Cardiac muscle (core skills) Flashcards
Describe the structure of cardiac muscle Understand the factors which affect cardiac muscle force generation Describe the metabolic requirements for contraction of cardiac muscle
What type of pump is the heart?
Dual peristaltic
Which side of the heart is oxygenated?
Left
Which side of the heart is deoxygenated?
Right
Describe inotropy:
Increased force of contraction, increased stroke volume
Describe chronotropy:
Increasing frequency of contraction, increased heart rate
What is cardiac output?
The product of stroke volume and heart rate
What part of the cardiac muscle improves productivity?
Intercalated discs with desmosomes and a helical appearance
What do desmosomes do?
Allow for strong adherence and low resistance at gap junctions. This allows propagation of the action potential through the heart
On an ECG, what is the P wave?
Atrial depolarisation
On an ECG, what is the short delay after the P wave?
Atrioventricular node slows down
On an ECG, what is the QRS complex?
Ventricular depolarisation
On and ECG, what is the T wave?
Ventricular repolarisation
What is the AP propagated into
Into the myocyte
What is the calcium membrane store called?
Sarcoplasmic reticulum
What branches off the sarcoma, into the myocyte and what is their purpose?
T - tubules, which help excitation
Is a cardiac action potential shorter or longer than skeletal and why?
It is longer, this is due to the plateau which is a regulated pause for synchrony
What ion is essential for cardiac contraction?
Sodium ions
What causes the cardiac plateau?
An influx of calcium ions from the extra-cellular space to cytosol
Why does the cardiac plateau occur?
The L-type calcium channels open for a long time
What are the differences between skeletal and cardiac muscle calcium handlers?
Skeletal muscle has Thin t tubules, extensive SR and triads. Cardiac has the opposite, which t-tubules, limited SR and diads
What energy source is used to power cardiac muscle?
ATP, lots of it due to never resting
Where is the majority of the hearts ATP produced from?
Fatty acid and some glucose
