Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Foundations of Nutrition > Digestion & Absorption > Flashcards

Digestion & Absorption Flashcards

1
Q

Define Digestion

A

Sequential ordered process with physiological links between each stage. Each specific stage allows the interaction of fluid and emulsifying agent, acid-base exchange, enzyme and substrate contact. Each stage is regulated and integrated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is digestion important?

A

Food contains a mix of nutrients, often within a complex chemical / compound that cannot be directly absorbed and digestion allows for access to the desired nutrients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two types of digestion

A

Chemical & Mechanical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the first part of digestion called

A

Mastication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name the functions of the mouth in digestion?

A

Mechanical Digestion -> chewing
Chemical Digestion -> salivary lipases & amylase
Propulsion of food into oesophagus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give 3 functions of saliva in digestion

A

Moistens food
Buffers pH of food
Antibacterial (immunoglobulins and lysozymes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does the oesophagus move food from mouth to stomach

A

Peristalsis (oesophagus tissue can secrete mucous for aid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Give 3 cell types in the stomach

A

Epithelial, Parietal Epithelial, Chief Cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of epithelial stomach cells?

A

Produce mucous and bicarbonate which makes an alkaline barrier to protect the epithelium and stomach from the acid produced -> i.e. cytoprotective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the function of stomach parietal epithelial cells

A

Secrete hydrogen and chloride ions to form HCl acid and also secretes intrinsic factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the functions of stomach chief cells

A

Secretion of zymogens and enzymes (pepsinogen, chymosin (carbohydrate enzymes) and gastric lipase).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Give 4 function of the stomach

A 
Stores chyme
Absorbs ethanol and lipid soluble drugs
Mechanical digestion -> churning
Chemical digestion -> gastric enzymes and acid
Sterilisation of food stuff
Inactivation of salivary amylase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is absorbed in the stomach?

A

Ethanol

Lipid soluble drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain the structure of the small intestine in regards to surface area

A

Mucosal folds forms villi

Apical villi contain further folds called microvilli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give 3 functions of the duodenum

A

Receives chyme from the stomach
Receives digestive juices from sphincter of Oddi (pancreatic, gall bladder and liver)
Duodenal gland cells secrete mucous and bicarb for lubrication and neutralisation
Fatty acid absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give the main function of the jejunum

A

Bulk of absorption takes place here - particularly carbs and amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Give 3 main functions of the ileum

A

Reabsorption of bile salts
Absorption of vitamins (+ particularly Vit B12 bound to IF)
Transport undigestible matter into colon via ileocaecal valve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Give 2 function of gall bladder/liver secretions in the lumen

A

pH neutralisation & fat emulsification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Give 2 main functions of pancreatic secretions in the lumen

A

pH neutralisation, chemical digestion (lipase, amylase and proteases)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Give the 3 main parts of the large colon along with one function

A

Caecum - receives undigested food
Colon - home of intestinal flora, absorbs water & mineral salts
Rectum - storage of faeces until defecation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is starch made up of?

A

Two polysaccharide chains called Amylose & Amylopectin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the bonding involved with amylose?

A

unbranched alpha 1-4, glycosidic bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the bonding involved with amylopectin?

A

alpha 1-4 glycosidic bonds with alpha 1-6 branching glycosidic bonds every 12 subunits of glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Explain the digestion of starch

A

Amylases in saliva and pancreatic juice breaks alpha-1,4 bonds in starch down into oligosaccharides, disaccharides (maltose), dextrins (smaller units containing the alpha-1,6 bonds).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What type of enzymes are found in the brush-border that digests carbohydrates / disaccharides?
Hydrolase enzymes
26
Name the three most common brush border enzymes involved in disaccharide digestion and their targets with breakdown products
Maltase -> Maltose -> 2 x glucose Sucrase -> Sucrose -> 1 glucose & 1 fructose Lactase -> Lactose -> 1 glucose & 1 galactose
27
What brush border enzyme can break down dextrin and why?
Sucrase-Isomaltase -> can hydrolyse both the 1,6 and the 1,4 glycosidic bonds
28
What transporters are important in the absorption of monosaccharides
``` SGLT-1 = Glucose & Galactose into enterocyte GLUT5 = Fructose into enterocyte GLUT2 = All 3 out of cell basolaterally ```
29
Does GLUT2 require ATP?
Yes
30
How efficient is protein digestion & absorption
Extremely efficient, 1g of nitrogen is excreted out of faeces every day regardless of intake (0-250g)
31
What part of protein digestion cycle is recyclable
Most enzymes used in the digestion of protein are all reabsorbed and recycled
32
Where is protein mostly absorbed?
upper two thirds small intestine
33
What is the 'classification' of enzymes involved with protein digestion? (Edwards question)
Protease & Peptidase Protease digests proteins in peptides Peptidases digest peptides but are a subclass of protease The two terms are used interchangeably
34
What is the first sight and stage of protein digestion?
Stomach
35
How does the stomach digest proteins
Acid denatures proteins Pepsinogen is secreted by chief cells in stomach and becomes activated to form pepsin by the acid which then acts as a protease to break down the protein into smaller peptides
36
What is the key feature of chyme moving to the duodenum in reference to protein digestion
Neutralisation turns off pepsin and turns on and allows for the pancreatic peptidases to work
37
What are the two main types of peptidases that work in the small intestine and how do they differ?
Endopeptidases - these attack internal peptide bonds giving smaller peptides / di/tri peptides etc Exopeptidases - these cleave off AAs at the end of peptide chains
38
What 3 main digestive enzymes are found in pancreatic juices that work on protein & classify them.
Trypsin, Chymotrypsin -> endopeptidases | Carboxypeptidases -> exopeptidases
39
Name 2 examples each of endo and exo peptidases
``` Endo = trypsin & chymotrypsin Exo = carboxypeptidase & dipeptidase ```
40
What is the final enzyme on the brush border on SI that works on dipeptides for final digestion before absorption?
Dipeptidases (a type of exopeptidase)
41
Explain the breakdown of proteins in terms of location
In the stomach whole proteins are broken down into large and small peptides. In the SI these peptides are further broken down into smaller peptides, tri, di peptides and AAs via the juices from pancreas. Brush border enzymes results in AAs, di and sometimes tri peptides.
42
How are amino acids and peptides absorbed?
A family of transporters that can absorb AAs, di and tri peptides into the enterocyte.
43
What features do protein transporters exhibit?
Stereospecificity -> prefer specific AAs only Broad Substrate Specificity -> likes multiple AAs Overlapping Specificty -> Allows AAs to have a choice
44
How can you classify amino acid and peptide transporters?
Based on amino acid it transports i.e. acid, basic etc | Based on mechanism of use i.e. facilitated, active etc
45
How does absorption of amino acids work to get them in the blood?
Only AAs can be absorbed and cross the basolateral aspect of the enterocyte. So extra enzymes are required to digest di and tri peptides into AAs within the cytosol
46
Explain the process of enzyme cascade in pancreatic juice/enzymes
Pancreas secretes zymogens - trypsinogen, chymotrypsinogen and procarboxypeptidase. Trypsinogen is converted to active trypsin via enterokinase / enteropeptidase (found in the lumen wall of jejunal and possibly duodenal cells). Activated trypsin converts chymotrypsinogen to chymotrypsin and then chymotrypsin converts procarboxypeptidases in carboxypeptidase
47
What is the main type of fat in the diet?
Triacylglyceride (<90%)
48
What are TAGs made up of?
Glycerol & Fatty acids esterfied
49
Name three potential places where enzymes are secreted to aid lipid digestion and absorption
Lingual, Gastric, Pancreatic Lipase
50
Name an enzyme other than lipase that can help digest lipids
Cholesterol Esterase or Phospholipase
51
Why do we need to emulsify lipids?
Lipids are non-water soluble, all the enzymes that digest lipids are water soluble. Therefore they can only act on the lipid surface of the droplets and emulsification helps to form smaller droplets to increases the SA for enzymes to act upon
52
What are some of the breakdown products from lipid digestion?
Glycerol, mono and di glyceride, fatty acids.
53
How does emulsified droplets form?
Mechanical digestion physically breaks up droplets into smaller ones, then bile salts and phospholipids (amphiphatic molecules) bind to the droplet surface. THe polar regions of the amphiphatic molecules allows for repelling between droplets and therefore keeping them apart and small.
54
how are micelles absorbed in the SI
The micelles are presented to the microvilli and the acidic micro-environment results in micelle breakdown and the contents of the micelle diffuse across apical membrane
55
What is the differences between fatty acid chain lengths in relation to absorption and digestion
Small chain FAs - not really present in diet but if they were they wouldn't be absorbed Medium Chain FA - these are amphiphatic so cross the mucous layer and can diffuse across the cell membrane. These then diffuse across basolateral side without processing, attach to albumin in blood and enter blood system Long Chain FAs - requires micelle transport to pass mucou layer, microenviroment being acidic breaks micelle down and releases contents to be diffused across membrane. Contents then enter cell and reformed into TAGs in sER and golgi apparatus packaged into chylomicrons and excreted into lacteals / lymphatic system
56
What are found inside chylomicrons
Phospholipids, Cholesterol, Fat Soluble Vitamins and newly formed TAGs
57
What is the difference in FA absorption rates vs cholesterol?
``` FA = 95% (diet up to 100g) Cholesterol = 40% ```
58
Name the components of bile (6)
Bile Acids & Bicarbonate - aids digestion | Cholesterol, Toxic Metals, Bile Pigments, Lecithin - waste products from the body
59
What are the main bile acids?
``` Cholic & Chenodeoxycholic Acid (synthesised by liver) Deoxycholic Acid (synthesised by gut bacteria) ```
60
Name 4 functions of bile acid
Acts as detergents for FA emulsification Promotes cholesterol, phospholipid & lecithin excretion Promotes colonic mobility Prevents undue dehydration of faeces
61
What two mechanisms are present to help newborns digest fat?
Lingual serous glands secrete lipase and maternal breast milk contains lipase
62
Give two causes of maldigestion and then two causes of malabsorption of fats
M/D = pancreatitis, liver disease, pancreatic head tumours, gall bladder disease M/A = coeliac, gastroenteritis, inflammatory conditions (due to the sensitised epithelium)
63
Does resection of the ileum lead to maldigestion or malabsorption of fats & describe the mechanism as to why
Ileum resections means bile salts are not reabsorbed so therefore there will be a lack of them and a lack of emulsification so therefore cannot properly digest it = M/D.
64
What regulates water absorption in the intestines?
Osmotic pressure gradients & aquaporins
65
How are electrolytes and minerals absorbed?
Carrier Mediated Diffusion - i.e. requires a transporter but diffuses through. Then they bind to intracellular proteins and are secreted into the blood via actie transport
66
What two minerals is the absorption tightly regulated for?
Calcium & Iron
67
How are vitamins absorbed?
Fat Soluble -> with micelles and chylomicrons Water Soluble -> diffusion Vit B12 -> bound to intrinsic factor & absorbed in ileum
68
Give 3 examples of anti-vitamins
Chelators -> effect Mg and Ca Phytates -> bind to Ca, Fe, Zn complexes Tanins -> Fe complexes High FA conc. can prevent Mg and Ca absorption Oxidising compounds can reduce Fe2+ to Fe3+ which is no longer absorbable
69
What cells secrete gastrin hormone
G cells in the gastric pit
70
Give 3 stimulants for gastrin hormone release
Amino acids / peptides in stomach Distention of stomach Vagal stimulation (cephalic phase) GRP (gastrin releasing peptide) from short neural reflex in the ENS
71
What inhibits gastrin secretion
Somatostatin | Low pH in stomach
72
What is the function of gastrin
Stimulates parietal cells to release ions | Stimulates ECL cells to release histamine
73
What cell secretes CCK?
Duodenal Mucosal Cells
74
What is the main function for CCK?
Aid digestion of nutrients
75
What stimulates CCK release?
Fat and amino acids in duodenum
76
Give 3 effects of CCK
Reduces gastric emptying Increases pancreatic enzyme secretion Gall bladder contraction Relaxation / Opening of Sphincter of Oddi
77
What cells release secretin?
Duodenal Mucosal Cells
78
What is the main function of secretin?
Acid Neutralisation
79
What stimulates secretin release?
Acid present in the duodenum
80
What 3 results are there following secretin release?
Inhibits HCl secretion by parietal cells Reduces gastric emptying Increases bicarb secretion from the pancreas, duodenal cells, and bile duct
81
What does GIP and GLP-1 hormones stand for?
``` GIP = gastric inhibitory polypeptide GLP-1 = Glucagon like peptide -1 ```
82
What term encompasses the GIP and GLP-1 hormones?
Incretin Hormones
83
What are the incretin homrones
GIP & GLP-1 | Gastric inhibitory polypeptide, Glucagon like peptide1
84
What stimulates incretin hormone release
Anything that stimulates insulin release from pancreatic b-cells -> amino acids and glucose presence in the duodenum
85
What is the overall function of the incretin hormones
Lower blood glucose levels
86
What 3 mechanisms does the incretin hormones directly do
Increases insulin secretion Decreases glucagon secretion Reduces gastric emptying

Foundations of Nutrition (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions