Which Nervous System Primarily Controls And Increases Salivation?

Chapter 15. Animal Nutrition and the Digestive System

15.4 Digestive System Regulation

Learning Objectives

By the end of this section, you volition be able to:

Discuss the function of neural regulation in digestive processes
Explicate how hormones regulate digestion

The brain is the control center for the sensation of hunger and satiety. The functions of the digestive system are regulated through neural and hormonal responses.

Neural Responses to Nutrient

In reaction to the smell, sight, or idea of nutrient, similar that shown in Figure fifteen.xx, the first hormonal response is that of salivation. The salivary glands secrete more saliva in response to the stimulus presented past food in grooming for digestion. Simultaneously, the stomach begins to produce hydrochloric acid to digest the food. Recall that the peristaltic movements of the esophagus and other organs of the digestive tract are nether the control of the brain. The brain prepares these muscles for movement as well. When the tummy is full, the office of the brain that detects satiety signals fullness. There are iii overlapping phases of gastric control—the cephalic stage, the gastric phase, and the intestinal phase—each requires many enzymes and is under neural control as well.

Figure 34.20. Seeing a plate of food triggers the secretion of saliva in the mouth and the production of HCL in the stomach. (credit: Kelly Bailey) — Figure 15.20.
Seeing a plate of food triggers the secretion of saliva in the mouth and the product of HCL in the tum. (credit: Kelly Bailey)

Digestive Phases

The response to food begins even before food enters the mouth. The showtime phase of ingestion, chosen the cephalic phas, is controlled past the neural response to the stimulus provided by food. All aspects—such every bit sight, sense, and olfactory property—trigger the neural responses resulting in salivation and secretion of gastric juices. The gastric and salivary secretion in the cephalic phase tin can too take place due to the thought of food. Right at present, if y'all think virtually a piece of chocolate or a crispy spud chip, the increase in salivation is a cephalic phase response to the thought. The fundamental nervous system prepares the stomach to receive food.

The gastric phase begins once the food arrives in the tum. It builds on the stimulation provided during the cephalic phase. Gastric acids and enzymes procedure the ingested materials. The gastric stage is stimulated by (i) distension of the breadbasket, (two) a decrease in the pH of the gastric contents, and (3) the presence of undigested textile. This phase consists of local, hormonal, and neural responses. These responses stimulate secretions and powerful contractions.

The intestinal stage begins when chyme enters the small intestine triggering digestive secretions. This phase controls the charge per unit of gastric emptying. In addition to gastrin emptying, when chyme enters the pocket-size intestine, it triggers other hormonal and neural events that coordinate the activities of the intestinal tract, pancreas, liver, and gallbladder.

Hormonal Responses to Nutrient

The endocrine arrangement controls the response of the various glands in the body and the release of hormones at the appropriate times.

1 of the important factors nether hormonal control is the tum acid environs. During the gastric stage, the hormone gastrin is secreted past K cells in the tummy in response to the presence of proteins. Gastrin stimulates the release of breadbasket acid, or hydrochloric acid (HCl) which aids in the digestion of the proteins. However, when the stomach is emptied, the acidic environment need not be maintained and a hormone chosen somatostatin stops the release of hydrochloric acid. This is controlled by a negative feedback mechanism.

In the duodenum, digestive secretions from the liver, pancreas, and gallbladder play an important role in digesting chyme during the intestinal phase. In order to neutralize the acidic chyme, a hormone called secretin stimulates the pancreas to produce element of group i bicarbonate solution and deliver it to the duodenum. Secretin acts in tandem with another hormone called cholecystokinin (CCK). Not only does CCK stimulate the pancreas to produce the requisite pancreatic juices, information technology also stimulates the gallbladder to release bile into the duodenum.

Concept in Action

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this website to learn more about the endocrine system. Review the text and watch the animation of how control is implemented in the endocrine organization.

Another level of hormonal control occurs in response to the composition of food. Foods high in lipids take a long fourth dimension to digest. A hormone chosen gastric inhibitory peptide is secreted by the small intestine to slow downwards the peristaltic movements of the intestine to allow fatty foods more time to be digested and captivated.

Agreement the hormonal command of the digestive organisation is an of import expanse of ongoing enquiry. Scientists are exploring the role of each hormone in the digestive process and developing ways to target these hormones. Advances could pb to noesis that may help to battle the obesity epidemic.

Summary

The brain and the endocrine system command digestive processes. The encephalon controls the responses of hunger and satiety. The endocrine organisation controls the release of hormones and enzymes required for digestion of food in the digestive tract.

Exercises

Which of the following is a pseudo-ruminant?
1. moo-cow
2. pig
3. crow
4. horse
Which of the following statements is untrue?
1. Roughage takes a long time to digest.
2. Birds swallow large quantities at one time then that they can fly long distances.
3. Cows do not have upper teeth.
4. In pseudo-ruminants, roughage is digested in the cecum.
The acidic nature of chyme is neutralized by ________.
1. potassium hydroxide
2. sodium hydroxide
3. bicarbonates
4. vinegar
The digestive juices from the liver are delivered to the ________.
1. stomach
2. liver
3. duodenum
4. colon
Which of the following statements is not truthful?
1. Essential nutrients can be synthesized by the trunk.
2. Vitamins are required in small quantities for bodily function.
3. Some amino acids can exist synthesized past the body, while others need to be obtained from diet.
4. Vitamins come in 2 categories: fatty-soluble and h2o-soluble.
Which of the following is a water-soluble vitamin?
1. vitamin A
2. vitamin E
3. vitamin Chiliad
4. vitamin C
What is the chief fuel for the body?
1. carbohydrates
2. lipids
3. protein
4. glycogen
Excess glucose is stored as ________.
1. fat
2. glucagon
3. glycogen
4. it is not stored in the body
Where does the majority of protein digestion take place?
1. stomach
2. duodenum
3. mouth
4. jejunum
Lipases are enzymes that break downwardly ________.
1. disaccharides
2. lipids
3. proteins
4. cellulose
Which hormone controls the release of bile from the gallbladder
1. pepsin
2. amylase
3. CCK
4. gastrin
Which hormone stops acid secretion in the breadbasket?
1. gastrin
2. somatostatin
3. gastric inhibitory peptide
4. CCK
Describe how hormones regulate digestion.
Describe one or more scenarios where loss of hormonal regulation of digestion can lead to diseases.

Answers

D
B
C
C
A
D
A
C
A
B
C
B
Hormones control the unlike digestive enzymes that are secreted in the stomach and the intestine during the process of digestion and absorption. For example, the hormone gastrin stimulates stomach acid secretion in response to food intake. The hormone somatostatin stops the release of stomach acid.
In that location are many cases where loss of hormonal regulation can lead to illnesses. For example, the bilirubin produced past the breakup of red blood cells is converted to bile by the liver. When there is malfunction of this procedure, there is backlog bilirubin in the blood and bile levels are low. Every bit a result, the trunk struggles with dealing with fatty food. This is why a patient suffering from jaundice is asked to swallow a diet with almost cypher fatty.

Glossary

bile: digestive juice produced by the liver; of import for digestion of lipids
cephalic phase: first phase of digestion, controlled past the neural response to the stimulus provided by nutrient
cholecystokinin: hormone that stimulates the contraction of the gallbladder to release bile
chyme: mixture of partially digested food and stomach juices
digestion: mechanical and chemical break down of food into pocket-size organic fragments
duodenum: first role of the small intestine where a large part of digestion of carbohydrates and fats occurs
endocrine system: organisation that controls the response of the various glands in the trunk and the release of hormones at the appropriate times
esophagus: tubular organ that connects the oral cavity to the stomach
gallbladder: organ that stores and concentrates bile
gastric inhibitory peptide: hormone secreted by the small intestine in the presence of fat acids and sugars; information technology also inhibits acid production and peristalsis in order to slow down the charge per unit at which food enters the small intestine
gastric phase: digestive phase beginning one time food enters the tummy; gastric acids and enzymes process the ingested materials
gastrin: hormone which stimulates muriatic acid secretion in the stomach
ingestion: human action of taking in food
intestinal stage: 3rd digestive stage; begins when chyme enters the small intestine triggering digestive secretions and controlling the rate of gastric emptying
jejunum: 2nd part of the pocket-sized intestine
liver: organ that produces bile for digestion and processes vitamins and lipids
pancreas: gland that secretes digestive juices
pepsin: enzyme found in the stomach whose main role is protein digestion
peristalsis: wave-similar movements of muscle tissue
roughage: component of food that is low in energy and loftier in fiber
ruminant: animal with a tummy divided into four compartments
secretin: hormone which stimulates sodium bicarbonate secretion in the pocket-sized intestine
small-scale intestine: organ where digestion of protein, fats, and carbohydrates is completed
somatostatin: hormone released to terminate acrid secretion when the stomach is empty
stomach: saclike organ containing acidic digestive juices
vitamin: organic substance necessary in small amounts to sustain life