Chapter 4 Human Digestion and Absorption

What are the four primary types of tissue?

• Eptihelial Tissue

• Connective Tissue

• Muscle Tissue

• Nervous Tissue

What is the epithelial tissue?

surface cells that line the outside of the body and all passage ways within it

What is connective tissue?

cells and their protein products that hold different structures in the body together. tendons and cartilage are composed largely of connective tissue

What is muscle tissue?

type of tissue adapted for contraction

What is nervous tissue?

tissue composed of highly branched, elongated cells that transport nerve impulses from 1 part of the body to another

What is the primary form of Energy that can be used by almost all cells?

The primary form of Energy that can be used is adenosine triphosphate (ATP)

What organs make up the digestive system?

• Mouth and salivary glands

• Esophagus

• Stomach

• Liver

• Gallbladder

• Pancreas

• Small intestine

• Large intestine (colon)

• Rectum

What is the alimentary canal and what are the four layers that make it up?

tubular portion of the digestive tract that extends from the mouth to the anus. The four layers are;

1. Mucosa - intermost layer, it is lined with epithelial cells and glands

2. Submucosa - second layer, consists of connective tissue, glands, blood vessles, and nerves

3. Muscle - the next layer, occurs as double layer in most parts of the GI tract

4. Serosa - the outermost layer, protects the GI tract

Name the 5 sphincters?

1. Lower esophageal sphincter

2. Pyloric sphincter

3. Hepatopancreatic sphincter

4. Ileocecal valve

5. Anal sphincters

What are the 5 sphincters primary function?

1. prevent blackflow (reflux) of stomach contencts into the esophagus

2. control the flow of stomache contents into the small intestine

3. control the flow of bile and pancreatix juice from the common bile and pancreatic ducts into the small inestine

4. prevent the contents of the large inestine from reentering the small inestine

5. prevent defecation until person desries to do

What is perstalsis and where does it most frequently occur?

Peristalsis is when food is mixed with digestive secretions and propelled down the GI tract. This frequently occurs in the small intestine, where contractions occur about every 4-5 seconds.

Name the important secretions of the digestive system and their function.

• Saliva = dissolves taste-forming compounds; contains many compounds that aid swallowing, digestion, and protection of teeth

• Mucus = protects GI tract cells, lucbritae digesting foods

• Enzymes = breakdowns CHO, fats, and protein into form small enough for absorption

• Acid (HCl) = promotes digestion of protein, destoyes microorganisms, increases the solubility of minerals

• Bile = aids in fat digestion (emulsifies fat)

• Bicarbonate = neutralizes stomach acid wheni reachers small intestine

• Hormones = regulate food intake, digestion, and absorption

How do enzymes help with hydrolysis reactions in the GI tract?

Enzymes help with hydrolysis reactions in the GI tract because they catalyze chemical reactions, breaking water molecules that are too large to pass through the GI tract.

What is a bolus?

chewed food mixed with saliva

What are the components and importance of saliva?

Saliva is a dilute, watery fluid that contains several substances, including mucus to lubricate the bolus and hold it together, lysozyme to kill bacteria, and amylase to break down starch into simple sugars.

What are the 5 basic tastes present in all areas of the tongue?

1. Salty

2. Sour

3. Sweet

4. Bitter

5. Umami

What is the process of swallowing?

Swallowing moves food from the mouth into the esophagus, the 10-inch-long muscular tube that extends to the stomach. At its entrance is the epiglottis, a flaplike sturcture that prevents food from entering the trachea. When food is swallowed, the epiglottis closes over the larynx. The food bolus drops onto the epiglottis, and the esophagus relaxes and opens.

Why is gastrin important, and what does it secrete in the body?

Gastrin is important because it’s a hormone that stimulates HCl and pepsinogen enzyme and acid secretion by the stomach.

What are the important functions of the stomach?

• mechical digestion

• protein digestion

• acid sterilization

Describe the location and function of the pyloric sphincter

The pyloric sphincter is located between the stomach and the duodenum (the first part of the small intestine). The function of the pyloric sphincter is to control the flow of chyme into the small intestine.

Where is the major site of digestion and absorption of food?

small intestine

Why are the circular folds in the small intestine important?

The circular folds are important because they increase the surface area and make the chyme flow slowly, following a spiral path as it travels through the small intestine.

What are the accessory organs of the digestive system?

• Liver

• Gallbladder

• Pancreas

What is enterohepatic circulation?

continual recyling of compound between the small intestine and the liver

What are the major regulatory hormones of the GI tract and their primary function?

• Ghrelin = increases appetite and food intake

• Gastrin = triggers the stomach to release HCl and pepsinogen

• Cholecystokinin (CCK) = stimulates relase of pancreatic enzymes and bile from the gallbladder

• Secretin = stimulates the release of pancreatic bicarbonate

What are the ways nutrients move from lumen of the small intestine into the absorptive cells?

Nutrients move from the lumen of the small intestine into the absorptive cells by;

• Passive diffusion

• Facilitated diffusion

• Active absorption

• Endocytosis

What are the primary nutrients absorbed in the stomach, small intestine, and large intestine?

• Stomach = alcohol (20% of total), water (minor amount)

• Small intestine = calcium, magnesium, and other minerals, glucose, amino acids, fats vitamins, water (70-90% of total), alcohol (80% of total), bile acids

• Large intestine = sodium, potassium

Name the 3 nutrients that are transported by the CVD system?

• water-soluble nutrients (proteins CHO, B-vitamins, and vitamin C)

• short-chain fatty acids

• medium-chain fatty acids

Name the 3 nutrients that are transported first in the lymphatic system

• fat-soluble nutrients

• long-chain fatty acids

• some proteins

After moving through the small intestine and into the large intestine, what nutrients are left over to be absorbed?

• water

• some minerals

• undigested food fibers

• starches

What are the 3 functions of the large intestine?

1. Houses gut microbiota that keep the GI tract healthy

2. Absorbs water and electrolytes such as sodium and potassium

3. Forms and expels

What benefits do probiotics have on bacteria in the large intestine?

Probiotics benefit intestinal bacteria; they help prevent bowel damage, digestive disorders, and acute infectious diarrhea, Ulcerative colitis, and IBS.

Where can probiotics be found in the diet?

Probiotics can be found in fermented foods.

• yogurt

• miso

• dietary supplemts in powder, liquid and capsule form

What benefits do prebiotics have on bacteria in the large intestine?

prebiotics are non-digestible food ingriends that promote th egorwoth of benefical bactiera in the large intestine

Where can prebiotics be found in the diet?

Prebiotics can be found in inulin, a carbohydrate that can be found in many foods like:

• chicory

• wheat

• onions

• garlic

• asparagus

• bananas

How does the body elimate feces?

• It takes 12-24 hours for the residue of a meal to travel through the large intestine

• 2/3 of its length, a semi-solid mass has been formed

• mass remains in the large intestine until peristaltic waves and mass movements push into the rectum

• feces in the rectum are poweful stimulation for defecation

What are some disorders that can occur when digestive processes go awry? Why would each one occur?

• Heartburn

• Gastroesophageal Reflux Disease (GERD)

  • Heartburn occurs when stomach acids back up into the esophagus causing a burning sensation or sour taste in the back of the mouth

  • GERD occurs when the lower esophageal spincter relaxes and lers stomach contents backflow into the esophagus