11. Chapter 41: Animal Nutrition Flashcards
Basic animal nutrition
All animals eat other organisms. Most animals are also opportunistic. (will eat a variety of things depending on what is available)
Three dietary categories
- Herbivores eat mainly autotrophs (gorillas, cows, and many invertebrates. 2. Carnivores eat other animals (sharks, spiders and snakes). 3. Omnivores consume animal and plant matter (cockroaches, bears, and humans).
What are the five main groups of the mechanisms by which animals ingest food?
- Many aquatic animals are suspension-feeders – sift small food particles from the water. (e.g. baleen whales) 2. Deposit-feeders, like earthworms, eat their way through sediments and extract organic material 3. Substrate-feeders live in or on their food source, eating their way through the food (e.g. maggots into animal carcasses and leaf miners through leaves) 4. Fluid-feeders make their living sucking nutrient-rich fluids from a living host. (E.g. Mosquitoes/ leeches suck bllod, Aphids tap plant saps, hummingbird/beed obtain nectar) 5. Most animals are bulk-feeders that eat relatively large pieces of food. (i.e. Their adaptations include tentacles, pincers, poisonous fangs, and jaws with teeth.)
Define Homeostasis
the steady state physiological condition of the body.
Define Negative-feedback. Example?
: a change in the variable being monitored triggers a response that counteracts the initial fluctuation. (primary mechanism of homeostasis, prevent small changes from becoming large) (E.g. Our body temperature is kept close to 37oC by the cooperation of several negative-feedback circuits)
Glucose regulation (negative-feedback)
- When blood glucose levels rise above a set point, 2.the pancreas secretes insulin into the blood. 3. Insulin stimulates liver and muscle cells to make glycogen, dropping blood glucose levels. 4. When glucose levels drop below a set point, 5. the pancreas secretes glucagon into the blood. 6. Glucagon promotes the breakdown of glycogen and the release of glucose into the blood. (The pancreas signals distant cells to regulate levels in the blood = endocrine function.)
Define Positive-feedback. Give two examples.
a change in some variable triggers mechanisms that amplify the change. 1. During childbirth, pressure of the baby’s head against sensors near the opening of the uterus stimulates uterine contractions. 2. Global warming (climate change)
What three things does a nutritionally adequate diet supply?
- Fuel (chemical energy) for all cellular work 2. Organic raw materials for biosynthesis 3. Essential nutrients, substances that the animals cannot make for itself from any raw material.
What do most of the calories you consume do?
ATP recycling accounts for the largest fraction by far of the energy budget of most animals. (Powers most cellular activity.)
Where is ATP derived from?
oxidation of organic fuel molecules in cellular respiration. (The monomers of carbohydrates, proteins, and fats (2x calories) can be used as fuel.)
When an animal takes in more calories than it needs to produce ATP, what can the excess be used for?
Biosynthesis: growth and reproduction.
In humans, what does that the liver and muscle cells store energy as?
Glycogen: Polymer made up of many glucose units. If glycogen stores are full, the excess is stored as fat.
What happens when fewer calories are taken in than are expended?
Fuel is oxidized: human body generally expends liver glycogen first, then muscle glycogen, and finally fat (Most healthy people have enough stored fat to sustain them through several weeks of starvation - Energy needs can be fueled by the oxidation of only 0.3kg of fat per day.)
What are the two severe problems that can occur if the energy budget remain out of balance for long periods?
- Undernourished: caloric intake is 90% of the recommended level. 2. Severely undernourished: if caloric intake is less than 80% of recommended level.
What happens when glycogen and fat are used up?
The body breaks down its own proteins for fuel: 1. Muscles decreases in size, brain becomes protein-deficient 2. If energy intake remains less than energy expenditure, death results
Over nourishment (obesity)
- now a common problem 2. Fat hoarding provided a fitness advantage for our hunting/ gathering ancestor 3. Genetic and environmental component to obesity
Animal diets must supply essential nutrients, source of carbon (sugars) and nitrogen (proteins) in order to fabricate organic molecules (cannot be fabricated from raw material) What is an example so specie specific essential for primates?
ascorbic acid (vitamin C)
Define Malnourishment.
An animal whose diet is missing one or more essential nutrients is said to be. (Much more common than undernourishment - not enough caloric intake, possible to be over nourished yet malnourished)
Malnutrition at a personal scale.
Malnutrition at a national scale.
How many amino acids are required to make proteins (most animals can synthesize half of these)
- 20 amino acids (essential amino acids must be obtained by food) 2. 8 essential AA in adult human (proteins in animal products are complete, plant proteins are incomplete and would result in protein deficiency diets)
How can protein deficiency be avoided?
By eating plant food that complement each other. (i.e. Beans supply lysine, corn provides methionine)
What are vitamins?
organic molecules required in the in small quantities. 1. serve primarily as coenzymes 2. required in small amounts 3. deficiency can lead to serious problems (overdose too)
How many vitamins have been identified to being essential to humans?
13: water-soluble and fat-soluble. A balanced diet will prevent deficiency (RDA for vitamin C = 60mg but Linus Pauling advocated 25,00mg)
What are minerals?
simple inorganic nutrients, required in small amounts. 1. humans require large quantities of Ca and P for bone construction 2. Iron in hemoglobin (oxygen binding protein of RBC) 3. Na and Cl influence osmotic balance b/w cells and interstitial fluids (Cdn eat 20 time more than require, too much = high blood pressure)
What is the four main stages of food processing?
- ingestion (first stage) 2. digestion (breaking down into smaller molecules) 3. absorption 4. elimination
Can animals directly use macromolecules in their polymer state?
No, Macromolecules required are not identical to those consumed. Plus, polymers are too large. However, all organisms use common monomers (e.g. the same 20 amino acids).
In digestion, what are macromolecules cleaved into? and what is it used for?
cleaved into monomers –used in biosynthesis or as fuel for ATP production.
In digestion, what are polysaccharides split into?
monosaccharides
In digestion, what are proteins broken down into?
Amino acids
In digestion. what are fats digested to?
glycerol and fatty acids
What type of digestion occurs before chemical digestion? Why is it important>
Mechanical fragmentation of the food; Increases the surface area exposed to digestive enzymes; a variety of hydrolytic enzymes catalyze digestion.
Where do the animal’s cells absorb the small molecules after digestion?
digestive compartment
What happens during elimination?
undigested material passes out of the digestive compartment
What are the simplest digestive compartments? What is it termed?
food vacuoles, organelles in which hydrolytic enzymes break down food (Termed intracellular digestion.)
In most animals, at least some hydrolysis occurs by?
Extracellular digestion: much larger prey can be ingested than by phagocytosis.
In contrast to Porifera, Cnidaria and Platyhelminthes, most animals have complete digestive tracts. What does it consist of?
Mouth, digestive tube, and an anus. (The tube is often organized into special regions.)
What can the food pass through?
esophagus, crop, gizzard, stomach, and/or intestine
Function of 1. Crops (and stomachs), 2. gizzards, 3. intestines
- food storage organs 2. grind and fragment food 3. nutrient absorbed into blood
What is the advantage of a complete digestive tract?
enable ingestion of additional food before earlier meals are completely digested
What does the mammalian digestive system consist of?
the digestive tract and various accessory glands that secrete digestive juices into the canal. (The accessory glands include: salivary glands: parotid, sublingual, submandibular, pancreas, liver, and gallbladder.)
Define peristalsis
rhythmic waves of contraction by smooth muscles in the walls of the canal to push food along
Define sphincters
muscular ring-like valves that regulate the passage of material between the specialized chambers
The oral cavity, pharynx, and esophagus initiate food processing. Both physical and chemical digestion begin in the mouth. What happens in this process?
- During chewing, teeth cut and grind food, increasing its surface area 2. A nervous reflex causes the salivary glands to deliver saliva 3. Saliva lubricates food with a slippery glycoprotein (mucin)
When the salivation occur? What does saliva contain?
- Salivation may occur in anticipation of eating, it contains water, mucin and salivary amylase (An enzyme that hydrolyzes starch and glycogen into smaller polysaccharides)
What does the tongue do?
tastes food, manipulates it, and shapes it into a ball called a bolus
What does the pharynx (throat) do?
opens to both the esophagus and the trachea (windpipe)
What happens when we swallow?
- the windpipe opening, the glottis, is blocked by a cartilaginous flap, epiglottis 2. When a food bolus reaches the pharynx, the epiglottis tips over the glottis and closes off the trachea 3. Then the esophageal sphincter relaxes and it is pushed by peristalsis to the stomach
Stomach
- stores food and performs more preliminary digestion 2. located in the abdominal cavity, just below the diaphragm (accordion-like folds (rugae) to stretch); (secretes gastric juice and churns this mixture)
Gastric juice
in the stomach, has a high concentration of hydrochloric acid and a pH of about 2, Kills most bacteria that are swallowed with food
Pepsin
present in gastric juice, Enzyme that begins the hydrolysis of proteins by breaking peptide bonds, Secreted in an inactive form, called pepsinogen, Hydrochloric acid converts pepsinogen to the active pepsin.
The stomach is also coated in mucus that protects the stomach lining.
Still, the epithelium is completely replaced by mitosis every three days. Gastric ulcers can be caused by an acid-tolerant bacterium. (treated with antibiotics)
Acid chyme
result of mixing and enzyme action, the food becomes a nutrient-rich broth.
Most of the time the stomach is closed off at either end. The opening from the esophagus dilates when a bolus arrives. Occasional backflow into the lower esophagus causes?
acid-reflex (heartburn)
Opening from the stomach to the small intestine is regulated by the ?
pyloric sphincter
How long does it take after a meal for the stomach to empty?
Depending on the meal, it takes about 2 to 8 hours
The small intestine
- major organ of digestion and absorption 2. longest sect of alimentary canal (6m) 3. enzymatic hydrolysis 4. absorption of nutrients into blood
The first 25 cm of the small intestine? Function?
, the duodenum, acid chyme mixes with digestive juices from the pancreas, liver, gall bladder, and intestinal epithelium.
The pancreas
produces several hydrolytic enzymes and an alkaline solution rich in bicarbonate which reduces the acidity of the chyme
Liver
performs a wide variety of important functions in the body, including the production of bile.
Bile? Where is it stored?
Bile contains bile salts which aid in the digestion of fats. It isstored in the gallbladder until needed.
Does a rat have a gall bladder?
No, because it is a nibbler, always eating.
Specific enzymes from the pancreas and the duodenal wall have specific roles in ?
digesting macromolecules.
The digestion of starch and glycogen continues in the small intestine. Pancreatic amylases hydrolyze polysaccharide into ??? List two examples.
into disaccharides; Maltase splits maltose into two glucose molecules; Sucrase splits sucrose into glucose and fructose
Digestion of proteins in the small intestine completes the process begun by ?
Pepsin; Trypsin and chymotrypsin, secreted in inactive form by the pancreas, attack specific peptide bonds (Other protein-digesting enzymes are secreted by the intestinal epithelium)
The fat in a meal reaches the small intestine ??
Undigested, Normally insoluble in water, but bile salts coat fats droplets and keep them emulsified. Lipase hydrolyzes fat molecules into glycerol and fatty acids.
Where does most digestion occur?
duodenum, The other two sections of the small intestine, the jejunum and ileum, function in the absorption of nutrients and water. (The small intestine has a huge surface area, roughly the size of a tennis court.)
Liver
performs a wide variety of important functions in the body, including the production of bile.
Bile? Where is it stored?
Bile contains bile salts which aid in the digestion of fats. It isstored in the gallbladder until needed.
Does a rat have a gall bladder?
No, because it is a nibbler, always eating.
Specific enzymes from the pancreas and the duodenal wall have specific roles in ?
digesting macromolecules.
The digestion of starch and glycogen continues in the small intestine. Pancreatic amylases hydrolyze polysaccharide into ??? List two examples.
into disaccharides; Maltase splits maltose into two glucose molecules; Sucrase splits sucrose into glucose and fructose
Digestion of proteins in the small intestine completes the process begun by ?
Pepsin; Trypsin and chymotrypsin, secreted in inactive form by the pancreas, attack specific peptide bonds (Other protein-digesting enzymes are secreted by the intestinal epithelium)
The fat in a meal reaches the small intestine ??
Undigested, Normally insoluble in water, but bile salts coat fats droplets and keep them emulsified. Lipase hydrolyzes fat molecules into glycerol and fatty acids.
Where does most digestion occur?
duodenum, The other two sections of the small intestine, the jejunum and ileum, function in the absorption of nutrients and water. (The small intestine has a huge surface area, roughly the size of a tennis court.)
Specific enzymes from the pancreas and the duodenal wall have specific roles in ?
digesting macromolecules.
The digestion of starch and glycogen continues in the small intestine. Pancreatic amylases hydrolyze polysaccharide into ??? List two examples.
into disaccharides; Maltase splits maltose into two glucose molecules; Sucrase splits sucrose into glucose and fructose
Digestion of proteins in the small intestine completes the process begun by ?
Pepsin; Trypsin and chymotrypsin, secreted in inactive form by the pancreas, attack specific peptide bonds (Other protein-digesting enzymes are secreted by the intestinal epithelium)
The fat in a meal reaches the small intestine ??
Undigested, Normally insoluble in water, but bile salts coat fats droplets and keep them emulsified. Lipase hydrolyzes fat molecules into glycerol and fatty acids.
Where does most digestion occur?
duodenum, The other two sections of the small intestine, the jejunum and ileum, function in the absorption of nutrients and water. (The small intestine has a huge surface area, roughly the size of a tennis court.)
The enormous surface of the intestine is an adaptation that greatly increases
the rate of nutrient absorption: has fingerlike villi, which has many microvilli
How many single cell layers separate the lumen of the intestine from the bloodstream?
two
Hepatic portal vessel
converge with veins that drain nutrients (leads directly to the live)
Liver
- has first access to amino acids and sugars 2. modifies and regulates 3. blood exiting the liver has a glucose concentration close to 0.1%, regardless of carbohydrate content of the meal
The large intestine. 1. major function
(The main branch of human colon is shaped like upside down U about 1.5m long) 1. reclaiming water (about 7L - over 90% of water reabsorbed) 2. Connected to small intestine at T-shaped junction (one arm of T is pouch called Cecum) 3. rich flora of mostly harmless bacteria (produce vitamins K and several B vitamins)
Cecum
small in humans and has fingerlike extension called the appendix
The appendix
makes minor contribution to body defense
Ileocoecal valve
B/w illeum and cecum
Does a rat have a cecum? What is it for?
Yes, rat cecum is big and is for digesting cellulose (full of bacteria), human one is a lot smaller
Structural adaptations of digestive systems are often associated with diet. What is an example?
- Dentition, reason for success. (nonmammalian have less specialized dentition except snakes) 2. carnivores: expandable stomach, go for long time b/w meals 3. length also correlated with diet (herb and omni have longer tracts than carni b/c veggie more difficult to digest) 4. chemicals to hydrolyze cellulose (housing symbiotic bacteria in special fermentation chambers
Ruminants (deer, cattle, and sheep) digestion
- Cow chews swallows, boluses enter rumen and reticulum (may regurgitate and re-chew the cud) 2. reswallows cud, moves to omasum, water removed 3. cud, with microoganisms passes abasum for digestion by cow’s enzyme
