blood sugar levels homeostasis via negative feedback
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Blood Sugar LevelsHomeostasis via Negative Feedback
Obesity may be gene related
• Leptin leptin levels appetite - loss of body fat leptin levels and appetite
and wt gain
• potential medications for obesity
• An animal whose diet is missing one or more essential nutrients is said to be malnourished.
Giraffe eats bone to get phosphorus nutrient
• Vegetarian diet may result in protein deficiency
• Need essential amino acids– beans lysine – corn the methionine
• Healthy diets requires essential amino acids otherwise protein synthesis is retarded.
• Special adaptations during molting (non-feeding time)– uses their muscle proteins
as a source of amino acids to make new proteins
Healthy Diets Require:
• Water
• Carbs, Proteins, Lipids, Amino Acids
• Vitamins:
- water-soluble (thiamine, riboflavin, folic acid)
- fat-soluble (Vitamin A, D, E, K)
• Minerals (Fe, Ca, P, Na, K)
Water
• Solvent in which the chemistry of life occurs– cell chemistry occurs in an aqueous medium– water carries essential nutrients to cells– water carries metabolic wastes away from cells– hydrolysis & dehydration reaction– stabilizes body temp
Carbohydrates
• Energy Metabolism– catabolism of glucose during cellular
respiration yields ATP for energy-requiring activities
– glucose stored as glycogen in the liver and muscle cell fibers
– dietary fiber
Lipids
• Triglycerides (Fats)– energy storage molecules– protect and cushion delicate body
organs– source of the raw materials for the
construction of phospholipids– unsaturated versus saturated fats
Lipids
• Steroids (e.g., cholesterol)– precursor molecules for steroid
hormones, vitamin D, bile salts– fundamental component of plasma
membranes (influence membrane fluidity)– HDL-cholesterol versus LDL-cholesterol
Proteins
• Enzymes• Structural proteins (shape and
form of cells and tissues)• Hormones• Immunoglobulins (antibodies)
Vitamins
• Organic compounds needed by the body in small, but essential amounts
• Cannot be synthesized by the body in sufficient amounts
• Function in a variety of ways in metabolic reactions
• Thirteen known vitamins
Minerals
• Essential inorganic elements
• Involved in a variety of metabolic processes
• Major minerals versus trace minerals
Feeding Types:
• Herbivores
• Carnivores
• Omnivores
• Detritivores
Some Feeding TypesSome Feeding TypesMany species don’t fit into convenient categories
• Algal Grazers and Browsers• Suspension Feeding• Filter Feeding• Deposit Feeding• Benthic Animal Predators• Plankton Pickers• Corallivores• Piscivores• Omnivores• Detritivores• Scavengers• Parasites• Cannibals• Ontogenetic dietary shifts
Overview of Food Processing
The four main stages of food processing:
1. Ingestion
2. Digestion
3. Absorption
4. Elimination
Digestion occurs in specialized compartments
The simplest digestive compartments are food vacuoles; it is a process termed intracellular digestion
Gastrovascular cavity
Complete Digestive Tracts (Alimentary Canal)
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 41.13
Digestive ProcessDigestive Process
1.1. IngestionIngestion2.2. PropulsionPropulsion3.3. Mechanical DigestionMechanical Digestion
• MasticationMastication• Churning food in stomachChurning food in stomach
4.4. Chemical digestionChemical digestion5.5. AbsorptionAbsorption6.6. DefecationDefecation
incisors
cuspid
premolars
molars
TeethTeeth
enameldentinpulp cavity
root canal
bone
blood vessels
crown
neck
root
Salivary Glands
Salivary Glands
Saliva
watermucin
amylase
The Tongue
Taste Buds
papilla
taste bud
taste pore
Peristalsis
The Stomach
esophaguscardiac sphincter
pyloric sphincterduodenum
Stomach Secretions
Gastric Gland:Gastric Gland:Mucus cellsMucus cellsChief cellsChief cells
Parietal cellsParietal cells
Mucous neck cells- found in upper region of gastric glands produce• mucous
Parietal cells- in gastric gland of mucosa
produce• HCl – kills most bacteria• Intrinsic factor (required for absorption of vit. B12 in sm intestine, which is needed for producing mature erythrocytes)
Zymogenic (chief) cells-
produce• pepsinogen (inactive form of pepsin, which becomes active in presence of HCl) • rennin (milk digestion in children) protein digestion
Enteroendocrine cells in stomach mucosaproduces:
• Gastrin- regulates stomach secretions and mobility• Histamine- activates parietal cells to release HCl• Endorphins- natural opiates• Serotonin- causes contraction of stomach muscle• Cholecystokinin (CCK)- (in duodenal mucosa) many
functions and affects many organs• Somatostatin- (stomach and duodenal mucosa) -
inhibits gastrin, pancreatic secretions, inhibits GI blood flow in sm intestine…
Gastric ulcers: • erosion of stomach wall• pain occurs 1-3 hrs after eating• new research90% of recurrent ulcers
due to bacterial infection (Helicobacter pylori), which destroys mucous protective barrier
• use antibiotic therapy to kill bacteria
• Many of the protein-digesting enzymes, such as aminopeptidase, are secreted by the intestinal epithelium, but trypsin, chymotrypsin, and carboxypeptidase are secreted in inactive form by the pancreas.– Another intestinal enzyme,
enteropeptidase, converts inactive trypsinogen into active trypsin.
– Active trypsin then activates the other two.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Fig. 41.18
Pancreatic Enzymestrypsin
chemotrypsin
carboxypeptidase
amylase
phospholipase
lipase
nucleases
lumenmuscle layers
foldsvilli
Intestinal StructureIntestinal Structure
epithelial cells
capillaries
lacteal
Intestinal VillusIntestinal Villus
stomach
duodenum pancreas
pancreatic duct
common bile duct
gallbladder
liver
Bilebile saltsbile salts
bile pigmentsbile pigments
Intestinal Membrane Enzymes
disaccharidasesdisaccharidasesaminopeptidaseaminopeptidase
dipeptidasesdipeptidasesnucleotidasesnucleotidasesnucleosidasesnucleosidases
cecum appendix
ascending colon
transverse colon
descending
colon
sigmoidal
colon
rectum
internal anal sphincter external anal sphincter
anal canal
• Dentition, an animal’s assortment of teeth, is one example of structural
variation reflecting diet.
Deep sea gulper
Large expandable stomach
• The length of the vertebrate digestive system is also correlated with diet.
• Cellulose is difficult to digest• Termites have symbiotic
bacteria• Some bacteria and protists
have enzymes that hydrolyze cellulose
Symbiotic microorganisms aid in digestion