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Metabolism of Food Components > 2. Process of Food Digestion and Nutrients Absorption in the Body > Flashcards

2. Process of Food Digestion and Nutrients Absorption in the Body Flashcards

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1
Q

What is digestive system?

A

Series of process to convert complex compounds (food) into simple compounds (nutrients) so that they can be utilized by the body (through mechanical and chemical process)

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2
Q

Explain the steps of digestive system

A
  1. Ingestion: entering food into the body through mouth to be digested mechanically and chemically
  2. Digestion: Process of breaking down food into molecules that are easily absorbed by the body
  3. Absorption: Process of nutrients absorption so they can be utilized by the body from small intestine -> blood vessels -> liver -> body
  4. Defecation: Process of emptying the intestine by removing unnecessary substanceq
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3
Q

Explain components of ingestion system

A
  1. Mechanical digestion:
    a) teeth: breaks down food into small pieces
    b) tongue: helps press crushed food (bolus) and pushes it down esophagus, stimulates salivary excretion
  2. Chemical digestion:
    Salivary glands (parotid, submandibular, sublingual)
    a) lubricating mouth and dissolving food
    b) amylase/ptyalin enzyme digests starch into maltose (food -> disaccharides)
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4
Q

Explain components of digestion system

A
  1. Gastric acid
    a) consist of HCL, KCl, NaCl, and digestive enzymes (Rennin only in infants), pepsin, lipase.
    b) Very acidic ph 2.0,
    c) used to digest food (acid hydrolysis), kills pathogenic microbes,
    d) secretion mechanism: reflex and influenced by GASTRIN HORMONE produced in gastric glands
  2. Chemical digestion
    a) protein: pepsin enzyme
    b) fat: gastric lipase
    c) milk protein coagulation: rennin (chymosin, rennet) -> further digested by pepsin
    d) dietary fiber and cellulose: passed (not digested)
  3. Mechanical digestion:
    a) Peristalsis by stomach muscles to mix food w/ gastric juisces -> forms pulp (chyme)
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5
Q

Why can’t children <12 m.o consume cow’s milk?

A

it contains a lot of casein protein while they particularly have low level of pepsin enzyme

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6
Q
  1. Casein + calcium ion produce? What enzyme is used? (a)
  2. (a) is broken down to (b) by using what enzyme? (c)
A

a) para-casein
b) peptide
c) pepsin

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7
Q

Explain components of digestive system prepared before absorption

A
  1. Liver
    a) Blood detoxification
    b) Carb metabolism
    - Glycogenesis: synthesis of glycogen from excess blood sugar
    - Glycogenolysis: breakdown of glycogen during fasting
    - Gluconeogenesis: Synthesis of glucose from non-sugar materials
    c) Fat metabolism:
    - synt of cholesterol and phospholipids
    - triglyceride oxidation -> energy
    d) protein synt
    e) bile acid secretion
    f) storage of vitamins (ADEK) and minerals (Fe)
  2. Pancreas
    a) Secretion of pancreatic fluid (NaCO3): 1 pH of chyme
    b) Secretion of insulin (lowers blood sugar) and glucagon (rises blood sugar)
    c) Produced enzymes:
    - alpha amylase: carb/starch -> simple sugar
    - Lipase: Fat -> fatty acid
    - Nuclease: Break down nucleic acids
    - Proteolytic enzymes:
    protein -> amino acids
    *Protease (large protein molecules)
    *Peptidase (Peptide)
    d) Enzyme secretion is stimulated by CCK hormone
  3. Gall bladder
    a) storage of bile acids
    b) transport bile acids into small intenstine w/ stimulation of cholecystokinin (CCK) hormone
    c) Bile acid is used to emulsify fat during digestive process in small intestine
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8
Q

Explain digestion and absorption components

A
  1. Duodenum
    a) length 25 cm
    b) receive chyme from stomach, NaCO3 from pancreas and bile acids from gall bladder
    c) Neutralize acids (pH 7-8) before entering jejunum
  2. Jejunum
    a) length 2.5 m
    b) chemical digestion and nutrients absorption occur here
    c) many villi to expand absorption surface
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9
Q

What enzymes are produced in digestion and absorption phase?

A
  1. Aminopeptidase: polypeptide -> simple peptide + AA
  2. Dipeptidase: Dipeptide + AA
  3. MG-lipase: MG -? FA + glycerol
  4. Disaccharide
    a) Sucrase: Sucrose -> fructose gluocse
    b) Maltase: glucose + glucose
    c) Lactose: Glucose + galactose
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10
Q

Where does defecation take place? Explain!

A

Colon.
1. Length and width: 1.5 m and 7.5 cm
2. Receive residual digestion after being absorbed in small intestine
3. Regulate water content of food reabsorption and digestion to form feces
4. Absorption of bile acids to be returned to liver
5. Absorption of vitamins synth by bacteria (vit. K, biotin, B5)
6. Absorption of organic waste by bacteria:
a) bilirubin -> urobilinogen (yellow pigment in urine) and stercobilinogen (brown pigment in feces)
b) peptide in feces -> ammonia, indole and skatole, H2S
c) fermentable dietary fiber -> flatus

  1. stool storage before disposal
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11
Q

What nutrients needed and not needed to be digested before absorption?

A
  1. Large organic moleecules must be digested before absorption can occur
  2. Water, electrolytes, vitamins, and alcohol can be absorbed without being digested, but req special transport
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12
Q

What is hydrolysis and what are the substances that is broken down through this process?

A

Hydrolysis is the process of breaking down molecular bonds in large organic molecules. Carbs, proteins, fats, and nucleic acids

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13
Q

Digestive enzyme based on hydrolysed substrate?

A

a) carbohydrase: break bonds between simple sugars
b) protease: break bonds between amino acids
c) lipase: separate fatty acids from glycerides

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14
Q

arrange the steps of digestion

A

chewing-churning-segmentation in small intestine- mass peristalsis

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15
Q

mechanism of digestive process?
1) circular layer contracts to propel chyme forward
2) longitudinal layer contracts, shortens the small intestine
3) circular layer contracts
4) mass peristalsis
5) segmentation

A

1-2-3-4-5

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16
Q

Chemical digestion consists of carbohydrate, protein, fat, and nucleic acid

A
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17
Q

how is carb digested?

A

a) amylase from pancrease
b) alpha dextrinase, sucrase, lactase, and maltase from brush border (small intestine)
c) end result: monosaccharides (glucose, galactose, fructose) which can be absorbed

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18
Q

how is protein digested?

A

a) trypsin, chymotrypsin, carboxypeptidase, and elastase from pancreas
b) aminopeptidase and dipeptidase from brush border (small intestine)
c) end result: amino acids which can be absorbed

19
Q

how is fat digested?

A

a) lipase from pancreas
b) emulsification by bile acids can increase the surface area of fatty substrate for enzyme
c) end result: fatty acids which can be absorbed

20
Q

how is nucleic acid absorbed?

A

a) ribonuclease and deoxyribonuclease in pancreatic juice
b) nucleoside and phosphatase from brush border (small intestine)

21
Q

stages of digestive process?
mouth, small intestine, colon, stomach

A
  1. mouth
  2. stomach
  3. colon
  4. small intestine
22
Q

what happens in mouth?

A
  1. process of ingestion and digestion are mechanical (mastication/chewing) and chemical (amylase enzyme)
  2. amylase: hydrolyze starch to disaccharides
  3. tongue pushes food into esophagus and stomach with peristaltis
23
Q

what happens in colon?

A
  1. contains food waste that cannot be digested/absorbed
  2. water and minerals are reabsorbed, increasing mass of feces
  3. peristalsis pushes stool into rectum, excreted into anus
24
Q

what happens in stomach?

A
  1. digestion process is mechanical (peristalsis) and chemical (HCl and pepsin enzyme)
  2. optimum pH; 2 -> hydrolysis of food by acids and inactivation of pathogenic microbes
  3. pepsin enzyme: hydrolyze protein to peptide and AA
25
Q

what happens in small intestine?

A
  1. Duodenum receives chyme from stomach and pH is neutralized using NaCO3
  2. Emulsification of fat by bile acids
  3. Mechanical digestion (peristalsis) by intestinal muscles and chemical by enzymes from pancreas (trypsin, amylase, lipase)
  4. end result: simple sugar, AA, FA -> can be absorbed
  5. Results of absorption are circulated by blood/lymph to the liver
26
Q

what is absorption?

A

entry of nutrients (simple form) into the body through small intestine -> blood vessels -> liver -> throughout the body

27
Q

what’s the mechanism of absorption?

A
  1. passiv diff: high to low concentration
  2. facilitated diff: requires a carrier/transporter (usually protein) ex: transferrin (Fe), transcobalamin (Vit B12), retinol binding protein (Vit A)
  3. Active diff: req ATP and/or ions (Na pump)
28
Q

absorption of monosaccharides?

A
  1. All dietary carbs are absorbed except for cellulose and fiber which are left in the feces (undigested)
  2. Absorbed by facilitated diff or active transport into blood vessels
29
Q

a) Polysaccharides is broken down by enzyme (a) to become (b). (b) is broken down into (c) by (d) enzyme

A

a) amylase
b) maltose
c) glucose + glucose
d) maltase

30
Q

lactase is used to?

A

break down lactose into glucose and galactose

31
Q

glucose and fructose are products of?

A

sucrose being broken down by sucrase

32
Q

explain steps of carbohydrates absorption

A
  1. Enzymes on the luminal surface (epithelial cell) digest disaccharides into monosaccharides
  2. monosaccharides are absorbed into cells by facilitated diffusion or secondary active transport with Na+
  3. Absorbed monosaccharides leave the epithelial cells by facilitated diffusion and enter the blood. bloodstream distributes nutrients throughout the body
33
Q

Explain mechanism of absorption of glucose and galactose

A
  1. SGLT (sodium-glucose linked transporter) (Na+): carrying glucose and galactose from small intestine to the brush border (villi) using energy from Na+ -> K+ pump out to replace Na+
  2. GLUT2 (Glucose transporter 2): Passive diffusion of glucose and galactose into blood vessels
34
Q

Explain mechanism of absorption of fructose

A
  1. GLUT5(Glucose transporter 5) carrying fructose into brush border
  2. GLUT 2 (Glucose transporter 2): Passive diffusion of fructose into blood vessels
35
Q

glycogen is broken down into (a) and (b) by (c)

A

alpha limit dextrins and oligosaccharides by alpha amylase which will ebentually be alpha dextrinase/glucoamylase. baca gambar aj dh

36
Q

Mechanism of absorption of AA, dipeptides, and tripeptides?

A
  1. most AA are absorbed via active transport to the blood vessels
  2. half of absorbed AA come from proteins in digestive juice and dead mucosal cells
37
Q

absorption of fats mechanism?

A
  1. all dietary fats absorbed by simple diffusion
  2. SCFA go directly to blood vessels for transport
  3. LCFA and MG:
    a) bile acids form micelles to carry these fats to absorptive cell surface (small intestine)
    b) reform into triglycerides and form chylomicrons
    c) leave cells (exocytosis)
    d) enter lacteal (fat absorption site) to eventually enter blood with protein coat of chylomicron, keeping them suspended and separated.
38
Q

proteins are broken down into a + b by c

A

a. oligopeptides
b. amino acids
c. pepsin + pancreatic peptidases.

lengkapnya cek gambar

39
Q

absorption of fatty acid?

A
  1. FA and MG (from fat digestion) are emulsified by bile salts to form micelles
  2. FA enter epithelial cells by leaving micelles and link to form triglycerides
  3. Triglycerides combine with proteins (inside golgi A) to form chylomicrons
  4. Chylomicrons eztruded from epithelial cell and enter a lacteal (lymph capillary)
  5. lymph in lacteal transports chylomicrons away from instestine
40
Q

mechanism of electrolytes absorption?

A
  1. obtained from GI secretions or food
  2. sodium (Na+) and other ions are absorbed via active transport
41
Q

mechanism of vitamins absorption?

A
  1. fat soluble vitamins (ADEK) are absorbed by passive diff and transported with fat to form micelles
  2. water soluble vitamins are generally absorbed by passive or active diff (Na pump), except for vit B12 which requires intrinsic factor from stomach (facilitated diffusion)
42
Q

minerals absorption mechanism?

A
  1. Generally absorbed by facilitated diffusion with protein carrier, or by active diffusion with Na+ pump and/or ATP
  2. Absorption of divalent minerals (Ca2+, Fe 2+) is slower than monovalent minerals (Na+, K+)
  3. Factors affecting mineral absorption:
    a) intrinsic, homeostatic regulation
    b) individual health
    c) consumption (phytate, dietary fiber, tannins, oxalates)
43
Q

SUMMARY:

  1. Nutrients (monosaccharides, amino acids, and SCFA) go through vein -> portal vein -> liver -> body
  2. Nutrients (fat in form of chylomicron) are absorbed by lacteal -> into lymph vessels -> thoracic duct -> left subclavian vein -> liver -> body
A

Metabolism of Food Components (5 decks)

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