Lecture 3

Question 1

What is the definition of electrochemical gradient?

Answer 1

the concentration(chemical) and the membrane potential(electrical) across the gradient

Question 2

What is the muscle conversion process?

Answer 2

Muscle converts chemical energy stored in ATP to mechanical work and heat

Question 3

What are the 4 main functions of the muscular system?

Answer 3

1. Produce body movement (Locomotion)
2. Stabilize body position (Posture)
3. Store and move substances(Glycogen, Cardiovascular and respiratory muscles help to move nutrients & oxygen)
4. Produce body heat(Thermoregulation)

Question 4

What are the 3 types of muscle tissue?

Answer 4

skeletal, smooth, cardiac

Question 5

What are the 2 types of muscle attachments? what’s the difference?

Answer 5

origin and insertion

origin is less movable and insertion is more movable

Question 6

What bone doesn’t have a muscle attached?

Answer 6

talus(ankle bone)

Question 7

Where is each type of muscle tissue found in the body?

Answer 7

skeletal-throughout body(attached to bones)
smooth-lines the organs
cardiac-heart

Question 8

What is the appearance of each type of muscle tissue?

Answer 8

skeletal-striated
smooth-no striations
cardiac-striated

Question 9

what is the type of each muscle tissue?

Answer 9

skeletal-voluntary
smooth-involuntary
cardiac-involuntary

Question 10

how is each type of muscle tissue innervated?

Answer 10

skeletal-somatic nervous system
smooth-autonomic nervous system
cardiac-autonomic nervous system

Question 11

which muscle tissue is under hormonal influence?

Answer 11

skeletal-no
smooth-yes
cardiac-yes

Question 12

which muscle tissue can initiate it’s own contraction?

Answer 12

skeletal-no
smooth-yes
cardiac-yes

Question 13

what type of contraction does each muscle tissue use?

Answer 13

skeletal-voluntary and varied
smooth-rhythmic
cardiac-static(tonal)

Question 14

what are the 4 properties of muscle?

Answer 14

• Excitability: capacity of muscle to respond to a stimulus
(chemical, stretch and electrical Δ across plasma membrane)
• Contractility: ability of a muscle to shorten and
generate pulling force
• Extensibility: muscle can be stretched
• Elasticity: ability of muscle to recoil to original resting
length after stretched

Question 15

What are the 3 layers of connective tissue?

Answer 15

• Epimysium: Surrounds entire muscle
-Separates muscle from surrounding tissues and organs
-Connected to the deep fascia
• Perimysium: Divides muscle into sections called fascicles
-Contains blood vessels and nerves
• Endomysium: Surrounds individual muscle Fibres
-also contains blood vessels, nerves, and *satellite cells
Collagen fibres of all 3 layers come together at each end of muscle to
form a Tendon: Attaches muscle to bone

Question 16

What does the nucleus do inside a muscle?

Answer 16

Stores genetic material for cell division and production of protein

Question 17

What are key aspects of myofibrils?

Answer 17

Myofibrils:

• cylindrical structures within muscle fibre
• are bundles of contractile protein = myofilaments
• myofibrils are anchored to the inner surface of the sarcolemma
• When myofibril shortens, muscle shortens (contracts)

Question 18

What are key characteristics of sarcoplasmic reticulum?

Answer 18

• Surrounds each myofibril
• A single T-tubule and the 2 terminal cisternae form a triad
• Sarcoplasmic reticulum stores calcium when muscle not contracting
• When stimulated, calcium released into sarcoplasm
• Sarcoplasmic reticulum membrane has calcium pumps that function to pump calcium out of the sarcoplasm back into the sarcoplasmic reticulum after contraction

Question 19

What are myofibrils made of?

Answer 19

Made up of a series of sarcomeres joined end-to-end

Question 20

What is a sarcomere?

Answer 20

smallest contractile unit of the muscle fiber

Question 21

What are the 3 types of myofilaments?

Answer 21

• Actin: Thin Filament
• Myosin: Thick Filament
• Titin: Elastic Filament (“springy” protein)
These filaments make up the contractile machinery of muscle

Question 22

What is the difference between tropomyosin and troponin?

Answer 22

• Tropomyosin
– Rod-shaped protein that occupies the
groove between the twisted strand of actin
molecules
– Blocks the myosin binding sites on the G-actin molecules
• Troponin
– A complex of three globular proteins.
• One is attached to the actin molecule
• One is attached to tropomyosin
• One contains a binding site for calcium

Question 23

What are key aspects of crossbridges in myosin?

Answer 23

• Composed of a rod-like tail and two globular heads
• Interacts with actin during contraction.
• Contain binding sites for both actin and ATP
-The enzyme ATP-ase is located at the ATP binding
site for hydrolysis of ATP

Question 24

What are key aspects of titin?

Answer 24

– Connects myosin to the Z-lines in the sarcomere
– It is very elastic
• Able to stretch up to 3 times its resting length
– Important molecule because it is responsible for muscle
flexibility

Question 25

What is the role of calcium?

Answer 25

• Electrical impulse travels through T-tubules and sarcoplasmic reticulum. The SR releases large quantities of Ca+2 into the sarcoplasm.
– Bind with troponin
– lifts tropomyosin from actin
– active sites are open
– myosin cross-bridges attach 
– Muscles can contract