concept 41.1: an animals diet must supply chemical energy, organic molecules, and essential...
TRANSCRIPT
Concept 41.1: An animal’s diet must supply chemical energy, organic molecules, and
essential nutrients
• An animal’s diet provides:1. Chemical energy, which is converted into ATP to
power cellular processes2. Organic building blocks, such as organic carbon and
organic nitrogen, to synthesize a variety of organic molecules
3. Essential nutrients, which are required by cells and must be obtained from dietary sources
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Essential Nutrients
• There are four classes of essential nutrients:1. Essential amino acids2. Essential fatty acids3. Vitamins - organic4. Minerals - inorganic
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• Animals require 20 amino acids and can synthesize about half from molecules in their diet
• The remaining amino acids, the essential amino acids, must be obtained from food in preassembled form
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What is the problem with a vegan diet?
Table 41.1
Table 41.2
Figure 41.3
Why is this fella licking the ground?
Review of Key points
• Essential amino acids are only those which the organism cannot self-produce
• Recall metabolism; why are vitamins needed in small capacity?
They form coenzymes vital for catalysis • If an animal is eating plenty of food but still appears
malnourished, how could you tell which nutrient in its diet it is lacking?
• By adding individual nutrient supplements to its diet and observing which nutrient eliminates signs of malnutrition
41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination
Hannah Ragozzino
Chapter 41: Nutrition
• Ingestion o the act of eating
• Digestion o the process of breaking down molecules small
enough for the body to absorb Mechanical digestion
• breaking up food into smaller pieces (chewing) Chemical digestion
• enzymatic hydrolysis splits bonds in molecules with addition of water
• Absorption o uptake of nutrients by body cells
• Elimination o passage of undigested material through the
digestive system
http://hodnett-ap.wikispaces.com/Chapter+41+Animal+Nutrition
Suspended (filter) Feeders• Suspended feeders
eat small organisms or food particles suspended in the watero Most aquatic
animals ex./ clams and oysters
http://www.flickr.com/groups/megaptera/discuss/72157594514167479/
Baleen
Substrate Feeders
• Animals that live in or on their food sourceo Leaf miner caterpillar (moth larva)
http://www.mun.ca/biology/mcolbo/Lectures%2015,16,17/003.%20Lecture%2017%20B1002.htm
Caterpillar
Feces
Fluid Feeders• Suck nutrient rich fluid from a living host
o Mosquitoes suck blood o Aphids tap phloem sap of plants
https://kleczekbiology.wikispaces.com/Digestive+Systemhttp://en.wikipedia.org/wiki/
Aphid
Bulk Feeders• Eat relatively large pieces of food
o Most animals, includes humans
http://dpshots.com/photo-inspiration/35-award-winning-photographs-from-around-the-world.html
http://aspiringbackpacker.com/2012/05/5-huge-eating-challenges-world/
• Extracellular Digestiono Breakdown of food
particles in compartments that are continuous within the outside of the animals body
Digestive Compartments
• Intracellular Digestiono Food particles engulfed by
endocytosis and digested within food vacuoles
Gastrovascular Cavity
• Many animals with simple body plans have digestive compartment with single openingo Functions in digestion and
distribution of nutrients
http://www.studyblue.com/notes/note/n/chapter-41/deck/2482484
Alimentary Canals• Most animals have a
complete digestive cavityo Two openings- mouth and anus
• Organized into specialized compartments that carry out digestion and nutrient absorption stepwise
Concept 41.3: Organs specialized for sequential stages of food processing
form the mammalian digestive system© 2011 Pearson Education, Inc.
mammalian digestive system- alimentary canal + accessory glands that secrete digestive juices through ducts
Liver
Salivaryglands
Gall-bladder
Esophagus
Pharynx
Oral cavity
Sphincter
Mouth
Stomach
Esophagus
Tongue
Pancreas
SmallintestineLargeintestine
RectumAnus
SphincterStomach
Duodenum ofsmall intestine
Pancreas
Schematic diagramAnusRectum
Largeintestine
SmallintestineLiver
Salivaryglands
Gall-bladder
Peristalsis-rhythmic contractions of muscles in the wall of the canal
Tongue
Pharynx
Glottis
Larynx
Bolus offood
Epiglottisup
EsophagealsphinctercontractedEsophagus
To lungs To stomach Relaxedmuscles
Contractedmuscles
Sphincterrelaxed
Stomach
Trachea
Figure 41.10-3
•The first stage of digestion is mechanical and takes place in the oral cavity•Salivary glands-deliver saliva to lubricate food
• salivary amylase initiates breakdown of glucose polymers•Saliva contains mucus, a viscous mixture of water, salts, cells, and glycoproteins
Digestion in the Stomach
• Stomach-stores food and secretes gastric juice, which converts a meal to acid chyme– Gastric juice has a low pH of about 2, which kills bacteria
and denatures proteins• Gastric juice is made up of hydrochloric acid (HCl) and pepsin• Pepsin is a protease, or protein-digesting enzyme, that cleaves
proteins into smaller peptides
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Gastric gland
Gastric pits oninterior surface
of stomach
Sphincter
Smallintestine
Epithelium
Mucous cell
Chief cell
Parietal cell
Chiefcell
Pepsinogen
Parietalcell
Pepsin
Folds ofepithelialtissue
Sphincter
Esophagus
Stomach
3
2
1
10
m
HCl
H
Cl
Figure 41.11
• Mucus protects the stomach lining from gastric juice
• 15 – 32 feet in humans• Duodenum- first portion of the small
intestine– chyme from the stomach mixes with
digestive juices from the pancreas, liver, gallbladder, and the small intestine itself
– Most of nutrient digestion here• Most nutrients pumped against gradient
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Most of absorption happens in the small intestine
Pancreatic Secretions• The pancreas produces proteases trypsin and chymotrypsin
that are activated in the lumen of the duodenum• Its solution is alkaline to act as a buffer
© 2011 Pearson Education, Inc.
Bile Production by the Liver• In the small intestine, bile aids in digestion and absorption of
fats• Bile is made in the liver and stored in the gallbladder• Bile also destroys nonfunctional red blood cells
Vein carryingblood to liver
Muscle layers
Bloodcapillaries
Villi
Intestinal wall
Epithelialcells
Largecircularfolds
Key
Nutrientabsorption
Villi Microvilli (brushborder) at apical(lumenal) surface
Epithelialcells
Lumen
Basalsurface
Lacteal
Lymphvessel
• Hepatic portal vein-carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart
• The liver regulates nutrient distribution, interconverts many organic molecules, and detoxifies many organic molecules
Fat digestionNucleic acid digestion
Protein digestion
Fat (triglycerides)DNA, RNA
Nucleotides
Pancreaticnucleases
Pancreatic lipase
Glycerol, fatty acids,monoglycerides
Nucleotidases
Nucleosides
Nucleosidasesandphosphatases
Nitrogenous bases,sugars, phosphatesAmino acids
Dipeptidases, carboxy-peptidase, andaminopeptidase
Small peptides
Pancreatic carboxypeptidase
Smallerpolypeptides
Pancreatic trypsin andchymotrypsin
Small polypeptides
Proteins
Pepsin
Carbohydrate digestion
Polysaccharides Disaccharides
Salivary amylase
Smallerpolysaccharides
Maltose
Pancreatic amylases
Disaccharides
Disaccharidases
Monosaccharides
Smallintestine(enzymesfromepithelium)
Smallintestine(enzymesfrompancreas)
Stomach
Oral cavity,pharynx,esophagus
Figure 41.12-4
Ascendingportionof colon
Smallintestine
AppendixCecum
The colon’s primary purpose is to absorb water from chyme.
Absorption in the Large Intestine
• > 90% of water reabsorbed– not enough water absorbed
back to body » diarrhea
– too much water absorbed back to body
» constipation• Cecum-aids in the fermentation of plant material
and connects where the small and large intestines meet
• The human cecum has an extension called the appendix, which plays a very minor role in immunity
http://www.youtube.com/watch?v=f2vCHNHkHG8
• There are approximately 500 species of bacteria comprising the gut flora (part of the “human microbiome”) that aid in digestion – 100 trillion cells compared to 10 trillion actual body cells
• Feces, including undigested material and bacteria (30% of dry weight), become more solid as they move through the colon
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Symbiotic bacteria and digestion
• Feces are stored in the rectum until they can be eliminated through the anus• Two sphincters between the rectum and anus control bowel movements, the top
being involuntary, the bottom (anus) being voluntary
Concept 41.4
Evolutionary adaptations of vertebrate digestive systems correlate with diet
Dental Adaptations
• The evolutionary adaptation of teeth for processing different kinds of food is one of the reasons why mammals are so successful
Omnivore
Carnivore
Herbivore
Stomach and Intestinal Adaptations
• Many carnivores have large, expandable stomachs
• Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation
Smallintestine Stomach
Cecum
Carnivore
Colon(largeintestine)
Small intestine
Herbivore
Mutualistic Adaptations
• Many herbivores have fermentation chambers, where mutualistic microorganisms digest cellulose
• The most elaborate adaptations for an herbivorous diet have evolved in the animals called ruminants
Reticulum
Esophagus
OmasumAbomasum
Intestine
Rumen1 2
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Concept 41.5 : Feedback circuits regulate digestion,
energy storage, and appetite
Rachel Sylvia Mr. Reis
AP Biology 18 March 2013
Regulation of Digestion: • Arrival of food triggers
secretion of substances which promote next stage of chemical digestion &muscle contractions which move food along canal
• Hormones:• - make sure digestive
secretions are only around when they need to be
• - transported through bloodstream Chyme=
partially
digested
food
• When an animal takes in more energy-rich molecules than it needs- it stores them
• Humans store energy first in the liver and muscle cells
• Stored in glycogen = polymer made of glucose units
• Excess energy is stored as fat in adipose cells
• Adipose tissue provides the most space efficient way for the body to store large amounts of energy
Too much
adipose tissue
Not enough adipose tissue
• Synthesis and breakdown of glycogen is central to
• - energy storage • -maintaining metabolic balance • Tissues in the body rely on ATP generation
by oxidation of glucose in order to fuel cellular processes
• Overnourishment = consumption of more calories than needed
• Causes obesity => health problems (colon & breast cancer, diabeetus, and cardiovascular disease)
• Hormones can contribute to appetite • Ghrelin- triggers feelings or hunger as mealtime
approaches • Insulin- secreted after eating- blood sugar level
rises • Leptin- suppresses appetite/ produced by adipose • *body fat decreases = leptin level decrease =
appetite increase• PYY- appetite suppressant which counters ghrelin
and is secreted by the small intestine after a meal
So basically…..
• Healthy weight is hard to maintain possibly because of evolution
• In the past fat hoarding was important to some for survival
• Ex. Baby petrels need protein/lipid rich foods in order to survive
• Babies are obese