Chapter 41 Flashcards
What is nutrition?
food being taken in, taken apart, or taken up
All animals are heterotrophs, but…
they need to eat enough food and have a balanced diet to survive and reproduce
Three nutritional needs
- Fuel for cells
- Organic materials for biosynthesis
- Essential nutrients
Fuel for cells
ATP
Organic materials for biosynthesis
proteins, carbohydrates, lipids, and nucleic acids
carbohydrates
sugars
lipids
fats
Essential nutrients
cannot by synthesized, must be consumed
Examples of essential nutrients
some amino acids, fatty acids, and vitamins and minerals
Malnutrition
occurs when diet lacks one or more essential nutrient or consistently supplies less energy than body needs
What can malnutrition cause?
deformities, disease, death
Undernutrition
occurs when diet lacks adequate sources of chemical energy (carbs, protein, lipids)
When are humans considered undernourished?
If they consume less than the recommended 2,200 kcals/day
Kwashiorkor
occurs mainly in children whose diet lacks high quality protein
Marasmus
caused by a diet low in protein and calories
Characterized by discolored skin and bloated stomach
Kwashiorkor
Characterized by being very thin, shriveled with low resistance to infection
Marasmus
Ingestion
the act of eating/feeding
Hydrolysis
using water to break down food
Digestion
breakingn down food into absorbable molecules
Two types of digestion
- Mechanical digestion
2. Chemical digestion
Mechanical digestion
breaks food into smaller pieces (chewing)
Chemical digestion
chemical breakdown of food particles into nutrients via enzymes
What are nutrients used for?
energy and biosynthesis
Protiens
amino acids
Carbohydrates
sugars
Lipids
fatty acids and glycerol
Absorption
cells take up (absorb) nutrients through the bloodstream
Steps to processing food
- Ingestion
- Digestion
- Absorption
- Elimination
Elimination
undigested material exits through the digestive track
How is it that animals do not digest their own cell tissues?
Digestive compartments
Digestive compartments
food processing happens in specialized areas of the body to prevent enzymes from breaking down animals’ own tissues
Digestion can be…
Intracellular or extracellular
Intracellular digestion
food particle engulfed by the cell
Where does intracellular digestion occur?
within organelles that contain digestive enzymes
Extracellular digestion
occurs outside cells in a specialized compartment and is continuous with exterior
When is food “inside” the body
nutrients cross a layer of cells (absorption)
Two types of extracellular digestion
- Gastrovascular cavity
2. Alimentary canal
Step 1 of the Gastrovascular cavity
Digestive enzymes are released from a gland cell
Step 2 of the gastrovascular cavity
enzymes break food down into small particles
Step 3 of the gastrovascular cavity
food particles are engulfed and digested in food vacuoles
Gastrovascular cavity
digestive sac with a single opening that functions as a mouth and anus
What does the gastrovascular cavity function in?
digestion and circulation of nutrients
Where is gastrovascular cavity observed in?
simple animals
Alimentary canal
- complete digestive tract
- two openings
- food moves in one direction
- specialized regions for different tasks
Two openings in alimentary canal
mouth and anus
Accessory glands of alimentary canal
secrete digestive juices through ducts into the canal
4 types of accessory glands
- Salivary glands
- Liver
- Pancreas
- Gullbladder
Peristaisis
alternate waves of contractions and relaxation in the smooth muscle lining the canal
What does the peristaisis do?
propels food
Sphincters
muscular valves that regulate passage of material between segmenets
What occurs in the oral cavity
mechanical digestion and chemical digestion
Mechanical digestion increases…
SA
What occurs during chemical digestion?
- Salivary glands release saliva
2. Salivary amylase begins carb digestion
What does the tongue do?
shapes the food into a bolus and pushes it to the pharynx
Pharynx
“throat,” opens to trachea and esophagus
Epiglottis
blocks trachea during swallowing
Esophagus
moves food from pharynx to stomach
What types of muscles near top of esophagus?
Skeletal (swallowing)
What type of muscles in the middle to lower esophagus?
Switches to smooth (involuntary contractions (peristalsis))