CXA107 2015

CXA107 Fundamentals of Bioscience
Practical and Independent Study: Circulatory Systems
TO PREPARE FOR THIS PRACTICAL:

Begin to familiarise yourself with the organs of the cardiovascular system by completing as many labelling exercises as possible BEFORE you attend. Your lecture notes, A&P Revealed and your Saladin textbook will be of assistance.
DURING THE PRACTICAL:

Use the time available in class to concentrate on becoming familiar with the structures in three dimensions on models or dissected specimens.

You must be able to locate and name each structure that is in bold typeface as you will be examined on a selection of these in your anatomy practical examination at the end of the semester. 
Ask questions/take notes about the questions or parts of activities in italics
INDEPENDENT STUDY AFTER THE PRACTICAL:

Complete the questions or parts of activities in italics as part of your independent study.

If you set aside 20 minutes, over a few days, for each activity you will make steady progress in developing your knowledge base.

Learning Objectives:
Completion of these learning activities should assist you in:
 Identifying the position of the heart and major vessels relative to musculoskeletal structures.
 Identifying internal and external features of the heart.
 Relating these anatomical features to the function of the heart.
 Identifying a selection of systemic blood vessels.
References you may find helpful for your learning:
Lecture notes, Circulatory Systems.
Saladin, K. 2015. Chapter 19 (Sections 19.1 & 19.2) and Chapter 20 (Sections 20.7 & 20.8)
A&P Revealed 3.0, Cardiovascular module:
Dissection
Animations – Blood flow through heart; Pulmonary & systemic circulations
Body regions from your Introductory Topics practical notes (will help with the names of blood vessels)
Resources to help you achieve the learning objectives:
You may use dissected specimens (if they are available), models, charts, A&P Revealed and texts to achieve the learning objectives.

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Part A: Anatomy of the Heart
Do the labeling before you come to the practical session and then locate and identify all of these structures on models or dissected specimens.

Location and External Features of the Heart
1. Examine the dissected specimens/torso models to determine the position of the heart in the thorax, and its relationship to other features. (a) Note the position of the base and apex of the heart.
(b) Identify the bony/surface landmarks that correspond to the borders of the heart:


Upper border of the right 3rd costal cartilage to the middle of the right 6th costal cartilage, approximately 1 cm lateral to the sternal border



Lower border of the left 2nd costal cartilage to the left 5th intercostal space at the mid-clavicular line
Learning strategy:
Palpate these surface landmarks on yourself to determine the location of your own heart.

(c) Identify the pericardium, make sure that you can locate the following layers:
• visceral
• parietal (use A& P Revealed to identify this layer if you are using torso models)
(d) Where is the pericardial cavity? What is contained in this cavity and what function does it serve? ................................................................................................................................................................
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2. Orientate an isolated specimen of the heart or a heart model.
(a) On the external aspect of the model/specimen, identify the following features:
Chambers of the heart:

Grooves in the surface of the heart that mark the boundaries between chambers:

right atrium left atrium right ventricle left ventricle

atrioventricular sulcus (also known as the coronary sulcus) anterior interventricular sulcus posterior interventricular sulcus

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Anterior view

Posterior view

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Internal Features of the Heart
3. On an isolated specimen or model, examine the internal features of the heart and the major blood vessels attached to it.
As you follow the path of blood flow through the heart (outlined on the following page), note the vessels and chambers that deoxygenated blood flows through (e.g. colour in blue) and those oxygenated blood flows through (e.g. colour in red).

right & left atria right & left ventricles interatrial septum interventricular septum epicardium (visceral pericardium) myocardium endocardium right & left atrioventricular valves pulmonary semilunar valve aortic semilunar valve chordae tendineae papillary muscles superior vena cava inferior vena cava aorta pulmonary trunk pulmonary veins opening of coronary sinus

(a) Compare and contrast the thickness of the walls of the atria and each ventricle.
How does the structure of the chamber walls suit their function as a receiving or pumping chamber? ................................................................................................................................................................
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Path of Blood Flow through the Heart
4. Explore the right atrium and locate the three openings into the atrium by which it receives deoxygenated blood from the veins of the systemic and coronary circulatory systems.
(a) Identify and name the three vessels that empty their contents via these openings:
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5. Blood flows through the right atrioventricular valve (also called the tricuspid valve) that spans the opening (orifice) between the right atrium and the right ventricle when the heart is relaxing between heart beats.
6. Blood pumped out of the right ventricle passes through the pulmonary semilunar valve that spans the orifice at the base of the pulmonary trunk.
(a) Where does blood pumped into the pulmonary trunk flow to?
................................................................................................................................................................
7. The left atrium receives oxygenated blood from four pulmonary veins, two from each lung.
8. Blood flows through the left atrioventricular valve (also called the bicuspid or mitral valve) that spans the orifice between the left atrium and left ventricle.
9. Blood pumped out of the left ventricle passes through the aortic semilunar valve that spans the aortic orifice.
10. To consolidate your understanding, summarise the role of each of the heart valves in ensuring one way flow of blood through the heart:
Heart valve

Action/function

Right atrioventricular valve
Pulmonary semilunar valve
Left atrioventricular valve
Aortic semilunar valve
(a) Note that the cusps of each of the atrioventricular valves are attached to chordae tendineae associated with papillary muscles. How do these structures assist the normal functioning of these valves?
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(b) What heart sounds (S1, S2) does closure of each of the heart valves correspond to?
S1 ...........................................................................................................................................................
S2............................................................................................................................................................
To assist you to remember which atrioventricular valve is on which side of the heart:
LAB RAT – Left Atrium Bicuspid – Right Atrium Tricuspid or if you like shopping, you may prefer “Tri before you bi”

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Part B: The Anatomy of the Systemic Blood Vessels
Do the labeling before you come to the practical session and then locate and identify all of these structures on models or dissected specimens.

Using the wet specimens, models or charts, follow the systemic circulation, finding the named vessels
(in bold type).

1. Major Arteries
For our purposes, we will examine only some of the major arteries. You must be able to locate and name them. If you follow specific pathways (outlined on the following pages) it will assist you.

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The Aorta
The aorta has three portions:
(i) The ascending aorta which has two branches:
- The right and left coronary arteries which supply the heart itself.
(ii) The aortic arch (also called the arch of the aorta) which has three branches:
- The first is the brachiocephalic trunk.
- The second is the left common carotid artery.
- The third is the left subclavian artery.
(iii) The descending aorta, which has two portions separated by the diaphragm:
- The thoracic aorta
- The abdominal aorta.
The carotid arteries
The left and right common carotid arteries branch at approximately the level of thyroid cartilage into the external and internal carotid arteries.
 The internal carotid artery supplies the brain, having no branches before entering the skull.
 The external carotid artery has a number of branches supplying structures of the head and neck. If auscultation of the common carotid artery reveals a murmur (carotid bruit), what does this indicate about blood flow through this vessel?
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Blood supply to the brain
Major arteries supplying blood to regions of the brain will be considered in a nervous system practical later in the semester.
The brachial arteries and distal upper limb
Locate the brachial artery in the arm. At the cubital fossa, look for the brachial artery dividing into its two branches, the radial and ulnar arteries. Trace these down to the wrist where the radial can be easily seen. The ulnar can be found under the tendon of flexor carpi ulnaris. In the hand, these two vessels anastomose (merge) to form a palmar arch.
Of what significance is the palmar arch anastamoses in clinical examination of the peripheral circulation? ……………………………………………………………………………………………………..............
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The descending aorta
At the level of T12, the aorta passes behind the diaphragm to enter the abdominal cavity. It gives rise to both paired and unpaired branches:
 The right and left renal arteries which supply the kidneys.
 The coeliac artery which branches into arteries that supply the stomach, liver etc.
 The superior mesenteric artery supplies the small intestine and the proximal half of the large intestine.
 The inferior mesenteric artery supplies the distal part of the large intestine.
At its most distal point, the descending abdominal aorta divides into the right and left common iliac arteries. The femoral arteries and distal lower limb
Follow the common iliac artery until it becomes the femoral artery. It is quite superficial and its pulse can be easily palpated. Follow it along into the popliteal fossa where it becomes the popliteal artery – another pulse point. The popliteal artery divides into two branches:
 The anterior tibial artery. It enters the dorsum of the foot as the dorsalis pedis artery.
The pulse of this vessel can be felt between the first and second toes.
 The posterior tibial artery.

CHECKLIST OF MAJOR ARTERIES:
By following the pathways previously described you should now have identified…
1.

ascending aorta

2.

brachiocephalic trunk external carotid artery (L & R)

subclavian artery (L & R)

brachial artery (L & R)

ulnar artery (L & R)

palmar arch (L & R)

thoracic aorta

abdominal aorta

renal artery (L & R)

coeliac artery

superior mesenteric artery

inferior mesenteric artery

common iliac artery (L & R)

internal iliac artery (L & R)

external iliac artery (L & R)

femoral artery (L & R)

popliteal artery (L & R)

posterior tibial artery (L & R)

5.

internal carotid artery (L & R)

radial artery (L & R)
4.

coronary artery (L & R)

common carotid artery (L & R)
3.

aortic arch

anterior tibial artery (L & R)

dorsalis pedis artery (L & R)

Mark the arteries that correspond with pulse points that are commonly used in clinical practice.
Once you have participated in the nervous system practical, add the arteries that supply blood to the brain to this checklist.

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2. Venous Drainage
Recall that blood returns from the systemic and coronary circulations to the right atrium of the heart via three sources:
• superior vena cava
• inferior vena cava
• coronary sinus.
It is appropriate to consider drainage in terms of tributaries of the venae cavae. The limbs, both upper and lower, have a ‘dual drainage’ system. There are deep veins which run with the arteries and are named accordingly, e.g. brachial, posterior, tibial etc. In addition there are superficial veins which do not run with the arteries but are quite close to the surface. In some people, these superficial veins are clearly visible on the surface of the skin. Superficial veins do not bear the same names as the arteries, but are named separately.
Begin your search for the veins at the distal aspect of the limbs using either a dissected specimen or the limb models and the torso model.
Upper limb (superficial)
Most of the venous blood from the limbs drains from the dorsal aspect of the hand. The superficial veins of the forearm and hand are rather variable, so we will not identify them by name.
However, they are more consistent at the cubital fossa, where we find the median cubital vein. Look for this on your own limb. This vein is commonly used as a venipuncture site – why do you think that would be?
…………………………………………………………………...
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Upper limb (deep)
The radial and ulnar veins converge to form the brachial vein.
Venous drainage from the upper limb ultimately enters into the subclavian vein.
Fluid (lymph) from the lymphatic system is returned to the cardiovascular system at the subclavian veins. Where has this fluid originated from?
…………………………………………………………………...
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The subclavian vein joins with the internal jugular vein to form the brachiocephalic vein.
Right and left brachiocephalic veins drain into the superior vena cava.
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Head and neck
The external jugular vein receives blood from parts of face and scalp. Its diameter varies but it is usually smaller than the internal jugular vein, which is deep to the sternocleidomastoid muscle and drains most of the blood from the brain.
Assessing jugular venous pressure (JVP) is part of cardiovascular system assessment in nursing and paramedicine practice. If a person has heart failure (i.e. decreased ability of a ventricle to pump blood efficiently), the JVP may be increased and the jugular veins may be distended (bulge) because of a backup of blood. Would this clinical assessment finding be more likely if the right ventricle or left ventricle was failing? (Hint: think about which side of the heart receives blood that has drained from the jugular veins)
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Lower limb (superficial)
There are two main superficial veins in the lower limb:
 the great saphenous veins, and
 the small saphenous veins.
As the name suggests, the great saphenous is the longer of the two.
It can be seen on the medial aspect of the leg and thigh.
Lower limb (deep)
Again, the deep veins follow the arteries and bear the same names.
Find the popliteal vein and follow it into the subsartorial canal, where it becomes the femoral vein, which receives blood from the greater saphenous vein.
Follow the femoral vein as it passes under the inguinal canal to become the external iliac vein. It runs along the pelvic brim to join the internal iliac vein, forming the common iliac vein. Right and left common iliac veins join to form the inferior vena cava.
Drainage of the gastrointestinal tract
The veins draining the gastrointestinal tract do not immediately join the blood returning to the heart and will be considered in the digestive system practical later in the semester.

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CHECKLIST OF MAJOR VEINS:
By following the pathways previously described you should now have identified…

1.

superior vena cava

inferior vena cava

coronary sinus

2.

internal jugular vein (L & R)

external jugular vein (L & R)

brachiocephalic vein (L & R)

3.

radial vein (L & R)

ulnar vein (L & R)

median cubital vein (L & R)

brachial vein (L & R)

subclavian vein (L & R)

great saphenous vein (L & R)

small saphenous vein (L & R)

popliteal vein (L & R)

femoral vein (L & R)

external iliac vein (L & R)

internal iliac vein (L & R)

4.

common iliac vein ( L & R)
Once you have participated in the renal and digestive system practical, add the veins that drain blood from the kidneys and GIT to this checklist.

PART C: Feedback on your learning of cardiovascular anatomy
In your anatomical laboratory examination at the end of the semester, you will be required to name landmark and functionally important structures of the human body on dissected specimens, anatomical models and/or photographic images and answer short (single word to one sentence) questions about some of the structures.
To provide you with feedback about your grasp of this week’s material and the standard required for success in the anatomy laboratory exam, your tutor will display an image of an anatomical model that has 7 structures labelled. Name the structures labelled 1-5 and answer two questions: i) and ii).
Try to be as specific as possible e.g. indicate right and left sides (if applicable), specific rather than general - 'right superior pulmonary vein', not just 'vein'.
1.
2.
3.
4.
5.
i) ii) 11

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PART D: Some review questions for you to complete as independent study
In your own study time, attempt the following questions which are typical theory exam questions for circulatory system anatomy. Diagrams are provided to give you some prompts for your answers.

1. Blood vessel types
Explain the differences in wall structure between arteries, veins & capillaries and relate the structural differences to their function.

2. Path of Blood Flow through the Heart and Pulmonary Circulation
Describe the flow of blood through the heart and lungs (the pulmonary circulation), mentioning all chambers, valves, and vessels through which blood must pass in order.

Johnson (2010), Fig 8.8

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3. Systemic Circulation
Outline the path that blood flows through from the aorta to:
a) the hand and back to the heart again
b) the foot and back to the heart again.

Johnson (2010), Fig 8.8

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