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Transcript Nerve activates contraction
Nutrition and Metabolism
Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and
Protein
Central Role of the Liver in
Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive
States
Developmental Aspects of
Metabolism
Sources of Nutrients in the Diet
Macronutrients: Carbohydrates, Protein, Lipids, H2O
Micronutrients: Vitamins, Minerals
Major source of vitamins & minerals
Major protein source
some vitamins
Major source of carbohydrates & B vitamins
Major source of lipids and
fat soluble vitamins A,D,E, K
Major source of minerals and
vitamins A and D, some protein
White rice, white bread,
potatoes, pasta, sweets:
use sparingly
Red meat, butter:
use sparingly
Dairy or calcium
supplement: 1–2 servings
Fish, poultry, eggs:
0–2 servings
Nuts, legumes:
1–3 servings
Fruits:
2–3 servings
Vegetables in
abundance
Whole-grain
foods at
most meals
Daily excercise and weight control
Plant oils
at most
meals
(b) Healthy eating pyramid
Figure 24.1b
Nutrition and Metabolism
Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and
Protein
Central Role of the Liver in
Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive
States
Developmental Aspects of
Metabolism
Oxidation-Reduction is Important in Energy Production
In biological systems, the electrons are often associated with hydrogen atoms.
Biological oxidations are often dehydrogenations.
Or FAD+
FADH2
Sugars, amino acids,
fatty acids
Figure 5.10
The Energy Stored in ATP Can Be Used to Perform Work in the Cell
• The energy released by ATP breaking down into ADP and P can power a
variety of needs in the cell
Energized ATP:
ADP
Discharged ATP:
ADP
Powering the synthesis of
molecule Z by coupling
oxidation to reduction:
P
P
X
+
Y
Z
Metabolic Pathways Involved in Cellular Respiration
An oxidation of glucose to reduce ADP to ATP
34
Overall Equation for Cellular Respiration
Aerobic Cellular Respiration
C6H12O6 + O2
sugar
oxygen
CO2 + H2O
carbon dioxide water
CO2
+ 34ATP
usable energy
glucose
Glycolysis
Cell
membrane
CO2
NAD
2 ATP
(substrate-level
phosphorylation)
NADH
2 pyruvates
CO2
4 ATP
Linking Step
mitochondrion
(substrate-level
phosphorylation)
Acetyl CoA
Krebs
Cycle
Electron
Transport
Chain and
ATP Synthase
O2
H 2O
30 ATP
(oxidative
phosphorylation)
ATP Synthase
ATP fuels
construction/synthesis
reactions inside the cell
Nutrition and Metabolism
Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of the Three
Macronutrients:
Carbohydrates, Fats, and
Protein
Central Role of the Liver in
Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive
States
Developmental Aspects of
Metabolism
Fat Metabolism
Fat metabolism handled mostly by the
liver
Some fats used to make ATP
•
Used to synthesize lipoproteins,
thromboplastin, and cholesterol
•
Release breakdown products to the
blood
Body cells remove fat and cholesterol to
build membranes, steroid hormones,
adipose cells, and myelin sheaths
Oxidation of Fats (ß-Oxidation) for ATP
•
Fat catabolism yields 9 kcal per
gram (vs 4 kcal per gram of
carbohydrate or protein)
•
Fats must first be broken down to
acetic acid, then in mito. to H2O,
CO2, and ATP
•
Ketones (acetoacetic acid and
acetone can accumulate, producing
acidosis/ketosis)
in liver
•
acetone and
acetoacetic
acid =
ketosis/acidosis
Protein Metabolism
urea
deamination
Three Macronutrients Used for ATP Production
Stage 1 Digestion in
GI tract lumen to
absorbable forms.
Transport via blood to
tissue cells.
PROTEINS
CARBOHYDRATES
Amino acids
Glucose and other sugars
Stage 2 Anabolism
Proteins
(incorporation into
molecules) and
catabolism of nutrients
NH3
to form intermediates
within tissue cells.
FATS
Glycerol
Glycogen
Glucose
Fatty acids
Fats
Pyruvic acid
Acetyl CoA
Stage 3 Oxidative breakdown
of products of stage 2 in
Infrequent
mitochondria of tissue cells.
CO2 is liberated, and H atoms
removed are ultimately delivered
to molecular oxygen, forming
water. Some energy released is
used to form ATP.
Krebs
cycle
H
CO2
Oxidative
phosphorylation
(in electron
transport chain)
O2
H2O
Catabolic reactions
Anabolic reactions
Figure 24.3
Nutrition and Metabolism
Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and
Protein
Central Role of the Liver in
Digestion/Metabolism
Cholesterol and Lipid
Transport
Absorptive and Postabsorptive
States
Developmental Aspects of
Metabolism
Role of the Liver in Metabolism
•
•
•
•
•
Produces blood proteins (albumin, clotting proteins) and lipoproteins
• Degrades hormones
•
Liver Modifications on Glucose Levels
Glycogenesis (making glycogen)
• Glucose molecules are
converted to glycogen
• Glycogen molecules are stored
in the liver
Glycogenolysis (breaking glycogen)
• Glucose is released from the
liver after conversion from
glycogen
Gluconeogenesis (rebuilding glucose)
• Glucose is produced from
amino acids and glycerol
• Protects against damaging
effects of hypoglycemia
Roles of Cholesterol in the Body
Keeping membranes fluid
Vitamin D synthesis
Steroid Hormone Synthesis
Cholesterol Transport
Cholesterol and fatty acids cannot freely circulate
in the bloodstream
They are transported by chylomicron
lipoproteins (lipid-protein complexes)
• Low-density lipoproteins (LDLs) transport
cholesterol to body cells; are increased by
dietary saturated and trans-fat
Triglycerides broken down by fat and
muscle tissue (lipoprotein lipase) into fatty
acids and glycerol
• High-density lipoproteins (HDLs) transport
from body cells to the liver for breakdown;
are increased by exercise, and limited coffee,
smoking, and saturated fats/trans fats
Healthy Ratios in the Blood
• Total Cholesterol/HDL < 5
• LDL/HDL < 2.5
Total cholesterol (mg/dL)
Under 200 - desirable
200-239
- borderline high
Over 240 - high
LDL cholesterol (mg/dL)
Below 100 - optimal
100-129
- near optimal
130-159
- borderline high
160-189
- high
Above 190 - very high
HDL cholesterol (mg/dL)
Below 40
- low
60 or above - high
Nutrition and Metabolism
Dietary Sources of Major
Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and
Protein
Central Role of the Liver in
Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive
States
Developmental Aspects of
Metabolism
Absorptive and Postabsorptive States
Absorptive (fed) state
•
During and shortly after eating; absorption of nutrients
•
Muscle and fat tissue: lipoprotein lipase hydrolyzes lipids of chylomicrons in
muscle and fat tissues; most glycerol and fatty acids are converted to
triglycerides for storage
•
Liver: Excess amino acids are deaminated and used for ATP synthesis or stored
as fat in the liver
•
Insulin facilitates glucose uptake, glycogenesis, triglyceride genesis, and
protein synthesis
Postabsorptive (fasting) state
•
When the GI tract is empty; energy sources are supplied by breakdown of
reserves
•
Liver: lipolysis, glycerol then fuels glycogenolysis
•
Skeletal muscle: glycogenolysis; protein catabolism if starving
•
Fat tissue: lipolysis tissues and the liver
•
Glucagon facilitates glycogenolysis and gluconeogenesis in the liver, fat tissue
lipolysis
Developmental Aspects of the Digestive System
Fetal Development
•
The alimentary canal is a continuous tube by the fifth week
of development
•
Digestive glands bud from the mucosa of the alimentary
tube
•
brain
damage and
retardation
in infancy
The developing fetus receives all nutrients through the
placenta
Birth and Infancy
•
In newborns, feeding must be frequent, peristalsis is
inefficient, and vomiting is common
•
Congenital conditions include cleft palate, phenylketonuria,
tracheoesophageal fistula
•
Teething (eruption of teeth) begins around age six months
PKU
Metabolism decreases with old age
Middle age digestive problems
•
Ulcers
•
Gall bladder problems
Old Age
•
Fewer digestive juices
•
Peristalsis slows
•
Diverticulosis and cancer are more common
Tracheoesophageal Fistula
Nutrition and Metabolism
Dietary Sources of Major Nutrients
Basics of Cellular Respiration
Metabolism of Carbos, Fats, and Protein
Central Role of the Liver in
Digestion/Metabolism
Cholesterol and Lipid Transport
Absorptive and Postabsorptive States
Developmental Aspects of Metabolism