Unit 8

How does nonenzymatic digestion work?

Nonenzymatic digestion is chemical digestion that does not use enzymes to breakdown feed. Ex. hydrochloric acid

What does an omnivore's diet consist of?

Omnivores are animals that have significant amounts of both plant and animal products in their diet.

What five digestive enzymes come from the pancreas?

Pancreatic lipase (fat digestion) Pancreatic amylase (starch digestion) Trypsin, Chymotrypsin and Carboxypeptidase (protein digestion)

What is peristalsis?

Peristalsis is a rhythmic, coordinated contraction of the gut that is the primary means of moving food from one part of the digestive tract to another. It also mixes the food material.

Why is the horses digestive tract considered to be efficient?

The horses digestive tract is efficient because it allows the horse to digest protein, starch and fat before the digesta reaches the microbes.

The large intestine is also the major site of what process?

The large intestine is also the main site of water reabsorption.

What is a monogastric animal?

A monogastric animal is an animal with one stomach such as pigs and humans.

What is absorption?

Absorption is the transport of small, digested molecules across the wall of the digestive tract into the bloodstream.

Where is bile synthesized and stored?

Bile is synthesized in the liver and stored in the gall bladder.

After the mouth where does food go?

Food travels from the mouth down the esophagus into the stomach.

How are free fatty acids and glycerol absorbed in the small intestine?

Free fatty acids and glycerol are absorbed through the intestinal wall by passive diffusion.

What percentage of the ruminant stomach is made up of the rumen?

80% of the total stomach volume is made up of the rumen.

What kind of digestion occurs in the stomach?

Chemical digestion occurs in the stomach.

What is chyme?

Chyme is the thin soupy mixture that is found in the stomach after HCl and pepsin have finished their job.

What is coprophagy?

Coprophagy is the act of an animal consuming its own feces.

What is crop milk?

Crop milk is the substance that is regurgitated to young chicks from their mother that contains cells that were shed from the crop itself.

Where does digestion begin?

Digestion begins in the mouth.

What is digestion?

Digestion is the breakdown of complex molecules into their smaller, individual components.

What are the three parts of the small intestine?

Duodenum Jejunum Ileum

Why is efficiency lower in ruminants than in other animals?

Efficiency for feeds other than roughages is lower in ruminants because the microbes are able to utilize the feed before the animal itself can.

What is eructation?

Eructation is the release of gas through belching.

What is gluconeogenesis?

Gluconeogenesis is when proprionate can be used in the liver to synthesize new glucose.

How is glucose absorbed in the small intestine?

Glucose is absorbed by specific glucose transport proteins using active transport.

What two things are secreted in the stomach to aide in chemical digestion?

HCl (nonenzymatic) and pepsin (enzymatic). Pepsin is originally secreted in its inactive form, pepsinogen.

What does a herbivore's diet consist of?

Herbivores derive almost all of their nutrients from the consumption of plant food products.

Horses are referred to as having what type of digestive system?

Horses are hind-gut fermenters.

What is the main difference in the digestive tract of a horse in comparison to that of a pig?

Horses have a much larger cecum and colon.

What enzyme is used to finish starch digestion?

Maltase from the intestinal wall breaks maltose down into its component glucose molecules.

What are some mechanical digestion processes?

Mastication Mixing Peristalsis

What is rennin?

Rennin is an enzyme that young animals secrete in the stomach that coagulates casein, the major protein in milk.

What are the four compartments of the ruminant stomach?

Rumen Reticulum Omasum Abomasum

What is missing in the saliva of ruminants?

Ruminant saliva does not contain any amylase.

What is the primary way that ruminants obtain energy from their diets?

Ruminants absorb VFAs across the rumen wall as their main source of energy.

What is rumination?

Rumination is the act of regurgitating feed material from the rumen back up to the mouth so that it can be chewed again.

What are on the surface of the valvulae conniventes?

Small finger-like projections called villi are on the surface of the valvulae conniventes.

What is the function of the abomasum?

The abomasum is the glandular stomach portion of the ruminant digestive tract. HCl and pepsin are secreted here, and it is also the beginning of the digestion of the microbes themselves.

What is the crop used for in birds?

The crop is used for food storage in birds.

What does a carnivore's diet consist of?

The diet of carnivores is composed primarily of protein and fats.

After the crop where does the digesta go?

The digesta goes from the crop into the proventriculus.

What is the efficiency of fat digestion?

The efficiency of fat digestion is 40-60%.

What is the efficiency of starch digestion?

The efficiency of starch digestion is >90%. Protein digestion is about the same

What is the esophageal groove?

The esophageal groove is a fold that allows milk to bypass the rumen and go directly to the omasum to prevent microbes from digesting the milk.

What are the two main parts of the large intestine?

The first part is the cecum and the second part is the colon.

What is the function of the omasum?

The omasum is the secondary filter.

What is the primary function of the small intestine at the duodenum end?

The primary function of the small intestine in the duodenum is to complete digestion.

What is the primary function of the small intestine at the ileum end?

The primary function of the small intestine in the ileum is to absorb nutrients.

What is the function of the proventriculus?

The proventriculus functions as the glandular stomach in birds. This is where HCl and pepsin are secreted.

What is the last part of the large intestine?

The rectum is the last part of the large intestine.

What is the primary function of the reticulum?

The reticulum acts as a primary filter. The inner surface of the reticulum is arranged into honeycomb-shaped ridges which catch large particles while small particles are able to continue through the digestive tract.

The rumen is the major site of what digestive process?

The rumen in the main site of microbial digestion.

What kind on digestion occurs in the small intestine?

The small intestine is the major site of chemical digestion.

What is digested in the stomach?

The stomach is used for just protein digestion.

How are triglycerides packaged so that they can be absorbed?

Triglycerides are packaged into chylomicrons.

What is the major energy source for horses?

VFAs are the major energy source for horses. VFAs are released by microbes and are readily absorbed across the large intestine.

Where do waste products leave the chickens digestive tract?

Waste products are excreted through the vent.

What type of digestion occurs in the large intestine?

Microbial digestion occurs in the large intestine.

How are amino acids absorbed in the small intestine?

Amino acids are absorbed by specific amino acid transport chains using active transport.

What enzymes are used to finish protein digestion?

Aminopeptidases and Dipeptidases are used to finish protein digestion.

What are the three main components that make up the microbe population in the rumen?

Bacteria Protozoa Fungi

What are the two classifications of chemical digestion processes?

Enzymatic Nonenzymatic

What are the enzymatic and nonenzymatic contents of saliva?

Enzymatic = ptyalin (salivary amylase) Nonenzymatic = buffers that neutralize acid

How does enzymatic digestion work?

Enzymatic digestion uses enzymes that catalyze the breakdown of feedstuffs in the digestive tract. Ex. pancreatic amylase

What are on the surface of the villi?

Even smaller villi called microvilli are on the surface of the villi.

Where does microbial digestion occur in birds?

In birds, microbial digestion occurs in its two ceca.

What is protein broken down into in the stomach?

In the stomach protein is broken down into amino acids called peptides.

What kind of digestion occurs in the mouth?

Mechanical and chemical digestion occur in the mouth. Mastication = mechanical Saliva = chemical

What vitamins do microbes synthesize?

Microbes synthesize vitamin K and some of the B vitamins.

What is microbial digestion?

Microbial digestion is the breakdown of fibrous materials by microbes in the digestive tract.

What do high-fiber herbivores consume?

Primarily leaves and stems (roughages).

What do low-fiber herbivores consume?

Primarily seeds and fruit (concentrates).

What are the folds in the wall of the intestine called?

The folds on the inner wall of the small intestine are called valvulae conniventes.

What type of digestion occurs in the gizzard?

The gizzard is the primary site of mechanical digestion in birds.

What do the microbes in the large intestine rely on to provide energy?

The microbes rely on anaerobic metabolic pathways or fermentation to provide energy.

Between the valvulae conniventes, villi and microvilli how much is the surface area of the small intestine increased?

The surface area is increased over 600-fold.

What is the terminal part of the chickens digestive tract called?

The terminal part of the chickens digestive tract is the cloaca.