Overview of Carbohydrate Digestion and Metabolism - PowerPoint PPT Presentation

Loading...

PPT – Overview of Carbohydrate Digestion and Metabolism PowerPoint presentation | free to download - id: 4c73d-OTczN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Overview of Carbohydrate Digestion and Metabolism

Description:

Overview of Carbohydrate Digestion and Metabolism. FST/AN/HN 761. FST 761. Dr. Jeff Firkins Carbohydrates. Dr. Josh Bomser Lipids. TA- Amy Long, MS ... – PowerPoint PPT presentation

Number of Views:1465
Avg rating:3.0/5.0
Slides: 31
Provided by: bom3
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Overview of Carbohydrate Digestion and Metabolism


1
Overview of Carbohydrate Digestion and Metabolism
2
FST/AN/HN 761
  • FST 761
  • Dr. Jeff Firkins Carbohydrates
  • Dr. Josh Bomser Lipids
  • TA- Amy Long, MS
  • Reading / Writing Assignments
  • Text - Biochemical and Physiological Aspects of
    Human Nutrition- Martha H. Stipanuk.
  • Today Overview of carbohydrates (Jan 7)

3
Carbohydrates
  • Carbohydrates are called carbohydrates because
    they are essentially hydrates of carbon (i.e.
    they are composed of carbon and water and have a
    composition of (CH2O)n.
  • The major nutritional role of carbohydrates is to
    provide energy and digestible carbohydrates
    provide 4 kilocalories per gram. No single
    carbohydrate is essential, but carbohydrates do
    participate in many required functions in the
    body.

4
Photosynthesis Suns energy becomes part of
glucose molecule
energy
Carbon dioxide Water Chlorophyll
GLUCOSE
6 CO2 6 H20 energy (sun)
C6H12O6 6 O2
5
120 grams of glucose / day 480 calories
6
Simple Sugars -
7
Disaccharides
8
Complex carbohydrates
  • Oligosaccharides
  • Polysaccharides
  • Starch
  • Glycogen
  • Dietary fiber (Dr. Firkins)

9
Starch
  • Major storage carbohydrate in higher plants
  • Amylose long straight glucose chains (a1-4)
  • Amylopectin branched every 24-30 glc residues
    (a 1-6)
  • Provides 80 of dietary calories in humans
    worldwide

10
Glycogen
  • Major storage carbohydrate in animals
  • Long straight glucose chains (a1-4)
  • Branched every 4-8 glc residues (a 1-6)
  • More branched than starch
  • Less osmotic pressure
  • Easily mobilized

G
G
G
G
G
G
G
G
G
G
G
a 1-6 link
G
G
G
G
G
a 1-4 link
G
G
G
11
Digestion
  • Pre-stomach Salivary amylase a 1-4
    endoglycosidase

G
G
G
a Limit dextrins
G
G
G
G
G
G
G
G
G
G
G
G
amylase
G
G
G
G
G
a 1-6 link
G
G
G
G
maltotriose
G
G
G
a 1-4 link
G
G
G
G
G
maltose
G
G
isomaltose
12
Stomach
  • Not much carbohydrate digestion
  • Acid and pepsin to unfold proteins
  • Ruminants have forestomachs with extensive
  • microbial populations to breakdown and
  • anaerobically ferment feed

13
Small Intestine
  • Pancreatic enzymes
  • a-amylase

maltotriose
maltose

G
G
G
G
G
G
G
G
G
G
a amylase
amylose
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
amylopectin
a Limit dextrins
14
Oligosaccharide digestion..cont
a Limit dextrins
G
G
G
G
sucrase
G
G
G
G
G
G
maltase
G
Glucoamylase (maltase) or a-dextrinase
G
G
G
a-dextrinase
G
G
G
G
G
G
G
G
G
G
G
15
Small intestine
Portal for transport of virtually all
nutrients Water and electrolyte balance
  • Enzymes associated with
  • intestinal surface membranes
  • Sucrase
  • a dextrinase
  • Glucoamylase (maltase)
  • Lactase
  • peptidases

16
Carbohydrate absorption
Hexose transporter
apical
basolateral
17
Glucose and galactose absorption
  • Read Chapter 5 and answer the questions on page
    102 of Stipanuk. Be prepared to discuss them on
    Friday

18
Carbohydrate malabsorption
  • Lactose intolerance (hypolactasia), page 100.
  • Decline lactase with age
  • Lactose fermented in LI
  • Gas and volatile FA
  • Water retention diarrhea/bloating
  • Not all populations
  • Northern European low incidence
  • Asian/African Americans High

b 1-4 linkage
19
  • Metabolism the chemical changes that take place
    in a cell that produce energy and basic materials
    needed for important life processes
  • millions of cells
  • Multiple organs (liver, adipose, heart, brain)
  • Thousands of enzymes
  • Various conditions (fed, fasted, exercise, stress)

20
Carbohydrates
  • Serve as primary source of energy in the cell
  • Central to all metabolic processes

Glucose
Cytosol - anaerobic
Hexokinase
Pentose Phosphate Shunt
Glc-1- phosphate
Glucose-6-P
glycolysis
glycogen
Pyruvate
21
cytosol
Pyruvate
mitochondria (aerobic)
Aceytl CoA
FATTY ACIDS
Krebs cycle
Reducing equivalents
AMINO ACIDS
Oxidative Phosphorylation (ATP)
22
Glucose Glucose Glucose
No mitochondria
Glucose Glycogen Lactate
The Full Monty
23
Fasted State
Glucose
Need 13.8 kJ/mol
ATP -30 kJ/mol -16.7 kJ/mol
G-6-Pase
Hexokinase
Pentose Phosphate Shunt
Glucose-6-P
Glc-1- phosphate
glycolysis
GNG
glycogen
Pyruvate
24
Controlling Metabolic Flux
1. Control enzyme levels
2. Control of enzyme activity (activation or
inhibition)
25
Control of enzyme activity
Rate limiting step
26
insulin
IR
P
Protein Kinase B (active)
Protein Kinase B (inactive)
OH
P
Glycogen synthase kinase (active)
OH
P
Glycogen synthase kinase (inactive)
OH
P
Glycogen synthase (inactive)
Glycogen synthase (active)
Glycogen formation
27
Controlling Metabolic Flux
1. Control enzyme levels
2. Control of enzyme activity (activation or
inhibition)
3. Compartamentalization
Fatty acid oxidation occurs in mitochondrial
matrix Fatty acid synthesis occurs in endoplasmic
reticulum membrane exposed to the cytoplasm of
the cell.
4. Hormonal control
28
Glucose utilization
29
Stage 1 postparandial All tissues utilize
glucose Stage 2 postabsorptive KEY Maintain
blood glucose Glycogenolysis Glucogneogenesis Lact
ate Pyruvate Glycerol AA Propionate Spare glucose
by metabolizing fat Stage 3- Early
starvation Gluconeogenesis Stave 4
Intermediate starvation gluconeogenesis Ketone
bodies Stage 5 Starvation
30
Carbohydrate Metabolism/ Utilization- Tissue
Specificity
  • Muscle cardiac and skeletal
  • Oxidize glucose/produce and store glycogen (fed)
  • Breakdown glycogen (fasted state)
  • Shift to other fuels in fasting state (fatty
    acids)
  • Adipose and liver
  • Glucose ? acetyl CoA
  • Glucose to glycerol for triglyceride synthesis
  • Liver releases glucose for other tissues
  • Nervous system
  • Always use glucose except during extreme fasts
  • Reproductive tract/mammary
  • Glucose required by fetus
  • Lactose ? major milk carbohydrate
  • Red blood cells
  • No mitochondria
  • Oxidize glucose to lactate
  • Lactate returned to liver for Gluconeogenesis
About PowerShow.com