Title: Lecture 13 Outline (Ch. 41)
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2Lecture 13 Outline (Ch. 41)
- I. Animal Nutrition Overview
- II. Essential Parts of Animal Diet
- III. Food Intake
- Digestive Compartments
- Adaptations
- Obesity
- Lecture Concepts
3Overview The Need to Feed
- Food is taken in, taken apart, and taken up in
the process of animal nutrition - In general, animals fall into three categories
- Herbivores eat mainly autotrophs (plants, algae)
- Carnivores eat other animals
- Omnivores regularly consume animals as well as
plants or algal matter
4How does a diet of lean fish help make a bear fat?
5Essential Parts of Diet
- Chemical energy, which is converted into ATP and
powers processes in the body - Organic carbon and organic nitrogen
- Essential nutrients must be obtained from dietary
sources
- Essential amino acids
- Essential fatty acids
- Vitamins
- Minerals
6Essential Parts of Diet
- Meat, eggs, cheese - provide all nine essential
amino acids ( complete proteins) - Individuals eating only plant proteins need
specific plant combinations for all essential
amino acids
7Essential Fatty Acids
- Animals can synthesize most fatty acids they need
- The essential fatty acids are certain unsaturated
fatty acids that must be obtained from the diet - Deficiencies in fatty acids are rare
8Vitamins
- Vitamins organic molecules, small amounts needed
- 13 vitamins essential to humans have been
identified - Two categories fat-soluble water-soluble
Table 41-1
Vitamin A Vitamin D Vitamin E Vitamin K
B-complex Biotin Vitamin C (ascorbic acid)
9Minerals
- Minerals simple inorganic nutrients, usually
required in small amounts
Calcium Phosphorus Potassium Sulfur Chlorine Sodiu
m Magnesium Iron
Table 41-2
10Dietary Deficiencies
- Undernourishment diet consistently low in
chemical energy - Malnourishment long-term absence of essential
nutrients
An undernourished individuals use up stores,
break down own protein and muscle
Malnourishment can cause deformities, disease,
and death
11Food Intake
- Ingestion the act of eating
- Suspension feeders - many aquatic animals, which
sift small food particles from the water - Substrate feeders are animals that live in or on
their food source - Fluid feeders suck nutrient-rich fluid from a
living host - Bulk feeders eat relatively large pieces of food
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13- Digestion is the process of breaking food down
into molecules small enough to absorb - In chemical digestion, the process of enzymatic
hydrolysis splits bonds in molecules with the
addition of water - Absorption is uptake of nutrients by body cells
- Elimination is the passage of undigested material
out of the digestive compartment
14Food Intake
15Digestive Compartments
- Most animals process food in specialized
compartments - Reduces risk animal digesting
its own cells/
tissues
16Digestive Compartments
- More complex animals digestive tube with two
openings (mouth, anus) - Tube called a complete digestive tract or an
alimentary canal - Can have specialized regions, carry out digestion
and absorption stepwise
17Digestive Compartments
- Mammalian alimentary canal and accessory glands
that secrete digestive juices through ducts
18Oral Cavity, Pharynx, Esophagus
- Food shaped into a bolus, lubricated by saliva,
digestion begins with amylase. - Pharynx, a junction that opens to both the
esophagus and the trachea (windpipe)
- The esophagus conducts food from the pharynx down
to the stomach by peristalsis - Epiglottis blocks entry to the trachea, and
larynx.
19Digestion in the Stomach
- The stomach stores food and secretes gastric
juice, which converts a meal to acid chyme
- Gastric juice - hydrochloric acid and the enzyme
pepsin - Mucus protects the stomach lining from gastric
juice
20Digestion in the Small Intestine
- The small intestine longest section of
alimentary canal - Major organ of digestion and absorption
- First is the duodenum - acid chyme from the
stomach mixes with digestive juices from the
pancreas, liver, gallbladder, and the small
intestine itself.
liver/gallbladder bile aids digestion and
absorption of fats
small intestine lining of duodenum (brush border)
produces several digestive enzymes jejunum and
ileum mainly absorb water nutrients
pancreas proteases trypsin chymotrypsin,
protein-digesting enzymes neutralizes the acidic
chyme
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22Absorption in the Small Intestine
- small intestine has huge surface area, from villi
and microvilli exposed to the intestinal lumen - enormous microvillar surface greatly increases
rate of nutrient absorption
23Absorption in the Large Intestine
- The colon of the large intestine is connected to
the small intestine - The cecum aids in fermentation of plant
material, connects where the
small and large
intestines meet - Human cecum has extension
(appendix), plays a minor
role in immunity
Feces stored in rectum until eliminated
24- The colon houses strains of the bacterium
Escherichia coli, some of which produce vitamins - Two sphincters between the rectum and anus
control bowel movements
25Adaptations
- Herbivores generally have longer alimentary
canals than carnivores, reflecting the longer
time needed to digest vegetation
26Mutualistic Adaptations
- Many herbivores have symbiotic microorganisms
that digest cellulose - The most elaborate adaptations in ruminants
27Energy Sources and Stores
- Animals store excess calories as glycogen in the
liver and muscles - Energy secondarily stored as adipose, or fat,
cells - When fewer calories are taken in than are
expended, fuel is taken from storage and oxidized
- Obesity is due to excessive intake of food
energy, excess stored as fat - Obesity contributes to diabetes (type 2), cancer
of the colon and breasts, heart attacks, and
strokes
28StimulusBlood glucoselevel risesafter eating.
Homeostasis90 mg glucose/ 100 mL blood
StimulusBlood glucoselevel dropsbelow set
point.
29Energy Sources and Stores
- The complexity of weight control in humans is
evident from studies of the hormone leptin - Mice that inherit a defect in the gene for leptin
become very obese
30Obese mouse with mutant ob gene (left) next to
wild-type sibling mouse.
31Obesity and Evolution
- The problem of maintaining weight partly stems
from our evolutionary past, when fat hoarding was
a means of survival - A species of birds called petrels become obese as
chicks in order to consume enough protein from
high-fat food, chicks need to consume more
calories than they burn
32Figure 41.25 A plump petrel
33Lecture 13 concepts
- - Name the three nutritional needs that must be
met by diet - - Describe the four classes of essential
nutrients - - Distinguish among undernourishment,
overnourishment, and malnourishment - - Describe the four main stages of food
processing - - Distinguish between complete digestive tracts
and gastrovascular cavities - - Follow a meal through the mammalian digestive
system - List important enzymes and describe their roles
- Compare where and how the major types of
macromolecules are digested and absorbed - - Explain where and in what form energy-rich
molecules may be stored in the human body - Make a list of new vocabulary with definitions.