Anatomy Physiology II

Unit 4

Metabolism

Chapter 26

Objective # 1

• Metabolism: all chemical processes necessary to sustain life.

A. Anabolism (synthesis): to build, uses up energy.Simple (Small) → Complex (Large)

Amino Acids → Proteins

B. Catabolism (analysis, decomposition): to breakdown, releases energy.

Complex (Large) →Simple (Small)

Fatty Acids → Acetyl groups

Proteins → AA’s

Glucose → Carbon dioxide + Water + Energy

Burning fat for energy

Hydrolysis: chemical breakdown involving water.ATP + Water → ADP + Phosphate

Oxidation: combining with oxygen, or losing hydrogens

Reduction: gaining electrons or hydrogens

Objective #2

C6H12O6 + 6 O2 + 38 ADP + 38 P → 6 CO2 + 6 H2O + 38 ATPThis is cellular respiration.

Objective #3Complete breakdown of glucose, using O2 takes place in 4 stages. O2 serves as the final hydrogen acceptor and combines with hydrogen to produce water.

H2 + O → H2O

Stage I (Glycolysis): Glucose (6C) is broken down into two pyruvic acid molecules (3C). This stage does not require O2 and it takes place in cytoplasm.

1 glucose → 2 pyruvic acid moleculesStage II (Intermediate Stage): This stage requires O2 , but it does not use

oxygen. In this stage, PA (3C) from glycolysis is changed to acetyl group (2C) and CO2. This stage takes place in the matrix ofmitochondria.

Stage III (Krebs Cycle): This stage, like stage II requires O2 but does not use it. In this stage, acetyl groups (2C) from stage II are broken down into CO2 and hydrogens are stored on NAD and FAD which act as hydrogen acceptors. This stage takes place in the matrix of mitochondria.

Stage IV (Electron Transport System – ETS): This stage requires and uses O2. In this stage all the hydrogens that are stored as NADH2 and FADH2 are taken through the ETS chain of enzymes and their energy is extracted. The extracted energy is put into ATP molecules.

• The hydrogens, as they emerge from the end of ETS, combine with Oxygen to produce H2O

• Production of ATP in this way (in ETS) is called Oxidative Phosphorylation. ATP is made in the presence of oxygen, and where O2 is being used. Some ATP is produced in other stages where oxygen is not involved. ATP production in those stages is by Substrate Phosphorylation. These ATP’s are all the same, only their mode of production is different.

• Dehdrogenation: Removal of hydorgen from a molecule.• Decarboxylation: Removal of CO2 from a molecule.• Coenzyme A (Co A): Carries acetyl groups from Intermediate stage to Krebs

Cycle.

Stage IV (ETS): In this stage, the energy stored in the electrons and hydrogens of NADH2 and FADH2 is extracted and put into ATP molecules. This energy extraction is done by a series of enzymes that have an assembly line arrangement. Hydrogens go through the line in pairs and from each pair maximum energy extracted can produce 3 ATP’s.

ETS enzymes are Coenzyme Q and Cytochromes which are bound to the cristae of mitochondria.

• The energy from each electron pair entering the chain at the very top produces three ATP’s. The e’s from NADH2 enter at the top but FADH2 e’s enter the second step and can only produce 2 ATP’s.

• Total ATP’s from one glucose by ETS: 10 NADH2 x 3 = 30 ATP’s 2 FADH2 x 2 = 4 ATP’s

▬▬▬▬▬ 34 ATP’s

• Total ATP’s from one glucose by all stages:34: by oxidative phosphorylation (ETS) 4: by substrate phosphorylation (glycolysis and Krebs)

▬▬38 ATP’s / Glucose: Total by Aerobic Respiration

• Therefore, ETS generates the most ATP’s and Krebs generates most of the hydrogens used in ETS.

• Where are the following produced or used?• CO2; H2O; O2; NADH2; FADH2; Acetyl groups; ATP’s; Glucose; Citric

Acid; Pyruvic Acid

Objective #4 Glycogen: animal starch. Large molecule, made up of glucose molecules.

• Glycogenesis: converting glucose to glycogen. Producing glycogen. Anabolic reaction.

• Glycogenolysis converting glycogen to glucose. Breakdown of glycogen--catabolic reaction.

• Gluconeogenesis: forming new sugar from protein, fat, LA, or other non-sugar substances.

• Lipid Catabolism Triglyceride Glycerol + 3 Fatty AcidsThis happens in the intestine. In liver: a. Glycerol (3 C) Glyceraldehyde-3-P Glucose

GlycogenesisBlood Cells Glucose Catabolism

b. Fatty Acids Acetyl groups (2 C) by β-oxidation

Blood Glucose Glucose catabolism Ketones

Cells Cells Blood Cells

• Protein CatabolismProteins Amino Acids in the intestine

Blood

Liver: Deamination Cells

(NH2 NH3 Urea) (for protein synthesis)

The rest of AA

Blood

Cells: enters glucose catabolism as acetyls, PA, or an intermediate of the Krebs Cycle.

Deamination: removing amino groups in amino acid catabolism.

Objective #5• Products of Lipid Anabolism

1. Fatty tissue for insulation and protection

2. Phospholipid bilayer in plasma membrane of all cells

3. Cholestrol in plasma membrane

4. Myelin sheath in nerve cells

5. Steroid hormones

• Products of Protein Anabolism1. Muscles

2. Bones

3. In plasma membrane (integral proteins and receptors)

4. Antibodies and hormones

5. Hair and nail

Objective #6• 85% of blood Cholesterol is made in liver and only 15% comes from our

food. Cholesterol is a very important nutrient needed for making bile salts, vitamin D, steroid hormones, cell membrane, etc. How cholesterol is transported in our blood and how it is used and disposed will determine if one is at risk for heart and circulatory problems or not.

• Excess cholesterol and triglycerides are either stored in adipose tissue or destroyed in liver to make bile salts. Lipids are not water soluble and cannot be carried directly in plasma. Binding to Lipoproteins (small lipid-protein complexes) makes them water soluble and can be carried in the plasma. Lipoproteins help carry lipids to cells where they are used up.

• There are two types of Lipoproteins in our body: Low Density Lipoproteins (LDL), and High Density Lipoproteins (HDL). LDL is responsible for carrying lipids to cells where they are used up and HDL carries lipids to liver to be broken down and changed to bile salts. Therefore, HDL plays a more beneficial role by helping cholesterol and other fats to be destroyed if there is no more use for them in our body. High levels of HDL and low levels of LDL are desirable. HDL>60 mg/dL, and LDL<70 mg/dL

• Saturated fats and Trans Fats (hydrogenated oils) stimulate liver into producing more cholesterol rather than destroying it. They are bad news.

Objective #7

• There are two types of hormones: Protein Hormones and Lipid Hormones (Steroid Hormones). Lipids can pass through the cell membrane and enter the cell, while protein hormones cannot cross the cell membrane. Therefore, the two types affect their target cell by two different mechanisms.

• A. Direct Gene Activation: Lipid hormone enters its target cell

directly and travels into the nucleus and reacts with a specific gene on a specific chromosome, causing activation of this gene.

• B. Second-messenger system: Protein hormone cannot enter its target cells. It reacts with specific receptors on the cell membrane. This results in production of cyclic AMP (cAMP). cAMP acts as a second messenger inside of the cell causing changes in the structure or activities of the cell.

Objective #8

Disease Cause Symptoms

Gigantism STH (GH) in children

Tall

Dwarfism STH in Children Short

Cretinism Hypothyroidism and low thyroxin levels

Mental retardation, short, disproportionate stature

Acromegaly STH in adults Enlarged facial features, hands, and feet

Diabetes Mellitus Insulin (hypoinsulinism) Hyperglycemia, fat deposits in arteries, polyurea

Hypoglycemia Insulin (hyperinsulinism)

Disorientation, convulsions, and death