nutrition and digestion chapter 41. breaking it down major macromolecules: polymers monomers?

Nutrition and Digestion

Chapter 41

Breaking It Down

Major macromolecules: polymers monomers?

Today We Are Serving Autotrophs

HeterotrophsConsumers

Herbivores Carnivores Omnivores

Decomposers

No Hands or ‘Utensils’

Baleen whales, oysters, and spongesMosquitoes, hummingbirds, and aphids

Most animals

Catepillars, earthworms, and maggots

Breaking It Down

Compartmentalizing Digestion Prevents self digestion Intracellular digestion

No digestive tract Individual cells and sponges

Extracellular digestion Incomplete digestive tract

Cnidarians and flatworms

Complete digestive tract Most animals

No Digestive Tract

Digestion is completely intracellular

Phago- or pinocytosis form food vacuoles

Broken down by lysosomes

Incomplete Digestive Tract

Single opening to a gastrovascular cavity

Starts extracellularly, but ends intracellularly

Complete Digestive Tract

Mouth and anus

Digestion is extracellular

Specialized organs

Mammalian Digestive Tract

Alimentary canal

Accessory organs (green)

Food moved by peristalsis

Regulated by sphincters

Time varies

Comparative Digestive Tracts Length related to diet

Herbivores & omnivores longer than carnivores

Cellulose in plants

Herbivores lose many nutrients to feces Recycle feces to regain

Ruminants have 4 chambered stomachs Regurgitate food from 1 to

another = chew cud

Mouth Mechanical digestion

Bite, tear, grind and crush Increase SA

Chemical digestion Salivary glands release saliva

Neural signal from food or association Amylase for carb digestion, bicarbonate to neutralize, and

mucins to lubricate

Tongue manipulates Evaluates food via taste and olfaction Forms a bolus

Pharynx Esophagus and

trachea Epiglottis and larynx

regulation Heimlich maneuver if

fails

Esophagus Peristalsis moves bolus Length varies b/w

species Cell types

Stomach Stores and mixes bolus Gastric juices convert to chyme (ph=2) Chemical digestion

Parietal cells: H+ & Cl-

Chief cells: pepsinogen Both inactive until lumen Protects gastric glands Positive feedback

Mucus & epithelial cells Gastric ulcers (Helicobacter pylori)

Sphincter regulation

The Final Breakdown Chyme and digestive juices mix in the

duodenum (SI)Pancreas: enzymes and bicarbonate solutionLiver/gallbladder: bile, emulsifier (2107 lab?)

Detoxifies and maintains homeostasis

Hormonal controlPositive and negative feedbackEnsures juices present only when necessaryFig 41.4

Summary of Chemical Digestion

Sucrase, maltase, and lactase

Breaking It Down

Small Intestine

3 folded regions Duodenum Jejunum Ileum

Increased SA increases absorption Circular folds contain villi covered in microvilli Diffusion or active transport to blood, lymph, and liver

Large Intestine Cecum for plant material; dead ends

Appendix Colon recovers water by osmosis

Remnants = fecesPeristalsis moves along, reclaiming more water

Irritation limits absorption = diarrhea Move too slowly = constipation

Rectum stores until eliminationTwo sphincters (voluntary and involuntary)

control

Breaking It Down

Nutritional Needs

Chemical energy Organic building

blocks Carbohydrates Proteins Lipids

Essential nutrients

Essential Nutrients Essential amino acids

8* of 20 can’t be made, must be consumed Lacking = protein deficiency (malnutrition) Eggs, meat, and cheese are complete; plants

are incomplete

Essential fatty acids Unsaturated fatty acids Seeds, grains, and

vegetables supply

plenty

Essential Nutrients (cont.) Vitamins

Organics needed in small amounts

13 (0.01-100 mg/day)

Water soluble Fat soluble

Benefits of supplements

Table 41.1

Minerals Inorganics needed

in small amounts Vary among species

(1mg-2500mg/day)

Excess can cause imbalances and toxic effects

Table 41.2

Imbalances in Energy Intake

Undernourishment Deficient calories Droughts and wars

Overnourishment Excess calories Evolution of food hording

Malnourished Deficient nutrients Eating habits