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Terms in this set (41)
What are the general functions of nutrients?
Biosynthesis, energy, essential nutrients; substances required for survival
What types of organic molecules serve as the main source of our energy?
carbohydrates and fats
How can a vegetarian ensure that he or she obtains all or the essential amino acids in the diet?
Eat combinations of plants so that they can receive all nutrients
What are vitamins and why is it necessary to ingest them in the diet?
Used to synthesize cofactors for enzymes (temporarily hold electrons)
What physiological purpose do vitamins typically serve?
Helps make bones, collagen, hemoglobin, etc.
What are some common dietary minerals?
Cu, Zn, Fe, I, Na, K, Cl, Ca, P
What are the functions of these dietary minerals?
Cu, Zn - enzymes
I - hormones
Na, K, Cl, Ca - electrolytes
Ca, P - bone formation
What are the four basic digestive processes?
Ingestion of food
Absorption into blood/lymph, elimination of indigestible material
What occurs during digestion?
Mechanical and chemical breakdown of food into monomers (monosaccharides, amino acids, fatty acids)
How does digestion in primitive organisms (such as cnidarians) differ from more complex bilateral organisms?
Cnidarians have incomplete digestive tracts
Single opening that acts in food ingestion and waste elimination
They take food in, Ingest food and eliminate waste via mouth, pharynx transports food and wastes, and the gastrovascular cavity is where digestion and absorption occur
Their ingestion and waste elimination occur at mouth, our ingestion occurs at mouth, waste elimination at anus
What are the main regions of the digestive tract?
What are the main accessory organs?
What digestive functions occur in the mouth?
Mechanical and chemical digestion
How do the teeth of omnivores, carnivores, and herbivores differ?
Omnivores have molars and bicuspids for grinding, carnivores have larges canines to tear, herbivores have large incisors for slicing
What enzymes occur in the mouth and what are their functions?
Salivary glands produce saliva
Amylase - enzyme that breaks down starch into disaccharides
Water and mucin provide lubrication
Lingual lipase - begin to break down fats into monoglycerides and fatty acids
During swallowing, what is the function of the epiglottis?
What is the function of the esophagus?
The esophagus conducts food from the oral cavity to stomach
What is the function of peristalsis and how does it occur?
a wave of muscular contractions that move food through esophagus
What are the functions of the stomach?
The stomach function in mechanical and chemical digestion of proteins
Churning of 3 muscle layers = solid food converted to liquid (chyme)
Function of Rumens
Rumens were evolved as a multi-chambered organ specialized for digesting cellulose
Function of Gizzards
Gizzards were evolved because birds lack teeth and need to accomplish mechanical digestion (chewing food) internally
What are the 2 main chemicals secreted by the glands of the stomach, and what are the functions of each?
HCl and Pepsin
Where is HCl secreted from and what is its function?
Where is Pepsin secreted from and what is its function?
produces protease that causes hydrolysis of peptide bonds
How is pepsin formed from the inactive proenzyme?
Secreted as inactive proenzyme (pepsinogen)
HCl converts pepsinogen to pepsin; Pepsin then converts more pepsinogen to pepsin
What is the advantage of secreting pepsin as a proenzyme?
it protects the chief cell from self-digestion
At what pH is pepsin most active?
What structures are responsible for the huge surface area of the small intestine?
Folds, villi, microvilli and crypts
What are the digestive secretions of the pancreas?
Peptidase, amylase, lipase
How are pancreatic proteases activated?
Pancreatic proteases activated by trypsin
How do bile salts and lipase both function in the digestion of fat molecules?
Lipase acts on fats that have been emulsified by bile salts
Large fat globules → bile salts emulsify → Small fat droplets → lipase digests
What are the two main functions of the small intestine?
Completes chemical digestion
Functions in absorption
How are polysaccharides digested? What are the breakdown products? How are they absorbed?
Carbohydrates → monosaccharide (glucose)
Digested by pancreatic amylase
Absorbed by facilitated diffusion
How are proteins digested? What are the breakdown products? How are they absorbed?
Proteins → amino acids
Digested by trypsin
Absorbed by facilitated diffusion and cotransport
How are lipids digested? What are the breakdown products? How are they absorbed?
Fats → fatty acids
Digested by bile salts and pancreatic lipase
Absorbed by exocytosis
What is the mechanism by which glucose is taken up into intestinal epithelial cells and then released into the blood?
Glucose is take up via glucose absorption
Na+ actively transported our of intestinal cell into blood lowering Na+ concentration
Na+ diffuses into cell from lumen through cotransporter proteins
Glucose is transported into cell along with Na+
Exits into blood via facilitated diffuson
What are the functions of the large intestine?
Absorption of water
Bacterial vitamin synthesis (K)
Formation of feces
How does its internal lining compare with that of the small intestine?
It is smooth
What is a cloaca?
Enlarged portion of rectum
Which organ systems terminate in the cloaca?
Junction of urinary, digestive, and reproductive systems
Where does digestion of carbs occur? Proteins? Lipids?
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