Digestion and Intestinal Absorption (part 2) Flashcards
state what it is meant by the key term - Fundus
the upper part of the stomach, next to the cardia
state 2 facts about the Fundus
- stores gas produced during digestion
2. doesn’t typically store food, but can do if the stomach is particularly full
state what it is meant by the key term - Lower oesophageal sphincter
a bundle of muscles at the lower end of the oesophagus, where it meets the stomach
state 1 additional fact about the lower oesophageal sphincter
prevents acids and stomach contents travelling back into the oesophagus
state what it is meant by the key term - body (of stomach)
lies between the fundus and the pyloric antrum
state an additional fact about the secretion in the body (of the stomach)
secretes mucus, pepsinogen and HCL
state what it is meant by the key term - antrum
the lower portion (near the small intestine) where the food mixes with the gastric juice
state an additional fact about the antrum
secretes mucus, pepsinogen and gastrin
state what it is meant by the key term - pyloric sphincter
a band of smooth muscle that controls the movement of partially digested food and juices from the pylorus into the duodenum
state 2 additional facts about the pyloric sphincter
- allows the stomach contents to enter the small intestine
2. prevents contents re-entering the stomach
state what it is meant by the key term - pylorus
the part of the stomach that connects to the duodenum (first part of the small intestine). a valve which opens and closes during digestion
state what it is meant by the key term - cardia
the part of the stomach closest to the oesophagus. foods and liquids pass through the cardia to enter the stomach from the oesophagus
how is it possible to live without the stomach ?
it is possible to live without the stomach with Vitamin B12 injections
what are the three main structures in the small intestine ? (in order)
- duodenum
- jejunum
- ilium
state what it is meant by the key term - duodenum
the first part of the small intestine immediately beyond the stomach, leading to the jejunum
state 2 additional facts about the duodenum
- produces hormones
2. receives liver secretions (bile) and pancreas secretions (pancreatic juices containing digestive enzymes)
state what it is meant by the key term - jejunum
the part of the small intestine between the duodenum and the ilium
state an additional fact about the jejunum
absorbs sugars, amino acids and fatty acids
state what it is meant by the key term - ilium
the third portion of the small intestine, between the jejunum and the caecum
state an additional fact about the ilium
absorbs final nutrients (bile acids + Vitamin B12 especially)
state what it is meant by the key term - villi
tiny hair like projections that line the inside of the small intestine with certain blood vessels to help absorb nutrients
state what it is meant by the key term - micro-villi
protrusions from the apical surface of the epithelial cells which function to increase cell SA and the efficiency of absorption
state what it is meant by the key term - brush border
the intestinal lining and is the site of terminal carbohydrate digestion
state what it is meant by the key term - krept of Lieberkuhn
the pit between villi in the small intestine
state an additional fact about the ‘krept of lieberkuhn’
contain numerous cells, such as stem cells to produce new cells, to replenish those lost due to abrasion as well as enteroendocrine cells to synthesise and secrete hormones
state what it is meant by the key term - enteroendocrine
Enteroendocrine cells are specialized cells found within the gastrointestinal tract, stomach and pancreas. They produce and release hormones in response to a number of stimuli
state the 3 roles of the pancreas in the digestion and absorption process
- secretion of pancreatic juices (bicarbonate)
- secretion of proteases
- secretion of pancreatic lipase
state the function of the gall bladder in the digestion and absorption process
the storage and concentration of bile
state the function of - amylase (salivary)
initial digestion of starch
state 4 functions of HCl in the digestion and absorption process
- denaturation of proteins
- acidification of pepsin action
- antibacterial
- activation of pepsinogen
state the function of - pepsin (secreted as pepsinogen)
initial digestion of proteins
state the function of - gastric lipase
lipid hydrolysis in the stomach
state the function of - bile
neutralisation of chyme
state the function of - bile salts
emulsification of fats
state the function of - saccus entericus (intestinal juice)
lubrication
state the function of - pancreatic juice
neutralisation of chyme
state the function of - proteases
digestion of proteins to oligopeptides and free amino acids
state the function of - pancreatic lipase
triacylglycerol hydrolysis
state the function of - diahaccharidase
disaccharide hydrolysis
state the function of - peptidases
hydrolysis of peptides to dipeptides and tripeptides
state 2 functions of the liver in the digestion and absorption process
- secretion of bile (bile and bile salts)
2. processing of absorbed nutrients
state 3 functions of bile in the digestion process
- bile salts
- phospholipids
- bicarbonate (HCO3-)
state the 3 functions of bile in the ‘substance removal from the blood’ function
- cholesterol
- bile pigments
- trace metals
state the names of the 2 incretin hormones you need to know
- Glucose dependent insulinotropic polypeptide (GIP)
2. Glucagon-like peptide 1 (GLP-1)
state 3 facts about glucose-dependent insulinotropic polypeptide (GIP)
- stimulated by nutrients in the small intestine
- secreted by K cells in the duodenum and jejunum
- stimulates insulin secretion
state 3/6 facts about glucagon-like peptide 1 (GLP-1)
- stimulated by nutrients in the small intestine
- secreted by L cells in the ilium
- promotes insulin release
- inhibits glucagon release
- delays gastric emptying
- surpasses appetite + energy intake
state 3 introductory facts about lipid emulsification
- lipids are insoluble in water
- lipase can only act on the surface of fat droplets
- emulsification increases surface area (SA)
explain the 6 step fat emulsification process
- emulsified
- hydrolysed by lipase
- temporarily stored as micelles
- transported into epithelial cells
- re-synthesised to triaglycerides (TAG)
- packaged as Chylomicrons
state 4 facts about small intestine motility
- more segmentation than peristalsis
- rhythmic contraction and relaxation by longitudinal muscles
- greater mixing of material
- contributes to the net flow through the small intestine
explain what it is meant by the key term - gastroileal reflex (2 points)
- segmentation increased in ilium with gastric emptying
2. once the majority of a meal is absorbed, segmentation is replaced with peristalsis
explain what it is meant by the key term - migrating myoelectric complex (MMC) - (2 points)
- moves undigested materials to the large intestine
2. prevents bacteria from remaining in the small intestine too long
state the 3 main functions of the colon/large intestine in the digestion and absorption process
- primary storage of material prior to defecation
- some digestion of undigested material (via bacteria)
- fluid absorption helps to concentrate fecal matter
state 2 facts about the iliocecal sphincter
- opens to allow chyme into colon from ilium when ilium contracts
- closes when large intestine distends
explain segmentation in the large intestine
slower in large intestine, approx 18-24 hour duration
state what it is meant by the key term - endopeptidases
Endopeptidase, or endoproteinase, are proteolytic peptidases that break peptide bonds of non-terminal amino acids
state what it is meant by the key term - exopeptidases
An exopeptidase is any peptidase that catalyzes the cleavage of the terminal peptide bond; the process releases a single amino acid or dipeptide from the peptide chain
state what it is meant by the key term - membrane bound dipeptidases
enzymes secreted by enterocytes are secreted onto the brush border of the villi in the small intestine and into the small intestine where they hydrolyse dipeptides into their two component amino acids prior to absorption
