Ch 21 Digestion and Nutrition

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Ch 21 Digestion and Nutrition
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Ingestion methods..

• All animals consume energy
• Herbivores
• Carnivores
• Omnivores

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• Suspension feeders particles suspended in water
  (clams, oysters, humpback whale)
• Substrate feeders live in or eat their way
  through (earthworm, maggot)

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Fluid Feeders obtain food by sucking
nutrient-rich fluids from a living host Ex
mosquitoes, ticks, butterflies Bulk
Feeders ingest large pieces of food Ex snake,
human
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4 stages of Food Processing

• Ingestion ? Digestion ? Absorbtion ?
  Elimination

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• Breaking down of Organic Molecules
• Lipids (Fat) ? glycerol fatty acid
• Polysaccharide ? Monosaccarides
• Proteins ? Amino acids
• Nucleic acids ? nucleotides

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• Some organisms only have one opening, a
  gastrovascular cavity, they eat and eliminate out
  of the same opening.
• Most have 2 openings, Alimentary canal, made up
  of a mouth and an anus.

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• The Human Digestive system consists of an
  alimentary canal and accessory glands
• Alimentary canal mouth, oral cavity, tongue,
  pharynx, esophagus, stomach, sm intestine, large
  intestine, rectum, anus
• Digestive glands salivary, pancreas, liver
• (Liver secretions stored in Gall bladder)

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• Digestion begins in the oral cavity
• Salivary glands secrete saliva
• glycoprotein slippery protection of oral
  cavity and lubrication of food
• Buffers neutralize food acids
• Antibacterial agents to kill bacteria
• Amylase digestive enzyme most active against
  carbohydrates
• Both mechanical and chemical digestion start in
  the oral cavity
• Tongue used to taste food and to form a bolus
  for swallowing pushes food into pharynx.

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• After swallowing, peristalsis moves food through
  the esophagus to the stomach
• Swallowing process
• Tongue pushes the food into the pharynx
• Esophageal sphincter
• relaxes
• Epiglottis covers larynx
• Peristalsis pushes the
• food toward the
• stomach

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• Stomach stores and breaks down food with acids
  and enzymes
• Chemical digestion - gastric juice which contains
  mucus, enzymes (pepsin), and HCl (pH2)
• Human stomach lining is fully replaced every
  three days cancer treatments
• Gastrin hormone stimulating the secretion of
  gastric juice
• Chyme nutrient rich broth formed after
  digestion of foods in the stomach
• Leaves the stomach only a little at a time

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• The small intestine is the major organ of
  chemical digestion and nutrient absorption
• 3 Parts
• Pyloric sphincter ?1. Duodenum ?2. Jejunum?3.
  illium
• Nutrients that result from digestion are absorbed
  into the blood from the small intestine
• Pancreas secretes digestive enzymes and buffer
  solution
• Liver produces bile to break down fats
• Bile is stored in the gallbladder
• Most digestion occurs in the duodenum
• Nutrient absorption occurs in the jejunum and
  ileum
• Villi and microvilli fingerlike projections
  that increase the surface area of the small
  intestine lining

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The large intestine (colon) reclaims water and
compacts the feces 3 parts cecum, rectum,
anus The small intestine empties into the cecum
of the large intestine -The appendix suggested
role in immunity attaches to the end of the
cecum Large intestine functions 1. Absorb
water resulting in solidification of
feces Inflammation of the lining cells may impair
this function and result in diarrhea 2. Absorb
vitamins produced by bacteria
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Adaptations of vertebrate digestive systems
reflect diet

• Carnivores often have large, expandable stomachs
  to accommodate large and infrequent meals
• Herbivores
• omnivores have longer
• canals to allow for digestion
• and absorption

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• Most herbivores have extra chambers to house
  digestive microbes
• May involved an enlarged cecum
• How could this be a draw back?

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• Ruminants four-chambered stomach found in
  herbivorous mammals
• Produces cud which is further breakdown of the
  cellulose in plants.
• Chambers contain symbiotic microbes
• Digest the microbes along with the nutrients
  produced

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Urinary SystemEliminates waste products from
the body and maintains fluid/salt balance.
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• The blood, which carries waste enters the kidneys
  through the Renal Artery
• 1,100-2,000 L of blood pass each day

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• blood moves through the kidneys, and is fitered
  by nephrons.
• Filtrate is refined to urine

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Nephron miniature filter

1. Bowmans capsule envelops a ball of capillaries
   called the glomerulus. (This is the blood
   filtering portion of the kidney)
2. Blood pressure forces water and solutes into the
   nephron tubule creating the 180 L of filtrate.
3. Rest of the nephron filters the filtrate solution
   down to urine (takes any nutrients out) Excess
   salts, water, urea, glucose, and amino acids make
   urine.

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• 4. Many nephrons drop their urine into a
  collecting duct.
• 5. Collecting duct directs urine into the renal
  pelvis and then the ureter and on to the bladder
  to wait for elimination through the urethra.

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• Urine in kidneys ? Ureters (tubes) ? bladder ?
  Urethra ? toilet

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Overview A healthy diet satisfies 3 needs

• All animals must obtain
• 1. Fuel to power all body activities
• 2. Organic molecules to build the animals
  molecules
• 3. Obtain essential nutrients the animal cannot
  make for itself

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Chemical energy powers the body

• Cellular metabolism produces the bodys energy
  currency, ATP, by oxidizing organic molecules
  digested from food
• The richest energy source is fat

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• The energy content of foods is measured in
  kilocalories
• Rate of energy consumed by the body is called
  metabolic rate
• Basal metabolic rate the number of kilocalories
  a resting animal requires for basic living
• Breathing, beating heart, maintain body
  temperature
• Any excess energy is stored as glycogen or fat

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• Diet must supply essential nutrients
• Essential nutrients must be obtained in
  preassembled form b/c cannot make
• minerals
• Malnourishment results of long-term absence of
  one or more essential nutrients
• 8 of the 20 amino acids are essential and must be
  obtained in the diet

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• A healthy diet includes 13 vitamins and many
  essential minerals
• Vitamin organic nutrient
• Helps activate enzymes during Chem Rxns
• Ex Vit. K helps with blood clotting
• Minerals inorganic nutrients usually required
  in small amounts
• Ex calcium, phosphorus
• You can have to much!!

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Too Much.

• Minerals
• calcification of organs,
• prevents absorption of other vitamins and
  minerals
• Black fingernails
• Garlic breath and skin
• Diarrhea
• Liver damage
• Seizures

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Too Much

• Vitamins
• rapid heartbeat
• Nausea
• Muscular incoordination
• Vertigo
• Joint pain
• Fainting
• Hair loss

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Food Labels