HM Practical - Cardiac Histology

Introduction

Adult human cardiovascular system

HMA Practical 8 Monday August 6 and Wednesday August 8.

HMA Practical 8 Virtual Slides

This page provides histology support information for cardiac histology.

Disclaimers

• does not form part of the actual practical class based upon the virtual slides.
• does not cover the pathology content.

HMA Links: Blood Vessel Histology | Cardiac Histology | Histology | Histology Stains | Blood Vessel Development | HMA Practical 3 Virtual Slides | HMA Practical 8 Virtual Slides

Introduction

Cardiac muscle, the myocardium, consists of cross-striated muscle cells, cardiomyocytes, with one centrally placed nucleus.

• Nuclei are oval, rather pale and located centrally in the muscle cell which is 10 - 15 µm wide.
• Cardiac muscle cells excitation is mediated by rythmically active modified cardiac muscle cells.
• Cardiac muscle is innervated by the autonomic nervous system (involuntary), which adjusts the force generated by the muscle cells and the frequency of the heart beat.
• Cardiac muscle cells often branch at acute angles and are connected to each other by specialisations of the cell membrane in the region of the intercalated discs.
  • Intercalated discs invariably occur at the ends of cardiac muscle cells in a region corresponding to the Z-line of the myofibrils.
• Cardiac muscle does not contain cells equivalent to the satellite cells of skeletal muscle.

Histology

Cardiac muscle histology

Image of primate heart stained with Alizarin blue. Red Blood Cells (orange cells) Cardiac Muscle Cells (blue) Cardiac muscle cells are cut longitudinally. At high magnification see both striations and the large nuclei of the cardiac muscle cells. Follow the course of individual cardiac muscle cells and note fine, dark blue lines which seem to cross (traverse) the fibres. Intercalated Discs that connect the individual muscle cells and permit the conduction of electrical impulses between the cells. seen in longitudinal sections.

Unlabeled Images

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Intercalated Discs

• seen in longitudinal sections.
• connect the individual muscle cells.
• permit the conduction of electrical impulses between the cells.

Purkinje Fibres

• modified cardiac muscle cells. Compared to ordinary cardiac muscle cells:
  • contain large amounts of glycogen.
  • fewer myofibrils.
  • thicker cells.
• extend from the atrioventricular node, pierces the fibrous body, divides into left and right bundles, and travels, beneath the endocardium, towards the apex of the heart.
• bundle branches contact cardiac muscle cells through specialisations similar to intercalated discs.
• conduct stimuli faster than ordinary cardiac muscle cells (2-3 m/s vs. 0.6 m/s).
• discovered in 1839 by Jan Evangelista Purkyně).

Links: Heart Histology | Cardiac AZB Labeled | Cardiac AZB | Cardiac label LS | Cardiac LS | Cardiac label TS | Cardiac TS | Purkinje fibres | Purkinje fibres detail | Histology

Terms

• cardiomyocyte -
• intercalated disc -
• Purkinje fibres -

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

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Cite this page: Hill, M.A. (2024, May 30) Embryology HM Practical - Cardiac Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/HM_Practical_-_Cardiac_Histology

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G