GLYCOLYSIS means “sugar splitting”

Kreb Cycle

Proteins embedded along inner membrane of mitochondria

Pyruvate reduced by NADH to: Lactate Animals & some bacteria Cheese & yogurt; sauerkraut Ethanol & carbon dioxide Yeasts Bread and alcoholic beverages Allows glycolysis to proceed faster than O2 can be obtained Anaerobic exercise Lactic acid accumulates Causes cramping and oxygen debt When O2 restored, lactate broken down to acetyl-CoA and metabolized

Aerobic Vs Anaerobic Efficiency CALORIES??????

Exercise – test of homeostasis Muscle contracts – increases demand for _______ This increases the demand for A) B) Oxygen debt – As training continues –

Test your oxygen debt Breathing rate = number of inhalations per minute Initial rate After exercise 5 minutes after exercise

The Demand for ATP WHY EXACTLY DO YOUR MUSCLES NEED ATP? 41.3 in textbook

Microscopic Anatomy and Physiology Sarcolemma Plasma membrane Sarcoplasmic Reticulum Modified endoplasmic reticulum Myofibrils Contractile structures in sarcoplasm Sarcomeres Units of contraction Consist primarily of proteins Myosin Actin

Skeletal Muscle Fiber Structure and Function

Muscle Contraction Sliding filament model

Neuromuscular Junction

CopyrightThe McGraw-Hill Companies, Inc CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Neuromuscular Junction CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuromuscular Junction 1. The site where the motor neuron and muscle fiber meet is the neuromuscular junction. a. The muscle fiber membrane forms a motor end plate in which the sarcolemma is tightly folded and where nuclei and mitochondria are abundant. b. The cytoplasm of the motor neuron contains numerous mitochondria and synaptic vesicles storing neurotransmitters.

CopyrightThe McGraw-Hill Companies, Inc CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display. Motor Units 1. A motor neuron and the muscle fibers it controls make up a motor unit; when stimulated to do so, the muscle fibers of the motor unit contract all at once.

Muscle Contraction Sliding filament model Depolarization of muscle causes sarcoplasmic reticulum to release Ca2+

Muscle Contraction Sliding filament model Ca2+ exposes binding sites on actin Myosin heads bind to actin Cross bridges form

Muscle Contraction Sliding filament model Myosin heads lose ADP + P Myosin heads change shape Actin pulled toward center of sarcomere Muscle contracts

Muscle Contraction Sliding filament model ATP binds to myosin heads Cross bridges break Muscle relaxes

Muscle Contraction Sliding filament model

Sliding Filament Model Actin filaments at both ends of sarcomere One end of each filament attached to a Z-plate at one end of the sarcomere Other end suspended in sarcoplasm Myosin filaments suspended in between Z-plates Myosin filaments contain cross-bridges which pull the actin filaments inward Causes Z-plates to move toward each other Shortens sarcomere Sarcomeres stacked together in series and cause myofiber to shorten Working muscles require ATP Myosin breaks down ATP Sustained exercise Requires cellular respiration Regenerates ATP

Cells alive muscle clip

Metabolic Pool: Catabolism (1) Foods: Sources of energy rich molecules Carbohydrates, fats, and proteins Catabolism (breakdown side of metabolism) Breakdown products enter into respiratory pathways as intermediates Carbohydrates Converted into glucose Processed as above

The Metabolic Pool Concept

Metabolic Pool: Catabolism (2) Breakdown products enter into respiratory pathways as intermediates (cont.) Proteins Broken into amino acids (AAs) Some AAs used to make other proteins Excess AAs deaminated (NH2 removed) in liver Results in poisonous ammonia (NH3) Quickly converted to urea Different R-groups from AAs processed differently Fragments enter respiratory pathways at many different points

Metabolic Pool: Anabolism (1) All metabolic reactions part of metabolic pool Intermediates from respiratory pathways can be used for anabolism Anabolism (build-up side of metabolism): Carbs: Start with acetyl-CoA Basically reverses glycolysis (but different pathway) Fats G3P converted to glycerol Acetyls connected in pairs to form fatty acids Note – dietary carbohydrate RARELY converted to fat in humans!

Metabolic Pool: Anabolism (2) Anabolism (cont.): Proteins: Made up of combinations of 20 different amino acids Some amino acids (11) can be synthesized from respiratory intermediates organic acids in citric acid cycle can make amino acids Add NH2 – transamination However, other amino acids (9) cannot be synthesized by humans Essential amino acids Must be present in diet or die

Review Glycolysis Transition Reaction Citric Acid Cycle Electron Transport System Fermentation Metabolic Pool Catabolism Anabolism