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Biology 12 - Circulation Study Guide KEY
1. What are the three types of blood vessels in the circulatory system? What are the functions of
each? Arteries- move blood away from heart (usually oxygenated except pulmonary artery)
Capillaries- diffusion of nutrients and wastes , connect arterioles and venules
Veins- bring blood to heart (usually deoxygenated)
2. How are veins similar to arteries? How are they different?
Similarities- both transport blood, both made of three layers & same types tissues (endothelium,
smooth muscle, connective), both part of systemic and pulmonary circuits, both connect to
capillaries
Differences- veins walls are much thinner- less smooth muscle, less connective tissue, have
valves, return blood to heart, usually veins transport deoxygenated blood vs arteries have
oxygenated, veins have larger space, expand more than arteries to act as blood reservoir.
3. How are arterioles related to blood pressure? Made up of mostly smooth muscle which can
contract to allow or restrict blood flow. Relaxation of the muscle fibers dilates arterioles and lowers
blood pressure.
4. Make a sketch of a capillary bed that shows arteries, arterioles, veins, venules, and capillaries.
See pg 240 Fig 13.1
5. Give the function for each of the following blood vessels: Use the diagram in your text on p.
235 and find each of this blood vessels on the picture.
 See Notes from class-> location describes where blood is being transported to/from
6. Draw a labelled sketch of the heart that shows the following:
 See Diagram on Back
7. The heart is described often as a "double pump." Explain why this is so and where these two
pumps pump to. The right ventricle of the heart pumps blood through the pulmonary circuit (to the
lungs) and the left side ventricle of the heart then pumps blood through the systemic circuit (to the
body)
8. What is the difference in structure and function between the atrioventicular valves and the
semilunar valves. Relate the structure of the mitral valve to its function.
Atrioventricular Valves are found between atria and ventricles and have either 2 or 3 flaps to
prevent back flow of blood along with chordae tendinae supporting them to prevent back flow. The
semilunar valves are found between ventricles and arteries and made up of flaps that look like half
moons.
9. Trace the path of a blood cell from the aorta through the body and back to the left ventricle.
List all the circulatory structures, in the correct order that the blood cell would pass through.
Aorta->Arteries->Arterioles->Capillaries->Venuoles->Veins_>Vena Cava-> R.atrium->r.Ventricle>Pulmonary artery->Lungs->Pulmonary Veins->Left Atrium-> Left Ventricle
10. Describe functions of the SA node, AV node, and Purkinje fibres. Why is the heartbeat
described as being "intrinsic"? Why is the SA node called the "pacemaker" node?
SA Node- initiates the heartbeat by sending out an electrical signal that makes the atria contract
ever 0.85 seconds it is the “pacemaker of the heart” because it starts the signal and keeps the
signal regular needed for the
AV Node- receives signal from AV node then passes it on to the AV bundles which eventually lead
to ventricles contracting
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11. Using such words as systole and diastole, describe the events that happen in the cardiac cycle
for a person whose heart is beating at 70 beats per minute.
The cardiac cycle is made up of phases of contraction (systole) and relaxation (diastole) of
different parts chambers of the heart which create a heartbeat that lasts about. 0.85 seconds.
During diastole phase when both atria and both ventricles are relaxed the heart is filling with
blood. Atrioventricular valves open & semi lunar valves closed.
Next, atrial systole means the atria contract to push the blood to the ventricles which are still in
diastole at this stage. The atrioventricular valves must stay open while the semilunar valves stay
closed
Finally, the ventricles are in systole, contracting to push blood through the pulmonary artery &
aorta (while the atria relax-diastole). The atrioventricular valves close while semilunar valves open
12. What is an ECG and what is it used for? Make a labelled sketch of a normal ECG.
An electrocardiogram is a graph that records changes in the electrical activity within the heart
muscle tissue during a heartbeat. See Fig 13.6
13. Explain how the brain controls the rate of the heartbeat. Be sure to specifically mention the exact
part of the brain is involved. What factors determine whether the systematic or parasympathetic
system is activated?
The medulla oblongata is part of the brain that can control heart beat by the 2 different divisions of
the autonomic nervous system. The parasympathetic system controls restful states and decreases
SA and AV activity. The sympathetic system operates during stress/active times to increase
heartbeat.
14. Look very carefully at the graph on p. 248. Compare and contrast blood pressure, blood
velocity, and total cross-sectional area for arteries, capillaries, and veins.
Fig 13.9- Arteries have the hightes tblood pressure and blood velocity as they are the vesses
moving blood away from the heart and need to withstand the greatest force/push from left ventricle
-Both Blood pressure and velocity drop off significantly in capillaries because they have the
greatest total cross sectional area.
15. What causes blood to flow in arteries? What causes blood to flow in veins?
The pumping of the heart (specifically left ventricle contraction) causes the blood velocity/flow in
arteries. In veins, blood is flowing back to the heart and it depends on the contraction of skeletal
muscles, valves, and breathing movements.
16. What is the pulmonary circuit? List the structures through which blood flows in the pulmonary
circuit.
The pulmonary circuit is made up of the heart and vessels that bring blood to the lungs and back:
Right atrium- right ventricle- pulmonary trunk- pulmonary arteries- lungs- pulmonary capillariespulmonary veins- left atrium
17. What is the systemic circuit? List the structures through which blood flows in the systemic
circuit.
The systemic circuit is made of the heart and all the vessels( arteries, capillaries and veins) that
deliver blood around the body.
18. Normal blood pressure is 120/80. Explain in detail what these two numbers mean. What is the
name of the instrument that measures blood pressure? Would it be possible to have a blood
pressure of 80/120? Why or why not?
Blood pressure is taken with a sphygmomanometer and is made up of the higher systolic
pressure- when ventricles contract and the diastolic pressure- when ventricles relax. It would not
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be possible to have a blood pressure of 80/120. The second reading is taken between
contractions of the heart, during the relaxation stage therefore it must always be less than the first
reading which is measuring the pressure of blood against an arterial wall as the heart contracts.
19. What are hypertension and hypotension? List at least 3 factors or lifestyle habits that are
thought to be associated with hypertension. Why is hypertension called the "silent killer"?
Hypertension is high blood pressure (anything above 140/90) and Hypotension is low blood
pressure.
Factors associated with hypertension include:
-genetics (etc over activity of angiotensin gene) –high saturated fat/high cholesterol diet
-being overweight – smoking
20. Describe the characteristics and causes of atherosclerosis.
Atherosclerosis is the formation of plaque build up in arteries due to accumulation of cholesterol/
fatty materials. Can prevent blood flow through the vessels and cause hypertension.
21. Differentiate between a heart attack and a stroke. How is diet related to these killers?
A heart attack occurs when part of the heart muscle is deprived of oxygen (ie) blockage of
coronary artery and as a result this heart tissue dies. The outcome (death or recovery)
from a heart attack may depend on the extent of heart muscle affected and any repair to
vessels needed to return regular blood flow to the heart. A stroke is cause by a blockage
such as an embolism or a burst in a small cranial arteriole. The lack of oxygen causes
part of the brain to die. Paralysis or death can result from a stroke.
Both stroke and heart attack are associated with hypertension and artherosclerosis which
are linked to high saturated fat and high cholesterol diets causing blockages in arteries.
22. Label the structures of the heart
1. superior vena cava
2. aorta
3. SA node
4. right atrium
5. AV node
6. inferior vena cava
7. Right atrioventricular
valve (Tricuspid)
10. left pulmonary vein
8. right ventricle
9. pulmonary artery
11. left atrium
12. Left atrioventricular
valve (bicuspid/mitral)
13. Aortic semilunar valve
14. left ventricle
15. septum
16. Pulmonary semilunar
valve
2. Colour the areas of the Heart where DEOXYGENATED BLOOD is found BLUE and the
locations where OXYGENATED Blood is found RED
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3. Draw arrows on the diagram to show the path that blood follows through the heart
23. Label the path of blood through the heart.
1. Superior and Inferior Vena Cava Collect Deoxygenated Blood and bring it to the Right
Atrium
2. Right Atrium sends blood through the R. atrioventricular (Tricuspid valve) to the right
ventricle
3. The right ventricle sends blood through the pulmonary semil lunar valve up into the
pulmonary trunk and pulmonary arteries
4. The pulmonary arteries bring deoxygenated blood to the capillaries at the lungs to drop
ov CO2 and pick up Oxygen
5. The pulmonary Veins bring OXYGENATED blood back to the Left Atrium of the heart
6. The Left atrium pushes blood through the L. atrioventricular valve (bicuspid/mitral) to
the left ventricle
7. The left ventricle does the largest push of blood up through the aortic semilunar valve
into the aorta
8. The aorta branches off into major arteries and blood is delivered around the body
24a. Label & Describe the systemic circuit and pulmonary circuit.
Pulmonary
Circuit
Systemic Circuit
b) Name and describe X on the diagram. What is it’s significance?
Hepatic Portal Vein- this vessels connects the capillaries in the villi of the intestines (which
absorb nutrients from digestion) with the capillaries in the liver (which monitors the make
up of the blood)
c) Label and describe the path of blood to the kidneys.
Left ventricle- Aorta- Renal Artery- arterioles- capillaries at kidneys- venuoles- Renal
Vein- Inferior Vena Cava
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