Transcript DNA Technology - Loyalsock Township School District

Ch. 41
Need to Feed
Animal nutrition
• Food being taken in, taken apart, and
taken up
Herbivores
• Dine mainly on plants
Carnivores
• Dine mainly on other animals
Omnivores
• Regularly dine on animals, plants, and
algae
Opportunistic Feeders
• Eat outside normal diet when usual
Essential Nutrients
Materials that an animal’s cells require but cannot synthesize
Essential Amino Acids
• Must be obtained from food (8)
Essential Fatty Acids
• Most are synthesized
Vitamins
• Organic molecules that have diverse functions and are
required in the diet in very small amounts
• Water soluble vs. fat soluble
Minerals
• Inorganic nutrients required in small amounts
• cofactors
Essential Nutrients
Essential Nutrients
Dietary Deficiencies
Diet that lacks one or more essential nutrients or
consistently supplies less chemical energy than the
body requires
Malnourished
• Failure to obtain adequate nutrition
Undernutrition
• A diet that fails to provide adequate sources of
chemical energy
Overnourished
• obesity
Assessing Nutritional Needs
Ingestion, Digestion, Absorption, Elimination
1.
Ingestion
– act of eating/feeding
2. Digestion
– Food is broken down into
molecules small enough for
the body to absorb
– Mechanical and chemical
3.
Absorption
– uptake of small molecules
from digestion
4. Elimination
– undigested material passes
out of the digestive
compartment
Four Main Feeding Mechanisms of Animals
Suspension feeders and filter
feeders
• Eat small organisms or food
particles suspended in the
water
– clams, oysters
• Use a filtering structure to
strain food from water
– Baleen whale
Substrate feeders
• live on or in their food source
• leaf miners
Feeding Adaptations
Deposit feeders
• substrate feeder that ingests partially
decayed organic matter
• Earthworms
Fluid feeders
• suck nutrient rich fluids from a living
host
• aphids, hummingbirds, bees, leeches,
mosquitoes
Bulk feeders
• eat relatively large pieces of food
• adaptations to kill prey or tear off
vegetation
Digestive Compartments
Intracellular Digestion
• Hydrolysis of food inside vacuoles
• Begins with phagocytosis or
pinocytosis
Food vacuoles
• organelle that digests its food
without hydrolytic enzymes
mixing with the cell’s cytoplasm
• Fuse with lysosomes
• Sponges
Digestive Compartments
Extracellular digestion
• Digestion occurs within
compartments that are
continuous, with the outside
of the body
Gastrovascular cavity
• digestive sac with a single
opening; functions in both
digestion and nutrient
absorption
• More complex animals have
alimentary canals
Digestive Compartments
Alimentary canal (complete
digestive tract)
• digestive tube running
between two openings:
mouth and anus
• organized into
compartments for
digestion and absorption
(increases efficiency)
• unidirectional passage of
food
Mammalian Digestion
Organs Specialized for Sequential
Food Processing
Alimentary Canal and
Accessory Organs
Peristalsis
• Alternating waves of
contraction and
relaxation in the smooth
muscles lining the canal
Sphincters
• junctions b/w specialized
compartments that act
like ringlike valves
Oral Cavity, Pharynx, Esophagus
Oral Cavity
• Beginning of physical and chemical
digestion
– chewing
– secretions from salivary glands
Saliva contains…
– mucin, buffers, antibacterial agents,
amylase
Bolus
– chewed food that enters the pharynx
Oral Cavity, Pharynx, Esophagus
Pharynx
• intersection for both
digestive and
respiratory systems
• epiglottis blocks
trachea during
swallowing
Esophagus
• conducts bolus from
pharynx to stomach
via peristalsis
Digestion in the Stomach
Food storage
• elastic wall with rugae to hold up to 2L of
food
Churning
• contraction of stomach muscles
• mixed about every 20 minutes; takes 2-6
hours to pass to the small intestine
• Begins digestion of protein
• bolus  chyme
• passes to small intestine through pyloric
sphincter
Digestion in the Stomach
Secretion
• controlled by the
hormone, gastrin
• mucous cells (secrete
mucin & gastrin)
• chief cells (release
pepsinogen or zymogen)
• parietal cells (secrete HCl
& intrinsic factor)
• HCl + pepsinogen 
pepsin (a protease – a
protein digesting enzyme)
Digestion in the Small Intestine
• Cholecystokinin
• Major organ of digestion and
absorption
• Pancreas, liver, gall bladder, and
small intestine all contribute to what
occurs here
• Products released into duodenum
– 1st part of the small intestine
• Jejunum and ileum
– Villi and microvilli
Pancreatic Secretions
Exocrine gland
Secretes hydrolytic enzymes
Produces bicarbonate solution to neutralize stomach acid
Bile Production and Secretions by Liver
Bile
• Mixture of substances made in the liver that act as
emulsifiers of fat
• Stored and concentrated in the gall bladder
Epithelial lining
• Source of many digestive enzymes
Absorption in the Small Intestine
Villi
• Fingerlike, epithelial
projections
• Microvilli – epithelial
projections on each villus
cell
Hepatic portal vein
• Blood vessel that leads to
directly to the liver
• Liver regulates
distribution of nutrients
and allows toxins to be
removed
Absorption in the Small Intestine
Chylomicrons
• Water soluble fat globules
made of triglycerides coated
in phospholipids, cholesterol
and proteins
Lacteal
• Vessel at the end of each villus
• Part of lymphatic system
Absorption in the Large Intestine
Cecum, colon, rectum
Appendix is an extension of the cecum
• lymphoid tissue
Water reabsorption
Feces moved along by peristalsis
• Becomes increasingly solid
Intestinal bacteria
• Methane, hydrogen sulfide, vitamin K, biotin, folic acid
Two sphincters (one voluntary and one involuntary)
control the exiting of the feces
Digestive System
Digestive System
Dental Adaptations
•carnivores: pointed
canines & incisors
•herbivores: broad,
ridged surfaces
•omnivores:
unspecialized
•snakes: fangs
Stomach and Intestinal Adaptations
Length of
tract and diet
–herbivores
and omnivores
have a longer
tract b/c cell
walls are more
difficult to
digest
Mutualistic Adaptations
Symbiotic bacteria and
protozoa
• Produce cellulase
• Horses: in large cecum
• Rabbits and some
rodents: in cecum and
colon
– Corophagy (”dung
eating”)
• Ruminants
– Deer sheep cattle
Regulation of Digestion
1. Gastrin
2. Cholecystokinin and secretin
Glucose Homeostasis
1. High blood glucose
– insulin
2. Low blood glucose
– glucagon
Regulation of Appetite and Consumption
Ghrelin
• Triggers feelings of
hunger
Insulin
• Suppresses appetite
Leptin
• Suppresses appetite
PYY
• Appetite
suppressant;
counters ghrelin