Phase 1 drive cardiovascular notes- heart Flashcards
Describe cardiac muscle
- Striated
- Relatively small cells
- Cells generally contain a single nucleus
- Cells joined by intercalated discs
What are intercalated discs?
Desmosomes + gap junctions
What is the function of desmosomes between the cardiomyocytes?
Holds cells together
What is the thick fimalment formed from?
Myosin
Describe myosin
Two large polypeptide heavy chains
Two light chains
Two globular heads
Long tail formed from two intertwined heavy chains
What are the binding sites on the myosin head for?
One for ATP
One for binding to actin
What type of enzyme does the binding site for ATP act as on the myosin head?
ATPase
What is the major component of the thin filament?
Actin
Describe the core of the thin filament?
Two chains of actin intertwined
How many binding sites are there for myosin on an actin monomer?
One
What overlies the myosin binding sites on the actin?
Tropomyosin
What does Ca2+ bind to in order for mysosin heads to be able to bind to actin?
Troponin
What causes tropomysosin the change shape, exposing the mysosin binding sites on the actin?
Binding of Ca2+ to troponin
What is the A band?
The region of the sarcomere that contains the myosin thick filaments
What is the I band?
The region of the sarcomere occupied by thin filaments only
What lines define the boundaries of a sarcomere?
Z lines
What is the H-zone?
Contains thick filaments only
Where is the M-line found?
In the centre of the H zone
What helps keep the thick filaments in the middle of each sarcomere?
M-line linkage Wbetween thick filaments
Titin filaments
How many H zones will you find in a single sarcomere?
1
How many A bands will you find in a single sarcomere?
1
Why is there a high Ca2+ concentration in the sarcoplasmic reticulum?
Ca2+ is actively transported into the sarcoplamsmic reticulum
What do the action potentials travel down in order to reach the sarcoplasmic reticulum
t tubules
Which arteries supply blood to the cardiomyocytes?
coronary arteries
Where is the origin of the coronary arteries?
the aorta
What is the vein that most of the coronary arteries drain into called?
the coronary sinus
Where does the coronary sinus empty into?
the right atrium
What connects myocardial cells that allows the spread of action potentials?
gap junctions
Where is the sinoatrial node located?
the right atrium (near the entrance of the superior vena cava)
Which node normally determines heart rate?
SA node
What are the leaky Na+ channels in nodal cells referred to?
funny, F-type