Biology 2 Test 2: Digestive System

What are the main roles of the liver?

-detoxifying harmful substance -glycogen storage -protein synthesis

What enzymes does the pancreatic duct excrete? And what do they excrete?

-trypsin (digests proteins) -chymotrypsin (digests proteins) -pancreatic amylase (digests starch) -lipase (digests fats) all are inactive until trypsin is activated by the brush border enzyme

Peristaltic contractions of the large intestine pass feces into the rectum that pass to the anus and out of the body. What are the 2 sphincters?

1) composed of smooth muscle and opens involuntarily in response to pressure inside the rectum 2) striated muscle that opens by voluntary permission of the brain

How is glucose and most amino acids transported across the membrane?

Active Transport

How are the proteins and carbohydrates transported across the brush border?

After enzymatic breakdown they are pushed through the epithelial cells that line the intestine by both active transport and facilitated diffusion.

Accessory organ: The liver produces _____.

Bile (a green solution that emuslifies fat)

The primary function of the large intestine is to concentrate wastes into solid form (feces) for release from the body. How does it accomplish this?

By absorbing water

Mastication

Chewing to break up food and mix it with fluid secrertions.

Is the pancreas an exocrine or endocrine gland?

It's both because it's islets of langerhans control blood levels of glucose and it secretes hormones into the duodenum

What are the 3 kinds of secretory cells?

Mucus-secreting cells parietal cells (HCl) Chief cells (pepsinogen-the inactive form of protease pepsin

Rhythmic waves of muscular contraction are called ______. They allow us to swallow even if we're upside down.

Peristalsis

Absorption

Products of chemical digestion passes through the epithelial lining of the gut into the blood. Anything not absorbed is excreted.

Define Mucosa

an epithelial that lines the interior, or lumen, of the tract. It is the innermost layer.

5 specialized regions of earthworm digestive tract

ingestion, storage, fragmentation, digestion, and absorption of food

Swallowing is initiated by voluntary action and continued under _________ control.

involuntary

The microvilli secrete enzymes that hydrolyze the disaccharides lactose and sucrose. If the brush border were to stop producing the enzyme lactase, what condition will develop?

lactose intolerance

Obese humans probably have high levels of leptin because

Weight gain leads to production of leptin

What are enterogastrones?

a duodenal hormone released in the blood when 1 set of chyme is processed to allow the next batch of chyme into the small intestine

Intestinal microorganisms aid digestion and absorption by a. digesting cellulose b. producing glucose c. synthesizing vitamin K d. Both a and c are correct

d. Both a and c are correct

Lysozymes

digest bacteria in the stomach and attack invading bacteria in eyes and mouth

Swallowing begins when the soft palate _______ and pushes back against the ____. Pressure on the pharynx sends info to the brain to send impulses to stimulate the muscles to contract and raise the ____ against the epiglottis.

elevates pharynx larynx

Carnivores

exclusively eats animals ex. crabs, squid, cats, some insects, trout

Herbivores

exclusively eats plants ex. algae eating snails, horses, insects, sparrows, etc.

When food arrives in the stomach, proteins in the food stimulates the secretion of a stomach hormone called _____. Following the secretion of gastrin, pepsinogen and HCl from gastric glands are secreted.

gastrin

The small intestine is specialized for absorption because it

has an extremely large surface area that allows extended exposure to food

Digestion of cellulose in so microorganism because it takes place in the cecum, because it is located beyound the stomach regurgitation is ______.

impossible

Neuropeptide Y (NPY)

induces feeding activity

Many birds possess crops, although few mammals do. Suggest a reason for this difference between birds and mammals.

irds feed their young with food they acquire from the environment. The adult bird consumes the food but stores it in her crop. When she returns to the nest, she regurgitates the food into the mouths of the fledglings. Mammals on the other hand feed their young with milk that is produced in the mother's mammary glands. Young feed by latching onto the mother's nipples and suck the milk. Mammals have no need for a crop in their digestive system because they don't feed their young in the same way as birds do.

Just outside the submucosa is the _____

muscularis, a double layer of smooth muscle. These muscles constrict the gut. The outer layers are arranged longitudinally and work to shorten it.

Most primitive digestive tract is seen in ______

nematodes where it is simply a tubular gut lined by an epithelial membrane

fragmentation

occurs through chewing action of teeth or grinding action of pebbles (in gizzard of earthworms or birds)

How does one get cirrhosis?

over abuse of alcohol can overtax the liver's detoxification capabilities

What are chylomicrons

they are triglycerides combined with proteins that are absorbed into the lymphatic capillaries

After being absorbed through the intestinal mucoase, glucose and amino acids are

transported directly to the liver by the hepatic portal vein

Rodents and lagomorphs eat their feces ___ to capture nutrients from cellulose.

twice

Over production of gastric acid can occasionally eat a hole through the wall of the stomach of duodenum and create an ____.

ulcer

How does the digestive system keep from being digested by the gastric secretions it produces?

The digestive tract secretes a mucous layer that helps to protect the delicate tissues of the alimentary canal from the acidic secretions of the stomach.

What do bile salts do?

Their emulsification with watery chyme produces a greater surface area of fat for the action of lipase enzymes, and thus allows the digestion of fat to proceed more rapidly.

What are gallstones and what happens if they block the bile duct?

They are hardened precipitates of cholesterol that form in some individuals.

Omnivores

eats both plants and animals ex. bears, pigs, crows, and humans

How is Fructose transported across the membrane?

facilitated diffusion

How many salivary glands do humans have?

3, and it also contains hydrolytic enzyme salivary amylase that initiates the breakdown of polysaccharide starch into disaccharide maltose

The small intestine is _____m long (6 m long when all the muscles have relaxed. The 1st ___cm is the duodenum, and the rest is divided into the jejunum and ileum.

4.5 m 25cm

Cloaca

A cavity in most mammals that the wast products emerge after the large intestine. It also receives the products of the urinary and reproductive systems.

Through the hepatic portal vein the _____ is the first organ to receive most of the products of digestion, except for fats.

liver

The _____ and _____ play important roles in the digestion system process by producing chemicals that are required to digest proteins, lipids, and carbohydrates.

liver;pancreas

Examples of enterogastrones example of what they do

Cholecystokinin (CCK) Secretin Gastric Inhibitory Peptide (GIP) They inhibit churning and gastric juice secretion to allow fatty meals to digest longer.

What are the 4 chambers of a ruminants stomach?

reticulum, rumen, omasum, and abomasum (true stomach that finally mixes it with gastric juice)

External surface of the tract is called the ______

serosa

fatty acids and monoglycerides are nonpolar and can this enter epithelial cells by ___ _____. Once in the epithelial cells they forms ______.

simple diffusion triglycerides

The movement of food from the esophagus into the stomach is controlled by a ring of circular smooth muscle, or a _______. It opens in response to the pressure exerted by the food

sphincter

Accessory organ: The gallbladder ____ and ____ the bile.

stores and concentrates

Lower passage of food in the body is more likely in developed colonies because of

the lack of fiber in certain diets, and can lead to colon cancer

When leptin is injected into ob/ob mice what happened?

the mice stopped overeating and lost weight

How does the duodenum have a slightly alkaline pH is the stomach releases HCl into it?

the pancreatic fluid contains a bicarbonate that neutralizes the HCl.

The epithelial wall of the small intestine is covered with tiny finger like projections called ____. Making it the brush border.

villi these increase the surface area of the small intestine

Melanocyte-stimulating hormone (α-MSH)

which suppresses feeding hormone

Define Acini

Digestive enzymes and bicarbonate from the pancreas that are produced in clustars of secretory cells

Although the stomach is normally thought of as the major player in the digestive process, the bulk of chemical digestion actually occurs in the ______

Duodenum

What might explain obesity in a person with normal leptin levels?

Even with normal leptin levels, individuals with reduced sensitivity in the brain to the signaling molecule may still become obese.

Why does fat not require transport to cross the intestinal epithelium?

Fats are broken down by emulsification into fatty acids and monoglycerides, both of which are nonpolar molecules. Nonpolar molecules are able to enter the epithelial cells by simple diffusion.

Suppose the GIP and CCK sensors in the hypothalamus didn't work. How would this affect levels of leptin production?

GIP and CCK send inhibitory signals to the hypothalamus when food is ingested. If the hypothalamus sensors did not work properly, leptin levels would increase; increased leptin levels would result in loss of appetite

What indicates satiety or being full to the brain?

GIP, CCK, leptin, insulin act as appetite suppressant

hydra, a cnidarians, has a ______ cavity

Gastrovascular The digestive cavity has only one opening that serves as both mouth and anus. There is no specialized regions and extracellular digestion occurs throughout the cavity.

Explain how the role of the mouth in digestion depends on the type of teeth.

Herbivores and omnivores chew their food, using the flat surfaces of their molars to break it into small components and to introduce saliva, which begins the digestive process. Carnivores tear off their food with their sharp teeth and swallow whole chunks of flesh, providing little time or opportunity for digestion to occur in the mouth.

How does one get jaundice?

If the excretion of bile pigments by the liver is blocked and the pigments accumulate in the blood causing yellow staining.

What is the action of insulin?

It decreases blood glucose levels by forming glycogen

Daily amount of energy the body consumes per day is based of BMR and physical exertion. What if excess energy is taken in?

It is stored as glycogen and fat. Glycogen reserves are limited and thus continued ingestion of excess food energy results primarily in accumulation of fat.

What does ghrelin do?

It stimulates food intake and can lead to obesity of too high

Suppose that you wanted to develop a new treatment for obesity based on the hormone leptin. What structures in the body produce leptin? What does it do? Should your treatment cause an increase in blood levels of leptin or a decrease? Could this treatment affect any other systems in the body?

Leptin is produced by the adipose cells and serves as a signal for feeding behavior. Since low blood leptin levels signal the brain to initiate feeding, a treatment for obesity would need to raise leptin levels, thereby decreasing appetite.

2 function of ingestion

1-source of energy 2-provides raw materials the animal is unable to manufacture for itself

Suppose you ate a chicken sandwich (chicken breast on bread with mayonnaise). Which of these foods would begin its breakdown in the stomach.

A chicken sandwhich includes carbohydrates (bread), protein (chicken), and fat (mayonnaise). The breakdown of carbohydrates begins with salivary amylase in the mouth. The breakdown of proteins begins in the stomach with pepsinogen, and the emulsification of fats begins in the duodenum with the introduction of bile. Therefore, the chicken begins its breakdown in the stomach.

The parietal cells of the stomach secrete HCl and also the intrinsic factor. What is the intrinsic factor?

A polypeptide needed for intestinal absorption of vitamin B12. Because this vitamin is required for the production of red blood cells, people who lack sufficient intrinsic factor develop anemia.

What is rumination?

As the 1st of 4 chambers in the stomach it regurgitates and rechews the contents of the rumen

What is the minimum rate of energy consumption under defined resting conditions called?

Basal Metabolic Rate

CCK and secretin function

CCK can stimulate pancreatic secretions of enzymes and gallbladder contractions. Secretin is to stimulate the pancreas to release more bicarbonate to neutralize chyme.

What goes wrong to cause someone to choke?

If the epiglottis doesn't shut before food/liquid enter the food could get stuck in their airway and cause choking.

how does the nervous system regulate the digestive tract?

Sight, smell, and consumption of food stimulate salivary and gastric secretions

Inactive forms of some molecules are secreted

So their activity can be regulated.

Alimentary Canal

Specialized digestive tract with both a separate mouth and anus, so that transport of food is one-way.

Where does a battery of digestive enzyme continue the digestion process?

The Small Intestine The products of digestion, together with minerals and water are absorbed through the wall of the small intestine into the bloodstream.

Where does the preliminary digestion occur?

The Stomach

What might be the advantages of a one-way digestive system?

The cells and tissues of a one-way digestive system are specialized such that ingestion, digestion, and elimination can happen concurrently, making food processing and energy utilization more efficient. With a gastrovascular cavity, however, all of the cells are exposed to all aspects of digestion.

How could a drop in plasma proteins and a decrease in bile production be related to alcohol and drug abuse?

The liver plays many important roles in maintaining homeostasis. Two of those roles are detoxifying drugs and chemicals and producing plasma proteins. A drop in plasma protein levels is indicative of liver disease, which in turn could be caused by abuse of alcohol or other drugs.

What does the pH of the stomach do?

The low pH helps denture the food and keeps the pepsin active. Active pepsin hydrolyzes food proteins into shorter chains of polypeptides until its truly digested in the small intestine. (chyme). It also kills bacteria.

What is the next major tissue area?

The submucosa which is composed of connective tissue

What is the function of the large intestine?

absorb water, remaining electrolytes and products of bacterial metabolism

How is the digestion of fats different from that of proteins and carbohydrates? a). Fat digestion occurs in the small intestine, and the digestion of proteins and carbohydrates occurs in the stomach. b). Fats are absorbed into the cells as fatty acids and monoglycerides but are then modified for absorption into the blood; amino acids and glucose are not modified further. c). Fats enter the hepatic portal circulation, but digested proteins and carbohydrates enter the lymphatic system. d). Digested fats are absorbed in the large intestine, and digested proteins and carbohydrates are absorbed in the small intestine.

b). Fats are absorbed into the cells as fatty acids and monoglycerides but are then modified for absorption into the blood; amino acids and glucose are not modified further.

Which of these pairing is incorrect? a. fat transport/lymphatic system b. glucose transport/lymphatic system c. amino acid transport/circulatory system d. all of these pairings are correct.

b. glucose transport/lymphatic system

Once the amino acids pass the epithelial membrane they move through the cytoplasm and are transported across the ______ membrane into blood capillaries within the villi.

basolateral

Accessory organ: The pancreas produces pancreatic juice which contains digestive enzymes and _________ buffer.

bicarbonate

Synthesis of vitamin K using intestinal bacteria is necessary for _____ ______.

blood clotting

chemical digestion

breakdown of larger food molecules of polysaccharides and disaccharides, fats, and proteins into their smallest subunits. These units go through hydrolysis reactions that liberate the subunit from the food.

The junction of the small and large intestines is the ___. The appendix is right next to it.

cecum