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Flashcards in Muscle Deck (15)
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1
Q

What are the two types of muscle contraction and how do they differ?

A

Isotonic – tension stays the same and length changes

Isometric – tension changes and length remains the same

2
Q

What are the two subtypes of one of the types of muscle contraction?

A

Isotonic = Concentric + Eccentric

3
Q

What is the Z-line made up of?

A

Alpha-actinin

CapZ

4
Q

What are the two types of receptors involved in excitation-contraction coupling of skeletal muscle?

A

Dihydropyridine receptor

Ryanodine recepto

5
Q

Describe the process of excitation-contraction coupling of skeletal muscle.

A

An action potential propagates along a T tubule and reaches the Dihydropyridine receptor
Depolarisation causes a conformational change in the DHPR allowing it to make contact with the Ryanodine Receptor on the sarcoplasmic reticulumRyR opens causing Ca2+ release from the SR
This triggers the muscle contraction

6
Q

What are the different components of a sarcomere?

A
Z-line 
Actin filaments 
CapZ and Tropomodulin 
Nebulin 
Titin 
Myosin 
Tropomyosin
7
Q

What is the structure of actin?

A

Two twisted alpha helices

8
Q

What does Titin do?

A

It holds the myosin in place

It is very large

9
Q

Where are CapZ and Tropomodulin found?

A

At the ends of the actin filaments

10
Q

What is the relationship between tension and load in isotonic and isometric contraction?

A

Isotonic – Tension > Force

Isometric – Tension = Force

11
Q

What specialised structure links adjacent cardiomyocytes?

A

Intercalated Discs

12
Q

What junctions are present in these structures?

A

Desmosomes (holds membrane structures together) Gap Junctions (allows electrical communication between cells)

13
Q

Which receptors are involved in excitation-contraction coupling of cardiac muscle?

A

Voltage Gated Calcium Channels

Ryanodine Receptors

14
Q

Describe the process of excitation-contraction coupling of cardiac muscle.

A

Action Potential propagates down T-tubules and leads to the opening of VGCCs This leads to influx of Ca2+
Ca2+ then binds to the RyR making them open leading to Ca2+ release from the SR and a further increase in intracellular Ca2+ (Calcium Induced Calcium Release)

15
Q

Describe the process of excitation-contraction coupling of smooth muscle

A

Action potential reaches the VGCC and makes it open leading to Ca2+ influx
Ca2+ binds to Calmodulin forming a Ca2+-CaM complex
This complex activates myosin light chain kinase
MLCK phosphorylates myosin light chains and leads to smooth muscle contraction