Animal Nutrition

Chapter 41

The Need to Feed

Animals are Herbivores Carnivores omnivores

Food and Nutrients Food Any substance, either raw or

processed which is meant for human consumption

Nutrients The components of food that the body can use for growth, repair and energy

Homeostatic RegulationGlucose level rises, insulin is secreted

Insulintransport of glucoseliver & muscle store glucose lblood levels drop

Glucose level drops glucagon is made to oppose the effect of insulin

Glucagon promotes the breakdown of glycogen blood glucose levels rise

Appetite Regulating Hormones

PYY is an appetite suppressant

Ghrelin triggers hunger

Insulin suppresses appetite

Leptin suppresses appetite

Figure 41.2 A ravenous rodent

Obesity related to leptin.

Types of Nutrients

Carbohydrates Proteins Fats Vitamins Minerals Water

Essential Nutrients

Essential AA Essential fatty acids Vitamins MineralsUndernourishment vs. malnutrition

Essential Amino Acids

Animals require 20 AA

Can synthesize most 8 are essential, must

obtain from food How do vegetarians

get all essential AA?

Essential Fatty Acids

Need to obtain from food Unsaturated FA Linoleic Acid

Essential Nutrients What happens if an animal’s diet is

missing an essential nutrient?Deficiency Diseases

scurvy — vitamin C (collagen production) rickets — vitamin D (calcium absorption) blindness — vitamin A (retinol production) anemia — vitamin B12 (coenzyme function) kwashiorkor — protein

Vitamin Requirements of Humans: Water-Soluble Vitamins

Vitamin Requirements of Humans: Fat-Soluble Vitamins

Mineral Requirements

Intracellular Digestion in Paramecium Digestion occurs in

specialized compartments

Intracellular digestion occurs in protists and sponges

Gastrovascular Cavities and Extracellular Digestion

Gastrovascular cavities do both digestion and distribution Ex. Cnidarians,

platyhelminthes (flat worms)

Two-way digestion

One Way Digestive Tracts

Stages of Food Processing

1. Ingestion: eating or drinking2. Digestion : Breaking food into smaller

molecules• Mechanical • Chemical (Enzymes)

3. Absorption: nutrient molecules enter blood, the circulatory system transports it through out the body

4. Elimination: undigested material passes out of the body

The Digestive System Functions like a series of tube like

organs which pass through the body from the mouth to the anus Alimentary Canal

Alimentary Canal can be about 30’ long

Accessory organs Pancreas, Liver, Gallbladder secrete enzymes that are released into the food tube

Digestion in the Mouth

It all begins in the mouth . . .

Teeth, tongueSalivary glands

MucusAmylase

Only carbohydrates are digested here

Swallowing and Peristalisis

Glottis and Epiglottis

From mouth to stomach: the swallowing reflex and esophageal peristalsis (Layer 2)

From mouth to stomach: the swallowing reflex and esophageal peristalsis (Layer 1)

Peristalsis

Rhythmic muscular contractions propel a bolus of food

The human digestive system

Digestion in the Stomach Muscular organ Acts as a

reservoir where food is prepared for digestion in the SI

Produces Gastric Juices

Stomach Functions1. Food Storage2. Mechanical Digestion3. Chemical DigestionSecretions:1. Mucus2. EnzymePepsinogen3. HCL

CHYME semi-fluid food mixture leaves.

Protection from Self-Digestion

Protective liningMain enzyme -Pepsin is inactive Pepsinogen when secreted

Digestion in the Stomach Pepsinogen Comes in contact with

HCl Pepsin Pepsin converts proteins into

peptones Acidity of Gastric juices kills some

bacteria that enters with food Gastric Juices stimulated by

psychological and chemical means Peristaltic process of moving chyme into

the SI takes place for 6hrs

Small Intestine

Digestion in the Small Intestine Main stage of Digestion As chyme enters the SI secretes juices that

are alkaline and neutralizes the acidity SI maltase,lactase,sucrase breaks

disaccharides Liver secretes bile emulsifies fats Dipeptidases dipeptides into AAs Pancreas

Trypsin & Chymotrypsin break down proteins

Amylase converts starch into maltoseLipase breaks fats

Process is complete in about 4 hrs

PancreasSecretes Hormones Sodium

bicarbonate Digestive

enzymesLipaseTrypsinogenAmylase

Secretes Blood clotting

enzymes Stores glycogen Bile

Stored in gall bladder

Emulsifies fat

Liver

1. Anatomy:2. Functions

a. Reclaim waterb. Synthesis of vitamins by E. coli

FecesRectumAnus

DiarrheaConstipation

Large Intestine = Colon

Can you name the parts and tell what they do?

Food as Fuel Carbohydrates, fats and proteins are

all used to generate ATP Fats9 Calories/gm, Proteins and

Carbs 4Calories/gm 1 Calorie (kilocalorie)= 1000 calories Basic Calorie need 2200 for female

teens, 2500 males

Accessory Organs

LIVER A. Secretions B. Functions

1. Digestive function 2. Glycogenesis 3. Gluconeogenesis 4. Glycogenolysis 5. Hematopoiesis in embryo 6. Detoxification 7. Damaged red blood cell

removal bile contains pigment by-

products of RBC bile pigments eliminated from

body with feces brown feces = rusty iron from

hemoglobin!

Pancreas a. Anatomy

Acinar cells Islets cells:Alpha, Beta

b. Functions c. Digestive Enzyme 1. trypsinogen 2. chymotrypsinogen 3. carboxypeptidase 4. aminopeptidase 5. pancreatic amylase 6. pancreatic lipase

These accessory organs secrete their enzymes and a basic fluid into the duodenum of the small intestine

Figure 41.16 The duodenum

Figure 41.18 Activation of protein-digesting enzymes in the small intestine

Small Intestinea. Anatomy

1. size2. villi3. lacteals4. glands

b. Functionsc. Secretions

1. mucus2. maltase3. sucrase4. lactase5. peptidase6. enterokinase

Figure 41.19 The structure of the small intestine

Absorption in the Small Intestinevillimicrovillichylomicrons fats, cholesterol, wrapped in protein

leave cells by exocytosis

lactealslymphatic systemhepatic portal vein

STOMACH

MOUTH

SMALL INTESTINE

What enzymes are made in the pancreas?

Hormonal Control Enterogastrone Gastrin Cholecystokinin secreted in

response to the presence of amino acids or fatty acids, causes the gallbladder to contract and release bile into the small intestine and triggers the release of pancreatic enzymes

Secretin chyme(acidic pH)enters the duodenum, signals the pancreas to release bicarbonate to neutralize the chyme

Flora of Large Intestines Living in the large intestine is a rich flora of

mostly harmless bacteria Escherichia coli

a favorite research organism bacteria produce vitamins

vitamin K; biotin, folic acid & other B vitamins generate gases

by-product of bacterial metabolism

methane, hydrogen sulfide

Large Intestines (colon) Reclaiming water

used as solvent for various digestive juices

~7L of fluid secreted intodigestive tract daily

> 90% of water reabsorbed diarrhea = insufficient

water absorbed constipation = too much

water absorbed

Numerous Goblet Cells

Large Intestine Wall

Figure 41.x1 Large intestine

Rectum Terminal portion of colon

Feces contain masses of bacteria undigested materials, mainly cellulose

roughage or fiber salts

appendix

Structural Adaptations reflecting diet have made mammals very successful

1. Dentition

Structural Adaptations

2. Length of Digestive System

Structural Adaptations3. # of Stomachs

Structural Adaptations

Digesting CelluloseHow well you digest cellulose governs life

strategy of herbivoresCOW

Can digest cellulose well; not need to eat supplemental sugars

GORILLACan’t digest cellulose well; must supplement with sugar sources, like fruit

Figure 5.8 The arrangement of cellulose in plant cell walls

Figure 41.x2 Termite and Trichonympha

Protozoans and Bacteria have enzymes to digest cellulose