CHAPTER 41 ANIMAL NUTRITION

LEPTIN = apetite suppressor (hormone produced by fat cells)

The four main stages of food processing are ingestion, digestion, absorption, and elimination

FUEL BIOSYNTHESIS ESSENTIAL NUTRIENTS

Why Eat?

Organic Macromolecules

ATP (Cell Respiration)

C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy (ATP + heat)

FUEL BIOSYNTHESIS ESSENTIAL NUTRIENTS

Why Eat?

Organic Macromolecules

ATP

CO2, other simple compounds

Everything you eat gets DIGESTED into glucose, amino acids, and glycerol + fatty acids

These 3 digestion products enter cell respiration (glycolysis and Kreb’s cycle)

Products of cell respiration – CO2, NH3, H2O, ATP

These end products can be used for cellular work (movement), generating heat, and BIOSYNTHESIS

Excess gets converted to GLYCOGEN or FAT!

FUEL BIOSYNTHESIS ESSENTIAL NUTRIENTS

Why Eat?

ATP

Carbon Skeletons, and other simple products of cell respiration

BIOSYNTHESIS = ANABOLIC PATHWAY

Biosynthesis = Making of New Proteins, Carbohydrates, Fats, Nucleic Acids needed by the body using the energy and raw material derived from food

How much energy do you get from food?

Carbohydrates – 4 kcal/gm Proteins – 4 kcal/gm Fats – 9 kcal/gm Calorie = heat required to raise

the temperature of water by 10c Kcal = 1000cal Cell Respiration = process that

“burns” food Carbs = quick energy release Fats, proteins = slow to release

energy

What happens to excess carbs?

Gets stored as glycogen in liver and muscle

Too much carb? -Gets converted into fat!!!!

Glycogen can be released quickly during exercise

Disadvantge – less energy (4 kcal/gm)

Fats – more energy (9kcal/gm), takes time to release

How is glucose regulated?

Insulin (produced by the Islets of Langerhans - in pancreas) = decreases blood sugar by ?

Glucagon (pancreas) = increases blood sugar by ?

Animals require 20 amino acids to make proteins.

Essential amino acids must be obtained from food in prefabricated form. (eight)

Protein Deficiency - Kwashiorkar

Essential fatty acids.– Certain unsaturated fatty acids, including

linoleic acids required by humans.– Deficiencies are rare.

Mahatma Gandhi once said, "Where ever flaxseeds become a regular food item among the people, there will be better health".

Vitamins -organic molecules required in the diet in very small quantities (upto 100 mg)

Fat Soluble Vitamins

Water Soluble Vitamins

A, D, E, K C, B, Niacin, Folic acid, Biotin

Fat Soluble Vitamin

Function Deficiency

A Vision, maintain healthy skin

Vision problems, dry skin

D Absorption of Calcium and phosphorous = helps bone growth

Rickets (bone deformities)

E Antioxidant – maintains cell membrane

K Blood clotting Clotting problems, Anemia

Water Soluble Vitamin

Function Deficiency

C Detoxification, antioxidant, collagen synthesis (gums)

Scurvy (skin, teeth, blood vessel degenration)

B (1,2,6,12)

Coenzyme component –FAD, amino acid and nucleic acid metabolism,

B1 – Beriberi (nerve disorder, anemia)

Minerals are simple inorganic nutrients, usually required in small amounts - from less than 1 mg to about 2,500 mg per day.

Mineral Function Deficiency

Calcium Bone and tooth formation, nerve and muscle function

Retarded growth, osteoporosis

Iron Hemoglobin component - cofactor

Anemia

Sodium Acid- base balance, water balance, nerve function

Too much – high blood pressure

Alimentary canal + accessory glands that secrete digestive juices into the canal through ducts.– Peristalsis: rhythmic waves-

push food along.

– Sphincters: muscular ringlike valves, regulate the passage of food

– Accessory glands - salivary glands, the pancreas, the liver, and the gallbladder.

Human Digestive System

–When does the lunch you had today complete its passage through your digestive system?

• Mouth: Seconds • Esophagus: Seconds • Stomach: 2-6 hours • Small Intestine: 5-6 hrs.• Large Intestine: 12- 24 Hours TOTAL = 19 – 36 hrs!!

Fig. 41.13

Physical: chewing -Increases surface area of food

Saliva - Moistens + Kills bacteria + Buffer

Chemical digestion: Enzyme Salivary Amylase – Acts on

“AMYLOSE” - long straings of glucose found in starch/glycogen

(starch + glycogen) -> (smaller polysaccharides + maltose)

The journey begins ……

Pharynx (throat) - opens to esophagus and the trachea (windpipe).– Epiglottis - cartilaginous flap prevents food

going into the windpipe

Epiglottitis

Fig. 41.14

        

        

                                                                      

    

 

Muscular Organ – peristalisis -chyme - mixture of gastric juice+food

Gastric juice - glands Parietal cells - HCl – pH 2!! -

kills bacteria; converts pepsinogen -> pepsin (inactive)->(active)

Chief cells - Pepsin – action = proteins -> polypeptides + amino acids

Mucous cells - Mucous prevents eating away of stomach lining

The stomach

        

          

                                                                  

  

Pyloric Sphincter-prevents back flow of food!

6 m long First section – duodenum LOTS OF ENZYMES FROM ACCESSORY

GLANDS Pancreas makes – 1)pancreatic amylase

- acts on polysachcharides -> tri, di saccharides; 2)bicarbonate - changes pH to make it basic so enzymes can act on the food; 3)trypsin, chymotrypsin - act on polypeptides ->tri & dipeptides , 4)lipase - acts on fats -> fatty acid and glycerol, 5)nucleases act on DNA and RNA -> nucleotides

Liver makes bile; gall bladder – stores bile; bile emulsifies fats

Lining of intestine – other enzymes (intestinal juice); convert to monomers

Small intestine is the major organ of digestion and absorption

.

Fig. 41.18

Jejunum, ileum – sections of small intestine – absorption of nutrients into lymph/blood - see notes in powerpoint slide for details

Passive transport - fructose

Active transport –glucose, amino acid, vitamins

Hormones released by wall of the stomach and duodenum

Ensure that digestive secretions are present only when needed.– Stomach wall - hormone gastrin (stimulates

gastric juice)– Duodenum – hormone Secritin (pancrease

releases bicarbonate)– Duodenum – hormone Cholecystokinin (CCK)-

gallbladder releases bile

Hormones help regulate digestion

Cecum- very mall in humans - appendix

Reclaiming water is a major function of the large intestine

Fig. 41.12

Structural adaptations of digestive systems are often associated with diet

(1)

Fig. 41.22