Chapter 41 Animal Nutritionand

Digestion

Need to Feed• Dietary categories

CarnivoreHerbivoreOmnivore

• Animals are truly opportunistic eaters meaning occasionally they will eat something out of the norm when resources are scarce

• 3 nutritional needs1. Fuel (chemical energy)2. organic raw materials for biosynthesis3. essential nutrients

Management of Energy Budget• Nearly all an animal’s ATP generation is based on the oxidation of

energy rich organic molecules – CHO, proteins, and fats• Severe problems occur if budget is out of balance for long periods

undernourishment – chronic deficiency in calories- stores of glycogen and fat are used up - body begins breaking down proteins- muscular atrophy- brain can become protein deficientovernourishment – excessive food intake- obesity is increasing problem- fat stores are compounded instead of being used for fuel- inheritance is a factor in obesity- hormone leptin may be a regulatory checkpoint to combat

obesity

Animal’s Diet• In order build complex molecules it needs to grow, maintain itself, and

reproduce, animals must obtain organic precursors (carbon skeletons) from its food

• Essential nutrients – must be obtained in preassembled form because animals’ cell cannot make them from raw materials

Ex: Vitamin Cmalnourishment – missing one or more essential nutrients4 classes of essentials:1. essential amino acids – 20 in diet; 10 naturally made2. essential fatty acids – rarely deficient3. vitamins water soluble – B complex, Folic acid, Cfat soluble – A, D, E, K4. minerals - calcium, phosphorus, iron, iodine, sodium

Stages of Food Processing• The 4 stages of food processing:

1. Ingestion – eating; brings in large polymers that need to broken down for use2. Digestion – mechanical and chemical break down

of polymers into monomers the body can absorb*enzymatic hydrolysis- adding water to break bonds of macromolecules in food

3. Absorption – uptake of small molecules into bloodstream

4. Elimination – passing of undigested material out of body

Digestive System• Peristalsis – rhythmic waves of contraction that moves food

down esophagus; smooth muscle control• Sphincters – ring like valves that act as junctions between

specialized regions of digestive tube• Accessory glands in digestion:

a. Salivary glands – digestive enzymesb. Pancreas – digestive enzymes and bufferc. Liver – production of biled. Gallbladder – storage and release to bile to break

up fats• Accessory to digestion because no food passes through these

organs

Digestive System• Mouth

- will mechanically and chemically break down food particles- Food in mouth will stimulate a reflex that causes saliva to be released by salivary glands

Saliva contains –- mucin- glycoprotein that coats the lining of mouth- buffers to prevent tooth decay- antibacterial agents - Amylase that hydrolyzes starch and

glycogen

Digestive System

• Mouth pharynx – region of throat that is the

junction between trachea and esophagusepiglottis- cartilaginous flap that covers

the opening to trachea• Esophagus – connects the mouth to stomach

no digestion takes place; peristalsis

Ingestion

Digestive System

• Stomach- stores food and begins digestion- elastic walls expand when food enters- mechanical action of smooth muscles

churn contents or chyme- gastric juice (HCl) mixes and dissolves

food particles; kills bacteria present with food- pepsin – enzyme in gastric juice that will hydrolyze proteins

Early Digestion

Digestive System

• Small Intestine3 sections:

1. Duodenum – mixes juices and bile from pancreas, liver, and gallbladder

2. Jejunum – absorption of nutrients

3. Ileum – absorption of nutrients and water

Enzymatic digestion

Digestive System

• Large Intestine- cecum is a pouch like extension of

intestine - contains appendix- dispensible organ contains white blood cells that may aid in immunity/ microbial breakdown

*Main function of colon is absorption of water and any useful remaining nutrients

• Rectum – terminal portion of colon

Evolutionary Adaptations

• Dentition, or assortment of teeth, has greatly contributed to success of vertebrate class

- utilization of different shaped teeth for particular types of food or modes of nutrition

• Expandable stomachs allowing large portions of food and long periods between meals

• Symbiotic bacteria in alimentary canals• Ruminants – 4 chambered stomach for digestive of

herbivorous material*rumen, reticulum, omasum, & abomasum

Adaptations