***Ch 24 Digestive System *** A&P II

Absorption of Amino acids, dipeptides and tripeptides

Most are absorbed as amino acids via active transport into the blood ½ of absorbed AA come from proteins in digestive juice and dead mucosal cells

Enteric nervous system (ENS)

Neurons extending from esophagus to anus with 2 plexuses

Which of the following small intestine cells secrete lysozyme? Mucosa cells Paneth cells S cells Goblet cells Absorptive cells

Paneth cells

Which of the following cells secrete hydrochloric acid? Parietal cells Serosa cells Chyme cells Mucous cells Chief cells

Parietal cells

Circular folds

Permanent folds (~1 cm deep) that force chyme to slowly spiral through lumen, allowing more time for nutrient absorption

Mucosa

The innermost layer of the human digestive tract; in some parts of the digestive system, it contains mucus-secreting cells and glands that secrete digestive enzymes

Large intestine overall function

complete absorption, produce certain vitamins, and form and expel feces

Muscularis of GI tract

composed of circular fibers and longitudinal fibers which is responsible for segmental contractions and peristaltic movement

bile salts

compounds in bile that aid in emulsification

pancreatic duct function

conducts pancreatic juice from the pancreas to the small intestine

Lamina propria digestion

connective tissue with blood and lymphatic vessels it is modified to allow the passage of a large number of ducts, which connect to the liver, pancreas, and salivary glands.

visceral peritoneum

covers organs also called the Serosa

what is the series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food

digestive tract

Microvilli in intestines

fingerlike extensions for increasing surface area for absorption/secretion of intestinal juice

Duodenum

first part of the small intestine

duodenum

first part of the small intestine

Hepatopancreatic duct

fusion of common bile duct and pancreatic duct into duodenum

which cell functions to store and concentrate bile produced by the liver until it is needed in the small intestine

gallbladder

large intestine

in all animals water is absorbed, bacterial fermentation takes place, and feces are formed

Sympathetic in digestion

inhibits digestion, don't want energy to go to digestion while running from bear

mucosa of GI tract

inner epithelial lining, it is the soft tissue that lines the body's canals and organs in the digestive, respiratory and reproductive systems which functions in absorption and secretion

what enzyme digests lipids?

lipase

_____is the heaviest gland of the body

liver

which organ is critical to the digestion and absorption of fats

liver

Hepatocytes

liver cells that produce bile

antrum of stomach

lower portion of the stomach

body of stomach

main central region of stomach

mixing waves

mix the stomach contents with stomach secretions to form chyme

Organs of the digestive system

mouth, pharynx, esophagus, stomach, small intestine, large intestine

MALT

mucosa associated lymphoid tissue; protects against ingested microbes

Myenteric plexus

nerve supply between the two layers of the muscularis externa; provides smooth, coordinated contraction for peristalsis

Serosa of GI tract

outer layer of connective tissue covered with visceral peritoneum which mostly composed of connective tissue and gives strength to the long digestive tract, attaching itself to surrounding structures.

which organ is critical for the digestion of fats, carbohydrates and protein?

pancreas

Which major duct carries a fluid rich in bicarbonate ions?

pancreatic duct

what enzyme digests proteins?

pepsin

In the mouth, the tooth sockets are lined with

periodontal ligament

gastric phase

phase of gastric secretion that begins when food enters the stomach

Bilirubin function

pigment released by the liver in bile, functioning to help liver break down food. It is a yellowish substance made during your body's normal process of breaking down old red blood cells

descending colon

portion of the colon that extends downward from the transverse colon

Which of the following is the forerunner of the gastrointestinal tract? foregut endoderm primitive gut midgut hindgut

primitive gut

smooth muscle in digestion

produces a forceful contractions that produce muscle shortening to propel the bolus along the gastrointestinal tract.

villi of small intestine

provide an enormous surface area that facilitates absorption.

rectum

A short tube at the end of the large intestine where waste material is compressed into a solid form before being eliminated

Esophagus

A simple conduit between the mouth and stomach

bolus

A soft mass of chewed food.

bile duct

A tube that carries bile from the liver and gallbladder to the intestine

Which of the following are the primary function(s) of the large intestine? A. Chemical digestion B. Absorption C. Feces formation D. Regulation of blood glucose

A, B & C

Which of the following are a function(s) of the liver? A.) Conversion of carbohydrates B.) Protein metabolism C.) Storage of bilirubin D.) Phagocytosis E.) Storage of vitamins

A, B, D & E

Which of the following processes is the primary function of the villi of the small intestine? Ingestion Secretion Mixing and propulsion Absorption None of these choices

Absorption

absorption of monosaccharides

All dietary carbohydrates digested are absorbed by facilitated diffusion or active transport into blood leaving only indigestible cellulose fibers left in feces

chief cells cells of stomach

epithelial cells in the gastric glands in the stomach lining. They are responsible for the secretion of pepsinogen and gastric lipase.

anal canal

region, containing two sphincters, through which feces are expelled from the body

pyloric sphincter

ring of muscle that guards the opening between the stomach and the duodenum (small intestine)

Sublingual gland

salivary gland under the tongue, smallest

Partoid gland

salivary gland within the cheek, just anterior to the ear

What is the enzyme present in saliva that breaks down fats?

salivary lipase

parietal cells of stomach

secrete HCl and intrinsic factor

chief cells

secrete pepsinogen and gastric lipase

Pepsin

secreted by chief cells, it's an Enzyme that breaks down proteins in the stomach

Parasympathetic in digestion

stimulates digestion, remember "rest and digest"

Chyme is created in the ________.

stomach

fundus function

stores undigested food and also the gases released from the chemical digestion of food

What organ breaks down food mechanically?

teeth in mastication

acessory digestive organs

teeth, tongue, salivary glands, liver, gallbladder, pancreas

Cecum

the cavity in which the large intestine begins and into which the ileum opens

Pancreatic juice

the clear alkaline digestive fluid secreted by the pancreas.

digestion of lipids in small intestine

Bile is secreted by the gallbladder to emulsify fat molecules and converts them into smaller fat droplets Pancreatic lipase breaks down small fat droplets into glycerol or monoglycerides.

cardia stomach function

Food and liquids pass through the cardia to enter the stomach from the esophagus. A valve near the cardia helps keep stomach contents from backing up into the esophagus

Mouth

Food is broken down mechanically by chewing and saliva is added as a lubricant. Saliva contains amylase, an enzyme that digests starch

saliva makeup

99.5% water, 0.5% solutes - uric acid, mucus,immunoglobulin A, lysozyme, and salivary amylase (acts on starch)

Submucosal Plexus

(plexus of Meissner) nerve supply that regulates the activity of glands and smooth muscle, aka secretions

Submucosa of GI tract

- areolar (loose) connective tissue - rich supply of nerves, blood and lymphatic vessels, and lymphoid follicles - abundant elastin and collagen

absorption of water

-9 L water, most from GI tract secretions, enter small intestine -95% absorbed in the small intestine by osmosis -Most of rest absorbed in large intestine -Net osmosis occurs if concentration gradient established by active transport of solutes -Water uptake coupled with solute uptake

muscles of the GI tract

-Purpose of these muscles are to mix food and ensure efficient digestion and absorption of nutrients

4 main regions of the stomach

1. Cardia 2. Fundus 3. Body 4. Pylorus

Enzyme activity and pH

Changing the pH will alter the charge and shape of the enzyme, which in turn will diminish its ability to bind the substrate, and help break down food

Which hormone is stimulated by high levels of dietary fat in the small intestine? Amylase Pepsin Secretin Gastrin Cholecystokinin

Cholecystokinin

Absorption of Lipids

Digestion begins in the small intestine (duodenum) and is complete by the end of the small intestine. Digestion of lipids CANNOT begin prior to their reaching the small intestine where the encounter bile and lipase. Triglycerides are broken down to fatty acids, transported across them membrane, then reformed into triglycerides. Enter at the LACTEALS. In order for lipids to travel in blood and lymph, they must 1) bind to a carrier protein (albumin) or 2) be formed into a chylomicron or micelle.

Cystic duct

Duct leading from the gallbladder to the common bile duct; carries bile

Role and composition of bile

Each day, hepatocytes secrete 800-1000 mL (about 1 qt) of bile, a yellow, brownish, or olive-green liquid. It has a pH of 7.6-8.6 consists mostly of water, bile salts, cholesterol, a phospholipid called lecithin, bile pigments, and several ions. principal bile pigment is bilirubin

Which of the following accessory organs stores bile? Pharynx Teeth Gallbladder Salivary glands Liver

Gallbladder

where are the liver's digestive juices stored?

Gallbladder

pepsinogen and gastric lipase do what?

Gastric lipases are responsible for the digestion of exogenous lipid Pepsinogen is initially activated by the H+ ions. The activated enzyme then acts autocatalytically to increase the rate of formation of more pepsin which breaks down proteins in food during digestion.

stomach acid

HCl, Breaks down proteins, breaks them down into sugar and acids

Which type of hepatitis is spread via fecal contamination of objects such as food, clothing, toys, and eating utensils and is characterized by loss of appetite, malaise, nausea, diarrhea, fever, and chills. Hepatitis C Hepatitis A Hepatitis D Hepatitis B Hepatitis E

Hepatitis A

periodontal ligament

Holds tooth in the socket

Peristalsis

Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system.

Chyme function

It increases the surface area of food by breaking it down into smaller components. It also stimulates digestive glands (gallbladder and pancreas) to secrete their respective solutions (bile, digestive enzymes, and bicarbonate)

Which of the following pancreatic enzymes digests lipids? Trypsin Elastase Lipase Pepsin All of these choices

Lipase

Which of the following accessory organs produces a fluid that functions to emulsify dietary fats? Gallbladder Pharynx Teeth Liver Salivary glands

Liver

what organ provides bile salts to the small intestine, which are critical for the digestion and absorption of fat?

Liver

Solid digestive organs

Liver and Pancreas

Which structure is composed of prominent lymphatic nodules that function in the immune response? Submucosa Mucosa Lamina propria MALT Serosa

MALT

Which layer functions by secreting a lubricating fluid? Mucosa Muscularis Muscularis MALT Serosa

Mucosa

what are the muscles of the GI tract?

Muscularis: The muscularis consists of two smooth muscle layers, a thin outer longitudinal layer that shortens and elongates the gut, and a thicker inner circular layer of smooth muscle, which causes constriction.

Which plexus is located between the longitudinal and circular smooth muscle layers of the muscularis?

Myenteric plexus

2 plexuses of the ENS

Myenteric plexus - GI tract motility Submucosal plexus - controlling secretions

Digestion of Nucleic acids

Ribonuclease and deoxyribonuclease in pancreatic juice---RNA and DNA broken down into nucleic acids

Which structure of the stomach allows greater distension for food storage? Sphincter Pylorus Rugae Cardia Fundus

Rugae

Which of the following accessory organs produces a fluid to soften food? Salivary glands Teeth Liver Gallbladder Pharynx

Salivary glands

Brunner's glands Secrete an acidic juice Secrete an acidic mucus Secrete an alkaline juice Secrete an alkaline mucus

Secrete an alkaline mucus

mucosa epithelium

Simple columnar with many goblet cells that secrete mucus to ease passage of food down the tract.

where are almost all nutrients are absorbed?

Small intestine

cementum

Specialized, calcified connective tissue that covers the anatomic root of a tooth.

Which of the following is NOT a function of the liver? Storage of vitamins Storage of bilirubin Conversion of carbohydrates Phagocytosis Protein metabolism

Storage of bilirubin

Gastric lipase

enzyme to digest fat, secreted by chief cells

True or False? The pancreas is Important as both an endocrine and exocrine organ.

True, As an exocrine gland, it secretes pancreatic fluid that contains bicarbonate and digestive enzyme And it also produces hormones in its 'endocrine' cells which monitor what is happening in the blood. They then can release hormones directly into the blood when necessary.

Why is digestion important?

We must break down the food we eat into smaller molecules that can be absorbed and carried to cells of the body Digestion involves mixing food with digestive juices, moving it through the digestive tract, and breaking down large molecules of food into smaller molecules. • Digestion begins in the mouth, when you chew and swallow, and is completed in the small intestine.

Stomach

Where the real action begins - enzymatic digestion of proteins initiated and foodstuffs reduced to liquid form.

Hepatopancreatic duct function

a connection between areas of your digestive system. It acts as a reservoir for pancreatic juices and bile, enabling the release of these substances that help your body break down and absorb food

submandibular gland

a salivary gland inside the lower jaw on either side that produces most of the nocturnal saliva

4 regions of large intestine

1. cecum 2. colon 3. rectum 4. anal canal

Phases of digestion

1. cephalic phase 2. gastric phase 3. intestinal phase

Jejunum

Middle portion of the small intestine

Lingual glands

Minor salivary glands of the tongue that secrete salivary lipase-begins to digest fats (triglycerides)

After ____ hours chyme then exits the stomach via the pylorus and enters the duodenum of the small intestine

2 - 4 hours

How many stages of deglutition are there? 3 8 4 5 2

3

Muscularis

3rd layer made of 2 layers of smooth muscle that move food along the GI tract

6 functions of the digestive system

1. Ingestion 2. Mechanical processing 3. Digestion 4. Secretion 5. Absorption 6. Excretion

Layers of the GI tract

1. Mucosa 2. Submucosa 3. Muscularis 4. Serosa

Steps of stomach acid production

1. Water and CO2 combine to form carbonic acid. 2. H2CO3 dissociates. 3. H+ and bicarbonate ions are transported into the gastric lumen. 4. Cl- diffuses into the gastric 5. Chloride ion combines with H+ in the gastric lumen.

3 regions of small intestine

1. Duodenum 2. Jejunum 3. Ileum

2 groups of organs compose the digestive system

1. Gastrointestinal (GI) tract or alimentary canal 2. Accessory digestive organs

Which of the following is NOT a change in the digestive system associated with aging? Decreased secretory mechanisms Decreased motility of the digestive organs Loss of strength and tone of the muscular tissue Changes in neurosensory feedback regarding enzyme and hormone release All of these are age related changes in the digestive system

All of these are age related changes in the digestive system

identify the calcified connective tissue

B

Why do emotions such as anger or fear slow digestion? Because they stimulate the somatic nerves that supply the GI tract Because they stimulate the parasympathetic nerves supplying the GI tract They do not affect digestion Because they stimulate the sympathetic nerves that supply the GI tract Because all emotions are controlled by the Vagus nerve

Because they stimulate the sympathetic nerves that supply the GI tract

absorption of vitamins

Fat-soluble vitamins A, D, E, and K absorbed by simple diffusion and transported with lipids in micelles Most water-soluble vitamins also absorbed by simple diffusion

Which structure regulates the flow of material into the colon? Sigmoid colon Pyloric sphincter Anal canal Ileocecal sphincter Appendix

Ileocecal sphincter

Pancreas

Important roles as both an endocrine and exocrine organ - provides a potent mixture of digestive enzymes to the small intestine which are critical for digestion of fats, carbohydrates, and protein

hepatitis

Inflammation of the liver usually results from viruses, drugs and chemicals such as alcohol.

Which of following processes is the primary function of the mouth? Ingestion Secretion Mixing and propulsion Absorption None of these choices

Ingestion

Which portion of the peritoneum is largely responsible for carrying blood and lymph vessels to the intestines? Lesser omentum Mesentery Falciform ligament Mesocolon Greater omentum

Mesocolon

chemical digestion

Process by which enzymes break down food into small molecules that the body can use

Which of the following is NOT a primary function of the large intestine? Mechanical digestion Regulation of blood glucose Chemical digestion Feces formation Absorption

Regulation of blood glucose

Which of the following is a contribution of the digestive system to the muscular system? Small intestine absorbs dietary calcium and phosphorous salts. The liver can convert lactic acid to glucose. Small intestine absorbs vitamin D. Excess dietary calories are stored as triglycerides in adipose cells. The liver synthesizes most plasma proteins.

The liver can convert lactic acid to glucose.

Submucosal plexus vs Myenteric plexus

The myenteric plexus increases the tone of the gut and the velocity and intensity of contractions. The submucosal plexus is involved with local conditions and controls local secretion, absorption, and muscle movements.

Liver vs Pancreas

The pancreas produces digestive enzymes that help break down proteins, carbohydrates and fats. Liver. The liver produces bile, a solution that helps you digest fats

fundus of stomach

The upper left portion of the stomach, which has a curved, dome-shaped appearance.

Saliva contains _______, an enzyme that digests starch

amylase

What enzyme digests starch?

amylase

sigmoid colon

an S-shaped structure that continues from the descending colon above and joins with the rectum below

colon

another name for the large intestine

Cardia

area around the opening of the esophagus

why don't we eat our own stomach?

because it is lined with epithelial cells, which produce alkaline mucus. This forms a barrier between the lining of the stomach and the contents.

Digestion begins in the ____ and ends in the ______ _____?

begins in the mouth and ends in the small intestine

Amphipathic

bile salts have hydrophobic and hydrophilic regions—form micelles

small intestine does what?

breaks down the food mixture evenmore so your body can absorb all the vitamins,minerals, proteins, carbohydrates, and fats

Mixing and propulsion

churning and propulsion of food through the GI tract

Liver

the center of metabolic activity in the body - its major role in the digestive process is to provide bile salts to the small intestine, which are critical for digestion and absorption of fats.

cephalic phase

the earliest phase of digestion, in which the brain thinks about and prepares the digestive organs for the consumption of food

transverse colon

the middle part of the large intestine, passing across the abdomen from right to left below the stomach.

Small intestine

the most exciting place to be in the entire digestive system - this is where the final stages of chemical enzymatic digestion occur and where almost all nutrients are absorbed.

intestinal phase

the phase of gastric secretion that begins when chyme enters the intestine and moderates gastric activity through hormones and nervous reflexes

Ileum

third part of the small intestine

ascending colon

travels upward from the cecum to the undersurface of the liver