Bio Chpt 44. For Exam 2
How many calories per gram in Carbohydrates?
4 cal/g
How many calories per gram in protein?
4 cal/g
What is the structure of glucose?
6 C ring linked @ C1 & C4 (alpha linkage)
How many fewer calories would nonfat milk have than an equivalent volume of whole milk with 8g of fat?
72 calories
How many calories per gram in fat?
9 cal/g
Bile is produced by the _____ and stored by the _____ until it is secreted into the small intestine.
Bile is continuously produced by the liver and is stored in the gall bladder until CCK triggers its release.
What is secreted by the liver and responsible for the emulsification of fats?
Bile salts that are stored in the gall bladder.
In the small intestine, emulsification results from small molecules called ___________.
Bile salts; break up the lipids in plasma membranes.
_____ is secreted by the _____ and acts to emulsify _____ in the _____.
Bile...liver...fats...small intestine
What breaks down the maltose molecules, and other disaccharides such as sucrose, into individual monosaccharides?
Disaccharidases, secreted by the walls of the duodenum, the first part of the small intestine, break down maltose, sucrose, and lactose from milk. The resulting monosaccharides are absorbed through the walls of the small intestine into the blood.
Sucrose is a type of ____.
Dissaccharide
Sucrose is a....
Dissacharide
______ digests fats.
Lipase
What enzyme digests fats?
Lipase - comes from the pancreas and breaks fat molecules into glycerol and fatty acids.
Which enzyme starts digestion of nucleic acids?
Nucleases from the pancreas.
When digested, nucleic acids are broken down into ______.
Nucleotides
The role of other enterogastrones
Slow stomach perastalsis
Fats are particularly hard to digest. If the material in the small intestine is rich in fats, other enterogastrones are released that slow digestion down. How might other enterogastrones slow digestion?
Slow stomach peristalsis - this slows down the movement of food into the small intestine so that digestive secretions have more time to work.
Protein digestion is completed in the __________.
Small intestine
The role of CCK
Stimulates gall bladder to release bile and pancreas to release enzymes
Chemical digestion of protein begins in the acidic environment of the
Stomach
Protein digestion begins in the ______.
Stomach
What is the correct response if the blood sugar drops for a person with type 1 diabetes mellitus?
give the person a candy bar
Incomplete Digestive Tracts
have a single opening that doubles as location where food is ingested and wastes are eliminated. The mouth opens into a chamber, called gastrovascular cavity, where digestion takes place.
Complete Digestive Tracts
have two openings - start at the mouth and end at the anus. Interior of this tube communicates directly with the outside environment via these openings.
Gastrin
hormone in the stomach produced by the arrival of food --> parietal cells then begin secreting HCl
Function of Secretin
induce flow of bicarbonate ions from pancreas to small intestine. Bicarbonate neutralizes acid arriving from the stomach
Benefits of large surface area of the small intestine
it increases the efficiency of nutrient absorption
Each villus contains blood vessels and a lymphatic vessel called a _________, which allows nutrients to pass quickly from epithelial cells into the body's transport systems.
lacteal
In the _____________, more water is absorbed. The material remaining is __________, which are eventually excreted.
large intestine (or colon).....feces
Tiny projections that line the surface of villi on the apical surface are called....
microvilli. (microvilli project into the lumen of the digestive tract)
Advantages to a tube-like digestive tract:
1.) animals can feed on large pieces of food - expanding food sources 2.) processes occur independently and in a certain sequence. 3.) one way flow of food and waste
What is the structure of a triglyceride?
3 fatty acids w/ a glycerol backbone
Protein molecules must be broken down to individual ______ in order to be absorbed.
Amino Acids
When digested, proteins are broken down into _____.
Amino Acids
What is the structure of a protein?
Amino Acids (amino & carboxyl group) linked by peptide bonds
As gastric juice is secreted, the stomach contents become more acidic. The acid helps break up food particles. What keeps the stomach from becoming too acidic?
As the pH of the stomach contents drops, the increasing acid inhibits secretion of gastrin, which slows gastric juice production and prevents the stomach from becoming even more acidic. This is an example of negative feedback.
When digested, fats are broken down into _____.
Both glycerol and fatty acids
In the mouth, enzymes in the saliva begin the chemical breakdown of
Carbs
Why do fats and other lipids provide over twice the energy per gram?
Fats contain more C-H bonds than carbs like starch and sugars.
Your small intestine can absorb ______ without being further digested.
Fructoses
The two organs most affected by CCK.
Gall Bladder and Pancreas
Bile is stored in the ________.
Gallbladder
The name of the hormone that triggers secretion of gastric juice.
Gastrin
Which hormones control digestion?
Gastrin, Enterogastrones, Secretin, and Cholecystokinin (CCK)
Most ulcers are associated with the infectious bacterium ___________.
Helicobacter Pylori (H-Pylori)
Because lipids are insoluble in water, fats tend to form large droplets that are hard to break up. Which organ secretes a substance that coats small fat droplets to help them mix with water?
Liver - produces a fluid containing an emulsifier that disperses lipid droplets
A fasting animal whose energy needs exceed those provided in its diet draws on its stored resources in which order?
Liver glycogen, then muscle glycogen, then fat
Bile Salts are synthesized in the ________ and secreted in a solution called _______.
Liver......Bile
Disaccharide produced by breaking down starch?
Maltose - produced when pancreatic amylase digests starch.
The disaccharide produced by breaking down starch.
Maltose is the disaccharide produced when pancreatic amylase digests starch. Each maltose molecule consists of two glucose molecules.
Starch can be broken down into the disaccharide known as ______.
Maltose- (each maltose molecule consists of two glucose molecules)
Fructose is a type of _____.
Monosaccharide
Fructose is a ...
Monosaccharide (does not need to be digested further in order to be absorbed.)
When digested, Carbs are broken down into _____.
Monosaccharides
Glucose absorption depends on the presence of an electrochemical gradient favoring an influx of ____ ions into the epithelium.
Na+ (Sodium)
Which organ secretes most of the enzymes that continue protein digestion?
Pancreas.
Which intestinal enzyme continues the breakdown of starch?
Pancreatic amylase breaks starch all the way down to disaccharide units. Pancreatic amylase is contained in pancreatic juice, secreted by the pancreas when food is present in the small intestine.
The source of HCl secreted into the stomach during digestion..
Parietal cells
the enzyme in gastric juice that begins the process of protein digestion.
Pepsin
The enzyme in gastric juice that begins the process of protein digestion.
Pepsin - partially digests protein, producing short polypeptides.
Starch is a ...
Polysaccharide
Starch is a type of ____.
Polysaccharide
In cattle, sheep, goats, deer, antelope, giraffe, species that are collectively called ___________, the stomach is specialized for digesting cellulose.
Ruminants
______ is in the enzyme in saliva that begins the break down of disaccharides and polysaccharides.
Salivary Amylase
What begins the break down of starch in the mouth? Then what intestinal enzyme continues the breakdown?
Salivary Amylase, Pancreatic Amylase (secreted by the pancreas when food is present in small intestine)
Monosaccharides like fructose are ready to be absorbed, but disaccharides and polysaccharides need to be broken down to monosaccharides by digestive enzymes.
Salivary amylase, secreted by the salivary glands, begins the digestion of starch.
The acidity of the stomach contents triggers the small intestine to secrete a hormone known as _____.
Secretin
The enterogastrone that triggers the pancreas to release bicarbonate.
Secretin - it stimulates the pancreas to secrete bicarbonate, which neutralizes the acid from the stomach.
Food being digested in the stomach is in a highly acidic environment. When the food is released from the stomach into the small intestine, why is the environment no longer acidic?
Secretin increases the flow of bicarbonate ions from the pancreas into the small intestine to neutralize the stomach acid.
What is pepsinogen?
The precursor to the protein-digesting enzyme pepsin. It is converted to active pepsin through contact with HCl.
The role of Gastrin
Triggers gastric juice secretion
The role of Secretin
Triggers secretion of bicarbonate by pancreas
True or false? It is dangerous to overdose on fat-soluble vitamins such as A and K?
True
Which pancreatic enzyme digests proteins?
Trypsin and Chymotryspin break peptide bonds adjacent to certain amino acids. Carboxypeptidase and aminopeptidase break off one amino acid at a time, starting at the ends of a polypeptide. Dipeptidases attached to the intestinal lining help too. Eventually, polypeptides are completely broken down into individual amino acids, which are transported through the walls of the small intestine, into the blood.
What mechanisms make it possible for epithelial cells to transport nutrients (like glucose) from the lumen of the small intestine into the bloodstream?
Two general principles- 1.) highly selective; proteins in the plasma membranes of microvilli are responsible for bringing specific nutrients into the cell 2.) it is active, meaning ATP is expended to bring nutrients into the epithelium across a concentration gradient.
The small intestine's epithelial tissue is folded and covered with fingerlike projections called __________.
Villi
Pancreatic Lipase
breaks certain bonds present in complex fats and results in the release of fatty acids and other small lipids
To maintain adequate nutrition, animals require dietary access to certain amino acids. An amino acid that is referred to as "nonessential" would be best described as one that
can be made by the animal's body from other substances
The presence of fatty acids and amino acids in the stomach contents triggers the small intestine to secrete a hormone known as _____.
cholecystokinin, or CCK
Pancreatic Amylase
continues the digestion of carbs that began in the mouth
Glucose is transported from the intestinal lumen into epithelial cells through _____ and from the intestinal epithelium into circulation by _____.
cotransport with sodium; facilitated diffusion
Nucleases
digest the RNA and DNA in food
Cholecystokinin (CCK) stimulates the _____ to secrete _____.
pancreas ... pancreatic enzymes ( The presence of fatty acids and amino acids in the stomach contents triggers the small intestine to secrete CCK. CCK then stimulates the pancreas to secrete enzymes that play a role in the digestion of these nutrients.)
Secretin stimulates the _____ to secrete _____.
pancreas, bicarbonate. This neutralizes the acid from the stomach.
Secretin
produced by the small intestine in response to the arrival of food from the stomach.
Proteases
protein-digesting enzymes; they are synthesized in an inactive form in the pancreas
When bile enters the small intestine, it _____ pH and emulsifies _____.
raises....fat
Pepsin
secreted by the walls of the stomach in an inactive form, and is activated when it comes into contact with acid in the stomach.
Chemical processing of the 3 major types of macromolecules - carbs, proteins, and lipids - is completed in the
small intestine
Nucleic acid digestion begins in the ______. And is initiated by ________ from the pancreas.
small intestine, nucleases
The main function of the HCl secreted into the stomach lumen by parietal cells is to...
start to unfold proteins and convert pepsinogen into active pepsin.
What is the role of the hormone secretin in digestion?
stimulates the pancreas to secrete bicarbonate into the small intestine. The bicarbonate neutralizes acid arriving with food from the stomach.
Cholecystokinin (CCK)
stimulates the secretion of digestive enzymes from the pancreas and the secretion of molecules from the gallbladder that aid in processing lipids.
How are ruminants able to harvest energy from cellulose?
symbiotic relationships with bacteria and unicellular protists.
Amino acids, dipeptides, and sugars are transported from intestinal epithelial cells into circulation. Lipids are first transported from the intestinal epithelium into _____.
the lymphatic system
Emulsification
the process that breaks up large fat globules before pancreatic lipase is able to act. (fats are insoluble in water)
Carbohydrate digestion ends with ....
the release of monosaccharides such as glucose
An elderly man arrives at the hospital severely dehydrated. The physicians find that there is glucose in his urine and that his blood glucose does not decline much upon administration of an insulin shot.
type 2 diabetes mellitus
The main component of gastric juice....
water
