bio 12: digestive system (PLO QUESTIONS)

six major functions of liver

- detoxifies and stores poisons in the blood - secretes bile into duodenum to act as emulsifier of fats - produces urea from ammonia (amino acids breakdown) - helps maintain body temp. with large metabolic rate - stores fat soluble vitamins - recycles red blood cells, breaks down hemoglobin and putting waste (bilirubin) into the bile

describe functions of e. coli in the colon

beneficial bacteria in large intestine, like E. coli, break down fibre and release vitamins (including vitamin B and K) that we absorb

explain role of bile in emulsification of fats

bile salts secreted into duodenum coat tiny fat droplets and keep them from combining. bc droplets are small, there is large surface area of fat exposed to lipase which is an enzyme that digests fat molecules

biological molecules

carbohydrates, proteins, nucleic acids, lipids

identify source gland for insulin and describe function

endocrine portion of pancreas called islets of langerhans produces + secretes insulin (and glucagon) into blood. when blood glucose rises after a meal, insulin (protein hormone) is released into the blood stimulating the liver and the muscles to remove glucose from blood and store as glycogen

pancreatic amylase:

glandular source: pancreas + sent to duodenum digestive reaction: starch to maltose pH: slightly basic (8.5)

lipase

glandular source: pancreas + sent to duodenum digestive reaction: triglycerides to glycerol + 3 fatty acids pH: slightly basic (8.5)

nuclease

glandular source: pancreas to duodenum digestive reaction: hydrolyze DNA + RNA in food into nucleotides. other hydrolytic enzymes break nucleotides down further into nitrogenous bases, sugars, ad phosphates (nucleic acids converted to nucleotides) pH: slightly basic (8.5)

proteases (pepsin, trypsin)

glandular source: pepsin - gastric glands + sent to stomach, trypsin - pancreas + sent to duodenum digestive reaction: protein to peptides pH: pepsin (acidic: 1) trypsin (slightly basic: 8.5)

peptidase

glandular source: present in mucosa of intestinal villi of SI (intestinal glands) (AKA SI glands) sent to duodenum digestive reaction: peptides into amino acids (with water) pH: slightly basic (8.5)

maltase

glandular source: present in mucosa of intestinal villi of SI (intestinal glands) (AKA SI glands) to duodenum digestive reaction: completes digestion of maltose into glucose (with water) pH: slightly basic (8.5)

relate the following digestive enzymes to their glandular sources and describe the digestive reactions they promote: salivary amylase

glandular source: salivary glands (mouth) digestive reaction: begins process of food digesting (specifically starch). starch to maltose pH: neutral (7)

lipid

lipase

intestinal juice (components)

maltase, peptidase, nuclease

intestinal juice (digestive action)

maltase: digests maltose to glucose peptidase: digests peptides to amino acids nuclease: digests nucleic acids to nucleotides

gastric juice (components)

mucus, HCl, pepsinogen

pancreatic juice (digestive action)

neutralizes acid chime in duodenum

nucleic acids

nuclease

proteins

pepsin, trypsin, peptidase

gastric juice (digestive action)

protects stomach lining from HCl, kills bacteria + converts pepsinogen to pepsin, inactive enzyme converted to pepsin in acidic environment

peristalsis:

rhythmic contraction of smooth muscle surrounding esophagus, stomach and small intestine. pushes food through digestive tract

carbohydrates

salivary amylase, pancreatic amylase, maltase

pancreatic juice (components)

sodium bicarbonate, amylase, lipase, trypsin

during swallowing:

soft palate moves up (to prevent food from entering your nasal cavity) and the larynx moves up under the epiglottis to prevent food from entering; this forces food into the esophagus

describe how the SI is specialized for digestion and absorption

wall of SI contains fingerlike projections called villi and each villus is divided into groups of smaller villa (microvilli) which increases absorptive SA even more. - very thin wall (1 cell thick) of ciliated columnar epithelium (for short distance for diffusion of nutrients) - has blood capillaries to transport hydrophilic nutrients (a.a, sugars, etc..) - lacteal (part of lymphatic system) to aid in absorption of hydrophobic nutrients (lipids)