Digestion and parasitism Flashcards
what enzyme breaks down triglycerides
lipase
what does lipase break down triglycerides into
glycerol and 3 fatty acids
enzyme that breaks down starch
amylase
the enzyme that breaks down sucrose
sucrase
enzymes that break down dipeptides into amino acids
dipeptidase
enzymes that break down polypeptides into dipeptides
proteases
endopeptidase
they cut in the middle of a polypeptide
exopeptidases
they cut at the terminal ends of the polypeptide
describe digestion in the buccal cavity
the food is broken down into small pieces in the mouth by the chewing action of the teeth (mastication)
it is then moistened by saliva
what does saliva consist of
water
mineral salts
lysozyme
salivary amylase
mucus
functions of mucus in digestion
acts as a lubricant
functions of lysozyme in digestion
it kills bacteria that may be present in the food
functions of mineral salts in saliva
they maintain the slightly alkali conditions
functions of salivary amylase
Hydrolyses starch to maltose
after digestion in the buccal cavity, what term is given to the food
bolus
peristalsis
a series of rhythmic contractions that move the bolus to the stomach
describe the series of muscle activities that occur during peristalsis to propel the bolus along the gut
the circular muscles behind the food contract and the longitudinal muscles relax
the name of the ridges on the stomach and their functions
rugae
they help with the mechanical breakdown of the food (churning)
how many layers of thick muscle does the stomach have, name them and is their collective function
three
longitudinal muscle
circular muscle
oblique muscle layer
they allow the stomach to contract and relax to grind the bolus
the function of the cardiac sphincter
it relaxes at the upper end of the stomach, allowing food to enter the stomach
the function of the pyloric sphincter
relaxes to allow food to exit the stomach into the duodenum
can the stomach stretch
yes
functions of the mucus released from goblet cells of the stomach
it protects the stomach wall from enzymes and acid
name three substances that the stomach absorbs
water
salts
alcohol
aspirin
which part of the stomach secretes gastric juice
it is secreted by glands in the mucosa of the stomach wall
which cells release HCl acid in the stomach
what are the functions of the HCl released
oxyntic cells
it kills most bacteria in the food swallowed
provides optimum ph for enzymes in the stomach
it activates pepsinogen
average ph of the stomach
1-2
the enzyme found in the gastric juice
pepsin
which cells release pepsin
chief cells
pepsin is released as inactive……… by chief cells
pepsinogen
which organ produces bile
where is bile stored
the liver
in the gall bladder
functions of bile
emulsifies lipids into small droplets(this increases the surface area, which in turn increases the rate of digestion)
aids in neutralizing the stomach acid as it enters the duodenum with food from the stomach
which type of glands in the pancreas secretes pancreatic juice
exocrine gland
the function of amylase and lipase
amylase hydrolyses starch into maltose
hydrolyses lipids into fatty acids and glycerol
is the duodenum alkaline or acidic
alkaline
Functions of the Brunner’s gland in the submucosa of the duodenum
it secretes mucus for lubrication and protection of the intestinal walls
it secretes alkaline juices which help to maintain the optimum ph for the functioning of the enzymes in this area
in which part of the duodenum is the carbohydrate and protein digestion completed
in the membrane of the epithelial cells of the mucosa
name two enzymes found in the duodenum and their functions
maltase: hydrolyses maltose into two glucose molecules
dipeptidases: hydrolyses dipeptides into amino acids
pepsin
an endopeptidase secreted by gastric glands in the stomach as inactive pepsinogen
trypsin
an endopeptidase secreted by the pancreas as inactive trypsinogen.
trypsin is activated by
enterokinase
name five things that the pancreas is composed of
sodium hydrogen carbonate
endopeptidases
exopeptidases
amylase
lipase
the function of the sodium hydrogen carbonate in the pancreas
raises the pH to alkaline levels, thereby neutralizing stomach acid. this provides optimum conditions for pancreatic enzymes
describe the process of chemical digestion of lipids
bile is added to lipids via the bile duct to emulsify the lipids into small droplets
the emulsified lipids get hydrolyzed by lipase from the pancreas, to form fatty acids and glycerol
adaptations of the ileum for absorption
the lining of the ileum is folded to increase the surface area for absorption
the surface of the villi found on the surface of the ileum is made of specialized epithelial cells with projections called microvilli. these also help to increase the surface area for absorption
epithelial cells of villi are made of many mitochondria that aid active transport of substances
describe the process of absorption of water-soluble vitamins
they pass through the epithelial membrane via facilitated diffusion through transport proteins and dissolve in the plasma
describe the process of absorption of fatty acids and glycerol in the ileum
they diffuse into the SER in the epithelial cells via the epithelial membranes.
they then recombine into triglycerides and are packaged into vesicles along with cholesterols and phospholipids
the triglycerides enter the lacteals, which are the center of the villus
they are then transported to the subclavian vein through the lymphatic system
they enter the blood system at the thoracic duct.
during absorption in the ileum, glucose, and amino acids are transported via the ………………… ……………………….vein to the ……………………………
hepatic portal
liver
how are glucose and other monosaccharides absorbed in the ileum
they are absorbed into the epithelial cells by co-transport with sodium ions and then into the capillaries by facilitated diffusion.
Sodium ions are actively pumped out of the epithelial cells into the capillaries during this process.
adaptions of the ileum to aid absorption
they have epithelial cells with microvilli to increase the surface area of the ileum for the absorption of molecules
they have goblet cells to secrete mucus
after deamination, what happens to the remaining C H and O
they are converted to carbohydrates
they are also used in respiration
what happens to the fatty acids(lipids) absorbed during absorption
they are used to produce phospholipids in cell membranes, to synthesize hormones
excess lipids are stored as fat
the function of the glucose absorbed by the ileum
used in aerobic respiration
excess glucose is converted to glycogen or fat and stored in the liver
the large intestines are divided into four main sections, name them
caecum
appendix
colon
rectum
the function of the colon
absorption of the remaining water and mineral salts
the absorb vitamins like folic acid, secreted by microorganisms living in the colon
why do carnivores have a short gut
because they feed on meat, which is high in proteins. and proteins are easily digested
the dentition of a dog is designed for …………………. the prey, …………………….. and ……………….. meat off the bones and …………………… bones
gripping
cutting and tearing
crushing
types of teeth in carnivores, their shape(structure) and their functions
incisors: they are small and shaped like chisels and are sharp. they are used to snip meat off bones and to cut lumps of meat up
canines: they are very long and sharp. they are used to impale and grip the prey, and to tear meat.
carnassial teeth: when the dog is eating, they fit together like a pair of scissors, sniping meat off the bone and also crushing bones
premolars and molars: they have strongly pointed cusps for cutting and tearing meat
the carnassial teeth
the last upper premolar and the first lower molar
types of teeth in carnivores, their shapes (structure), and function
incisors: they are small but are shaped like chisels and sharp. they are used to snip meat off bones and to cut lumps of meat up
canines: they are very long and sharp. they are used to impale and grip the prey to tear the meat
carnassial teeth: they fit together like a pair of scissors, snipping meat off bones and also crushing bones.
molars and premolars: they have strongly pointed cusps for cutting and tearing meat
what is the dentition of herbivores designed for
for cutting off the grass from the plant when grazing
grinding the grass efficiently to smash the cellulose cell walls
thus releasing the digestible plant cell contents
diastema
a space between the horny pad and the upper premolars
function of the incisors in herbivores
they bite against the horny pad on the upper jaw. This enables the vegetation to be snipped off the plants during feeding
the function of the diastema, and the advantage it grants the herbivore
it is filled with extra grass during feeding so that they can stop feeding until the grass is chewed and swallowed
this enables the herbivore to look around frequently to watch for predators
is the diastema found in carnivores
no
it is a characteristic of herbivores
how is the circular grinding motion of herbivores obtained, and what is the importance of this
through the horizontal movement of the lower jaws during chewing
this effectively breaks open the cellulose walls of plant cells
the teeth of herbivores can grow throughout their lifespan, why is this
because the root cavities of their premolars and molars remain open throughout their lives. this means a good blood supply is maintained to the teeth, and it can therefore grow throughout their lives
structure and function of the premolars and molars of herbivores
they are strengthened with ridges of cement which help to prevent the edges of the teeth from being chipped away by abrasive food
why are herbivore guts longer than carnivore guts
because the cellulose cells walls in the food of herbivores need more time and enzyme action to be broken down
more space is required to accommodate bulkier plant material
name an organism with a monogastric digestive system
humans
name three animals with the ruminant digestive system
cow
sheep
goat
the stomachs of sheep and cows are divided into ………….. chambers
name the chambers
4
rumen
reticulum
omasum
abomasum
how do mammals break down cellulose cells walls in their food
they have cellulase-secreting bacteria that break down cellulose in plant cell walls
do mammals contain cellulases
nope
products of fermentation and their functions
beta glucose and large quantities of fatty acids
they form a major energy source for the animal
describe the process of digestion in ruminants
mutualistic bacteria are mainly found in the rumen and reticulum. after chewing, the food is passed into the rumen
from the rumen, the food passes into the smaller reticulum. the food is then regurgitated from the reticulum into the buccal cavity for chewing of the cud
when the food is re-swallowed, it is channeled into the omasum
in the omasum, the food is churned about. It is then passed to the abomasum which produces the typical acid and secretions of all mammalian stomachs
any bacteria that enter the abomasum are killed by acid secretions and digested.
the food then goes into the intestines where the products of digestion can be absorbed
which chamber of the stomach is known as the true stomach
the abomasum
why is food churned in the omasum
to allow for further bacterial fermentation
