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Physiology > Ch 5 > Flashcards

Ch 5 Flashcards

1
Q

Anabolism

A

requires the input of energy to synthesize large molecules

“building something up”

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2
Q

Catabolism

A

releases energy by breaking down large molecules into small molecules
“breaking something down”

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3
Q

Catabolism drives anabolism

A

The catabolic reactions that break down glucose, fatty acids, and amino acids serve as ENERGY SOURCES for the anabolism of ATP.

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4
Q

aerobic cellular respiration

A

Complete catabolism of glucose requires oxygen as the final electron acceptor.

But…breaking down glucose requires many enzymatically catalyzed steps, the first of which are anaerobic

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5
Q

Glycolysis (general)

A

conversion of glucose into two molecules of pyruvic acid

–> no oxygen needed

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6
Q

Glycogenesis

A

production of glycogen (mostly in skeletal muscles and liver)

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7
Q

Glycogenolysis

A

hydrolysis (breakdown) of glycogen

–> yields glucose 6-phosphate for glycolysis or free glucose that can be secreted in the blood

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8
Q

Gluconeogenesis

A

production of glucose from noncarbohydrate molecules, including lactic acid and amino acids, primarily in the liver

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9
Q

Lipogenesis

A

the form of triglycerides (fat), primarily in adipose tissue

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10
Q

Lipolysis

A

hydrolysis (breakdown) of triglycerides, primarily in adipose tissue

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11
Q

Ketogenesis

A

formation of ketone bodies, which are 4-carbon long organic acids, from fatty acids, occur in the liver

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12
Q

Three steps in aerobic respiration of glucose

A
  1. Glycolysis: occurs in cytoplasm, anaerobic
  2. Citric Acid (Krebs) Cycle: occurs in matrix of mitochondria, aerobic
  3. Electron Transport: occurs in cristae of mitochondria inner membrane, aerobic
    - -> where we get the MOST ATP
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13
Q

Glycolysis (detailed)

A

• First step in catabolism of glucose
• Occurs in the cytoplasm of the cell
• Glucose is split into two pyruvic acid molecules
• 6-carbon sugar–> 2 molecules of 3-carbon pyruvic acid
• C6H12O6 –> 2 molecules C3H4O3
——> (don’t need to know structure, just that it moves from one 6-carbon to two 3-carbon)
• Note loss of 4 hydrogen ions. These were used to reduce
2 molecules of NAD (2NAD + 4H+ –> 2NADH+ H+(2NADH))
——> no need for oxygen

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14
Q

Glycolysis equation

A

Glucose + 2 NAD + 2 ADP + 2 Pi –> 2 pyruvic acid + 2 NADH + 2 ATP
(4 hydrogens reduced to 2 in product)

pyruvic acid –> used in citric acid cycle
NADH –> oxidized to make ATP

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15
Q

Lactic Acid Pathway

A

When there is NO oxygen to complete the breakdown of glucose, NADH has to give its electrons to pyruvic acid.

  • ->This results in the reformation of NAD and the conversion of pyruvic acid to lactic acid.
  • anaerobic metabolism/lactic acid fermentation
  • net yield of 2 ATP
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16
Q

muscle cells

A

can survive for awhile without oxygen by using lactic acid fermentation

17
Q

RBCs

A

only use lactic acid fermentation because they lack mitochondria

18
Q

Citric Acid Cycle

A

Acetyl CoA (from pyruvic acid) + oxaloacetic acid = citric acid

  • citric acid moves through reactions to produce more oxaloacetic acid
  • -> One GTP is produced, which donates a phosphate group to ADP to form ATP
  • 3 molecules NAD –> reduced to NADH
  • 1 molecule FAD –> reduced to FADH2
  • **events occur for each acetic acid, so it happens twice for each glucose molecule
19
Q

Citric Acid Cycle: for each glucose we produce…

A
  • 6 NADH
  • 2 FADH2
  • 2 ATP
  • 4 CO2
20
Q

Electron Transport & Oxidative Phosphorylation

A
  • molecules in the cristae (folds) of the mitochondria act as electron transporters
  • -> they accept electrons from NADH and FADH2 (produced in Krebs Cycle). H+ NOT transported.
  • -> Oxidized FAD and NAD are reused
21
Q

Electron Transport Chain

A

Electron transport molecules pass the electrons down a chain, with each being reduced and then oxidized

  • exergonic reaction: energy produced - ADP –> ATP
  • -> ADP experienced (direct) oxidative phosphorylation - less than 50% efficient (some released as heat)
22
Q

Oxidative Phosphorylation Steps

A
  1. Electron transport fuels proton pumps
    - H+ pumped from the mitochondrial matrix –> space between the inner/outer membranes
  2. Creation of a huge concentration gradient between membranes
  3. H+ can ONLY move through the inner membrane through structures called respiratory assemblies
  4. Movement of H+ across the membrane provides energy to the enzyme ATP synthase, which converts ADP to ATP.
23
Q

Why is the mitochondrial outer membrane important?

A

**no outer membrane would mean the H would diffuse into cytosol = no concentration gradient, outer membrane is important to get max ATP!!

24
Q

Oxygen

A
  • Final electron acceptor
  • citric acid cycle/electron transport require oxygen

Water is formed in the following reaction: O2 + 4e- + 4H+ –> 2H2O

25
Q

Where do we get our total ATP?

A

Direct (substrate-level) phosphorylation in glycolysis + citric acid cycle = 4 ATP
Oxidative Phosporylation = varying amounts of ATP (32-34)

–> Theoretical ATP yield is 36-38 per glucose, but actual yield is 30-32 ATP per glucose b/c energy is needed to move ATP from mitochondria to cytoplasm

26
Q

Glycogenesis

A
  • Cells can’t store much glucose because it will pull water into the cell via osmosis.
  • Glucose is stored as a larger molecule called glycogen in the liver, skeletal muscles, and cardiac muscles.
  • Glycogen is formed from glucose via glycogenesis.
27
Q

Glycogenolysis

A

• When the cell needs glucose, it breaks glycogen down again.
• Produces glucose 1-phosphate (cannot leave muscle or heart cells)
–> The liver has an enzyme called glucose 6- phosphatase that removes the phosphate so glucose can reenter the bloodstream
• Glycogen phosphorylase is the catalyst (breaks it down)

28
Q

Glycogenolysis: liver

A

brain is glucose dependent, but doesn’t store it well

liver stores the glucose as glycogen —> breaks it down and sends it into the blood where it can get to the heart

29
Q

The Cori Cycle

A

exchange of lactic acid between skeletal muscles and liver

SKELETAL MUSCLE: glycogen –> glucose –> pyruvic acid –> lactic acid

*lactic acid enters bloodstream

LIVER: lactic acid –> pyruvic acid –> glucose

*glucose enters bloodstream

30
Q

Why do you need to warm down after a workout?

A

so you can keep the blood flowing and wash the lactic acid out of the skeletal muscles

31
Q

Lipid and Protein Metabolism

A
  • can be used for energy by same pathways as metabolism of pyruvic acid
  • excess food energy (glucose) is then stored as glycogen/fat (none is stored as ATP)
32
Q

Lipid Metabolism

A
  • ATP levels rise –> ATP production inhibited
  • Glucose doesn t complete glycolysis to form pyruvic acid
  • -> Acetyl CoA already formed is joined together to produce a variety of lipids, including cholesterol, ketone bodies, and fatty acids.
  • lipogenesis
33
Q

Lipogenesis

A

Fatty acids combine with glycerol to form triglycerides in the adipose tissue and liver

–> making fat, in fat cells, in times of excess (intake exceeds immediate energy requirements)

34
Q

Fatty Acids as an Energy Source

A

β-oxidation: Enzymes remove acetic acid molecules from fatty acids to form acetyl CoA

  • For every 2 carbons on the fatty acid chain, 1 acetyl CoA can be formed.
  • Each acetyl CoA –> 10 ATP + 1 NADH + 1 FADH2 (decent yield of ATP)
35
Q

Acetyl CoA can turn into….

A
  1. cholesterol (steroids, bile acids)
  2. ketone bodies
  3. citric acid cycle (CO2)
  4. fatty acids (triglycerides, phospholipids)
36
Q

Amino Acid Metabolism

A

-provides nitrogen for body
-Amino acids from dietary proteins are needed to replace
proteins in the body (we can only make 12/20)
–>essential AA: from diet
-If more amino acids are consumed than are needed, the excess amino acids can be used for energy or converted into carbohydrates or fat

37
Q

Amino Acids as Energy

A

different amino acids enter in at different places/times to drive the reactions
(none funnel in during glycolysis)
—> can use AA to funnel in for energy

38
Q

Energy Sources

A
  • LIVER: Glucose and ketone bodies
  • ADIPOSE TISSUE: Fatty acids
  • MUSCLE: Lactic acid and amino acids
39
Q

Energy Sources: Brain

A

brain requires lots of glucose, little ketone bodies (can’t use fatty acids/lactic acid)
–> why it’s important to keep blood glucose levels regular

Physiology (29 decks)

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