BBS2041
Human Intermediary
Metabolism
,Table of Contents
Case 1 → Digestion, uptake and transport of macronutrients 3
EXAM QUESTION 13
Case 2 → Metabolism 14
Case 3 →Starvation 27
Case 4 → Fuel and Physical activity 33
s → Muscle breakdown and synthesis 43
Case 6 →Micronutrients 55
Cofactor for methionine synthase Error! Bookmark not defined.
Cofactor for L-methylmalonyl-coenzyme A mutase Error! Bookmark not defined.
Case 7 →Iron 65
Case 8 →Body composition and energy expenditure 75
Case 9 →Alcohol 79
Journal CLub 88
Lecture: Exam questions 89
Lecture: Microbiota 90
,Case 1 → Digestion, uptake and transport of macronutrients
1. Structure of the macronutrients (proteins, fats, carbohydrates)
carbohydrates
Only three major sources of carbohydrates:
- glucose, fructose, sucrose, maltose, lactose, and starches starch=not digestible
the monosaccharides (monomers) and the oligosaccharides (short polymers) and
polysaccharides (long polymers)
→ Monosaccharides, the monomers of carbohydrates, are absorbed without further ado.
- The storage form of carbs in animal tissues is glycogen
Proteins
4 structures:
are chemically long chains of amino acids bound together by peptide linkages
The characteristics of each protein are determined by the types of amino acids in the protein
molecule and by the sequential arrangements of these amino acids
Fats
triglycerides, each molecule of which is composed of a glycerol nucleus and three fatty acid
side chains
unsaturated fat → liquid at room temperature contains double bonds
saturated fat → from plants, solid at room temperature
2. Anatomy of the GI-tract
Mouth+ teeth, tongue, and salivary glands
- teeth and tongue for mechanical breakdown and mixing
- salivary glands produce saliva which contains enzymes → amylase and lingual lipase
oesophagus
- a muscular tube that is involved in food propulsion
stomach
- food gets converted to chyme
- the stomach lining contains millions of gastric pits which produce gastric juice
- the mucosal barrier to prevent gastric juice from leaking into other tissue layers
1. cephalic, or reflex, phase of gastric secretion occurs before food enters the
stomach. stomach gets ready for food
2. a gastric phase once the food has reached the stomach, formation of HCl
, - Mucous neck cells: produce thin, soluble mucous
- Parietal cells: found in the apical regions of
gastric glands, they secrete hydrochloric acid (HCL) and intrinsic factor(is a
glycoprotein necessary for the absorption of vitamin B12 later on in the ileum of the
small intestine). HCL makes the stomach acidic, a condition which is necessary for
activation and optimal activity of pepsin (degrades proteins).
- Chief cells: found in the basal regions of gastric glands produce pepsinogen (an
inactive form of pepsin) –when those cells are stimulated the first pepsinogen
molecules they release are activated by HCL encountered in the apical region of the
gland. Once pepsin is present it also catalyzes the conversion of pepsinogen to
pepsin. Also, secrete lipases.
- Enteroendocrine cells: deep in the gastric glands, release histamine (activates
parietal cells to release HCL) and serotonin (causes contraction of stomach muscle)
and somatostatin.
small intestine + gallbladder, liver and pancreas
- duodenum - jejunum - ileum
- many circular folds which increase the surface area of the absorptive mucosa (3x)
especially in duodenum and jejunum and decrease the speed of the food
- on the epithelial surface there are millions of villi, increases the surface area (10x)
- each villus has a brush border with 1000 microvilli increase surface area (20x)
- the brush border contains actin filaments for contraction and causes continual
movements of the microvilli → keeping them constantly exposed to new quantities of
intestinal fluid
Human Intermediary
Metabolism
,Table of Contents
Case 1 → Digestion, uptake and transport of macronutrients 3
EXAM QUESTION 13
Case 2 → Metabolism 14
Case 3 →Starvation 27
Case 4 → Fuel and Physical activity 33
s → Muscle breakdown and synthesis 43
Case 6 →Micronutrients 55
Cofactor for methionine synthase Error! Bookmark not defined.
Cofactor for L-methylmalonyl-coenzyme A mutase Error! Bookmark not defined.
Case 7 →Iron 65
Case 8 →Body composition and energy expenditure 75
Case 9 →Alcohol 79
Journal CLub 88
Lecture: Exam questions 89
Lecture: Microbiota 90
,Case 1 → Digestion, uptake and transport of macronutrients
1. Structure of the macronutrients (proteins, fats, carbohydrates)
carbohydrates
Only three major sources of carbohydrates:
- glucose, fructose, sucrose, maltose, lactose, and starches starch=not digestible
the monosaccharides (monomers) and the oligosaccharides (short polymers) and
polysaccharides (long polymers)
→ Monosaccharides, the monomers of carbohydrates, are absorbed without further ado.
- The storage form of carbs in animal tissues is glycogen
Proteins
4 structures:
are chemically long chains of amino acids bound together by peptide linkages
The characteristics of each protein are determined by the types of amino acids in the protein
molecule and by the sequential arrangements of these amino acids
Fats
triglycerides, each molecule of which is composed of a glycerol nucleus and three fatty acid
side chains
unsaturated fat → liquid at room temperature contains double bonds
saturated fat → from plants, solid at room temperature
2. Anatomy of the GI-tract
Mouth+ teeth, tongue, and salivary glands
- teeth and tongue for mechanical breakdown and mixing
- salivary glands produce saliva which contains enzymes → amylase and lingual lipase
oesophagus
- a muscular tube that is involved in food propulsion
stomach
- food gets converted to chyme
- the stomach lining contains millions of gastric pits which produce gastric juice
- the mucosal barrier to prevent gastric juice from leaking into other tissue layers
1. cephalic, or reflex, phase of gastric secretion occurs before food enters the
stomach. stomach gets ready for food
2. a gastric phase once the food has reached the stomach, formation of HCl
, - Mucous neck cells: produce thin, soluble mucous
- Parietal cells: found in the apical regions of
gastric glands, they secrete hydrochloric acid (HCL) and intrinsic factor(is a
glycoprotein necessary for the absorption of vitamin B12 later on in the ileum of the
small intestine). HCL makes the stomach acidic, a condition which is necessary for
activation and optimal activity of pepsin (degrades proteins).
- Chief cells: found in the basal regions of gastric glands produce pepsinogen (an
inactive form of pepsin) –when those cells are stimulated the first pepsinogen
molecules they release are activated by HCL encountered in the apical region of the
gland. Once pepsin is present it also catalyzes the conversion of pepsinogen to
pepsin. Also, secrete lipases.
- Enteroendocrine cells: deep in the gastric glands, release histamine (activates
parietal cells to release HCL) and serotonin (causes contraction of stomach muscle)
and somatostatin.
small intestine + gallbladder, liver and pancreas
- duodenum - jejunum - ileum
- many circular folds which increase the surface area of the absorptive mucosa (3x)
especially in duodenum and jejunum and decrease the speed of the food
- on the epithelial surface there are millions of villi, increases the surface area (10x)
- each villus has a brush border with 1000 microvilli increase surface area (20x)
- the brush border contains actin filaments for contraction and causes continual
movements of the microvilli → keeping them constantly exposed to new quantities of
intestinal fluid
