Chapter 41 Animal Nutrition. I. Homeostasis and Nutrition

Chapter 41

Animal Nutrition

I. Homeostasis and Nutrition

A. Glucose Regulation

1. Lots of Glucose

2. Insulin is produced by the pancreas

3. Glucose can enter the cells easier and the liver makes glycogen

4. Glucose levels in the blood drop

5. Glucose gets low

6. Pancreas secretes glucagon which does the opposite of insulin

7. Glucose is released from glycogen stored

B. Nourishment

1. Undernourishment – body uses protein for fuel because it is not getting enough “energy”

2. Overnourishment – body is obese

- if we eat lots of carbs it increases carb oxidation and fat is not used

- leptin regulates fat levels

C. Essential Nutrients

• Animal’s can not make these and must be consumed preassembled

• Malnourished if missing one• 4 classes

1. Essential Amino Acids2. Essential Fatty Acids3. Vitamins4. Minerals

1. Essential Amino Acids

• We can not make every amino acid we need

• Animals produce complete proteins

• Plants produce incomplete proteins

8 Essential Amino Acids

2. Essential Fatty Acids

• Can’t make certain unsaturated fatty acids required for phospholipids

• Deficiencies very rare

3. Vitamins

• Organic molecules needed in small amounts

• Water soluble and fat soluble groups

• 13 essential vitamins in humans

a. Some Water Soluble Vitamins

• Niacin – component of NAD and NADH

• Folic Acid – coenzyme on N.A. and A.A. metabolism

• B12 – coenzyme in N.A. metabolism and needed for Red Blood Cells

• C – collagen production and anti-oxidant (protects phospholipids)

b. Some Fat Soluble Vitamins

• A – vision, skin, protects cell membrane

• D – bone growth, absorption of Ca and P

• E – antioxidant

• K – blood clotting

4. Minerals

• Inorganic molecules needed in small amounts

• Ca – bone, nerve and muscle function• P – bone, nucleotide• Cl and Na – nerve function• Fe – hemoglobin, electron carrier• F – maintenance of teeth• I – thyroid hormone

II. Food and Feeding

• Herbivores, Carnivores, Omnivores

• Most animals are opportunistic feeders

• 4 types of feeders:

A. Types of Feeders

1. Suspension feeders – sift particles from water / clams and oysters

2. Substrate feeders – live on food source and eat through it / deposit feeder is one type / maggots and earthworms

3. Fluid feeder – suck nutrients from host / mosquitos and leeches

4. Bulk feeder – large pieces of food consumed / us

III. Basics of Digestion

A. 4 Parts to Digestion

1. Ingestion

2. Digestion – (enzymatic) hydrolysis

3. Absorption

4. Elimination

B. Types of Digestion

1. Intracellular – use food vacuoles and enzymes / protists

2. Extracellular- gastrovascular cavity = very simple with one opening / digestion and distribution of nutrients occurs here / cniderians and planarians- complete digestive tract = mouth and anus / one direction with special regions for digestion

Intracellular

Extracellular – Gastrovascular Cavity

Extracellular – Complete Digestive Tract

IV. Mammalian Digestive System

A. Oral Cavity

• Physical and Chemical Digestion here

• Teeth

• 3 pairs of salivary glands

• Saliva contains mucin, buffer, and salivary amylase

• Forms bolus which is pushed to the pharynx by the tongue

B. Pharynx

• Junction between the esophagus and trachea

• Epiglottis found here which keeps food from entering the trachea

C. Esophagus

• Moves food to stomach via peristalsis

• Peristalsis – muscular pushing of food through digestive system

• Top is striated (voluntary) and the bottom is smooth

• Covered with mucus lining

D. Stomach

• Stretchy• Secretes “gastric juices”• Pepsinogen (chief cells) is converted to pepsin

by HCl which is made by the parietal cells• Pepsin is used to break down proteins• Coated in mucus (mucus cells)• Produces chyme• Top has the cardiac orifice and the bottom has

the pyloric sphincter

E. Small Intestines

1. Basics- most hydrolysis and absorption of nutrients occurs here- starts with the duodenum where bile (fat digestion and bicarbonate) and pancreatic enzymes (pancreatic amylase, pancreatic lipidase, and trypsin) enter- jejunum and ilium are next / enzymes secreted here-Villi and microvilli absorb with small vessels of the lymphatic system called lacteal and blood vessels found inside

- drain into the hepatic portal vessel heading to liver

Video

2. Macromolecule Digestion

a. Carb digestion – salivary amylase, pancreatic amylase, maltase, sucrase, lactase

b. Protein digestion – pepsin, dipeptidases, aminopeptidase / trypsin, chymotrypsin, and carboxypeptidase are made by pancreas and turned into their active forms by enteropeptidase in the small intestines

c. Nucleic Acid digestion – nucleases

d. Fat digestion – lipase breaks it down after bile emulsification

F. Large Intestines

• Cecum / appendix found here / may be large in some animals

• Recovers water

• Lots of mutualistic bacteria (E. coli) which produce vitamins

• Rectum is the end with 2 sphincters, one involuntary and one voluntary

G. Hormones and Digestion

1. If you see food:

- gastrin is made by the stomach and released into the blood stream

- stomach secretes acids

- if pH gets too low gastrin is stopped

2. Enterogastrones / Secretin and CCK

- release bicarbonate and help break down A.A. and F.A.

V. Crazy Ways to Digest

Cows, Rabbits, and Termites