nutrition and digestive systems

Question 1

what are protiens?

Answer 1

polymers of Amino Acids. Some amino acids cannot be manufactured in the body and must be ingested. In humans, we recognize about 7-8 amino acids that must be eaten regularly- essential amino acids. Meats provide all the essential animo acids, vegetarians need eat a variety of plants to ensure they obtain all the essential amino acids.

Question 2

what are lipids?

Answer 2

fatty acid chains off a glycerol backbone. Lipids contain lots of C-H bonds. Cells break these covalent bonds to generate ATP molecules.

Question 3

what are carbohydrates?

Answer 3

polymers of simple sugars

Question 4

what are nucleic acids?

Answer 4

polymers of nucleotides

Question 5

mechanisms to process food: what is simple absorbtion in regards to parasites?

Answer 5

lack a digestive tract and absorb nutrients through cells of their body wall, By living in the digestive tract, they are bathed in nutrients being digested by their host.

Question 6

mechanisms to process food: what are food vacoules?

Answer 6

feed by phagocytosis. With phagocytosis, small food particles taken into cell and surrounded by a membrane in vesicle or food vacuole. Digestive enzymes are dumped into the vacuole so food is digested within the cell. Sponges feed strictly by food vacuoles associated with their Choanocytes or collar cells that are flagellated.

Question 7

mechanisms to process food: what is intracellular digestion?

Answer 7

breaking down of food to usable size molecules within a cell.

Question 8

mechanisms to process food: what is extracellular digestion?

Answer 8

food products are digested outside of cells. Food is processed as it moves through the lumen of the digestive tube. Epithelial cells lining the lumen (luminal epithelium) secrete enzymes that break down the food into simple molecules that can be absorbed into other luminal epithelial cells. us.

Question 9

mechanisms to process food: what is phagocytosis?

Answer 9

cell engulfs food and for vesticles arounf it to digest it

Question 10

what is an incomplete digestive system?

Answer 10

use the same opening to eliminate waste and take food in. a single opening serves as the mouth and anus (Gastrovascular cavity)

Question 11

what is a complete digestive system?

Answer 11

a mouth and a separate anus on the opposite end of a digestive tract. This one-way flow of foodstuffs allows for continuous digestion, rather than digestion in batches. Also, complete digestive systems allow animals to feed on larger food items, and it allows for a separation of physical and chemical processes through its length.

Question 12

what is an earthworms complete digestive system like?

Answer 12

They have a mouth that leads to a muscular pharynx, that leads to an esophagus (a short passageway), which takes food to a Crop (an expanded portion of the tube that acts to store food-so birdies dont freeze). From the Crop, food is carried to the gizzard, which is a muscular chamber (stomach) that breaks down food. Food is released from the gizzard to the intestine where nutrients are absorbed. The intestine terminates in an anus. There are structural modifications within the intestine (e.g., typhlosole) that increase surface area to allow for efficient absorption of nutrients. The typhlosole is a large fold of lumen epithelium. Also, earthworms have digestive glands located outside of the intestine that secrete chemicals into the intestinal lumen

Question 13

teeth: what is homodont dentitions?

Answer 13

teeth have a similar appearance (sharp cones, often recurved) and function (grabbing and holding on to prey).

Question 14

teeth: what is heterodont dentitions?

Answer 14

teeth differ in structure and function. ex: many mammals have heterodont dentitions in which we recognize. incisors (clipping teeth), canines (piercing, grabbing teeth), molars and premolars (cheek teeth). The use of cheek teeth should alert you that cheeks are associated with a grinding function of the teeth, and the evolution of cheeks.

Question 15

teeth: what are polyphydonts?

Answer 15

their teeth are regularly lost and replaced.

Question 16

teeth: what are diphyodonts?

Answer 16

have two sets of teeth (milk or deciduous teeth and permanent teeth)

Question 17

teeth: what are monophyodonts?

Answer 17

only one set of teeth.

Question 18

what is saliva?

Answer 18

come from glands. helps lubricate the food so that it can be more easily swallowed. Saliva also contains digestive enzymes, including Salivary Amylase, which begins digestion of starch into disaccharides, and lingual lipase, which begins breakdown of fats. Food is not kept very long in the oral cavity, so activity of enzymes in your saliva is not substantial.

Question 19

what is the tongue?

Answer 19

evolved in terrestrial vertebrates to help with the capture and intra-oral transport of prey.

Question 20

what is the pharynx? what is and how do the epiglottis and uvula tie into this?

Answer 20

region where respiratory and digestive systems cross. epiglottis is a cartilaginous structure that blocks the opening to the larynx (the opening is the glottis) when we swallow. The uvula is a fleshy extension from the soft palate that swings upward each time we swallow to prevent food from entering into the nasal passageways. Occasionally, you laugh when eating and corn will come out your nose—laughter disrupted the normal function of the uvula.

Question 21

what is the esophagus?

Answer 21

Essentially a passageway to the stomach in mammals. begins the start of a long tube through which food will travel, be digested, and nutrients absorbed. Undigested and non-absorbed substances and many bacteria are eliminated from this tube through the anus. the upper end of the esophagus has skeletal muscle in its lining, which allows for voluntary control to initiate swallowing. three of the four chambers of the ruminant “stomach” are modified esophagus.

Question 22

tubular organs and their arrangements: what are some tubular organs and what are the four layers?

Answer 22

the Stomach, and Intestines: Small intestine and Large intestine (colon). mucosa, submucosa, muscularis externa, and serosa/visceral peritoneum

Question 23

tubular organs and their arrangements: what is the mucosa layer?

Answer 23

luminal surface epithelium with many unicellular glands. A simple epithelium in most organs, but stratified in the esophagus.

Question 24

tubular organs and their arrangements: what is the submucosa layer?

Answer 24

thick layer of connective tissue for support—also, blood vessels flow through the submucosa (not the mucosa). Nerves are present also.

Question 25

tubular organs and their arrangements: what is the muscularis externa layer?

Answer 25

this layer of smooth muscle consists of two (three in stomach) sections: an inner layer in which the smooth muscle cells encircle the tube so that the lumen can be constricted when the layer contracts, and an outer layer of smooth muscle cells in which the cell are oriented down the length of the tube. The circular muscle layer and longitudinal muscle layer work in unison to generate waves of contraction that propel food down the tubes. These waves of contraction are called Peristalsis.

Question 26

tubular organs and their arrangements: what is the serosa/visceral peritoneum?

Answer 26

(a simple squamous epithelium) that signifies the outer surface of the tube (recall that an adventitia is present if the section of the gut tube is not in a cavity, such as the cervical portion of the esophagus).

Question 27

organs of the digestive tract: what is the stomach?

Answer 27

a storage organ, but also a site of mechanical and chemical digestion of food.

Question 28

organs of the digestive tract: how the stomach works: what do glands in the mucosa of the stomach secrete?

Answer 28

hydrochloric acid and pepsinogen

Question 29

organs of the digestive tract: how the stomach works: how does hydrochloric acid work?

Answer 29

released from pariental cells. HCl is a strong acid with a pH of 1 when secreted. HCl lowers the pH of the stomach contents to about 2.0–2.5. The low pH kills many bacteria, including some that can be pathogenic (dont kill all pathogenic bacteria-thus we can get food poisoning). The low pH also activates protease (enzyme that digests proteins). Also, some large proteins can be broken into smaller units or denatured. One consequence of the low pH is that amylase from the saliva is inactivated and digestion of starch ceases.

Question 30

organs of the digestive tract: how the stomach works: how does pepsinogen work?

Answer 30

from chief cells. This substance is converted to Pepsin by the HCl and begins protein digestion. Pepsin is one of a handful of enzymes that do not end in -ase--a designation for an enzyme (Trypsin, another enzyme that works on proteins comes to mind also). Lipase is also secreted by Chief cells and some digestion of fats occurs in the stomach.

Question 31

organs of the digestive tract: how the stomach works: what is the mechanical process of the stomach? what is the third layer? Absorbtion?

Answer 31

a churning action—the stomach has a third layer of smooth muscle cells in its muscularis externa (an oblique layer) that facilitates the churning. not a major site of absorption of nutrients, although water, some vitamins, and alcohol can be absorbed through its mucosal lining.

Question 32

organs of the digestive tract: how the stomach works: what are the sphincters and what do they do?

Answer 32

A creamy substance, chyme, leaves the stomach after passing through a pyloric sphincter, which is a tight band of muscularis externa that regulates passage of material form the stomach into the small intestine. A similar sphincter muscle, the Cardiac sphincter, is present at the top of the stomach and functions to limit back flow of stomach contents into the esophagus.

Question 33

organs of the digestive tract: what are the functions of the pancreas? what does insulin and glucagon do?

Answer 33

exocrine functions (bicarbonate secretion, enzyme secretion of zymogen tissue) and endocrine functions (hormone production). raised pH to 7.2 by release of bicarbonate (with a pH of 9.0). Also, the pancreas secretes enzymes into the small intestine. Note that enzymes from the pancreas digests components of each of the four major types of organic compounds: Carbohydrates, proteins, nucleic acids, and lipids. The hormone Insulin allows glucose to enter certain cells, such as skeletal muscle cells, and is thus involved in regulating circulating levels of sugar(keep from being low or high). The hormone Glucagon converts glycogen into many glucose molecules and releases that sugar into the blood stream. Glucagon and insulin work to stabilize blood sugar levels in healthy individuals(keep from being low).

Question 34

organs of the digestive tract: pancreatic functions: what are the five enzymes and what do they digest? Endopeptidases, Carboxypeptidases, lipase, Amylase, nucleases

Answer 34

1) Endopeptidases: trypsin and chymotrypsin. Digest proteins by breaking bonds in the interior of protein molecules. 2) Carboxypeptidases: cleave off terminal amino acid from the carboxyl end of protein molecules. 3) lipase: splits fatty acids from glycerol backbone. 4) Amylase: starch digestion into disaccharides. 5) nucleases: digests DNA and RNA into nucleotides.

Question 35

organs of the digestive tract: what enzymes do the unicellular glands in the small intestine secrete and what do they do? Aminopeptidases, Disaccharidases- maltase, sucrase, lactase

Answer 35

1) Aminopeptidases. Cleave amino acids from polypeptides. 2) Disaccharidases: digests disaccharides into monosaccharides. Several types. A) maltase: maltose into glucose B) Sucrase: sucrose into fructose and glucose. C) lactase: lactose (milk sugar) into glucose and galactose.

Question 36

organs of the digestive tract: liver related: what does the liver produce? what are the different types of this?

Answer 36

Bile. Produced in the liver and stored in gall bladder. Bile contains water, bile salts and pigments, the latter come form breakdown of red blood cells. A) Bile salts: help break up fats by splitting them into small droplets: lipase from pancreas then works to digest the smaller droplets. B) bile pigments: waste from hemoglobin in red blood cells. Excreted via feces—gives reddish brown color to feces.

Question 37

organs of the digestive tract: liver related: what is the hepatic portal system?

Answer 37

Each villi of the small intestines has blood capillaries and lymph capillaries (=lacteals). Blood capillaries leave intestines as part of the hepatic portal system, taking blood from digest organs to the liver. Amino acids and monosaccharides are absorbed by the blood capillaries and go straight to liver, where their abundance is monitored. Excessive sugars are converted to glycogen for temporary storage. Excessive amounts of amino acids are broken down—the Amine portion (NH2) is converted to urea, which is one reason why people taking Amino Acid supplements but not building muscle mass are peeing out their money—bodies do not store amino acids. In between meals, glycogen is converted to glucose and released into blood steam. This helps to maintain relatively constant circulating levels of blood glucose in-between meals.

Question 38

organs of the digestive tract: intestines: what are the large intestines?

Answer 38

houses trillions of bacteria. Substances entering large intestine are relatively low in nutrients, but insoluble material is high in content (think cellulose). Major functions of the large intestine include water absorption, but bacteria produce some vitamins, including Vitamins B and K in humans, which do get absorbed.

Question 39

organs of the digestive tract: intestines: what is the small intestine? what are some modifications to the small intestine to help absorbtion?

Answer 39

The small intestine in mammals is significantly longer than the large intestine. small int-Chyme entering the small intestine stimulates the release of intestinal juices and enzymes. Major site of chemical digestion and absorption of nutrients. 1) Great elongation and coiling. 2) Highly folded luminal wall (and great elongation of the intestine). 3) Villi: microscopic folds of the luminal epithelium with a core of submucosa. 4) microvilli: small projections of the apical surface of luminal absorptive cells.

Question 40

organs of the digestive tract: what are the "last stops" in the digestive tract? what do some other animals practice regarding feces?

Answer 40

large and small intestines forms a blind ending pouch called a Cecum. In humans, the cecum is relatively short, but we have a remnant of our longer cecum—the vermiform appendix. Length of cecum is associated with diet—significantly longer in some herbivores, such as rabbits and rodents. Many nutrients are released by the gut bacteria—these animals routinely practice coprophagy (eating feces) to obtain the nutrients. Indeed, they suffer from malnourishment if they are unable to eat the appropriate feces. Note that most absorption occurs in the small intestine, thus the need to eat their poop.

Question 41

three hormones of digestion?

Answer 41

gastrin, secretin, and cholecystokinin

Question 42

three hormones of digestion: what is gastrin?

Answer 42

Gastrin secretion is stimulated proteins (certain amino acids and peptides, also) in food that enters the stomach and by stretching or distension of the stomach wall. Although gastrin is produced by cells lining lumenal epithelial cells of the stomach, it is secreted into the bloodstream and travels throughout the body. Parietal cells in the lumenal epithelium of the stomach that secrete HCl are among its primary target cells. Recal that HCl decrease pH, killing millions of bacterial cells in the foods we eat and converting pepsinogen to pepsin, which digests proteins.

Question 43

three hormones of digestion: what is secretin?

Answer 43

Secretin secretion is stimulated by the acidic chyme that enters the small intestine. Secretin is secreted by cells lining the small intestine into the bloodstream and travels through the body. Its primary target cells are in the pancreas, which it stimulates to secrete bicarbonate into the lumen of the small intestine to increase the pH form the chyme that entered from the stomach. The increase in pH produces an environment conducive for enzymes from the pancreas and intestinal luminal epithelium to function.

Question 44

three hormones of digestion: what is cholecystokinin(CCK)?

Answer 44

Secretion of CCK is stimulated largely by fats in the contents of the small intestine, but some amino acids and even HCl can stimulate secretin of this hormone. stimulates the pancreas to secrete pancreatic enzymes, and the gall bladder to release bile into the small intestine.