GLYCOLYSIS means “sugar splitting” Kreb Cycle

GLYCOLYSIS means “sugar splitting”

Kreb Cycle

• Proteins embedded along inner membrane of mitochondria

k

• 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 –

– A)– B)

Oxygen Debt

• Oxygen debt refers to the amount of oxygen that liver cells require

to convert the accumulated lactic acid into glucose, plus the amount that muscle cells need to resynthesize ATP and creatine phosphate to their original concentrations.

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 FiberStructure and Function

Muscle Contraction

• Sliding filament model

Neuromuscular Junction

CopyrightThe 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.

CopyrightThe 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.

CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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

Respiratory system

Lungs

Lungs: internal

Inhaling and exhaling- again with the physics and chemistry

Boyle’s law and breathing

• Volume and pressure are inversely proportional – mark this with arrows in your notes!

• See the balloon model

• ADAM

Partial pressures and the unloading and loading of respiratory gases

• Gases (like all molecules) will move from an area of high partial pressure to lower partial pressure

Focus on Oxygen

• Hemoglobin – found in RBCs

Oxygen

• Hemoglobin (contains iron) and binds up to 4 molecules of oxygen

• Affinity changes as oxygen molecules bind or release,– One oxygen attaching causes hemoglobin to have a

greater affinity for even more oxygen – how?

• http://en.wikipedia.org/wiki/Hemoglobin#Binding_of_ligands– An oxygen released causes hemoglobin to release

even more

• pH levels affect hemoglobin affinity for oxygen also

• when CO2 levels are high, this causes blood pH to lower and a greater release of oxygen

• CO2 + H2O --- HCO3- + H+

Oxygen Disassociation Curves

Oxygen Disassociation Curves

Carbon dioxide focus: tissue to blood

STEPS:

Carbon dioxide: blood to lungs

STEPS:

Explain this

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