cardiac mucle

Question 1

What are the characteristics of a cardiac muscle

Answer 1

• 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

Question 2

What is the thee different type of muscle in cardiac muscle?

Answer 2

• atrialmuscle
• ventriacular muscle
• specialazed exitatory and conductive muscle fibers

Question 3

what are the 2 types of cells in cardiac muscle?

Answer 3

Autorhytmic cells (pacemaker) 1%
Contractive cells 99%

Question 4

Whats is the characteristics of the aurorytmic cells in cardiac muscle?

Answer 4

• 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)

Question 5

Whats is the characteristics of the Contractile cells in cardiac muscle?

Answer 5

• 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

Question 6

What is an intercalated disc?

Answer 6

Gapjuctions = allows free diffusion of ions an action potential between adjacent fibers (electrical union)
- Desmosomes and fasciae adherens hold cells tightly together (mechanical union)

Question 7

What is syncytium?

Answer 7

Heart = uniqe functional unite: functional syncytium.
ATRIAL SYNCYTIUM (2 walls of the atria)

VENTRICULAR SYNCYTIUM (walls of 2 ventricles)

Question 8

What are the characteristics of the conducting system?

Answer 8

• Sinoatrial node SAN
• Atrioventricular node AVN
• Bundle of his
• R and L bundle branches
• Pjurkines fibers

Question 9

what is SA NODE

Answer 9

= 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

Question 10

3 types of cardiac muscle?

Answer 10

atrial,
ventricular muscle
specialized excitatory and conductive muscle fiders

Question 11

what is sarcoplasmic reticulum?

Answer 11

its a membrane-bound structure found within muscle cells that are similar to endopalsmatic reticulum. the main function is to store calciums

Question 12

what are the characteristics of sarcoplasmic reticulum in cardiac muscle?

Answer 12

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

Question 13

what is an intercalated disk?

Answer 13

membrane junctions that hold adjacent cells together and transmit the concentration force to each cell

Question 14

gap junctions?

Answer 14

are the most important intercellular junctions that allow interchange and communication between sarcoplasm o connected cardiac muscles

Question 15

which are the two types of cells in the cardiac heart?

Answer 15

autorhytmic (pacemaker) 1%

contractile cells

Question 16

characteristics of the sequence in cardiac muscle?

Answer 16

are distrube in orderly fashion SAN —> AVN –> BUNDLE OF HIS – Right and left BUNDLE BRANCHES —> PJURKINES FIBERS.

Question 17

which is the functional syncytium of the cardiac muscle

Answer 17

atrial synscytium and ventricular syncytium

Question 18

name the unions if the intercalated disks

Answer 18

gapjuctions that allow free diffussion of ions and AP between adjacent fivers (electrial union)

desmosomes and fasciae adherens (hold cells tighty togehter (menichal union)

Question 19

what are the function of desmosomes and fascia ahherens?

Answer 19

its a mechnical union) hold cells tigthly togehter

Question 20

atrial syncytium contists….

Answer 20

2 walls of the atria

Question 21

what is the electrical activity of the heart?

Answer 21

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)

Question 22

describe the contractile cells in heart

Answer 22

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

Question 23

describe the all or non response

Answer 23

either both atria contract, or both do not contract

either both ventricles contract or do not contract at all

Question 24

What rate do the SA node have?

Answer 24

70mph

Question 25

whats a non-SA node tissue?

Answer 25

a latent pacemaker than can take over if the normal pacemaker fails

Question 26

what are the electrical activity of cardiac muscle?

Answer 26

can generate impulses automatically
specialized muscle cells NOT NERVOUS CELLS
trigger and organize heart beat

Question 27

describe the electrical activity of The cardiac muscle

Answer 27

the are all excitable - able to respond to an external stimuli by generating an electrical response followed by corresponding contractile response

Question 28

what are the characteristics of action potential in contractile fibers

Answer 28

larger action potential - platue
fast Na+ channels and slow ca++
heart muscle membrane permeability to k diminshes 5 times