Hole's Anatomy & Physiology: Chapter 17 (Digestive System)

Describe mechanical digestion:

Breaking larger pieces into smaller pieces without altering their chemical composition.

Describe chemical digestion:

Food is broken down into simpler chemicals

How long is the alimentary canal?

8 meters

Name the four layers of the alimentary wall:

Mucosa, submucosa, muscular, serosa

Which layer of the alimentary alimentary folds to increase surface area?

Mucosa

Which alimentary wall layer includes glands that secrete mucus and digestive enzymes?

Mucosa

Which alimentary layer is for protections secretion, and absorption?

Mucosa

Which alimentary canal layer contains glands, blood vessels, lymphatic vessels, and nerves?

Submucosa

Which alimentary canal layer nourishes surrounding tissues and carries away absorbed materials?

Submucosa

Which alimentary canal layer provides the movements of the tubes?

Muscular layer

Describe the effect of circular fiber contraction:

The diameter of the canal decreases

Describe the effect of longitudinal fiber contraction:

The canal will shorten

Which alimentary canal layer is composed of visceral peritoneum?

Serosa

What do these visceral peritoneum cells secrete?

Serious fluid

What is the function of serous fluid?

Moistens and lubricates to reduce friction so organs slide freely against one another.

Name the two types of movements in the alimentary canal:

Mixing (Segmentation)

Propelling (Peristalsis)

List the functions of the mouth:

Mastication, speech, sensory reception

How does the tongue contribute to these functions?

The position of the tongue helps when forming words.

Tongue moves food to be chewed and swallowed

Sensory reception: Taste buds

What are papillae?

Rough projections on the tongue

What are the functions of papillae?

House taste buds

How are the uvula and soft palate beneficial during swallowing?

Upward movement of the uvula and soft palate close the opening of the nasal canal preventing food entry to the nasal cavity

How are incisors adapted to handle food?

Bite off large pieces of food

How are canines adapted to handle food?

Grasp and tear food

How are pre-molars/molars adapted to handle food:

Grind food particles

List the functions of saliva:

Moistens food particles

Binds food particles together

Begins chemical digestion

Cleanses mouth and teeth

Promotes food tasting

What is the pH of the mouth?

6.5-7.5

How does saliva help maintain the pH balance of the mouth?

Saliva includes bicarbonate ions which are basic which help buffer the acidic in the mouth

Name the two types of secretory cells that are part of salivary glands:

Serous cells

Mucous cells

Name the parts of the pharynx:

Nasopharynx, Oropharynx, Laryngopharynx

What is the function of the esophagus?

Pushes food down towards the stomach

List the functions of the stomach:

Receives food from esophagus

Mixes food with gastric juice

Initiates digestion of proteins and some lipids

Carries on limited absorption

Movies food into small intestine

What is the purpose of the lower esophageal sphincter?

Closes the entrance to stomach

Helps prevent regurgitation of stomach contents

What is the purpose of the pyloric sphincter?

Controls gastric emptying

Name the three types of secretory cells in the gastric glands:

Mucous cells, cheif cells, parietal cells

Which type of secretory cells release a solution containing HCL?

Parietal cells

What is the pH of the stomach?

1-3

Which type of secretory cell released intrinsic factor?

Parietal cells

Which type of secretory cells release digestive enzymes?

Chief cells

What is the function of intrinsic factor?

Required for B12 absorption in the small intestine

Name the enzymes and the substrate Chief cells act on:

Pepsinogen

Gastric lipase

Name the semifluid paste produced by stomach actions:

Chyme

Does the type of food affect how quickly it leaves the stomach?

Liquids will go through stomach the fastest then carbs then proteins then fats.

What is secreted from the endocrine portion of the pancreas?

Hormones

Name the cells that secrete hormones:

Alpha cells, beta cells, delta cells

What is secreted from exocrine portion of the pancreas?

Pancreatic juice

What is the special name given to these exocrine cells of the pancreas?

Aciner cells

Into what structure do these pancreatic secretions go?

Pancreatic duct

Name the enzymes secreted by the aciner cells:

Pancreatic amalayse, pancreatic lipase, tripsin, chymotrypsin, carboxypeptidase, nuclease

Secreted by the pancreas, to digest carbohydrates

Pancreatic amalayse

Secreted by the pancreas, to digest lipids

Pancreatic lipase

Secreted by the pancreas, to digest proteins

Tripsin, chymotripsin, carboxypepidase

Secreted by the pancreas, to digest nucleic acids

Nucleic acids

What promotes the release of secretin?

Acidic chyme entering the duodenum

What effect will bicarbonate ions have on chyme?

Neutralize acid in chyme and create a favorable environment for the enzymes that will follow

Name the functional units of the liver:

Hepatic lobules

By what vessels does blood enter the liver?

Hepatic portal vein, hepatic artery

Describe the blood entering the liver:

Vein: Nutrients and pathogens

Artery: Oxygenated blood

By what vessel does blood leave the liver?

Hepatic vein

What is the function of Kupffer cells?

Phagocytize bacteria and pathogens from the blood as it passes through these sinusoids

Name the cells that secrete bile:

Hepatic cells of the liver

List the components of bile:

Water, bile salts, bile pigments, cholesterol, electrolytes

Which ingredient in bile has a digestive function?

Bile salts

How is the gallbladder related to bile?

The gallbladder...

Stores blile, concentrates bile by reabsorbing water, contracts to release bile into the duodenum of the small intestine

What promotes the release of CCK?

Proteins and lipids in the small intestine

How do bile salts function in digestion?

Emulsification

How are bile salts a benefit to digestion?

Bile salts reduce the surface tension of fat globules so they break into smaller fat droplets with greater surface for enzymes to act upon

List the functions of the small intestine:

Receives secretions from the pancreas and liver

Completes digestion of nutrients in chyme

Absorbs the products of digestion

Transports remaining residue to the large intestine

Name the parts of the small intestine:

Duodenum, jejunum, ieum

What is the function of the villi and microvilli?

Increases surface area to enhance absroption

What is occurring in the intestinal glands/crypts?

Mitosis

What is secreted from the intestinal glands/crypts?

Large volumes of watery fluid

What is the pH of the watery fluid secreted from the intestinal glands/crypts?

6.5-7.5

What is embedded in the membranes of microvilli?

Digestive enzymes (Pepidase, sucrase, maltase, lactase, intestinal lipase)

What are the products of carbohydrate catabolism?

Monosaccharides

What are the products of protein catabolism?

Amino acids

Protein catabolism begins in the ____________.

Stomach

Carbohydrate catabolism beings in the _____.

Oral cavity

What are the products of fat catabolism?

Fatty acids and glycerol

List some ions that are absorbed by the small intestine:

Sodium, potassium, chloride, nitrate, bicarbonate

How many hours might it take chyme to move through the small intestine?

3-10 hours

List the functions of the large intestine:

Absorbs injected water and electrolytes that remain

Reabsorbs and recycles remnants of secretions

Forms and stores feces

Describe the internal anal sphincter:

Smooth muscle involuntarily controlled

Describe the external anal sphincter:

Skeletal muscle, voluntarily controlled

The primary secretion of the large intestine is:

Mucous

What are the functions of the mucous secreted by the large intestine?

Protects the intestinal wall against abrasive action of materials passing through it

Holds fecal matter together

Controls pH of intestinal contents

How does peristalsis in the large intestine differ from peristalsis in the small intestine?

Large intestine uses contractions instead of peristalsis

What events might promote this peristalsis?

Following a meal or irritation of intestinal mucosa

Describe the composition of feces:

Non-digestible remains, water, electrolytes, mucous, bacteria, bile pigments, epithelial cells