HAPII Test 3: Digestive System, Nutrition, Urinary System, and Fluid + Electrolyte Balance

6

How many activities are involved in Digestion

Ingestion, Propulsion/Motility, Mechanical Breakdown, Chemical Digestion, Absorption, Defecation

What are the 6 activities of Digestion?

Ingestion

-Taking food into the mouth

-Step 1 of Digestion

Propulsion/Motility 

-Moving Food through alimentary canals

-Includes Deglutition and Peristalsis

-Step 2 of Digestion 

Deglutition

-Swallowing the food

-Begins as a voluntary activty 

*Part of Propulsion/Motility

Peristalsis 

-Rhythmic wave-like contractions moving food through GI Tract

-Part of Propulsion/ Motility 

Mechanical Breakdown

-Mastication

• Churning food in stomach

• Segmentation

-Step 3 of Digestion

Mastication

-Chewing the food

• Small enough to swallow

• Mixing with saliva

Segmentation 

-Rhythmic contractions that mix food 

• Occurs in the small intestine

Chemical Digestion 

-Involves enzymes breaking down food molecules into chemical building blocks

• Step 4 in Digestion 

Absorption

-Passage of digested fragments from lumen of the GI tract into blood or lymph

• Step 5 of Digestion

Defecation

-Elimination of indigestible substances

-Waste material passes to the rectum

-Occurs when the rectal pressure rises and external anal sphincter relaxes 

• Step 6 in Digestion

Gastrointestinal Tract, GI Tract, Gut

What are the three other names for the Alimentary Canal?

Alimentary Canal

What’s another name for the Gastrointestinal Tract, GI Tract, and Gut?

Alimentary Canal

-Continuous muscular tube from the mouth to the anus

-Digests food: Breaks the food into smaller fragments

-Absorbs fragments through lining into blood

Mouth, Pharynx, Esophagus, Stomach, Small intestine, Large intestine, and Anus 

What are the structures of the Alimentary Canal?

Teeth, Tongue, Gallbladder, Digestive Glands

What structures are a part if the Accessory Digestive Organs?

Digestive Glands

-Produce secretions to break down food

• Includes the salivary glands, Liver, and Pancreas

Salivary Glands, Liver, and Pancreas 

What are the Digestive Glands?

Parietal Peritoneum

-Line the cavity wall

• Orange

Visceral Peritoneum

-Lines the Organs

• BlueP

Peritoneal Cavity 

-Space between

-Filled with Serious Fluid 

Mesenteries

-Double layered folds of membrane

-Stabilize Organs

-Types

• Greater Omentum

• Lesser Omentum

• Mesentery Proper

• Mesocolon

Greater Omentum 

-Red

Lesser Omentum

-Purple

Mesentery Proper

-Green

Mesocolon 

-Brown 

Intraperitoneal Organs

-Organs located within the peritoneum

-Stomach, spleen, liver, small intestine, and transverse colon

Stomach, Spleen, Liver, Small Intestine, and Transverse Colon

What are the Intraperitoneal Organs?

Retroperitoneal Organs 

-Outside, or posterior to, peritoneum 

-Include most of pancreas, duodenum, and parts of large intestine 

Pancreas, Duodenum, and Parts of Large Organ

What are the Retroperitoneal Organs?

Mouth, Esophagus, Stomach, Pancreas, Duodenum, Jejunum, Ileum, Cecum, Large intestine, Anus

What is the order of the Alimentary Canal

Oral Cavity

-Mouth

• Cheeks

• Teeeth

• Salivary Glands

• Tongue

• Palate (Hard and Soft)

• Uvula

-Digestion Begins here

• Mechanical and Chemical

Mouth

Where are the salivary Glands Located?

Mouth

Where does digestion begin?

Mechanical and Chemical

What are the two types of Digestion?

Teeth

-Parts

• Crown

• Neck

• Root

-Composition

• Dentin

• Cementum

• Enamel

Salivary Glands

-3 Major Parts

• Parotid

• Sublingual

• Submandibular

-1-2 L Saliva/day

-Saliva

1-2 Liters a day

How many Liters of Saliva do we make a day?

Saliva

-Moistens food

-Cleans Teeth (lysozome)

-Protects/ Lubricates Mouth (mucus)

-Digests starch (amylase)

• **Form of Chemical Digestion

Lysozome

What enzyme cleans teeth?

Mucous 

What enzyme protects the mouth?

Amylase

What enzyme digests starch?

Nasopharynx, Oropharynx, Laryngopharynx

What is the order of the Pharynx?

Lumen

Open tube of the Gastrointestional Tract 

4

How many Layers (tunics) are there?

Tunica Serosa and Adventitia, Tunica Muscularis, Tunica Submucosa, Tunica Mucosa

What are the 4 tunics?

Tunica Serosa and Adventitia 

-Outermost layer

-Serosa

• Made of Areolar Tissue

-Adventitia 

• Made of Areolar Connective

• Retroperitoneal

Tunica Muscularis  

-2 Layers of Smooth Muscle

• Outer Layer = longitudinal

• Inner Layer = Circular

• Peristalisis

  • Peristaltic Waves

• Segmental Contractions

Longitudinal

What is the outer layer of the Tunica Muscularis?

Circular

What is the inner layer of the Tunica Muscularis?

Tunica Submucosa

-Dense irregular Connective Tissue

-Lots of Elastic Fibers

-Large # of Vessels, glands, nerves

Tunica Mucosa

-Internal

-3 Sublayers

• Muscularis Muscosae

  • Thin layer of smooth muscle

• Laminal Propria

  • Areolar tissue, Capillaries, Lymph vessels

• Epithelium

  • Usually Simple Columnar

  • Modified in some sections of canal

Muscularis Mucosae 

Thin layer of smooth muscle in the Tunica Mucosa?

Lamina Propria

Consists of Areolar tissue, capillaries, and lymph vessels in the Tunica Mucosa

Epithelium

-Usually Simple columnar and is modified in some canals of the Tunica Mucosa

Esophagus 

-~10 in

-Tunic Modifications 

• T. Mucosa = Stratified Squamous Tissue 

• T. Muscularis = Skeletal muscle in the upper 2/3

-Lower esophageal sphincter (Gastroesophageal Cardiac sphincter)

-Peristalsis: Surrounds cardiac orifice

• Localized reflex in response to the distention of the wall by bolus

  • Rate of 2-4 cm/sec

Peristalsis of Esophagus 

-Surrounds cardiac orifice 

-Localized reflex in response to distention of wall by bolus 

• Rate of 2-4 cm/sec

Stomach

-Most distensible part of GI Tract

-Functions:

• Store food

• Initiate digestion of proteins

• Kills bacteria

• Converts bolus of food to paste-like chyme

• Moves food (chyme) into intestine

-Empty stomach has ~50ml Volume

• Can expand to 4 L

• Empty, mucosa forms folds called rugae

Functions of the Stomach

• Store food

• Initiate digestion of proteins

• Kills bacteria

• Converts bolus of food to paste-like chyme

• Moves food (chyme) into intestine

4 L

How much can an empty stomach expand to?

Rugae

-Gastric Folds formed by the mucosa when the stomach is empty

Structure of Stomach

-Folded Mucosa

• Gastric folds/rugae

-Three Muscle layers

• Outer longitudinal

• Middle Circular

• Inner Oblique

-Pyloric Sphincter Muscle is present

-Gastric Pits

• Contain Gastric Glands

• Enteroendocrine cells (secretes gastrin)

• Parietal cell (secretes hydrochloric acid and intrinsic factor)

• Chief cells (secretes pepsinogen

• Secretes alkaline mucin

Gastric Pits

• Contain Gastric Glands

• Enteroendocrine cells (secretes gastrin)

• Parietal cell (secretes hydrochloric acid and intrinsic factor)

• Chief cells (secretes pepsinogen

• Secretes alkaline mucin

Gastric Glands

What Secretes alkaline mucin

Enteroendocrine cells

*Secretes Chemical Messengers:

• Acts as paracrines (local hormones)

  • Serotonin

  • Histamine,

• Hormones

  • Somatostatin,

  • Gastrin

• Also secretes Cholecystokinin (CCK)

Parietal Cells 

Secretes Hydrochloric Acid and Intrinsic Factor

Chief Cells

Secretes Pepsinogen and Lipases 

Small Intestine

-20 ft (6m) long

-Supported by mesenteries

-3 Regions

• Duodenum

• Jejunum

• Ileum

Duodenum

*Part of the Small intestine

-1ft, Retroperitoneal

-Secretions from the gallbladder/pancreas

Jejunum

*Part of the Small intestine

-7+ ft, upper left

-Main site of absorption

Ileum

*Part of the Small intestine 

-10ft, middle/lower right 

Small Intestine

-Mucosa Folded

• Larger Ridges = Circular Folds

• Smaller Folds = Villi(Villus)

• Cell Folderd = microvilli

  • Columnar cells absorb nutrients

-Capillaries and Lacteals 

• All  blood from capillaries goes to liver via hepatic portal system 

Circular Folds

What are large ridges in the mucosa folded part of the Small intestine?

Villi (Villus)

What are smaller folds in the mucosa folded part of the Small Intestine?

Microvilli

What are the cell folded parts of the mucosa folded part of the small intestine?

Columnar Cells

What types of cells absorb nutrients in microvilli

Large intestine 

-Large, Unfolded tube 

-5-6ft long 

-Bulges along length = haustra

-Teniae Coli

Haustra

Bulges along length of the Large intestine

Teniae Coli

Three thickened bands of tunica muscularis

4

How many regions are the large intestine?

Cecum

*1st Region of the Large Intestine

-Contains the Ileocecal Valve

-Contains the Vermiform appendix

Colon

*2nd Region of the Large intestine

-Contains Ascending, Transverse, Descending, Sigmond, and Flexures

Rectum

*3rd Region of the Large Intestine 

-7in

-Attached to Sacrum

-Lined with Stratified Squamous 

Anal Cavity

*4th Region of the Large Intestine

-1in

-Internal Sphincter Muscle

-External Sphincter Muscle

Internal Structure of Large Intestine

-Contains Simple Columnar Epithelium

• No Villi

-Intestinal Glands

• Contains Goblet Cells

-Outer muscle layer is incomplete (teniae coli)

Splanchnic Circulation

-Serves Digestive organs

-Arteries branching off aorta

-Hepatic Portal System/ Circulation 

Hepatic, splenic, left gastric arteries, Inferior and Superior Mesenteric arteries

What are the arteries that are branching off the aorta?

Hepatic Portal System/ Circulation

-Drains nutrient-rich blood from digestive organs

-Delivers blood to liver for processing

Liver

-Largest internal organ

-Regenerative

-4 Lobes

-Internal Structure 

• Lobules

• Sinusoid Capillaries

• Hepatocytes

• Hepatic Portal Vein  

Right and Left Lobes, Caudate Lobe, Quadrate Lobe

What are the 4 lobes of the Liver?

Lobules, Sinusoid Capillaries, Hepatocytes, and Hepatic Portal Vein

What are the internal structures of the Liver?

Gallbladder

-Small organ btwn lobes of liver

-Stores Bile 

-Contraction of gallbladder ejects bile into duodenum

• Via common bile duct

Bile

-Released into cystic duct and common bile duct

-Emulsifies fats (but it’s not an enzyme)

-About 250-1500 ml a day is produced by the liver

Bilirubin, spleen, bone marrow, and liver

What is bile pigment and where is it produced?

Common Bile Duct

Contraction of the gallbladder ejects bile into the duodenum via this?

Urobilinogen

What do intestinal bacteria convert bilirubin to?

Pancreas

-Leaf-like organ on duodenum

-Produces digestive enzymes from pancreatic acini

-Released into the duodenum

Mechanical Digestion

-Chewing

-Peristalsis, stomach movement (segmentation, “churning”)

Enzymatic Hydrolysis 

-Enzymes use water to break chemical bonds 

-Intrinsic and accessory gland enzymes