muscle function chemical

What is cellular respiration?

Series of reactions that break down glucose to produce ATP

What are the 3 main stages of cellular respiration?

Glycolysis Citric acid cycle Oxidative phosphorylation

What is ATP?

Energy currency of the cell

What type of pathway is cellular respiration?

Exergonic multistep metabolic pathway

What happens to organic molecules in cellular respiration?

They are oxidized and broken down

Why is oxygen important?

Required for maximum ATP production

What is energy?

Capacity to do work

What is potential energy?

Stored energy

What is kinetic energy?

Energy of motion

What is chemical energy?

Energy stored in chemical bonds

What does the first law of thermodynamics state?

Energy cannot be created or destroyed only transformed

What does the second law of thermodynamics state?

Energy transformations release heat and are inefficient

What is an endergonic reaction?

Requires energy input

What is an exergonic reaction?

Releases energy

What is ATP cycling?

Continuous formation and breakdown of ATP

How is ATP formed?

Energy from exergonic reactions binds ADP and Pi

What happens when ATP is used?

ATP breaks into ADP and Pi releasing energy

What is oxidation?

Loss of electrons

What is reduction?

Gain of electrons

What are redox reactions?

Electron transfer reactions

What are NAD+ and FAD?

Coenzymes that carry electrons

What do NADH and FADH2 do?

Carry electrons to the electron transport chain

Where does glycolysis occur?

Cytosol

Does glycolysis require oxygen?

No

What is the starting molecule of glycolysis?

Glucose

What is the end product of glycolysis?

Two pyruvate molecules

How many ATP are used in glycolysis?

2

How many ATP are produced in glycolysis?

4

What is the net ATP gain from glycolysis?

2 ATP

How many NADH are produced in glycolysis?

2

What enzyme regulates glycolysis?

Phosphofructokinase (PFK)

What inhibits phosphofructokinase?

High ATP levels

What happens to pyruvate when oxygen is present?

It enters the mitochondria

What happens to pyruvate when oxygen is absent?

It is converted to lactate

What causes the burning sensation in muscles?

Accumulation of hydrogen ions from lactate

Where does the intermediate stage occur?

Mitochondrial matrix

What happens to pyruvate in the intermediate stage?

Converted to acetyl CoA

What is released during pyruvate conversion?

Carbon dioxide

What is produced during the intermediate stage?

NADH

Where does the citric acid cycle occur?

Mitochondria

What is the starting molecule of the citric acid cycle?

Acetyl CoA

What is produced per cycle of the citric acid cycle?

1 ATP 3 NADH 1 FADH2 2 CO2

How many turns of the citric acid cycle per glucose?

2

What is the rate limiting enzyme of the citric acid cycle?

Isocitrate dehydrogenase

What are the total products of the citric acid cycle per glucose?

2 ATP 6 NADH 2 FADH2

Where is the electron transport chain located?

Inner mitochondrial membrane

What do NADH and FADH2 provide to the ETC?

Electrons

What is the final electron acceptor in the ETC?

Oxygen

What are hydrogen ion pumps?

Proteins that create a proton gradient

What is oxidative phosphorylation?

ATP production using energy from electrons

How much ATP is produced per glucose overall?

About 30 ATP

How are fatty acids used for energy?

Converted into acetyl CoA

Can fatty acids be used without oxygen?

No

What happens to amino acids used for energy?

They are deaminated and excreted as urea

How many muscles are in the human body?

Over 600

What percentage of body mass is muscle?

Over 50 percent

What are the three types of muscle?

Skeletal cardiac smooth

What is skeletal muscle?

Voluntary striated muscle attached to bones

What is cardiac muscle?

Involuntary muscle found in the heart

What is smooth muscle?

Involuntary muscle in organs and vessels

What are the main functions of muscle?

Movement posture stabilization heat production

What is a muscle fiber?

A muscle cell

What is a myofibril?

Bundle of contractile proteins

What are myofilaments?

Actin and myosin filaments

What is a sarcomere?

The functional contractile unit of muscle

What are A bands?

Dark bands in muscle fibers

What are I bands?

Light bands in muscle fibers

What is excitability?

Ability to respond to a stimulus

What is contractility?

Ability to shorten

What is extensibility?

Ability to stretch

What is elasticity?

Ability to return to original length

What is a motor unit?

One motor neuron and all the muscle fibers it controls

What is the neuromuscular junction?

Synapse between a neuron and muscle fiber

What is an action potential?

Electrical signal that triggers muscle contraction

What is depolarization?

Cell becomes more positive due to ion movement

Which ion causes depolarization?

Sodium (Na+)

Which ion helps restore resting state?

Potassium (K+)

Where does muscle contraction occur?

Within the sarcomere

What happens in the sliding filament theory?

Filaments slide past each other

What are the main contractile proteins?

Actin and myosin

What are regulatory proteins?

Troponin and tropomyosin

What ion is required for contraction?

Calcium (Ca2+)

Where is calcium stored?

Sarcoplasmic reticulum

What does calcium do in contraction?

Exposes binding sites on actin

What forms when myosin binds actin?

Cross bridge

What is the power stroke?

Myosin pulling actin filament

What causes myosin to detach from actin?

ATP binding

What resets the myosin head?

ATP breakdown

Where does the contraction signal begin?

Central nervous system

What neurotransmitter is released at the NMJ?

Acetylcholine

What does acetylcholine do?

Opens sodium channels

What happens after sodium enters the cell?

Depolarization spreads

What structure carries the signal into the cell?

T tubules

What releases calcium into the cell?

Sarcoplasmic reticulum

What stops muscle contraction?

Breakdown of acetylcholine

What enzyme breaks down acetylcholine?

Acetylcholinesterase

What happens when calcium is no longer available?

Binding sites are covered again

Why do muscle cramps occur?

Lack of ATP prevents detachment of myosin from actin

What happens without ATP in muscle contraction?

Muscle remains contracted