Branching Patterns in the Circulatory System

Rationale Throughout Standard Grade Biology we return to branching patterns: arteries and veins, the kidney, and the bronchioles in lungs for example. It is difficult to investigate the fine degree of branching of capillaries and bronchioles and the all pervasive nature of the cardiovascular system as most textbook diagrams are simplified. This activity seeks to promote an active exploration of branching by examining and counting the degree of branching in images of the body presented in the exhibition Anatomy Acts. It is not necessary to visit the exhibition for this activity as the images used are available on the web site.

Learning Outcomes
• Standard Grade Biology: Topic 5 The Body In Action, sub-topic (c) The need for energy Learning outcomes 9, 10 and 11
• Intermediate.1 Biology: Health and Technology, sub-topic 2, A healthy heart, sub-topic 3 healthy lungs

Objectives
• To investigate the branching of arteries, veins and capillaries in humans

Aims
• To estimate the number of branches that come off a sample length of the main arteries and veins in the human body.

Resources
• Good quality copies of the following images drawn from the Anatomy Acts exhibition.OHPs or powerpoint images and pupil copies.

fig 1	fig 2

Outputs
• An annotated copy of Tabulae anatomicae sex, Andreas Vesalius (fig 1) and a table noting the number of branching events for each of the five main branches of the vena cava
• An annotated copy of Geburtshilflicher Röntgen Atlas (fig 2) with each branching event marked and numbered.

Procedure
• On OHP or powerpoint projected onto a surface that can be drawn on (white board) project - Vesalius’ Tabulae anatomicae sex, Andreas Vesalius (fig 1).
• Starting from an extremity, say the left arm trace the vein path towards the vena cava noting how many branches come together as you move towards the central vena cava just around the liver.
• Colour the vein that you chose and number the branching events.
• Record the colour of the vein you chose and the number of branching events in a simple table.
• Pupils can now chose another vein, repeat the process you have just demonstrated and record the colour they chose to mark the vein and number of branching events in a similar table.
• Pupils can start in the head, the right or left arm and right or left leg.

• Project image - Geburtshilflicher Röntgen Atlas, Tab. 10, pl. 9, Dresden (fig 2). This image shows the arterial system so start from the Aorta just between the lungs and trace the artery from the Aorta towards the left arm counting and marking the branching events. This is far more challenging.
• Encourage the students to follow you as you are marking the branching events. If pupils copies are laminated then non-permanent OHP pens can be used to mark each branching point. Right and left arms can be done as well as both legs.
• It should be pointed that this still born baby was lacking a lung and that the shadow can be clearly seen here

fig 1. Anatomy Acts Object Guide No.8
Tabulae anatomicae sex, six plates, 1538
Andreas Vesalius (1514-1564)
Glasgow University Library, Special Collections, Az.1.10

fig 2. Anatomy Acts Object Guide No.143
Geburtshilflicher Röntgen Atlas, Tab. 10, pl. 9, Dresden, 1908
G. Leopold and T. Leisewitz Leopold
Courtesy of The Royal College of Surgeons of Edinburgh, RR Q7