (__) causing severe pain and vomiting

cholecystitis

Pancreas contains __ cells

acinar

Acinar cells produce and release

digestive enzymes

Pancreatic Juice is made of

water, HCO3 (bicarbonate), and digestive enzymes

Pancreatic Amylase digests what

starch

Pancreatic Lipase digests what

triglycerides

Proteases digests what

protein

Nucleases digests what

nucleic acids