Histology of Cardiac Muscle by DR. Roomi

8/2/2019 Histology of Cardiac Muscle by DR. Roomi

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CARDIAC MUSCLE HISTOLOGY

BY

DR. MUDASSAR ALI ROOMI (MBBS, M. PHIL)


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Cardiac muscle


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Cardiac muscle

Involuntary but striated

Length: 100 um

Width: 15 um Nucleus: 1-2 large oval

nucleus in the centre.

Branching fibers***

Intercalated disc ispresent.***

Surrounding the musclecells is a delicate sheath ofendomysium containing a

rich capillary network.


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Sarcoplasm of cardiac muscle fibers

Abundant sarcoplasm (due towhich cross striation are notmuch clear).

Numerous mitochondria forcontinuous aerobicmetabolism (occupy about40% volume of cell) MCQ

Glycogen granules, fat dropletsare present.

Fatty acids are the major fuel

of the heart. MCQ Lipofuscin pigment granules

are often found near thenuclei of cardiac muscle cellsof old persons (MCQ)


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Sarcotubular system

T-tubule of greater diameter than that of

skeletal muscle

T-tubules lie at the level of Z-disc. MCQ

sarcoplasmic reticulum is less well developed

No triads are present


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Intercalated disc

Deeply staining cross bands

0.5-1 um thick

Bands are irregular or step-likecourse

Desmosomes, gap junctions and

fascia adherens are present in it. Gap junctions (nexus) permit

rapid impulse conductionbetween the muscle cells. Heartacts as a functional syncytium.MCQ

gap junctions, provide ioniccontinuity between adjacentcells. These act as "electricalsynapses. MCQ


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Blood supply of cardiac muscle

Through coronary

arteries

Blood supply is greater

than that of skeletalmuscles***


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Nerve supply of heart

Nerve supply is by

autonomic nervous

system (Sympathetic

and parasympatheticnerve fibers).


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HOW TO DRAW

IT!!!!


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cardiac muscle

IDENTIFICATION POINTS****

1. Cross striations present

2. Branching of fibers-

present

3. Intercalated disc-present

4. 1-2 oval central nuclei


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Histology of Cardiac Muscle by DR. Roomi

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