Exam 4: Study Guide: Chapter 10 & Chapter 11

Characteristics of skeletal muscle

Voluntary, long, skinny fibers, striations and many nuclei

What do striations help with?

Generate force for pull strongly

Lots of nuclei=

Lots of power

Characteristics of cardiac muscle

Involuntary, shorter and branched, striations, and one or two nuclei, connected by special links called intercalate discs

Characteristics of smooth muscle

Involuntary, short and fat, non-striated, one nucleus

What does a cell having no striations cause?

Slow and steady movements, perfect for squeezing things gently (like food in your stomach)

What type of tissue holds the whole muscle together and helps pull on bones?

Connective

How many muscle fibers does endomysium wrap?

One

How many muscle fibers does perimysium wrap?

A bundle (or fascicle)

How many muscle fibers foes perimysium wrap?

The whole muscle

What does blood vessels contribute to the muscle?

Brings oxygen and nutrients but also removes waste from muscle metabolism, supporting energy production and metabolic processes

What do nerves do for a muscle?

Tells them to contract

What happens if the muscle has no nerve signal?

No movement

Sarcolemma=

Cell membrane

Sarcoplasm=

Cytoplasm

Myofibrils=

Long rods inside the cell

Sarcomere=

Smallest unit of contraction

What are thick filaments made of?

Myosin

What are thin filaments made of?

Actin

What is a characteristic of myosin?

Has heads that grab and pull

Contractile proteins?

Actin and myosin

Regulatory proteins? (Control the work)

Troponin and tropomyosin

Structural proteins? (Holds things in place)

Titin, keeps the muscle from falling apart

Filaments don’t shrink they ____?

Slide

What is the correct order of the cross-bridge?

Attach, release, cock, bind, pull, repeat

What happens when ATP binds to myosin?

Myosin releases actin

What does ATP hydrolysis (break down) do to the myosin head?

“Cocks” the myosin head into the high-energy, ready position

What is a cross bridge?

The connection formed when myosin binds to actin

What is a power stroke?

Myosin pulls action toward the center of the sarcomere

What causes a muscle to shorten?

Actin filaments sliding past myosin

Do actin and myosin filaments change length during contraction?

No, they slide past eachother

What is the role of ATP in the cross bridge cycle?

Detaches myosin from actin and provides energy to reset (cock) the myosin head

What repeats during the muscle contraction

Cross bridge cycle

Which produces the most ATP?

Aerobic respiration

What is muscle fatigue caused by?

Low ATP, lactic acid build up, and Ion imbalance

What are 3 ways muscles produce ATP?

Creatine phosphate, anaerobic glycolysis, and aerobic respiration

Which ATP system is the fastest?

Creatine phosphate (CP)

What types of activities use creatine phosphate?

Short, explosive movements such as sprinting, heavy lifting

Does anaerobic glycolysis require oxygen?

No

Where does anaerobic glycolysis occur?

Cytoplasm

What does anaerobic glycolysis produce?

2 ATP and lactic acid

How long does anaerobic glycolysis last?

30-60 seconds

What type of exercise uses anaerobic glycolysis?

Short, intense activity such as a 400m run

Does anaerobic respiration require oxygen?

Yes

Where does aerobic respiration occur?

Mitochondria

How much ATP does aerobic respiration produce?

About 36 ATP

Which ATP system lasts the longest?

Aerobic respiration

How long does creatine phosphate last?

About 15 seconds

What is a motor unit?

One motor neuron and all the muscle fibers it controls

What happens when a motor neuron fires?

All muscle fibers in that motor unit contract

Which muscles have small motor units?

Muscles needing precision (eyes, fingers)

Which muscles have large motor units?

Large muscles for power (Legs, back)

What is recruitment?

Increasing the number of the motor units activated to produce more force

How does the body increase muscle force?

By recruiting more motor units

What is a muscle twitch?

One quick contraction relaxation cycle

What are 3 phases of a muscle twitch?

Latent, contraction, relaxation

What happens during the contraction phase?

Muscle shortens and tension increases

What are the three types of skeletal muscle fibers?

Slow oxidative (SO), fast oxidative (FO), fast glycolytic (FG)

Which muscle fibers are most resistant to fatigue?

Slow oxidative (SO)

Which muscle fibers produce the most force but fatigue quickly?

Fast glycolytic (FG)

Which muscle fibers are intermediate in speed and fatigue resistance?

Fast oxidative (FO)

Which fibers rely on anaerobic metabolism?

Fast glycolytic (FG)

Which fibers have the most mitochondria and myoglobin?

Slow oxidative (SO)

Which muscle fibers benefit most from endurance training?

Slow oxidative (SO)

How does resistance (strength) training affect muscle fibers?

Increases muscle size (hypertrophy) and strength

Which muscle fibers benefit most from strength training?

Fast glycolytic (FG)

What is hypertrophy?

Increase in muscle fiber size

Does exercise increase the number of muscle fibers?

No (it increases size, not number)

Is cardiac muscle voluntary or involuntary?

Involuntary

Where is cardiac muscle found?

Heart

What makes cardiac muscle cells unique?

Intercalated discs

What do intercalated discs do?

Allow cells to connect and contract together

Are cardiac cells striated?

Yes

How many nuclei do cardiac muscles usually have?

One (sometimes two)

Why does cardiac muscle not fatigue easily?

It has many mitochondria and relies on aerobic respiration

What is the main function of cardiac muscle?

Pump blood continuously

Is smooth muscle voluntary or involuntary?

Involuntary

Where is smooth muscle found?

Walls of hollow organs (Intestines, blood vessels, bladder, uterus)

Are smooth muscle cells striated?

No

What is the shape of the smooth muscle cells?

Spindle shaped

How many nuclei do smooth muscle cells have?

One

What is the main function of smooth muscle?

Move substances through organs

Does smooth muscle contract quickly or slowly?

Slowly and continuously (fatigue resistant)

What happens to muscle mass with again?

DecreasesH

How does aging affect muscle strength?

Strength decreases

What is sarcopenia?

Age related loss of muscle mass and strength

How does aging affect muscle fibers?

Decrease in size and number

What is muscular dystrophy?

Genetic disorder causing progressive muscle weakness

What is myasthenia gravis?

Autoimmune disorder affecting communication between nerves and muscles, leading to weakness and fatigue

What is a common symptom of muscle disorder?

Muscle weakness

How do skeletal muscles produce movement?

By pulling on bones (muscles contract, bones move)

Can muscles push?

No, muscles only pull

What is the relationship between muscles and bones?

Muscles attach to bones and move them across joints

What is a lever in the body?

A rigid structure (bone) that moves around a fulcrum

What is a fulcrum?

The pivot point (joint)

What are the 3 parts of a lever system?

Effort (muscle), load (resistance), fulcrum (joint)

What is the most common lever in the body?

Third-class lever

In a third-class lever, where is the effort located?

Between the fulcrum and the load

What is a prime mover (agonist)?

Main muscle responsible for movement

What is an antagonist?

Muscle that does the opposite movement