Chapter 41 Flashcards
Nutrition
process of organisms taking in and making use of food substances
- Food intake and use of nutrients vary with animal and environment
- Animals are opportunistic feeders
3 Categories of animal feeders
herbivores
carnivores
omniovres
Herbivores
eat mainly plants and algae
Longer alimentary canals- longer time needed to digest vegetation
Herbivores and Omnivores
Carnivores
eat other animals
Large expandable stomachs
Carnivores
Omnivores
consume animals and plants or algae
4 Classes of Essential Nutrients:
Amino Acids
Fatty Acids
Minerals
Vitamins
How many Amino acids are animals required?
20 Amino Acids
- Synthesize about half from molecules in diet
- Other half must come from food to make a “complete protein”
Examples of Amino Acids
- Meat, cheese, eggs
- Most plant are not complete proteins, need to eat specific plant combinations to get all essential amino acids
Fatty acids
- Fatty acid deficiencies are rare
- Animals synthesize most of fatty acids needed
Essential fatty acids
include unsaturated fats (fatty acids with one or more double bonds) must be obtained from diet
Vitamins
are organic molecules required in diet in small amounts
What are the two categories of Vitamins?
- Fat-soluble
- Water- soluble
Minerals
Simple inorganic nutrients (required in small amounts)
What can upset homeostatic balance if ingest large amounts?
minerals
Under-nutrition
When diet does not provide enough chemical energy
5 common reactions body goes through when undernourished?
- Use up fat and carbohydrates
- Breaks down it own proteins
- Lose muscle mass
- Suffer protein deficiency of brain
- Die or suffer irreversible damage
What can provides info about an individuals nutrition?
Genetic defects that disrupt food uptake
Epidemiology
study of human health and disease in population, insight of human nutrition
Hemochromatosis
cause iron buildup without excessive iron intake
Deficiency of folic acid in pregnant woman results in…
Neural tube defects
Four food processing stages
Ingestion
Digestion
Absorption
Elimination
Ingestion
act of eating
Digestion
breaking food down into molecules small enough to absorb
Absorption
up take of nutrients by body cells
Elimination
passage of undigested material out of the digestive system
Four types of feeders
Suspension and filter feeders
Substrate feeders
Fluid feeders
Bulk feeders
Chemical digestion
splits food into small molecules, pass thru membranes, used to build larger molecules
Mechanical digestion
chewing and increasing foods surface area
Enzymatic hydrolysis
splits bonds in molecules with water
Enteric division of what organ system helps regulate digestion?
nervous system
Endocrine system regulates digestion by…
releasing and transporting hormones
Two organ systems to help regulate digestion
Nervous and Endocrine system
What glands secrete digestive juices through ducts?
alimentary canal and accessory glands
Sphincters (valves)
regulates movement of material between compartments
Four accessory glands in the digestive system
salivary glands, pancreas, liver, and gallbladder
Peristalsis
(food is pushed along) rhythmic contractions of muscles in the wall of the canal
Helps prevent chyme from entering esophagus and regulate entry into small intestines
Sphincters (valves)
Which food processing stages is activates each step as needed?
Digestion
Esophagus
connects to stomach
Pharynx
opens both the esophagus and trachea
Trachea (windpipe)
leads to lungs
Bolus
shape tongue makes and helps swallowing
Amylase
initiating breakdown of glucose polymers
1st stage of digestion is ________ and takes place in the ________
mechanical and oral cavity
What in the oral cavity breaks food into smaller particles?
Teeth
Salivary glands
delivers saliva to lubricate food
Saliva contains mucus, a mixture of…
water, salt, cells, and glycoproteins
Mucus
protects the stomach lining from gastric juice
Digestion in Stomach
Contraction and relaxation of stomach muscles churn contents
Stomach
stores food and secretes gastric juice and converts a meal into acid chyme
Gastric juice
- Has low pH (about 2)
- kills bacteria and denatures proteins
What is made of hydrochloric acid (HCl) and pepsin?
gastric juice
Pepsin
is protease a protein- digesting enzyme, cleaves proteins into smaller peptides
Parietal cells
secrete hydrogen and chloride ions separately in the lumen (stomach cavity)
Chief cells
secrete inactive-pepsinogen which activates when mixed with hydrochloric acid in stomach
Small intestine
longest section of alimentary canal
Major organ of digestion and absorption
Small intestine
Hepatic portal vein
carries nutrient-rich blood from capillaries of the villi to liver to heart
Transport across epithelial cells can be passive or active
Depending on nutrient
Liver
regulates nutrient distribution, interconverts and detoxifies organic molecules
What organ has a large surface area due to absorption?
Small Intestine
Duodenum
1st portion of the small intestine
Most digestion occurs in what part of the small intestine?
duodenum
What does duodenum epithelial lining produce?
digestive enzymes
Pancreas
produces proteases trypsin and chymotrypsin that are activated in the lumen of duodenum
- Solution is alkaline and neutralizes the acidic chyme
Enzymatic digestion
peristalsis moves chyme and digestive juices along small intestine
Jejunum and ileum
absorption of nutrients and water
Where does chyme from stomach mixes with digestive juices from pancreas, liver, gallbladder, and small intestine?
duodenum
Bile
aids in digestion and absorption of fats
Where is bile made and stored?
Made in the liver stored in the gallbladder
What destroys nonfunctional red blood cells?
Bile
The colon of the large intestine is connected to the _______
small intestine
Feces
undigested material and bacteria, becomes more solid when moved thru colon
Rectum
feces is stored until eliminated thru anus
Appendix
extension of cecum, play minor role in immunity
Cecum
aids in fermentation of plant materials and connects where small and large intestine meet
What controls a bowel movement?
Two sphincter between rectum and anus
Two major functions of the colon
- Recover water that has entered alimentary canal
- Houses bacteria that lives on unabsorbed material and vitamins
Oxidation of glucose
generates ATP to fuel cellular processes
What does the body do to energy-righ molecules that are not needed right away for metabolism?
Body stores the energy-rich molecules for later use
Energy stores first in the
liver and muscles cells in polymer glycogen
Where is excess energy stored
in adipose tissue: most space-efficient storage tissue
Where does Glucose Homeostasis occur?
In the liver
Low blood sugar causes…
glucagon to stimulate breakdown of glycogen and release glucose
Carbohydrate-rich meal raises…
insulin levels which triggers synthesis of glycogen
The do the hormones insulin and glucagon do?
regulate the breakdown of glycogen to glucose
What does over-nourishment cause?
obesity- excessive food intake energy with excess stored fat
What common diseases does obesity contribute to?
diabetes (type 2), cancer (colon, breast), heart attack, and strokes
Leptin
Helps suppress appetite
Why do the petrels (bird) become obese as chicks?
they become obese as chicks to consume enough protein from high-fat food, chicks need more calories than they burn
Hormones regulate long and short term appetite by affecting the “_____”
“satiety center” in the brain
What produces leptin?
adipose tissue
