HM Practical - Blood Vessel Histology: Difference between revisions

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==Terms==
==Terms==
* '''tunica intima''' - (intima) innermost layer in both arteries and veins.
* '''tunica intima''' - (intima) innermost layer in both arteries and veins.
'''Search Pubmed:''' [http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=search&term=Cardiovascular%20System%20Development Cardiovascular System Development]





Revision as of 18:26, 8 July 2012

Introduction

Adult human cardiovascular system
Historic drawing of a small artery and vein.

HMA Practical 3 for Monday July 23 and Wednesday July 25.

HMA Practical 3 Virtual Slides

This page provides histology support information for blood vessel structure.

Disclaimers

  • does not form part of the actual practical class based upon the virtual slides.
  • does not cover the pathology content.
  • does not cover lymphatic vessels, they are covered in the SH lymphatic practical.


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

Aims

  • To understand the microscopic appearance of normal blood vessels of different dimensions and to recognize changes in the arterial wall as seen in atherosclerosis.

Key concepts

  • Normal structure of large and medium blood vessels; tunica intima, tunica media & tunica adventitia and capillaries.
  • Relation of blood vessel structure to function.
  • Abnormalities of arteries in atherosclerosis.

Practical class activities

Note the features listed for the following virtual slides linked from: http://vslides.unsw.edu.au

  1. Aorta (elastic artery) - (2 virtual slides) Showing layers of the wall: tunica intima, tunica media and tunica adventitia. The media is extensive with multiple layers of smooth muscle mixed with elastic laminae, some of which are fenestrated. Vasa vasorum and nervi vasorum in the tunica adventitia; capillaries in adipose tissue surrounding the artery. (Note: capillaries are roughly 8 micrometers in diameter, enough to see 1 or 2 red blood cells inside the lumen).
  2. Medium sized (muscular) artery and vein - (2 virtual slides) Distinct layers of wall of an artery: tunica intima, internal elastic lamina, tunica media (many layers of smooth muscle), external elastic lamina (multiple layers) extending into tunica adventitia; In the vein, the same 3 tunics can be seen but the tunica media is reduced, and the tunica adventitia is wider compared to the artery.
  3. Vena cava - Showing the 3 layers with an extensive tunica adventitia. Special features are the longitudinal smooth muscle bundles in the tunica adventitia.
  4. Atherosclerosis, artery - (Pathology is not covered on this histology support page) This section of a muscular artery from a 60-year-old male is very different from the normal vessels that you have just looked at. An adaptive tutorial is available to assist you to identify the features in this section.


Aorta

Blood vessel wall
  • tunica intima - delimits the vessel wall towards the lumen of the vessel and comprises its endothelial lining (typically simple, squamous) and associated connective tissue.
  • tunica media - layer of circumferential smooth muscle and variable amounts of connective tissue. A second layer of elastic fibers, the external elastic lamina, is located beneath the smooth muscle.
  • tunica adventitia - mainly of connective tissue fibres. The tunica adventitia blends with the connective tissue surrounding the vessel, and the definition of the outer limit of the tunica adventitia is therefore somewhat arbitrary.

Labeled

Artery histology 05.jpg Artery histology 06.jpg
Aorta overview Aorta elastin

Unlabeled

Arteries

  • elastic arteries - the tunica intima of elastic arteries is thicker than in other arteries.
  • arterioles - smaller vessels with a diameter below 0.1 - 0.5 mm. Endothelial cells are smaller than in larger arteries, and the nucleus and surrounding cytoplasm may 'bulge' slightly into the lumen of the arteriole. Endothelium rests on a internal elastic lamina, which may also be incomplete. The tunica media consists of 1-3 concentric layers of smooth muscle cells. Difficult to identify an external elastic lamina or to distinguish the tunica adventitia from the connective tissue surrounding the vessel. Smooth muscle regulates tissue blood flow and arterioles receive both sympathetic and parasympathetic innervation.
  • capillary - arise from the final branches of arterioles, lined by a endothelial cells, each cell forms the wall around the entire circumference of a segment of the capillary. The lumen only allows 1-2 red blood cells to fit side by side in the capillary. Three main types of capillaries (continuous, fenestrated and discontinuous) can be distinguished based on features of their endothelium.
Artery histology 01.jpg Artery histology 02.jpg
Artery overview Artery detail
Artery histology 03.jpg Artery histology 04.jpg
Artery elastin Artery elastin detail

Unlabeled

Vena cava

Vein histology 02.jpg Valves are absent.
  • tunica intima - contains some subendothelial connective tissue.
  • tunica media - comparatively thin with collagen and elastic fibres.
  • tunica adventitia - very wide, contains bundles of longitudinal smooth muscle and the transition to the surrounding connective tissue is gradual.

Vein

Vein valve

Small to medium-sized veins are characterised by the presence of valves.

Vein valve animation.gif

Animation shows how venous valves prevent the back flow of blood.


  • valves are formed by loose, pocket-shaped folds of the tunica intima.
  • one to three pockets form the valve.
  • Valves are absent in largest veins of the abdomen and thorax.

Vein histology 01.jpg

Venule with endothelium (simple squamous epithelium) lining.

Terms

  • tunica intima - (intima) innermost layer in both arteries and veins.


Search Pubmed: Cardiovascular System Development


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Cite this page: Hill, M.A. (2024, March 29) Embryology HM Practical - Blood Vessel Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/HM_Practical_-_Blood_Vessel_Histology

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