Nutrition Flashcards
What does the liver make to help digestion?
Bile
Where is bile stored?
Gall Bladder
When is bile secreted onto the food?
As it’s leaving the stomach and entering the duodenum
What does Bile do?
It emulsifies lipids, produces a large surface area and lipid droplets
and provides an alkaline solution to neutralise acidic chyme
Where is lipase produced?
pancreas
when is lipase secreted?
onto the emulsified lipids in the duodenum
what does lipase do?
digests ester bonds in the lipids
what bonds do protease enzymes digest?
peptide bonds
what do endopeptidases do?
digests peptide bonds within the polypeptide leaving di or tri - peptides
what do exopeptidases do?
hydrolyse the terminal peptide bonds releasing single amino acids
what is released to aid digestion and maintain a low ph in the stomach and for what?
Hydrochloric acid maintains at ph1.5 for proteases to work at their optimum
What is partly digested food called in the stomach?
Chyme
What are the 4 layers of the gut wall?
Mucosa
Submucosa
Muscularis externa
serosa
what is the structure of the mucosa?
Glandular epithelium + connective tissue containing blood and lymph vessels. surrounds lumen
what is the structure of the submucosa?
connective tissue containing blood and lymph vessels + elastic fibres and collagen
what is the structure of the muscularis externa?
circular and longitudinal smooth muscle fibres
what is the structure of the serosa?
loose connective tissue
what is digestion?
the breakdown of complex, insoluble, organic molecules, into small, simple soluble molecules
what is mechanical digestion?
the physical breakdown of large food particles into smaller particles
what is chemical digestion?
the hydrolysis of complex molecules into simple soluble molecules - catalysed by enzymes
what is mastication?
the mechanical grinding of food into smaller pieces by teeth, chewing
what is the purpose of mastication?
smaller food particles are easier to swallow
creates a larger surface area for chemical digestion by salivary amylase
what is peristalsis?
the movement of food down the alimentary canal
how does peristalsis occur?
brought about by wavelike contraction and relaxation of circular and longitudinal muscle in the muscularis externa
where does the circular muscle contract?
behind the bolus
where does the longitudinal muscle contract?
in front of the bolus
what do carbohydrases do?
catalyse the hydrolysis of glycosidic bonds in carbohydrates
what do proteases do?
catalyse the hydrolysis of peptide bonds in proteins and polypeptides
what do lipases do?
catatlyse the hydrolysis of ester bonds in triglycerides
what are the stages of carbohydrate digestion?
Starch broken down to dextrins that are broken down into maltose - both in saliva and pancreatic juice
maltose is broken down into glucose - membranes of microvilli of ileum endothelium
How is the mouth and buccal cavity involved in carbohydrate digestion?
food is masticated and mixed with saliva from salivary glands.
what is the optimum ph of the buccal cavity?
6.7-7.3
what is the optimum ph of the duodenum?
7
what is the optimum ph of the ileum?
Between 7 and 8
what is the role of the salivary amylase?
Breaking down carbohydrates into simpler sugars
what is the role of the lysozyme?
Fighting infections
what is the role of the mucus?
trapping unwanted substances like bacteria and dust before they can get into the body – particularly the sensitive airways
what is the role of the chloride ions?
Neuronal signaling
what is the role of the chloride ions?
Neuronal signalling
what is the role of the duodenum?
receive secretion from pancreas and liver, Brunner’s glands secrete intestinal alkaline juice to neutralise acidic chyme
What is the role of amylase?
Amylase is a digestive enzyme that acts on starch in food, breaking it down into smaller carbohydrate molecules
What is the role of alkaline salts?
digestion and absorption of nutrients and also serve as a means for excretion of several waste products from the blood
What is the role of lipase?
breaks down dietary fats into smaller molecules called fatty acids and glycerol
What is the role of protease?
responsible for breaking down proteins into amino acids that our bodies need
What is the role of maltase?
catalyses the breakdown of a molecule of maltose into two molecules of glucose which can be absorbed into the blood
What is the role of lactase?
digests lactose
What is the role of sucrase?
catalysing the hydrolysis of starch, sucrase, and isomaltase, among other dietary carbohydrates
what is absorption?
the passage of soluble products of digestion into the bloodstream, most occurs in the small intestine
How is the small intestine adapted for absorption?
Has villi that has a large surface area, is long (about 5m) also increases surface area
what does the mucus do?
lubricates food
protects the endothelium from effects of digestive enzymes
