Physiologic anatomy of cardiac muscle. Comparison between the morphological characteristics of the three major types of muscle cells.

Question 1

structure 1

Answer 1

shape

• short
• cylindrical
• branched

Question 2

structure 2

Answer 2

nucleus
= centrally located

Question 3

structure 3

Answer 3

INTERCALATED DISCS

= connect cardiomyocytes to ensure all cells contract at same time

Question 4

structure 3a

Answer 4

gap junctions
= direct communication between adjacent cells for AP transmission

Question 5

structure 3b

Answer 5

2 - desmosomes

mechanical adhesion between adjacent cardiomyocytes so they stick together

Question 6

structure 3c

Answer 6

3 - fascia adherens

connects actin filaments of each cardiomyocyte

Question 7

structure 4

Answer 7

MYOFIBRILS

rod like structures running over cardiomyocyte
made of repeating units called sacromres delined with z discs

Question 8

structure 5

Answer 8

T-tubules

invaginations of sacrolemme cell membrane
helps AP from sarcolemma -> myocyte

Question 9

structure 6

Answer 9

sarcoplasmic reticulum

contains/ releases Ca2+ for muscle contraction

Question 10

structure 7

Answer 10

sarcomeres

actin + myosin = overlap well forming striated appearance

Question 11

structure 8

Answer 11

metabolism

• highly active = lots of mitochondria producing ATP
• released by oxidative phosphorylation

Question 12

structure 9

Answer 12

blood supply

• a. coronaria gives oxygenated blood to heart

Question 13

structure 10

Answer 13

innervation

ANS = SNS + PNS

Question 14

structure 11

Answer 14

regulation

• rhythmic excitation mechanism