cardiac mucle Flashcards
What are the characteristics of a cardiac muscle
- branching cells
- one/two nuclei per cell
- straithed
- Ca++ source: sarcoplasmic reticulum + extracellular liquid
- contains actin and myosin
- tropomyosin + troponin
- abundant mitochondria
- INVOLUNTARY
- medium speed contractions
- NO MOTOR UNITS
- An extensive system of T-tubules (that release large quantities of calcium ions)
- gap junctions
- contains intercalated discs
What is the thee different type of muscle in cardiac muscle?
- atrialmuscle
- ventriacular muscle
- specialazed exitatory and conductive muscle fibers
what are the 2 types of cells in cardiac muscle?
Autorhytmic cells (pacemaker) 1% Contractive cells 99%
Whats is the characteristics of the aurorytmic cells in cardiac muscle?
- pacemaker cells 1%
- forms the conduction system of the heart
- are distrube in orderly fashion SAN —> AVN –> BUNDLE OF HIS – Right and left BUNDLE BRANCHES —> PJURKINES FIBERS.
- Autorytmic = spontaneous generate and discharge an electrician impulse within the heart
- Exitability= cell responds to an electrical charge
- Conductivity = ability to transmit an electricn impulse from ine cell to on other
- Refractory- the inability of the cardiac cell to initiate another action potential for some duration of time (250ms)
Whats is the characteristics of the Contractile cells in cardiac muscle?
- Makes muscular walls of the atrium and ventricles
- contractility = the ability of the cell to contract in response to stimulation
- Extensibility= the ability of the cell to stretch
What is an intercalated disc?
Gapjuctions = allows free diffusion of ions an action potential between adjacent fibers (electrical union)
- Desmosomes and fasciae adherens hold cells tightly together (mechanical union)
What is syncytium?
Heart = uniqe functional unite: functional syncytium. ATRIAL SYNCYTIUM (2 walls of the atria)
VENTRICULAR SYNCYTIUM (walls of 2 ventricles)
What are the characteristics of the conducting system?
- Sinoatrial node SAN
- Atrioventricular node AVN
- Bundle of his
- R and L bundle branches
- Pjurkines fibers
what is SA NODE
= acts like a pacemaker, have the fastest rate of the general action potential.
- generates impulses automatically
- specialized muscle cells
- no neurons cells
- triggers and organizes the heart beat
3 types of cardiac muscle?
atrial,
ventricular muscle
specialized excitatory and conductive muscle fiders
what is sarcoplasmic reticulum?
its a membrane-bound structure found within muscle cells that are similar to endopalsmatic reticulum. the main function is to store calciums
what are the characteristics of sarcoplasmic reticulum in cardiac muscle?
the terminal cisternae contains less Ca++ than skeletal muscle, the strength of the cardiac muscle depends largely on the influx of Ca++ from extracellular space in addition to tah released from the sarcoplasmic reticulum
what is an intercalated disk?
membrane junctions that hold adjacent cells together and transmit the concentration force to each cell
gap junctions?
are the most important intercellular junctions that allow interchange and communication between sarcoplasm o connected cardiac muscles
which are the two types of cells in the cardiac heart?
autorhytmic (pacemaker) 1%
contractile cells
characteristics of the sequence in cardiac muscle?
are distrube in orderly fashion SAN —> AVN –> BUNDLE OF HIS – Right and left BUNDLE BRANCHES —> PJURKINES FIBERS.
which is the functional syncytium of the cardiac muscle
atrial synscytium and ventricular syncytium
name the unions if the intercalated disks
gapjuctions that allow free diffussion of ions and AP between adjacent fivers (electrial union)
desmosomes and fasciae adherens (hold cells tighty togehter (menichal union)
what are the function of desmosomes and fascia ahherens?
its a mechnical union) hold cells tigthly togehter
atrial syncytium contists….
2 walls of the atria
what is the electrical activity of the heart?
autorythmicity–> ability to spontanius generate and discharge an electrician impulse
exitability ..> the ability of the cell to resond to an electrical impulse
conductivity—> the ability to transmitt an elecrican impulse from ine cell to another
Refractory–> the inability of cardiac cells to iniatiate another action pontentiall fomr some durationof time (-250ms)
describe the contractile cells in heart
make upp the walls of atrium an ventricles
- possess specific properties:
- contractility – the abillity for a celll to contract
- extensibility – the ability of the cell to stretch
describe the all or non response
either both atria contract, or both do not contract
either both ventricles contract or do not contract at all
What rate do the SA node have?
70mph
whats a non-SA node tissue?
a latent pacemaker than can take over if the normal pacemaker fails
what are the electrical activity of cardiac muscle?
can generate impulses automatically
specialized muscle cells NOT NERVOUS CELLS
trigger and organize heart beat
describe the electrical activity of The cardiac muscle
the are all excitable - able to respond to an external stimuli by generating an electrical response followed by corresponding contractile response
what are the characteristics of action potential in contractile fibers
larger action potential - platue
fast Na+ channels and slow ca++
heart muscle membrane permeability to k diminshes 5 times
