ANAT2241 Cardiovascular System

ANAT2241 This practical support page content is not part of the virtual science practical class and provides additional information for student self-directed learning purposes. All practical class pages are located on Moodle - ANAT2241

Introduction

Adult human cardiovascular system

--Mark Hill 17:32, 6 February 2013 (EST) Pat do you cover heart here or in muscle class?

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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Cardiac Layers

Endocardium

• Inner layer of the heart, contains blood vessels. Has 3 sublayers
  • Endothelium - innermost portion a simple squamous epithelium.
  • Smooth Muscle and Connective Tissue - middle layer of the endocardium is mix of connective tissue and smooth muscle.
  • Subendocardial Layer - outer layer of the endocardium is loose connective tissue joining the endocardium and myocardium.

Myocardium

• Middle layer of the heart, thickest contains cardiomyocytes, blood vessels.
• Muscular layer.

Epicardium

• Outer layer of the heart, contains blood vessels and lymphatics.
• Visceral layer of pericardium rather thin.

Cardiac Features

Cardiac muscle (electron micrograph)

Cardiac muscle (electron micrograph)

Intercalated Discs

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

Histology "step-like" appearance due to:

• transverse part - crossing fibres at right angle to myofibrils.
• lateral part - runs in parallel to myofibrils.

Junctional Components

1. Fascia adherens – major portion of transverse component. Anchoring sites for actin, and connect to the closest sarcomere.
2. Macula adherens – (desmosomes) transverse and lateral components. Bind individual myocytes to one another. stop separation during contraction by binding intermediate filaments, joining the cells together. Macula adherens junctions are also called desmosomes.
3. Gap junctions - lateral component. Allow action potentials to spread between cardiac cells by passage of ions between cells, producing depolarization of the heart muscle. Allows muscle to act as syncytium.

Links: EM image - intercalated disc

Purkinje Fibres

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 -
• chordae tendineae - tricuspid and mitral valves connective tissue bands attached on the other end to the papillary muscles.
• intercalated disc -
• nodule - (of semilunar valve) small fibrous nodules located in the middle of the flaps, the nodules of the semilunar valve come closely together to fill the triangular opening.
• Purkinje fibres -

Course Links

Moodle - ANAT2241 - 2019

Histology 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 | ANAT2241 Support | Histology | Histology Stains | Embryology Glossary

Common Histology Stains
Histology Stains - Common Stains and Their Reactions Stain Nucleus Cytoplasm Collagen RBCs Other Haematoxylin blue - - - mucins - light blue Eosin - pink pale pink bright red colloid - pinkmuscle - red Iron Haematoxylin blue/black - - - Van Gieson - brown/yellow red yellow muscle: yellow/browncartilage - pink Verhoeff's Elastin black - - - elastic fibres - black Tartrazine - yellow yellow yellow Silver Impregnation - - grey/brown - reticular fibres - black Methyl Green dark green light green light green green Nuclear Fast Red red pink pink pink Gomori's Trichrome purple/red purple green red keratin - redmuscle - purple/red Heidenhain's Azan red purple/red deep blue red muscle - red Osmium Tetroxide - - brown brown myelin, lipids - black Alcian Blue - - - - mucins, - blue Periodic acid-Schiff (PAS) - - pink - mucins, glycogen, glycocalyx - magenta Phosphotungstic Acid-Hematoxylin (PTAH) blue - red blue muscle bands - blue Masson's Trichrome blue/black red green/blue red cartilage, mucins - blue or green; muscle - red Luxol Fast Blue - - - variable myelin - blue Aldehyde Fuchsin - - - - elastic fibres, mast cells - deep purple Light Green - - light green - Gallocyanin dark blue - - - nucleic acids, Nissl granules - dark blue Romanowsky (e.g. Leishman's) blue pink acidophils - red, basophils - blue, azurophilic - purple Aldehyde Pararosanilin elastic fibres - purple
Haematoxylin and Eosin One of the most common staining techniques in pathology and histology. Acronym "H and E" stain. (H&E, HE). Haematoxylin Stains nuclei blue to dark-blue. Stains the matrix of hyaline cartilage, myxomatous, and mucoid material pale blue. Stains myelin weakly but is not noticeable if combined with eosin stain. combined with Orange G (H & Or. G.) instead of eosin, specifically stains the granules of acidophilic cells of the adenohypophysis (anterior pituitary). Eosin Stains cytoplasm pink to red; red blood cells are also bright red. Common counterstain to hematoxylin. Stain intensity varies with the formula as well as the fixative.

Practical Support

Pages can be accessed from any internet connected computer.

ANAT2241 Support Links: The Virtual Microscope | Covering and Lining Epithelia | Glandular Epithelia | CT Components | CT Types | Bone, Bone Formation and Joints | Muscle | Nervous | Blood | Eye | Cardiovascular | Respiratory | Integumentary | Gastrointestinal | Gastrointestinal Organs | Lymphatic and Immune | Endocrine | Urinary | Female Reproductive | Male Reproductive | Histology Stains | Histology Drawings | Practicals Health and Safety 2013 | Moodle - 2019

ANAT2241 This practical support page content is not part of the science practical class and provides only background information for student self-directed learning purposes.

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Cite this page: Hill, M.A. (2024, May 8) Embryology ANAT2241 Cardiovascular System. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/ANAT2241_Cardiovascular_System

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