Chapter 14: The Physiology of Digestion

jejunum

-2.5m in length -absorbs nutrients

ileum

-connects to large intestine -Ileum is about 2-4 m in length -absorbs nutrients but mainly absorbs vitamin B12

duodenum

-connects to stomach -consists of hepatopancreatic sphincter -.3 m in length -most of chemical digestion occurs here

liver

-good portion covers the stomach -produces bile (emulsifies fat but doesn't digest it)

On a scale of 0-10, how much digestion would you say bile accomplishes?

0

how many digestive enzymes are AT WORK in the stomach?

1

how many digestive enzymes are produced in the stomach?

1, pepsin

How many regions of the small intestines are there and what are they?

3, and duodenum, jejunum, ileum

how many digestive enzymes are produced in the small intestine?

4

how many digestive enzymes are AT WORK in the small intestine?

9

THE LIVER

A good portion of the liver covers the stomach. There is a tube from the gallbladder and liver that enters into the duodenum of the small intestine at the location of the hepatopancreatic sphincter. The liver produces bile (emulsifies fat but does not digest fat), which is stored in the gallbladder. Bile leaves the liver or gallbladder and enters into the small intestine where it emulsifies fat.

It is in the small intestine where ______ is finally digested.

Fat

Stomach

Food stretching the stomach triggers gastrin. The targets are: stomach cells (parietal cells cause release of HCl and chief cells causes release of pepsinogen)

what cells of the stomach produce the hormone gastrin?

G cells

THE PANCREAS

In order to see the pancreas, the stomach has to be lifted up a bit since the pancreas is mostly posterior to the stomach. The pancreatic duct from the pancreas enters into the duodenum of the small intestine at the location of the hepatopancreatic sphincter. The pancreas produces not only hormones but also buffers and numerous digestive enzymes. These buffers and digestive enzymes enter into the duodenum of the small intestine via the hepatopancreatic sphincter.

Digestive enzyme trypsin

Is produced by the pancreas digestion occurs in the small intestine digest proteins

Digestive enzyme salivary amylase

Is produced by the salivary gland's in the mouth digestion occurs in the mouth digests carbohydrates

Digestive enzyme sucrase

Is produced by the small intestine and digest carbohydrates (sucrose)

Digestive enzyme lactase

Is produced by the small intestine and digests carbohydrates (lactose)

Digestive enzyme Maltase

Is produced by the small intestine and digests carbohydrates (maltose)

Digestive enzyme pepsin

Is produced by the stomach and digests proteins

Digestive enzyme carboxypeptidase

Is produced in the pancreas digestion occurs in the small intestine it digest proteins

This emulsification process helps _______ do a more efficient job of digesting fat. Remember, bile does not digest fat it only emulsifies it.

Lipase

The stomach actually does very _________ digestion

Little

Major Organs of Digestion

Mouth, Esophagus, Stomach, Small intestine, Large intestine (very little digestion occurs here)

Small intestine

Presence of acidic chyme triggers secretin which targets: Liver to cause the production of bile Pancreas to cause the release of buffers

Small intestine

Presence of glucose triggers glucose insulinotropic peptide (GIP) which targets beta cells of the pancreas causing beta cells to release insulin

Small intestine

Presence of nutrients triggers vasoactive intestinal peptide (VIP) which targets capillaries inside the intestinal villi and causes villi capillaries to dilate

Small intestine

Presence of protein and fat in small intestine triggers cholecystokinin (CCK) and targets: Pancreas causing release of pancreatin Gallbladder causing release of bile into the dupdenum Hepatopancreatic sphincter causing the sphincter to open at the duodenum

Digestive enzyme peptidase

Produced by the small intestine and digests protein

Digestive enzyme pancreatic amylase

Produced in the pancreas digestion occurs in the small intestine digests carbohydrates

Digestive enzyme lipase

Produced in the pancreas digestion occurs in the small intestine digests fat

Digestive enzyme chymotrypsin

Produced in the pancreas digestion occurs in the small intestine digests protein

Accessory Organs of Digestion

Salivary glands, Liver, Gallbladder, Pancreas

Gastrin targets the parietal and chief cells of the stomach and causes those cells to manufacture HCl and pepsinogen, respectively. combination

The combination of HCl and pepsinogen results in the digestive enzyme, pepsin.

THE GALLBLADDER

The gallbladder stores bile. Bile leaves the gallbladder and enters the cystic duct. From the cystic duct, bile enters the common bile duct. The common bile duct terminates at the hepatopancreatic sphincter. Bile then enters into the duodenum of the small intestine.

THE MOUTH

The mouth consists of: Teeth Tongue (with taste buds) Salivary glands (parotid, sublingual, and submandibular Produce saliva, which consists of salivary amylase (digestive enzyme).)

THE SMALL INTESTINE

The small intestine is a highly coiled organ. The majority of the digestion takes place in the small intestine. (While it is longer than the large intestine, it is called the small intestine because it is smaller in diameter than the large intestine.) There are three regions to the small intestine: 1. Duodenum The duodenum consists of the hepatopancreatic sphincter The duodenum is about 0.3 m in length Most of the chemical digestion occurs in the duodenum 2. Jejunum The jejunum is about 2.5 m in length Absorbs nutrients 3. Ileum The ileum is about 2-4 m in length Absorbs nutrients but mainly absorbs vitamin B12 *The duodenum connects to the stomach and the ileum connects to the large intestine.

THE STOMACH

The stomach is located a bit to the left of the midline of the body. The G cells of the stomach produce gastrin (hormone). Gastrin targets the chief cells and parietal cells of the stomach. These cells produce pepsinogen and hydrochloric acid respectively. (The combination of pepsinogen and hydrochloric acid yields pepsin (digestive enzyme).)

The food is swallowed and passes through the esophagus by peristaltic activity. o This mainly undigested food is called

a bolus.

Vinegar was used in this lab activity because it represents a/an ________.

acid

partially digested food

acidic chyme

This partially digested food is now called

acidic chyme.

how are digestive enzymes produced?

acinar cells within the pancreatic lobules

Vasoactive intestinal peptide will cause the capillaries in the villi to dilate therefore allowing the villi to absorb maximum nutrients to be transported to

all parts of the body.

The large intestine functions primarily for the elimination of waste

and the reabsorption of water.

Dish soap in this exercise represents ________.

bile

mainly undigested food

bolus

peristalsis

bolus of food will pass from the mouth to the stomach via a muscular action of the esophagus via

It is in the small intestine where the rest of the

carbohydrates are digested and the rest of the proteins are digested.

Almost any food substance we consume will consist of

carbohydrates, proteins, and fats.

food substances consist of

carbohydrates, proteins, fats

The mouth will only partially digest

carbohydrates.

what does the hormone gastrin target?

chief cells and parietal cells of the stomach

The hepatopancreastic sphincter has to open in order to allow digestive enzymes to enter the small intestine from the pancreas. What causes this sphincter to open?

cholecystokinin

what hormone causes the pancreas to release pancreatin?

cholecystokinin

what hormone targets the hepatopancreatic sphincter causing it to open allowing pancreatic to enter into the duodenum of the small intestine?

cholecystokinin

Nutrients are absorbed into the intestinal villi and then into the capillaries, and then ultimately into

circulation.

Lactose intolerance is a condition where the individual lacks adequate amounts of lactase to

digest lactose.

Bile does not __________ fat; it only __________ fat.

digest; emulsifies

The small intestine does the majority of the

digestion.

The hepatopancreatic sphincter is where the ducts from the gallbladder and liver meet with the

duct from the pancreas to join the small intestine.

Pancreatic buffers, pancreatic enzymes, and bile enter into the ____________ at the hepatopancreatic sphincter.

duodenum

The sphincter located at the junction of the esophagus and the stomach is called the

esophageal sphincter.

Heartburn is the burning sensation in the _________.

esophagus

True or false: Bile is produced by the gallbladder

false

True or false: Emulsification is defined as the digestion of fat

false

True or false: The massive bubbling created by your catalase experiment means that catalase was denatured?

false

Bile from the liver and/or gallbladder will enter into the small intestine to emulsify

fat.

The small intestine will thoroughly digest carbohydrates, protein, and

fat.

Glucose insulinotropic peptide (GIP) is also known as

glucose dependent insulinotropic peptide (GDIP).

GIP or GDIP

glucose insulinotropic peptide, or glucose dependent insulinotropic peptide

The pancreas plays a huge role in the digestion of food products while at the same time is

heavily involved in the production of hormones.

The pancreatic duct and common bile duct merge at the _________________ entering into the duodenum of the small intestine.

hepatopancreatic sphincter

where does digestion BEGIN?

in the mouth

what organ produce the most catalase?

liver

The _________ makes bile and the __________ stores bile.

liver; gallbladder

Digestive enzymes are produced via acinar cells within the pancreatic

lobules.

esophageal sphincter

located at the junction of the esophagus and the stomach

pyloric sphincter

located at the junction of the stomach and the small intestine

bile

made in liver -liver or gallbladder to small intestine -gallbladder to cystic duct to common bile duct -common bile duct terminates at the hepatopancreatic sphincter then enters into the duodenum of the small intestine

pancreas

mostly posterior to the stomach -produces hormones but also buffers numerous digestive enzymes -the pancreatic duct enters into the duodenum of the small intestine at the location of the hepatopancreatic sphincter

A very small amount of carbohydrates will only be partially digested in the

mouth.

Digestion begins in the

mouth.

what is chyme called when it is throughly digested?

nutrients

The small intestine does the majority

of the digestion.

Buffers from the pancreas will enter into the duodenum of the small intestine in order to stabilize the pH of the small intestine around

pH 7-8.

All of the digestive enzymes that work in the small intestine work best at a

pH of 7-8.

In order to resists a change in the pJ in the small intestine a buffer is released into the small intestine to stabilize the pH. Where does this buffer come from?

pancreas

Cholecystokinin targets the hepatopancreatic sphincter causing it to open thus allowing _____________ to enter into the duodenum of the small intestine.

pancreatin

what are the three salivary glands?

parotid, sublingual, submandibular

The teeth will mechanically break down food followed by

partial digestion via enzyme activity.

the combination of pepsinogen and hydrochloric acid yields?

pepsin

what do G cells produce?

pepsinogen, hydrochloric acid

A bolus of food will pass from the mouth to the stomach via muscular action of the esophagus called

peristalsis.

The acidic chyme is passed into the small intestine by

peristaltic activity.

Catalase is an enzyme made in the liver cells. What cell organelle is responsible for the production of catalase?

peroxisomes

what does the pancreas do?

plays huge role in the digestion of food products, while heavily involved in the production of hormones

Anatomically, the pancreas is located___________ to the stomach.

posterior

what does the liver do?

production of bile

The liver has numerous functions and one of them is the

production of bile, which is used in the digestive system.

The stomach will partially digest

protein.

The sphincter located at the junction of the stomach and the small intestine is the

pyloric sphincter.

where does the majority of the digestion occur?

small intestine

where is carbs, proteins and fats finally digested?

small intestine

The main organ that digests fat is the

small intestine.

The majority of the digestion occurs in the

small intestine.

why is it called the small intestine?

smaller in diameter than the large intestine

If we add iodine to a white substance and that white substance turns dark, that means the substance is _______.

starch

Acid in the small intestine could alter the small intestine pH and therefore denature the digestive enzymes. Where does this acid come from?

stomach

The ______________will only partially digest protein.

stomach

Digestion continues in the

stomach.

gallbladder

stores bile

what does the mouth consist of?

teeth, tongue (with taste buds), salivary glands (3)

what does the large intestine function for?

the elimination of waste and the reabsorption of water

Pancreatin enters the duodenum of the small intestine through

the hepatopancreatic sphincter.

True of false: The bugger experiment showed that buffers resist changes in pH

true

True or false: Pancreatin consists of numerous digestive enzymes one of which is amylase

true

what will cause the capillaries in the villi to dilate therefore allowing the villi to absorb maximum nutrients?

vasoactive intestinal peptide

hepatopancreatic sphincter

where the ducts from the gallbladder and liver meet with the duct from the pancreas to join the small intestine