Cardiac Mucle Flashcards
Where is cardiac muscle located?
heart
What does cardiac muscle form in the heart?
thick layer called myocardium
What is the function of cardiac muscles?
- pumps blood through body
- heart beat
What is the structure of cardiac fibers (cardiomyocytes)?
- short
- branched
- striated
Are cardiac fibers (myocytes) striated?
yes
Do cardiac fibers (myocytes) have nuclei?
one central nucleus per fiber
How are cardiac fibers joined to each other?
joined by intercalated disks
Is cardiac muscle contraction voluntary or involuntary?
involuntary (spontaneous)
inherent rhythmicity – heart has specialized pacemaker cells that start the electrical sequence of depolarization and repolarization
What are intercalated disks?
junctional complexes found between two adjacent cardiac fibers – in a step-like pattern
What are the two parts of an intercalated disk?
transverse part (TR) lateral part (LAT)
Where is the transverse part (TR) of intercalated disks?
runs across fibers at right angles
Where is the lateral part (LAT) of intercalated disks?
runs parallel to myofilaments
What are the two types of junctions in transverse part (TR) of intercalated disks?
- zonula adherens
- desmosomes (macula adherens)
What does the zonula adherens do?
anchor actin myofilaments of terminal sarcomeres to plasma membrane
What is the one type of junction found in the lateral part (LAT) of intercalated disks?
gap junctions
