Nutrition - Anatomy & Physiology

Nutrition

Applied biochemistry and physiology

Diet formulation

Application of nutrition and economics

Nutrient allocation

What is most effective way to use a source of nutrients

Nutrients - Carbohydrates (energy/ ATP)

• CHO = end product of photosynthesis

  • Base source if energy

Non structural CHO vs Structural CHO

• Nonstructural CHO= sugar and starches

  • Easy to digest

• Structural CHO= fiber

  • cellulose

  • resistant to digestion

  • not digestible by mammalian enzymes

Nutrients - Protein (energy/ ATP)

Macromolecule made of AA

• contains nitrogen

• 10 essential AA, must be absorbed by small intestine

• 10 non essential AA, can be synthesized by mammal

Nutrients - Lipids (energy)

Fat, soluble in organic solvents

• 2 essential fatty acids

Minerals

Rocks, inorganic

• macro minerals %= Ca, P, Na, Cl, K, Mg, S

• microminerals ppm/ppb= Mn, Zn, Fe, Cu, Se, Mo, Co, I, Fl

  • Over and under supplement

Vitamins

• Fat soluble= ADEK, KADE

• H2O soluble= daily consumption

Water

Clean and abundant

• Hot → access

• Cold → access is a concern

Enzymes

• Proteins, biological catalysts (increase rate of reaction)

• Increasing biochemical reaction by interacting with reactants and products to increase likelihood of reaction occurring

• Proenzymes and zymogen= inactive form of an enzyme that must be activated

Metabolism

Sum of biochemical reactions in the body

• anabolism= biosynthesis, building more complex molecules, requires energy

• catabolism= degradation of complex molecules into simple ones, yield energy

Digestive physiology

How the digestive tract of an animal is built

• Diet selection or dietary strategy

• Animals ability to extract nutrients from a feedstuff

Monogastrics (non ruminants)

Swine, horse, human, cat, dog

Pig vs horse

Auto vs alloenzymatic digestion

• Autoenzymatic digestion= digestion using enzymes made my mammal

• Alloenzymatic digestion= digestion using microbial enzymes

Ruminants

• Reticulum, rumen

  • Reticulorumen= alloenzymatic digestion, microbial fermentation

Cow

Lumen

• Space inside of gastrointestinal tract

  • mouth to anus

  • outside of body

  • digestion occurs in lumen

  • absorption occurs at surface of lumen

Sphincters

• Comparable to cork, slows rate of passage of digesta (through longer passageways) for food to get digested/absorbed

  • Increase retention time

  • Block flow

Kp

• Rate of passage

  • How fast digesta moves

  • Slow Kp, higher retention time, higher digestion

• Make nutrients smaller for absorption

  • → mechanical breakdown= enzymatic breakdown

Kd

• Rate of digestion= how fast nutrients are digested

  • % of nutrient absorbed

    • extent of digestion = kd/ kd+ kp

    • higher kd= higher extent of digestion

    • higher kp= lower extent of digestion

Oral cavity

• Mouth

  • Mechanical breakdown & mastication

  • lower particle size, higher digestion because higher surface area

  • surface area= higher enzymatic access

  • mixing saliva and food

    • important for lubrication and swallowing of food

    • saliva has enzymes, starts digestion

    • saliva has buffers and minerals

    • saliva is important for oral health

      
      

Esophagus

Tuve that transports food from mouth to stomach

Stomach

Has multiple functions

1. Storage= provides place to store meal

2. Controls flow of digestion (food + secretions) to small intestine (controls kp)

3. Mixing= physical processing

4. Secretes enzymes, acids, buffer & mucus

5. Digestion= chemical (acid), low ph

   • enzymatic, activating zymogens

6. Absorption= H20, alcohol, Cu, Fl, Mo, aspirin

Secretion in stomach

• Acid → HCl, decreases pH, denatures proteins and kills microbes

• Buffer → HCO3-, raises pH, close to stomach surface, maintain near neutral pH, protect stomach

• Mucus → protects surface of stomach from acids & enzymes

Digestion in stomach definition

Preparing ingested for absorption

• Mechanical, reduces particle size

• enzymatic, hydrolytic reaction (hydrolysis), resulting in H2O

  • NCHO= monosaccharides

  • Proteins= AA, dipeptides, tripeptides

  • Lipids (fats)= monoacylglyceride and 2 fatty acids

• Digesta pH 1-3

Absorption in stomach definition

• When a molecule moves from the lumen (outside) into the body, typically when it crosses a cell membrane

Monogastric stomach - Pyloric Sphincter

• Controls flow of digesta into small intestine, determines kP

Monogastric stomach - Gastroesophageal Sphincter

• Prevents acid reflux

Monogastric stomach - folds of rugae

• Characterized by an S shape

• Allows stomach to stretch

Small intestine

• Primary site of digestion and absorption

• Functions=

  • Secretion: secretes enzymes and buffer

  • Digestion: enzymes hydrolyze the molecules into smaller molecules for absorption

  • Absorption: monosaccharides, AA, dipeptides and tripeptides, monoacylglycerol and 2 fatty acids

  • Immune

Bile/ Pancreas duct - Bile salts

• Helps with lipid digestion

• Made in liver

• Stored in gall bladder (horses have none)

Bile/ Pancreas duct - exocrine function of the pancreas

• Pancreatic enzymes and zymogens

• 1-2 kg/day of secretions

• 6-20g of enzymes/ zymogens per day

• Makes up 84% of pancreatic mass

Exocrine means…

Secretion goes outside the body

Bile/ Pancreas duct - endocrine functions of the pancreas

• 4% of pancreatic mass

• Cells = glucagon

  • alpha cells: increase blood glucose

  • beta cells: produces insulin, decreases blood glucose

  • Both are islets of langerhans

What produces sodium bicarbonate ? (NaHCO3)? Why?

• Pancreas

• Brunner’s glands in stomach

• Increases pH which protects small intestine from acid

Small intestine - duodenum

• Most proximal, next to stomach

• pH 5-6

• <1m

• Sphincter of oddi

• Brunners glands

• Starts enzymatic digestion of NCHO, proteins, lipids

Small intestine - Jejunum

• pH 7-7.5

• most of digestion and absorption of NCHO, proteins, lipids, occurs in jejunum

• proximal Jejunum has lots of enzyme production and structure to decrease kP and increase surface area

• slow rate of passage to help with capacity to digest/ absorb digesta

• enzyme production and structures decrease as we move more distally

Ileum

• pH >7.5

• <1m