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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. Why Eat?. C 6 H 12 O 6 + 6O 2 -> 6 CO 2 + 6 H 2 O + Energy (ATP + heat). ATP (Cell Respiration).

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CHAPTER 41 ANIMAL NUTRITION

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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


Why Eat?

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

ATP (Cell Respiration)

  • FUEL

  • BIOSYNTHESIS

  • ESSENTIAL NUTRIENTS

Organic Macromolecules


  • 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!

CO2, other simple compounds

Why Eat?

ATP

  • FUEL

  • BIOSYNTHESIS

  • ESSENTIAL NUTRIENTS

Organic Macromolecules


Carbon Skeletons, and other simple products of cell respiration

Why Eat?

ATP

  • FUEL

  • BIOSYNTHESIS

  • ESSENTIAL NUTRIENTS

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)


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


Human Digestive System

  • 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.


  • 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


The journey begins ……

  • 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)


  • Pharynx (throat) - opens to esophagus and the trachea (windpipe).

    • Epiglottis - cartilaginous flap prevents food going into the windpipe


Epiglottitis


Fig. 41.14


The stomach

  • 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


Pyloric Sphincter-prevents back flow of food!


Small intestine is the major organ of digestion and absorption

  • 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


  • .

Fig. 41.18


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

Active transport –glucose, amino acid, vitamins

Passive transport - fructose


Hormones help regulate digestion

  • 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


Reclaiming water is a major function of the large intestine

  • Cecum- very mall in humans - appendix


Fig. 41.12


Structural adaptations of digestive systems are often associated with diet


(1)

Fig. 41.22


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