Nutrition Metabolism

Front 1

Glucose-sparing effect

Back 1

An effect of Fats or other E substrates in which they used as fuel by most cells , so those cells do not consume G; this makes G more available to cells such as Neurons that cannot use alternative E substrates.

Front 2

Glycogenesis

Back 2

The synthesis of glycogen

Front 3

Glycogenolysis

Back 3

The hydrolysis of glycogen, releasing glucose

Front 4

Hepatitis

Back 4

Inflammation of liver

Front 5

Hyperclycemia

Back 5

Th execess Glucoise in the blood

Front 6

Hyperthermia

Back 6

Excessive high core body T, as in heartstroke or fever

Front 7

Hypoglycemia

Back 7

A deficiency Glicose in the blood

Front 8

Hypothalamic Thermostat

Back 8

A neuronal pool in the hypothalamus that monitors body T and send afferent signals to the hypotalamic heat-promoting or heat-losing centers to maintain thermal homeostasis.

Front 9

Kilocalorie

Back 9

Amount of heat E needed to rise T of 1 kg by 1 C;
1000 cal; also called Calorie or large calorie

Front 10

Libido

Back 10

Sex Drive

Front 11

Lipid

Back 11

Hydrophobic organic compound composed mainly from carbon and high ratio hydrogen to oxygen; includes fatty acids, fats, phospholipids, steroids, prostaglandins, eicocanoids,

Front 12

Lipoprotein

Back 12

Protein coated lipid droplet in the blood plasma or lymph, serving as means of lipid transport, examples : chylomicrons, LDL, HDL (high and low density lipoproteins).

Front 13

Metabolic Rate

Back 13

The overall rate of body's metabolic reactions at any given time, determining the rate nutrients and

Front 14

Acetate

Back 14

A two C carboxylic acid ; the ionized form of acetic acid
CH3COO-. The monomer of fatty acids and intermediate of aerobic metabolism that enter the Citric Acid Cycle.

Front 15

Aerobic Respiration

Back 15

Oxidation of organic compounds in reaction that requires oxygen and produces ATP.

Front 16

Amino group

Back 16

The factional group with formula -NH2, found in amino acid and other organic molecules.

Front 17

Anaerobic Fermentation

Back 17

A reduction reaction independent of oxygen that convert pyruvic acid in lactic acid and enablers glycolysis to continue under anaerobic conditions.

Front 18

Basal Metabolic Rate (BMR)

Back 18

The rate of E consumption of person who is awake, relaxed, at comfortable T and has not eating from 12 to 14 hours; usually expressed as kilocalories per square meter of body surface area per hour.

Front 19

Coenzyme

Back 19

Small organic molecule, usually derived from vitamin, that is needed to make enzyme catalytically active; acts by accepting electrons from enzymatic reaction and transferring them to different reaction chain.

Front 20

Cytochromes

Back 20

Enzyme on the mitochondrial cristae that transfers elections to the final reaction chain of aerobic respiration.

Front 21

Deamination

Back 21

Removing of amino group from organic molecule; step in catabolism of amino acids.

Front 22

Gluconeogenesis

Back 22

The synthesis of glucose from noncarbohydrates such as fats or amino acids.

Front 23

Oxidation

Back 23

Chemical reaction in which one or more electrons are removed form the molecule, lowering its free E content, opposing of reduction reaction and always linked to reduction reaction.

Front 24

Overall Reaction for Glucose Catabolism

Back 24

C6H12O6  6 O2 → 6 CO2  6 H2O
Function of this reaction is not to produce carbon
dioxide & water but to transfer E from glucose to ATP

Front 25

Major pathways of glucose Catabolism

Back 25

1.Glycolysis, which splits a glucose molecule into 2
molecules of pyruvic acid;
2. Anaerobic fermentation, which occurs in absence of oxygen &reduces pyruvic acid to lactic acid
3. Aerobic respiration, which occurs in the presence of oxygen & oxidizes pyruvic acid to carbon dioxide
& water.

Front 26

Coenzymes important in glucose catabolism

Back 26

1) NAD+ (nicotinamide adenine dinucleotide)
2)FAD (flavin adenine dinucleotide).
Coenzymes are temporary carriers of E extracted
from glucose metabolites.
(a) Enzymes remove electrons (as H atoms) from intermediate compounds, but they do not bind them, just transfer H atoms to coenzymes, & last donate them to other compounds later in one of reaction pathways.
b)Both are derived from B vitamins: NAD+ from niacin(B3) and FAD from riboflavin(B2). H atoms are removed from metabolic intermediates in pairs
(2 protons & 2 electrons - 2 H a& 2 e) at time & transferred to a coenzyme. This produces a reduced coenzyme with a higher free E content than before reaction.
FAD+ 2 H → FADH2 & NAD+  + 2 H → NADH + H

Front 27

Steps of Glycolysis

Back 27

1) Phosphorylation; (Enzyme hexokinase transfers Pi from ATP (ATP-->ADP to G producing G6P; G6P can G6P also can be converted to fat or amino acids, polymerized to form glycogen for storage, or further oxidized to extract its E.
2) Priming; (Isomerization of G6P to F6P, which is phosphorylates to F-1,6 diP with ATP->ADP which provides Activation E)
3) Cleavage; (splitting of F-1,6diP to 2 (3 C) molecules PGAL- phosphoglyceralehyde or glyceraldehyde 3- phosphate)
4) Oxidation; (each PGAL oxidiezed by removing 2 H atoms; 2 electons & 1 proton are picked up by coenzyme NAD+ & 1 one proton is realizing in cytosol, yeilding NADH +H+; also Pi is added to each PGAL from free Pi pool)
5) Dephosphorylation; (2 steps, Pi groups are taken from PGAL by 2ADP converting it to 2ATP making 2 pyruvic acids;  end products of glycolysis:
2 pyruvic acids + 2 NADH + 2 H+ + 2 ATP+heat

Front 28

Glucose Catabolism

Back 28

1. Glycolysis, which splits a G molecule into two
molecules of pyruvic acid;
2. Anaerobic fermentation, which occurs in the
absence of O2 & reduces pyruvic acid to
lactic acid;
3. Aerobic respiration, which occurs in the presence of O2 & oxidizes pyruvic acid to CO2 & water.

Front 29

Fate of Puruvic Acid

Back 29

1) Anaerobic Fermentation. In absence of O2 NADH donates a pair of electrons to pyruvic acid which is reduced to lactic acid & regenerated NAD+(last one keep glycolysis going).
2) Aerobic Respiration. In presence of O2. Where pyruvic acid is oxidized to CO2 & water.

Front 30

Anaerobic Fermentation

Back 30

1) In absence of O2 lactic acid via blood travels to liver.
2) When O2 became available again , liver oxidized lactic acid back to pyruvic acid which can enter aerobic respiration pathway.
3) The O2 required for this part is Oxygen debt & created by exercising skeletal muscles, cardaic muscles are less tolerant, & brain employs almost no anaerobic fermentation.
4) Liver also can convert lactic acid i lactic acid back to G6P which can: (1) polymerize it to form glycogen for storage; (2) remove phosphate group & release free G to blood.
5) Anaerobic fermentation keeps glycolysis run little longer but it 1) Wasteful because of most E of Glucose still in lactic acid & does not have useful work; 2) Lactic acid is toxic & contributed to muscle fatigue.

Front 31

Does lactic acid has more free Energy than pyruvic acid?

Back 31

Yes

Front 32

How different muscles handle anaerobic fermentation

Back 32

1) Skeletal muscle is relatively tolerant of anaerobic fermentation, & cardiac muscle is less so.
2)Brain employs almost No anaerobic fermentation. 3)During birth, when the infant’s blood supply is cut off, almost every organ of its body switches to anaerobic fermentation; thus they do not compete with the brain for the limited supply of O.

Front 33

Where Glycolysis occurs?

Back 33

In Cytosol

Front 34

How many molecules ATP are produced from one molecule of Glucose under the Anaerobic condition?

Back 34

Glycolysis: 2 ATP (net)
2 NADH
1)Under anaerobic conditions, only metabolic path used to produce ATP is Glycolysis.
2)For every G molecule consumed, cell produces net of 2 ATPs & 2 reduced NADH e-carriers during Glyco- lysis. In the absence of O, NADH does not go on to participate in ATP -producing reactions, becuase oxidative phosphorylation can not take place & not aplicable converting pyruvate (product of glycolysis ) to Acetyl -CoA as well as citric acid cycle.

Front 35

How many molecules ATP are produced from one molecule of Glucose during the Aerobic condition?

Back 35

38 ATP total
a) Glycolysis:
2 ATP net
2NADH=approx. 6ATP
b) Converting Pyruvate to Acetyc -CoA
2 NADH=approx. 6ATP
c)2GTP=2ATP
6NADH=approx. 18 ATP
2QH2(FADH2)=approx. 4ATP
1) Under aerobic conditions, ATP is generated by 3 metabolic pathways:1)Glycolysis, 2)Citric Acid Cycle & 3) Oxidative Phosphorylation.
3) Reduced e-carriers from glycolysis & citric acid cycle are funneled to electron transport chain, & undergo series of oxidation & reduction reactions. This establishes Pproton Gradient that spans the inner mitochondrial membrane, which ultimately drives Oxidative Phosphorylation of ADP to ATP. Therefore, under aerobic conditions, NADH & reduc- ed ubiquinone, or QH2(FADH2), serve cell by increa- sing its ATP-producing potential.

Front 36

Aerobic Respiration Pathways

Back 36

1) Most ATP is generated in mitochondria, which
require O as the final e-acceptor.
2) In the presence of O, pyruvic acid enters mitocho- ndria & is oxidized by aerobic respiration by 2 steps.
a) Matrix Reactions (their controlling enzymes are
in the fluid of mitochondrial matrix).
b) Membrane Reactions (their controlling enzymes are bound to membranes of the mitochondrial cristae or inner membrane)

Front 37

Which compound transverse mitochondrial membrane
to connect Glycolysis and Citric Acid Cycle (TCA)?

Back 37

Pyruvate (product of Glycolysis)
1) In cytosol, glucose is broken down to pyruvate (two 3-C molecules) during glycolysis. The resulting 3-C molecules are called pyruvate. Pyruvate is trans- ported across the mitochondrial membrane where in mitochondrial matrix is broken down to 2-C com po und called acetyl-CoA & CO2( carbon dioxide). Acetyl-CoA initiates the citric acid cycle (TCA).
It is transported across mitochondrial membrane. With hin mitochondrial matrix pyruvate undergoes further oxidation as it is converted to Acetyl-CoA by pyruvate dehydrogenase compex.

Front 38

The Matrix Reactions

Back 38

1)Most of the matrix reactions constitute a series
called the Citric Acid Cicle ( Krebs cycle or Tricarboxylic Acid cycle-TCA ), conists form 8 -steps.
2) Preceding TCA this are 3 steps that prepare pyruvic acid to enter the TCA cycle & link glycolysis to it.

Front 39

Pyruvic Acid--> Acetyl-CoA

Back 39

3 steps.
1) Pyruvic acid is decarboxylated;( CO2 is removed & pyruvic acid (C3) compound, becomes C2 compound.
2) NAD removes hydrogen atoms from the C2 com- pound (oxidation reaction) & converts it to acetyl group (acetic acid).
3) The acetyl group binds to coenzyme A (derivative
of pantothenic acid - B5 vitamin) which results in acetylcoenzyme A (acetyl-CoA) formation.
4) Acetyl-CoA etners Citric Acid Cycle.

Front 40

Citric Acid Cycle or TCA

Back 40

1) Central metabolic pathway that completes oxida- tive degradation of fatty acids, amino acid & mono- saccharides.
2) Series of chemical reactions which are used by all aerobic organisms to generate E through oxidation of acetate in form of acetyl-Coa derived from 1)ca- rbohydrates, 2)fats, 3)proteins into CO2 & chemical energy in ATP.
3)TCA cycle has 2 main purpose:
a) Increase cell's ATP producing potential by generating reduced e-carrier as NADH (coenzyme) & reduced FADH2 (QH2); (NADH than fed into oxidative phosphorylati- on path (e-trasnport chain) & in a lot of biochemical rxns).
b) To provide cells with variety of metabolic precursors.
4)Both prokaryotic & eukaryotic cells uses TCA cycle to meet Energetic & Moleclar needs.
5) In eukaryotic cells, TCA occurs in matrix of mitoch-
ndrion (fluid)
6) In respiring prokaryotic cells (as bacteria which is lack of mitochondria) in cytosol (with further proton gradient for ATP production is being across cell's surface -plasma membrane, not inner membrane).
5)Respiring prokaryots TCA cycle in cytosol

Front 41

Reactants and Products of Citric Acid Cycle

Back 41

1) Overal reaction of TCA:
3NAD+ + FAD + GDP + Pi + acetyl-CoA → 3NADH + FADH2 + GTP + CoA + 2CO2 (x2, because has 2 turns)
(The NADH and FADH2 are utilized to produce “energy currency” ATP in oxidative phosphorylation.)

Front 42

Short Reactions Summary of TCA Cycle

Back 42

1)Pyruvate generated from glycolysis is converted to acetyl-CoA( Acetyl-CoA is a “high-energy” compound since it has a “high energy” S~C bond which before entering the citric acid cycle).
2)At initial reaction, acetyl group from acetyl-CoA & oxaloacetate react to form citrate.
2) 3NADH, FADH2 & GTP are generated from one acetyl-CoA oxidation/(x2 from 2 turns)
3)2CO2 are released from the portion of o xaloaceta- te in the first turn).
4) At the final reaction, oxaloacetate is regenerated

Front 43

Overall reactions and total amount ATP generated from Glycolysis, Pyruvate conversion to Acetyl-CoA and TCA Cycle in Aerobic Respiration from one Glucose Molecule

Back 43

1) Glycolysis:
Glucose + 2NAD+ + 2ADP + 2Pi → 2 pyruvate + 2NADH + 2ATP
2) Acetyl-CoA Formation:
2pyruvate + 2NAD+ + 2CoA → 2acetyl-CoA + 2NADH + 2CO2
3) TCA cycle:
2acetyl-CoA + 6NAD+ + 2FAD + 2GDP + 2Pi → 6NADH + 2FADH2 + 2GTP + 2CoA + 2CO2 ___________________________________________________
Total: Glucose + 10NAD+ + 4ADP + 4Pi + 2FAD → 10NADH + 2FADH2 + 4ATP + 6CO2
→ 30ATP + 4ATP + 4ATP = 38ATP
(where from further oxidative phosphorylation NADH=3 ATP, FADH =2 ATP, GTP=ATP,
3 NADH=30 ATP, 2 FADH2 =4 ATP, plus 4 ATP (where 2ATP from glycolysis & 2GDP-directly from TCA cycle which=2 ATP), so total amount of ATP from aerobic respiration of one glucose molecule = 38 ATP.

Front 44

Is Citric Acid Cycle Catabolic or Anabolic?

Back 44

Amphibolic.
TCA cycle is neither purely anabolic nor purely catabolic. If reactions that possess this dual character of building and degrading molecules are considered amphibolic.
1) Reactions of the citric acid cycle oxidize acetyl - CoA’s acetyl group to 2 molecules of CO2. During rea ction cycle, electrons are transferred from acetyl-Co A to electron carriers. Once an electron carrier accepts an electron, it is referred to as “reduced” & than they participate in downstream paths that generate ATP, the energy currency of the cell.
2) Many citric acid cycle intermediates serve the cell as both reaction precursors & reaction products. For example, a-ketoglutarate may act as a precursor for amino acids in an anabolic pathway, or it may be catabolized to CO2 during reactions of TCA cycle.

Front 45

In final reaction of TCA cycleis oxidation-redaction catalyzed by enzyme malate dehydogenase. Which compounds reduced?

Back 45

reaction: Malate+NDH+--->Oxaloacetete +NADH + H+
Answer: Malate & NADH are reduced (NDH+ & Oxaloac etate are oxidized)

Front 46

Catabolism of TCA - broken down molecules for serving E needs.

Back 46

TCA occurs in 8 main steps where produces intermediates:
1) Citrate, 2) Isocitrate, 3) alfa-Ketoglutarate, 4) Succinyl -CoA, 5)Succinate, 6) Fumarate, 7) malate, 8) Oxaloace- tate

Front 47

Analobism of TCA -building Molecules from Intermediates Parts

Back 47

1) Citrate---> fatty acids, cholesterol
2) alfa-Ketoglutarate ---> amino acids, nucleotides
3) Succinyl-CoA---> heme
4) Malate ---> pyruvate
5) Oxaloacetater ---> glucose

Front 48

Biomolecules that serve as a sources of Acetyl-CoA

Back 48

1) Monosaccharides (exmp: glucose)
2) Polysaccharides
2) Fatty acids, triglycerides (exmp: palmitate -16C)
3) Proteins (exmp: lysine, glutamate)

Front 49

8 steps of Citric Acid Cycle in details

Back 49

1) Acetyl-CoA (2C of acetyl group) + oxaloacetate (4C)+H2O ----> citrate(6C) + HS-CoA
type: condensation; enzyme: citrate synthase, exerg- onic; product: citrate
2) Citrate---> Aconitate--->Isocitrate (6C)
Type: 2 steps, sequential dehydration & hydration resulting in isomerisation of citrate; enzyme: aconi- tase; product: isocitrate
3) Isocitrate--->alfa-Ketoglutarate (5C) (which is accomplished by reduction of NDH+ to NADH & H+ & elimination of CO2
type: oxidative decarboxylation; enzyme: isocitrate dehydrogenase; products: (5C) alpha-ketoglutarate. NADH, H+; exergonic
4) alpha-Ketoglutarate + CoA-SH + NAH+ ---> succinyl -CoA(4C) + NADH + CO2 + H+
type: oxidative decarboxylation; enzyme: alpha-keto- glutarate dehydrogenase; products: succinyl-CoA , NADH, CO2(elimination), H+; exergonic
5) Succinyl-CoA +H2O+GDP+Pi --->Succinate+GTP +SH-CoA
type: substrate level phosphorylation; enzyme: succi nyl-CoA synthase; products: succinate (4C), GTP, CoA-SH
6) Succinate + Enz-FAD <---> Fumarate + Ena-FADH
type: dehydrogenation or oxidation-reduction,
enz: succinate dehydrogenase; products: fumarate (4C), ubiquinone;
7) Fumarate +H2O<---> Malate(4C)
type: hydration; enzyme: fumarase; product: malate
8) Malate + NAD+ <---> Oxaloacetate (4C)+NADH + H+
type: dehydrogenation; enzyme: malate dehydroge- nase: productds: oxaloacetate, NADH, H+

Front 50

During TCA Cycle 2 reactions (steps) molecules of CO2 are released, that enzymes catalyse these reactions?

Back 50

1) reaction 3 (step 3), oxidative decarboxylation; - enzyme: isocitrate dehydrogenase
2) reaction4 (step 4), oxidative decarboxylation; enzyme: alpha-ketoglutarate dehydrogenase;

Front 51

How many electrons are lost to electron carriers during oxidation of two C atoms for every molecule of Acetyl-CoA which enters TCA cycle?

Back 51

1) Four pair of electrons
2) These two oxidized C atoms released as 2 molecules of CO2
3) Two C atoms are released as CO2 during one rou- nd of TCA cycle. These C atoms do not originate from the acetyl-CoA molecule that initiated TCA. Acetyl carbons are released during subsequent rounds of circular pathway.

Front 52

Which 3 reaction of TCA Cycle are Exergonic?

Back 52

1) condensation; enzyme: citrate synthase, product: citrate
3) oxidative decarboxylation; enzyme: isocitrate dehydrogenase; products: (5C) alpha-ketoglutarate. NADH, H+;
4) oxidative decarboxylation; enzyme: alpha-keto- glutarate dehydrogenase; products: succinyl-CoA , NADH, CO2, H+;
These reaction are exorgonic becase they far from equilibrium, making the forward direction higly favorable; if cellular energy were no in demand, forward progression of these reaction will be wastful.

Front 53

Regulation of TCA Cycle: Inhibition

Back 53

1) After a buildup of TCA cycle products & intermedi- ates accumulate, these compounds affect enzyme activity near & far, to greatly decrease cycling of the TCA reactions.
2) Key regulatory compounds that act to decrease the level of TCA cycle activity are inhibitors of TCA:
1) citrate, 2)NADH, & 3) succinyl-CoA
(with each successive cycle, the levels of key regulato ry compounds increase, cycle acivity is decreased).
3) Building of NADH gives feedback inhibition to few steps:
a) Inhibition of step 1:
enz:citrate synthase;
substrate availability: Acetyl-CoA, Oxaloacetate; product inhibition: citrate;
feed back inhibition: NADH, Succinyl-CoA
b) Inhibition step 3 :
enzyme: isocitrate dehydogenase
feedback inhibition: NADH from pool generated by TCA cycle
c) Inhibition of step 4:
enzyme: alpha-ketoglutarate dehydrogenase
product inhibition: Succinyl-CoA & NADH
feed back inhibition: NADH from pool generated by TCA.

Front 54

Regulation of TCA Cycle: Activation

Back 54

In contrast, positive regulators, called activators, function to up-regulate the activity of the citric acid cycle when the cell’s energetic or molecular needs are not met. key activators include:
1) Ca2+ & 2) ADP
They signal to increase the activity of isocitrate (step 3) dehydrogenase & a-ketoglutarate dehydrogenase (step 4); Ca2+ & ADP generally signify the need to generate cellular free E.
a) Activation of step 3:
oxidative decarboxylation;
enzyme: isocitrate dehydrogenase;
activators: Ca+2 & ADP
b) Activation of step 4:
oxidative decarboxylation;
enzyme: alpha-keto glutarate dehydrogenase;
activator Ca+2.

Front 55

Anaplerotic Reactions

Back 55

Reactions which "feed" TCA with intermediates are anaplerotic reactions.
Reactions exist to replenish cell with TCA cycle inter- mediates which is especially important with increasi ng metabolic activity as vigorous exercises. The catabolism of 3 kind of compounds 'feed" TCA Cycle at different points.

Front 56

Fatty Acids are sources of Acetyl-CoA

Back 56

b oxidation of free fatty acid (FFA)--> Acetyl-CoA
When a cell’s metabolic needs increase, free fatty acids enter the mitochondrion where the degra-dative reactions called b oxidation ensue. A fatty acid shortened by two carbon atoms plus a free acetyl-CoA molecule results from each round of b oxidation. Acetyl-CoA initiates the citric acid cycle.

Front 57

Amino acids are sources of Acetyl-CoA

Back 57

Deamination of amino acids--> skeleton -->Acetyl- -Coa or Pyruvate
1)In starvation, protein degradation increases & free amino acids that result may be used as a source of metabolic fuel.
2) If intake of free amino acids exceed eds its prote-in-building needs, the free amino acids are metabo-lized. No storage mechanism for excess amino acids.
3)Amino group of an amino acid is removed in dea- mination reaction. The remaining carbon skeleton is broken down to various products. In some cases, re- m aining carbon skeleton is broken down to acetyl- -CoA, or to pyruvate, or even to intermediate such as a-ketoglutarate. All a.a ----> CO2.
4)Examples, catabolism of lysine yeilds CO2 & acetyl- CoA; glutamate breaks down to a-ketoglutarate, CO2 & acetyl-CoA. Acetyl-CoA initiates the citric acid cycle.

Front 58

Short Summary of TCA Cycle

Back 58

1) Citric Acid Cycle catabolizes Acetyl-CoA
2) Couples of Acetyl-Coa Oxidation to generation of reduced co-factors.
3) Products are used to produce E for the cell.
4) Serves as central metabolic pathways for generating building blocks for the cell.

Front 59

Membrane Reactions ( short summary)

Back 59

1)The final reactions of aerobic respiration are mem- brane reactions, which occur on inner mitochondr-i al membrane.
2) Enzymes & other electron carriers here transport electrons from NADH & FADH2 to oxygen, producing water as end product.
3) E from these electron transfers drives proton pumps, which create a steep H+ electrochemical gradient between the mitochondrial membranes.
4) This gradient drives chemiosmotic mechanism by
which ATP synthase generates ATP.

Front 60

Membrane Reactions (in details)

Back 60

1) Membrane rxns have 2 purposes:
a) to further oxidize NADH & FADH2 &transfer their E to ATP
b) to regenerate NAD & FAD & make them available again to earlier reaction steps.
2) The membrane reactions are carried out by series of compounds called mitochondrial electron-transpo rt chain & most members of the chain are bound to the inner mitochondrial membrane.
3) They are arranged in a precise order that enables each one to receive pair of e-s from member on one side of it (or, in two cases, from NADH & FADH2) & pass these electrons along to member on other side.
4) In the end of chain cool”—its E has been used to make ATP.

Front 61

Members of Electron Transport Chain

Back 61

1) FMN (Flavin mononucleotide) derivative of ribofla- vitB2,similar to FAD, bound to membrane protein.
FMN accepts electrons from NADH.
2) Fe-S(Iron–Sulfur) centers. Complexes of Fe & S atoms bound to membrane proteins.
3) CoQ (Coenzyme Q), which accepts electrons
from FADH2. Relatively small, mobile molecule that moves about in the membrane.
4)Cu (Copper ) ions bound to 2 membrane proteins.
5)Cytochromes, 5 five enzymes with Fe-cofactors, so are named due to brightly colored in pure form. 6)Order of cytochoromes of participation in chain:
cytochromes: b, c1, c, a, & a3.

Front 62

Electron Transport

Back 62

1) H atoms are split during transfer from coenzymes to chain; protons are pumped into intermemb rane space; electrons travel in pairs (2 e) along chain.
2) Each e-n carrier in chain becomes reduced
when it receives an e-n pair & oxidized again when it passes electrons along to next carrier. E is liberated at each transfer.
3) Final electron acceptor in chain is O2. Each O2 atom (half of an O2 molecule) accepts 2electrons
(2 e) from cytochrome a3 & two protons (2 H) from the mitochondrial matrix.
4) The result is a molecule of water:
1/2 O2  2 e  2 H → H2O, this is body’s 1-ry source of
metabolic water—water synthesized body rather than ingested in food & drink.

Front 63

The Chemiosmotic Mechanism

Back 63

1)What happens to E liberated by the e-s as they pass along chain? Some of it is unavoidably lost as heat, so- me of it drives respiratory enzyme complexes.
2) 1-st complex: FMN & five or >Fe-S centers;
3) 2-nd complex : cytochromes b & c1 & Fe-S center;
4) 3-d complex: 2Cucenters & cytochromes a & a3. 5) Each complex acts as proton pump that removes H
from mitochondrial matrix &pumps it into intermem brane space (b-n inner & outer mito-al membranes)
6) Coenzyme Q transfers electrons from 1-st pump to 2-nd; CytochromeC between 2-nd & 3-d pumps.
7) These pumps create very high H concentration
(low pH) & positive charge between membranes
compared with a low H concentration &negative
charge in mitochondrial matrix.
8) They create steep electrochemical gradient across inner mitochondrial membrane.
9)Inner membrane, however, is permeable to H
only through specific channel proteins called ATP synthase ((separate from the electron-transport system).
10) As H flows through these channels, it creates an electrical current (which, you may recall, is simply moving charged particles)& ATP synthase harnesse E of this current to drive ATP synthesis.
11) This process is called chemiosmotic mechanism, which suggests “push” created by electrochemical H gradient.

Front 64

Total 38 ATP created by Aerobic Respiration of one molecule of Glucose

Back 64

1) Aerobic respiration of G can be represented in summary equation:
C6H12O6 + 6O2 + 38 (ADP+Pi)-->6CO2 + 6 H2O + 38ATP
2) 39 ATP is Theoretical maximum.
3) Some uncertainty exist how much H must be
pumped between mitochondrial membranes to generate 1 ATP due to:
a) Some of E from protons current is consumed by pumping ATP from the mitochondrial matrix into cytosol & exchanging it for more raw materials (ADP
&Pi) pumped from cytosol into mitochondria.
b) NADH generated by glycolysis cannot enter mito- chondria & donate e-s directly to e-n-transport chain.
c) In liver, kidney, & myocardial cells, NADH passes its electrons to malate, “shuttle” molecule that delivers the e-s to beginning of the e-n-transport chain & here NADH yields E to generate 3 ATP.
d)In skeletal muscle & brain cells, glycolytic NADH transfers its e-s to glycerol phosphate & results in production of 2 ATP (so the amount of ATP produced per NADH differs from one cell type to another and is still unknown for others).
4) if maximum ATP yield, every mole of Glucose (180 g) releases enough E to synthesize 38 moles of ATP. Glucose E content= 686 kcal/mole; ATP =7.3kcal/mo- le (7.3x 38=277.4 kcal in 38 moles). It means that aerobic respiration has efficiency=40 % (ratio of E output to input or 244.4/686 kcal x100%= 40%). The other 60% (408.6 kcal) is body heat.

Front 65

ATP is E-transfer molecule, not E- storage molecule

Back 65

1) ATP is quickly used after it is synthesized - is an E transfer molecule, not an E-storage molecule.
2) If body has ample amount of ATP & more Glucose still in blood, it does not produce & store excess ATP but converts the glucose to compounds better suited for E storage: glycogen & fat.

Front 66

Glycogen

Back 66

1)Average adult body contains t 400 -450 g of glycogen:
2)Near 1/4 it in liver, 3/4 in skeletal muscles, & small amounts in cardiac muscle & other tissues.

Front 67

Glycogenesis (Anabolic rxn)

Back 67

1) Synthesis of Glycogen by polymerizing Glucose.
2) Stimulated by Insulin.
3) Glucose 6-phosphate (G6P) is isomerized to
glucose 1-phosphate (G1P).
4)Enzyme glycogen synthase then cleaves off phos- phate group & attaches G to growing polysaccharide .

Front 68

Gluconeogenesis (Anabolic rxn)

Back 68

1)Synthesis of Glucose from noncarbohydrates such as glycerol & amino acids.
2) Occurs chiefly in liver, but after several weeks of
fasting, kidneys also undertake this process & produce just as much G as liver does.

Front 69

Glycolysis (Catabolic rxn)

Back 69

1)Splitting of Glucose into 2 molecules of pyruvic acid in preparation for 1)anaerobic fermentation
or 2) aerobic respiration

Front 70

Glycogenolysis

Back 70

1)Hydrolysis of glycogen to release free glucose (G) or glucose 1-phosphate (G1P).
2) Releases G between meals when new G is not bei- ng ingested. Process is stimulated by glucagon & epinephrine.
3) Enzyme glycogen phosphorylase phosphorylates glycogen to G1P molecule, which isomerizes to G6P,
which can enter glycolysis.
4) G6P usually cannot leave the cells that produce it.
Liver cells have enzyme Glucose 6-phosphatase, which removes Pi group & produces free G.
5)Free G can diffuse out of cell into blood & any cells.
6) Muscle cells cannot directly release G into blood, they contribute indirectly to blood G [c] because they release pyruvic &lactic acids, which are convert- ed to G by liver.

Front 71

Glycolysis & Mitochondrial Reactions Can be used for
Lipids & Proteins Oxidation

Back 71

Glycolysis & Mitochondrial Reactions can be used in
1) In oxidation of carbohydrate, proteins & lipids
2) As source of metabolic intermediates that can be used for their synthesis.

Front 72

Lipids

Back 72

1) Adipocytes store & release most of the body’s fat (triglycerides) & remains for about 2- 3weeks. 2)Although total amount of stored triglyceride
remains quite constant, there is continual turnover as lipids are released, transported in blood, oxidized for E or redeposited in other adipocytes.

Front 73

Lipogenesis

Back 73

1)Lipogenesis is synthesis of fats from precursors such as sugars, amino acids.
2) Diet high in sugars causes us to put on fat & gain Weight.
3)Lipogenesis uses sugars & amino acids to synthe- size glycerol & fatty acids (triglyceride precursors).
3) PGAL (phosphoglyceraldehyde) one of intermedia- tes of G oxidation, can be converted to glycerol.
4) As glucose & amino acids enter TCA cycle by way of acetyl-CoA, it can also be diverted to make fatty acids.
5)Glycerol & fatty acids can then be condensed to
form triglyceride, which can be stored in adipose tissue or converted to other lipids.



and glycerol. Fatty acids are degraded
by the process of beta oxidation.
Oxidation of a typical fatty acid can
yield 129 ATP—much more than glucose
oxidation.

Front 74

Lipolysis

Back 74

1)Lipolysis is breakdown of fats, starting with hydro- lysis & continuing with oxidation of fatty acids.
2) Begins with hydrolysis of triglyceride into glycerol & fatty acids— stimulated by1) epinephrine, 2)norep inephrine, 3) glucocorticoids, 4) thyroid hormone, & 5) growth hormone.

Front 75

Oxidation of Glycerol

Back 75

1)Glycerol is converted to PGAL & enters glycolysis.
2) It makes 1/2 of ATP & 1/2 of pyruvic acid compare to Glucose (PGAL is C3 compound, glucose is C6).

Front 76

Oxidation of Fatty Acids

Back 76

1)Fatty acid are catabolized in mitochondrial matrix by beta oxidation.
2) 2 C atoms removes at time. Resulting acetyl (C2) groups then bonded to coenzyme A to make Acetyl- CoA (entry point of TCA cycle).
3) Excess acetyl groups can be metabolized by liver in ketogenesis.




6) F.A. of 16 C atoms can yield 129 molecules of ATP (much more E than from G molecule, each fat molecule makes 3 f.a.).

Front 77

Ketone Bodies

Back 77

a)Acetoacetic acid, b)beta-hydroxybutyric acid & c)acetone
1)Produced during incomplete fatty acid oxidation -
ketogenesis (metabolism of excess of acetyl (2C) groups in liver; acetyl groups are product of fatty acids oxidation)
2) Some cells convert acetoacetic acid back to acetyl -CoA & feed C2 fragments into TCA cycle to extract their E.
3)When body is rapidly oxidizing fats, excess ketone bodies accumulate which causes ketoacidosis typical of type 1 diabetes mellitus (cells must oxidize fats because they cannot absorb glucose.
4)

Front 78

Can Fatty Acids and Glycerol be used for Gluconeogenessis?

Back 78

1) Glycerol - Yes, 2) Fatty acids - No
1)Glycerol oxidized to PGAL -->G6P->Glucose
2) Fatty acids - No
Acetyl-CoA cannot go backward up the glycolytic
pathway & produce glucose, because this pathway is
irreversible past the point of pyruvic acid.

Front 79

Ketosis

Back 79

Ketosis is elevated ketones in the blooddue to exess of ketones.
1) Fats cannot be completely oxidized when there is not enough carbohydrate in diet.
2) This is because mitochondrial reactions cannot proceed w/out oxaloacetic acid (entering TCA cycle)
3) When carbohydrate is unavailable, oxaloacetic acid is converted to G & becomes unavailable to TCA.
4) Fat oxidation then produces excess ketones, leading to elevated blood ketones (ketosis) & poss.resulting pH imbalance (ketoacidosis). Ketosis is a serious risk of extreme lowcarbohydrate diets.

Front 80

Scheme of Liponeogenesis

Back 80

Glucose--->G6P<--->PGAL--->Pyruvic Acid--->Glycerol
Pyruvic Acid--->Acetyl-CoA--->TCA Cycle
Acetyl-CoA--->Fatty Acids
(Glycerol & Fatty Acids)----> New Triglycerides

Front 81

Scheme of Lipolysis

Back 81

Stored Triglycerides--->Glycerol & Fatty Acids
Glycerol---> PGAL
Fatty Acids--->beta Oxidation--->Acetyl Groups--->
Acetyl Groups--->Acetyl CoA
Acetyl Groups--->Ketones Bodies (β-hydroxybutyric acid, Acetoacetic acid, & Acetone)

Front 82

Proteins

Back 82

1)100 g of tissue protein breaks down each day into free a.a. & combine with a.a. from diet to form a.a. pool to make new proteins.
2)Fastest rate of tissue protein turnover is in intesti- nal mucosa, where epithelial cells are replaced at very high rate.
3) Dead cells are digested along with food & contrib- ute to a.a. pool.
4) Of all a.a. absorbed by small intestine: 50% is from diet, 25% from dead epithelial cells, & 25% from enzymes that have digested each other.
5) Some a.a. in pool can be converted to others.
6) Free a.a. also can be converted to glucose & fat or directly used as fuel.

Front 83

How amino acids can be use

Back 83

Free amino acids can be use to synthesized proteins, converted to Glucose, Fat, or use as a Fuel

Front 84

What is Deamination, Aminatuon , & Transamination?

Back 84

1) Deamination: removal of an amino group (–NH2)
2 )Amination: addition of (–NH2)
3) Transamination: transfer of –NH2 from one molecule to another.

Front 85

Use of Amino Acids as a Fuel

Back 85

1) After –NH2 group is removed, remainder of
molecule is called a keto acid.
2) Depending on which a.a. is involved, resulting ke- to acid may be converted to 1) pyruvic acid, 2) acetyl - CoA, 3) one of acids of TCA cycle
4) Some of these reactions are reversible.
5) When there is a deficiency of a.a., TCA cycle inter-
mediates can be aminated & converted to a.a. which are then available for protein synthesis.
6) In gluconeogenesis, keto acids are used to synthe-size Glucose, essentially through reversal of glycoco lysis reactions.
7)Scheme: proteins<---> aminio acids<--->(-NH2)---> keto acids--->Pyruvic acid <---> Glucose
keto acicds --->Acetyl-CoA
keto acids<---> 3) TCA cycle intermediates

Front 86

Transamination, Ammonia, and Urea

Back 86

1) When a.a. is deaminated, its NH2 is transferred to TCA cycle intermediate, alpha -ketoglutaric acid, converting it to glutamic acid.
2) Such transamination rxs are route by which several a.a.enter tTCA cycle.
3) Glutamic acid can travel from any of body's cells
to liver & its –NH2 group is removed, conver ting it back to alpha-ketoglutaric acid. –NH2 becomes ammonia (NH3), very toxic.
4) So, liver by path called the urea cycle, quickly com -bines ammonia with CO2 to produce less toxic waste, urea.
5)Urea is then excreted in the urine as one of the body’s nitrogenous wastes.
6) When a diseased liver cannot carry out the urea cycle, NH3 accumulates in the blood & death from hepatic coma may ensue within few days
7) Scheme: aminio acids--->-NH2--->+Alpha-ketoglutaric acid (form TCA cycle)--->glutamic acid--->enter liver:
in lver: 1)glutamic acid -NH3---->alpha-ketoglutaric acid--->out of liver< --->a) enter TCA cycle or b) combined with deaminated amino acid to glutamic acid to enter liver.

Front 87

Protein Synthesis

Back 87

1) Protein synthesis is complex process involving DNA, mRNA, tRNA, ribosomes, & often rough ER.
a) Protein synthesis begins with transcription, pro- cess in which enzyme RNA polymerase makes an
mRNA mirror-image copy of the gene.
b) Messenger RNA usually leaves nucleus & binds to ribosome in cytoplasm.
c) Protein synthesis continues with translation, in which a ribosome binds mRNA, reads coded messa- ge, & assembles corresponding protein.
d) After translation, protein may undergo structural changes called posttranslational modification, often
carried out in rough ER & Golgi complex, followed in many cases by secretion from the cell.
e) Genes are turned on or off by regulatory proteins in accordance with changing needs for proteins they
encode. Regulatory proteins may be activated by hormones & other chemical messengers.
f) DNA directly controls protein structure & indirect- ly controls synthesis of other molecules by coding for enzymes that make them.
2)Protein synthesis is stimulated by growth hormone thyroid horm ones, and insulin, & it requires supply of all amino acids necessary for a particular protein.
3)Liver can make many of these amino acids
from other amino acids or from TCA cycle intem-ediates by transamination reactions.
4)Essential amino acids must be obtained from diet.

Front 88

Liver Functions in Brief

Back 88

1) Liver is connected to the digestive tract & genene- rally is digestive gland, but overwhelming majority of its functions are nondigestive.
a) Carbohydrate metabolism
b) Lipid metabolism
c) Protein and amino acid metabolism
d) Synthesis of plasma proteins
e) Vitamin and mineral metabolism
f) Digestion
g) Digestion
h) Phagocytosis
3) Except for phagocytosis, all of these are perform- ed by cuboidal hepatocytes.
4) Functional diversity is remarkable in light of unifo - rm structure of these cells.

Front 89

Liver function in details
a) Carbohydrate Metabolism

Back 89

1) Converts dietary fructose & galactose to glucose. 2) Stabilizes blood glucose [c] by storing excess gluco se as glycogen (glycogenesis),
3)Releasing glucose from glycogen when needed
(glycogenolysis).
4)Synthesizing glucose from fats &amino acids
(gluconeogenesis) when glucose demand exceeds glycogen reserves.
5) Receives lactic acid generated by anaerobic ferme ntation in skeletal muscle & other tissues & converts it back to pyruvic acid or G-6P.

Front 90

Liver function in Details
b) Lipid metabolism

Back 90

1)Degrades chylomicron remnants.
2)Carries out most of the body’s lipogenesis (fat synthesis), synthesizes cholestero,l & phospholipids; 3)Produces VLDLs to transport lipids to adipose tissue & other tissues for storage or use; & stores fat in its own cells.
4) Carries out most beta oxidation of fatty acids; produces ketone bodies from excess acetyl-CoA. 5)Produces HDL shells, which pick up excess cholesterol from other tissues and return it to liver;
6) Excretes the excess cholesterol in bile.

Front 91

Liver function in Details
c)Protein and amino acid metabolism

Back 91

1)Carries out most deamination & transamination of amino acids.
2) Removes NH2 from glutamic acid & converts resul ting ammonia to urea by means of the urea cycle.
3) Synthesizes nonessential amino acids by transamination reactions.

Front 92

Liver function in Details
d) Synthesis of plasma proteins

Back 92

Synthesizes nearly all the proteins of blood plasma, including
albumin, alpha and beta globulins, fibrinogen, prothrombin,
and several other clotting factors. (Does not synthesize plasma
enzymes or gamma globulins.)

Front 93

Liver function in Details
e) Vitamin and mineral metabolism

Back 93

1) Converts vitamin D3 to calcidiol, step in the synthesis of calcitriol;
2) Stores a 3- to 4-month supply of vitamin D.
3) Stores 10-month supply of vitamin A & enough vitamin B12 to last one to several years.
4) Secretes hepcidin to regulate Fe absorption; 5) Stores Fe in ferritin & releases it as needed.
5) Excretes excess Ca by way of bile

Front 94

Liver function in Details
f) Digestion

Back 94

1)Synthesizes bile acids & lecithin, which emulsify fat &
promote its digestion;
2)Produces micelles, which aid in absorption of dietary lipids

Front 95

Liver function in Details
g) Disposal of drugs, toxins, and hormones

Back 95

1)Detoxifies alcohol, antibiotics, & many other drugs.
2) Metabolizes bilirubin from RBC breakdown & excretes it as bile pigments.
3)Deactivates thyroxine & steroid hormones & excre- tes them or converts them to a form more easily excreted by the kidneys.

Front 96

Liver function in Details
h) Phagocytosis

Back 96

1)Macrophages cleanse blood of bacteria & other foreign matter.

Front 97

Hepatitis

Back 97

1) Hepatitis, inflammation of the liver, is usually caused by one of 5 strains of hepatitis viruses.
2) They differ in mode of transmission, severity of resu lting illness, affected age groups, & best strategies for prevention.
3) Hepatitis A is common & mild. Over 45% of peop- le in urban areas of US have had it. It spreads rapidly in such settings as day-care centers & residential institutions for psychiatric patients; can be acquired by eating uncooked seafood as oysters.
4) Hepatitis B & C are more serious & tansmitted sexually & through blood, other body fluids;
5)Incidence of hepatitis C has surpassed AIDS as sexually transmitted disease
5) Initial signs & symptoms of hepatitis: fatigue, malaise, nausea, vomiting, & weight loss.
6)Liver becomes enlarged & tender. Jaundice tends to follow as hepatocytes are destroyed, bile assages are blocked, & bile pigments accumulate in blood.
7) Hepatitis A causes up to 6 months but most people recover & then have permanent immunity. 8) Hepatitis B and C lead to chronic hepatitis, which can progress to cirrhosis or liver cancer.
More liver transplants are necessitated by hepatitis C
than by any other cause.

Front 98

Cirrhosis

Back 98

1) It is irreversible inflammatory liver disease.
2)It 1develops slowly over a period of years, but has high mortality rate & is one of the leading causes of death in the US.
3) It is characterized by disorganized liver histology in which regions of scar tissue alternate with nodul- es of regenerating cells, giving liver lumpy or knobby appearance & hardened texture.
4) Blockage of the bile passages results in jaundice; protein synthesis declines as liver deteriorates, leadi ng to ascites, impaired blood clotts, other CV effects.
5) Obstruction of hepatic circulation by scar tissue leads to angiogenesis, growth of new blood vessels to bypass liver. Deprived of blood, condition of liver worsens, with increasing necrosis & liver failure.
6) Most cases of cirrhosis result from alcohol abuse, but hepatitis, gallstones, pancreatic inflammation,
and other conditions can also bring it about.

Front 99

Absorptive state

Back 99

1)Lasts about 4 hours after a meal. During this time,
nutrients are absorbed from intestine & may be used immediately. Blood glucose is readily available
for ATP synthesis; it serves as 1-ry fuel & spares body from having to draw on stored fuels
2) Glucose level is high & excess glucose is stored as glycogen or converted to fat.

3) Status of Carbohydrates, major aspects :
a)Blood glucose rising
b)Glucose uptake
c)Glucose stored by glycogenesis
d)Gluconeogenesis suppressed

5) Status of Fats, major aspects:
a)Lipogenesis occurring
b)Lipid uptake from chylomicrons
c)Lipid storage in fat & muscle

6) Status of Amino Acids, major aspects:
a)Amino acid uptake, protein synthesis
b) Excess amino acids burned as fuel

Front 100

Status of Carbohydrates in Absorptive state

Back 100

1) Sugars--> Liver, 2) Most G passes through liver & becomes available to cells everywhere in the body. 3) G in excess of immediate need, however, is absorbed by liver & may be converted to glycogen or fat. 4) Most fat synthesized in liver is released into the circulation; its further fate is comparable to that of dietary fats.

Front 101

Status of Fats in Absorptive State

Back 101

1)Fats--->Lymph as chylomicrons (initially bypass liver)
(liver disposes of chylomicron remnants).
2)Fats are 1-ry E substrate for hepatocytes, adipocytes, & muscle cells.

Front 102

Status of Amino Acids in Absorptive State

Back 102

1)Amino acids--->liver.
2) Most pass through & become available to other cells for protein synthesis.
3) Some are removed by liver &:
(1) used for protein synthesis;
(2) deaminated & used as fuel for ATP synthesis;
(3) deaminated & used for fatty acid synthesis.

Front 103

Regulation of Absorptive State

Back 103

1)Absorptive state is regulated mainly by insulin, (secreted by in response to elevated blood G & ami- no acid levels & to intestinal hormones: gastin, sec- re tin, cholecystokinin (CCK), & glucose-dependent insulinoropic peptide (GIP)) & promotes
a) glucose uptake & oxidation,
2) glycogenesis, & lipogenesis;
3)protein synthesis;
4)inhibits gluconeogenesis.
Insulin regulates the rate of G uptake by nearly all cells except neurons, kidney cells, & RBC, which have independent rates of uptake.
5)Other regulatory hormones: gastrin, secretin, CCK, GIP.

Front 104

Postabsorptive state

Back 104

1) Prevails between meals & overnight, when stom-
ach & small intestine are empty & body uses stored fuels.
2)Glycogenolysis & gluconeogenesis maintain blood glucose level during this state.
3) Fatty acids derived from lipolysis are used as fuel by many cells .
4) Homeostatically regulate blood G[c] within about
90 to 100 mg/dL.
5) Especially critical to brain, which cannot use altern ative E substrates except in cases of prolonged fasting.

Front 105

Status of Carbohydrates, Fats and Amino Acids in Postabsorptive State

Back 105

1)Carbohydrates:
Blood glucose falling
Glucose released by glycogenolysis
Gluconeogenesis stimulated
2)Fats:
Lipolysis occurring
Fatty acids oxidized for fuel
Glycerol used for gluconeogenesis
3) Amino Acids:
Amino acids oxidized if glycogen & fat stores
are inadequate for E needs.
In Details:
a) Carbohyrdates:
Glucose is drawn from the body’s glycogen reserves (glycogenolysis) or synthesized from other compounds (gluconeogenesis). Liver usually stores enough glycogen after meal to support 4 hours of postabsorptive metabolism before significant gluconeogenesis occurs.
b)Fats:
Adipocytes & hepatocytes hydrolyze fats &convert glycerol to G. Free fatty acids (FFAs) cannot be converted to glucose, but they can affect blood G[c]. As liver oxidizes them to ketone bodies, other cells
absorb & use these, or use FFAs directly, as their
source of E. By switching from G to fatty acid catabo- bolism, they leave G for use by brain (G-sparing effect). After 4 to 5 days of fasting, the brain begins to use ketone bodies as supplemental fuel.
c)Proteins: Some proteins are more resistant to catabolism than others. Collagen is almost never broken down for fuel, but muscle protein goes quick ly. Extreme wasting away seen in cancer & some oth er chronic diseases, resulting from loss of appetite (anorexia) as well as altered metabolism (cachexia).

Front 106

Regulation of Postabsortive State

Back 106

1)Principally glucagon, symphatetic nervous system,
also multiple hormones.
1)Epinephrine, Norepinephrine, Growth hormone promote lipolysis & glycogenolysis;
3)Cortisol promotes fat & protein catabolism;
4)Cortisol & glucagon promote gluconeogenesis;
5)Growth hormone raises bloodG by antagonizing insulin.

Front 107

Metabolic rate

Back 107

1)Metabolic rate is the amount of E released in body in given time, such as kcal/day.
2)It varies according to metabolic state, physical,
mental, & hormonal conditions.
3) Metabolic rate can be measured directly by putting
person in a calorimeter
4) Metabolic rate can also be measured indirectly with a spirometer,

Front 108

Basal metabolic rate (BMR)

Back 108

1)BMR is basal metabolic rate (BMR) is standard of reference based on comfortable, resting, awake, postabsorptive statein 12 to 14 hours after the last meal.
2) It is not the min rate needed to sustain life, however.
3) When one is asleep, metabolic rate is slightly lower
than the BMR.
4)Total metabolic rate is higher nonresting rate that takes muscular activity into account.
5)BMR is about 2,000 kcal/day. Low level of physical activity increases the daily E need to about 2,500 kcal/day, & hard physical labor can increase it to as much as 5,000 kcal/day.
6) Metabolic rate also varies with age, sex, mental state, stress, & health or illness.
7) Aside from physical activity, factors that raise
TMR & caloric requirements: pregnancy, anxiety (which stimulates epinephrine release & muscle tension), fever (TMR rises about 14% for each
1C of body temperature), eating (TMR rises after
meal), catecholamine & thyroid hormones.
8)TMR is relatively high in children a& declines with
age. Therefore, as we reach middle age we often find
ourselves gaining weight with no apparent change in
food intake.

Front 109

Thermoregulation

Back 109

1)Thermoregulation is homeostatic control of body temperature.
2) Excessively highbody T is hyperthermia, low body T is
hypothermia can be fatal.

Front 110

Core temperature

Back 110

1)Core T can be estimated from rectal temperature and is usually 37.2 to 37.6C. It most important body temperature -T of organs in the cranial, thoracic, & abdominal cavities. It may be as high as 38.5C (101°F) in active children and some adults.
2) Shell temperature, usually estimated from oral temperature, is usually 36.6 to 37.0C, but may be as high as 40C (104F) during hard exercise.
3) Normal” body temperature depends on when, where, & in whom it is measured. Body temperature fluctuates about 1C (1.8F) in a 24-hour cycle. It tends to be lowest in the early morning and highest in late afternoon & varies from one place in body to other.

Front 111

Body heat

Back 111

1)Body heat is generated mainly by exergonic chemi- cal reactions, especially in brain, heart, liver,
& endocrine glands at rest & in skeletal muscles during activity.
2) The body loses heat by radiation, conduction, & evaporation.
Radiation: It is emission of infrared (IR) rays by movi-
ng molecules. In essence, heat means molecular
motion, & all molecular motion produces IR rays.
When IR rays are absorbed by an object, they increa
se its molecular motion & raise its temperature.The-
refore, IR radiation removes heat from its source
& adds heat to anything that absorbs it. Our bodies continually receive IR from objects around us & give off IR to our surroundings. Since we are usually war- mer than the objects around us, we usually lose mo- re heat this way than we gain.
Conduction: It is the transfer of kinetic energy from molecule to molecule as they collide with one another. The warmth of your body thereby adds to the molecular motion & T of clothes you wear, chair you sit in, & air around you. Conductive heat loss is aided by convection, motion of a fluid due to uneven heating. Air is fluid that becomes less dense and rises as it is heated. Thus warm air rises from body & is replaced by cooler air from below.
Evaporation is the change from liquid to gaseous
state. Sweat wets skin surface & its evaporation
carries heat away. Breeze or fan enhances heat
loss by conduction & evaporation. It has no effect
on radiation.
A nude body at an air temperature of 21C (70F) loses about 60% of its heat by radiation, 18% by condcuct ion, and 22% by evaporation.

Front 112

The hypothalamic thermostat

Back 112

Monitors blood T & receives signals from peripheral
thermoreceptors in the skin.

Front 113

To Rid the body of Excess Heat

Back 113

Thermostat sends signals to hypothalamic heat-loss center, which triggers cutaneous vasodilation & sweating.

Front 114

To Generate and retain heat

Back 114

Thermostat sends signals to hypothalamic heat-promo moting center, which triggers shivering & cutaneous
vasoconstriction.

Front 115

Nonshivering Thermogenesis

Back 115

Heat can also be produced by nonshivering thermogen esis, in which metabolic rate is increased &releases more heat from organic fuels

Front 116

Behavioral Thermoregulation

Back 116

Behavioral thermoregulation includes behaviors that adjust body temperature, such as adding or removing
clothes, or getting into shade or sun.

Front 117

Heat cramps, heat exhaustion,
and heatstroke

Back 117

3 effects of hyperthermia. Heatstroke often progresses to fatal multiorgan dysfunction. Hypothermia may be
fatal if the core temperature reaches 32C or lower.