1. Circulatory System 2
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11.3 & 11.4

2. Blood Vessels
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Joining all the blood vessels in your body in a straight line would go across Canada 4 times (~ km)

3. Arteries carry blood away from the heart toward body tissues
elasticity of the walls ensures constant flow of blood
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4. Image from: http://www. emergencymedicaled
Taking the pulse is very useful procedure in determining the heart rate.
Can feel pulse when large arteries close to the skin expand as blood pumps through.
Most common are radial & carotid.

5. Take your pulse…
Crotid pulse image:
Radial & Brachial pulse image:
Mini Investigation pg 488

6. Arterioles smallest arteries
smooth muscles in arterioles can cause vasoconstriction or vasodilation
diverts blood flow toward areas of need, e.g., during exercise, cold temperatures, etc.
Vasoconstriction – a decrease in the diameter of arterioles that decreases the blood flow to tissues
Vasodilation – an increase in the diameter of arterioles that increases the blood flow to tissues
Controlled by nervous system to control the blood flow to certain parts of the body.
When you are resting, your muscles do not require much blood  constriction of arterioles diverts blood away from the muscles to other areas of the body where blood is required.
During exercise, muscles require lots of blood, so blood flow to the lungs and muscles is increased, while reduced to other parts of the body.

7. Capillaries smallest blood vessels
no body cell is further than 2 cells away from a capillary
site of gas, nutrient, waste exchange
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The walls of the capillaries are only a single cell layer thick.

8. Image from: http://www. studyblue
Precapillary sphincters control blood flow through capillaries.

9. Venules & Veins carry blood toward the heart
smooth muscle layer not as thick (not as elastic)
valves & skeletal muscles ensure blood flow
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The internal diameter of veins is greater than that of arteries.
Lower blood pressure than in arteries.
Valves to ensure the blood flows in only one direction.
When the muscles contract, they squeeze the veins increase the pressure in the veins and helps push the blood back toward the heart.

10. Hypertension
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Hypertension – commonly known as high blood pressure.
- blood pressures consistently above the normal levels
It is dangerous because it forces the heart to work harder to pump blood around the body
Serious event, such as a heart attack or stroke.

11. Varicose Veins
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As people age, their veins and other blood vessels tend to become less elastic.
Individuals who have spent long periods of time standing or sitting may damage the valves in the veins of the lower legs.
If the valves are not functioning properly, there is a greater accumulation of blood in the veins and the veins stretch but do not rebound, creating varicose veins.

12. The Lymphatic System
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Part of 2 systems:
- circulatory system
- immune system

13. Image from: http://www.livescience.com/26983-lymphatic-system.html

14. Circulatory Functions
lymphatic system helps ensure that blood volume is maintained
collects excess tissue fluids (lymph) and returns it to the blood
Lymph contains a variety of components:
- the fluid itself
- bacteria
- other foreign cells
- dead or damage cells
- fat molecules absorbed through the lacteals in the villi of the small intestine
These are either delivered back into the bloodstream or filtered from the system and removed.

15. Immune System Functions
removes bacteria & other harmful components from blood
lymph nodes are enlargements where leukocytes gather
spleen is a filtering station & reservoir of erythrocytes & leukocytes
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Spleen is the largest organ of the lymphatic system
When required, spleen provided additional leukocytes
Increase oxygen delivered by providing additional erythrocytes

16. The Heart Where is your heart? On the left side?
- Middle of the chest, directly under the breastbone!
You’ve learned that the heart has 4 chambers and mammals have two-circuit circulatory system.
In this section, you will examine the structure of the human heart more closely, look at circulation in the two-circuit system, and investigate normal and abnormal heart rhythms.

17. Image from: http://commons. wikimedia
Septum separates the heart into two parallel pumps, each with an atrium and a ventricle.
Atria at the top of the heart, receive blood and pump it into the ventricles
The ventricles at the bottom of the heart, pump blood out into two circuits: the pulmonary circuit (the right side of the heart), to the lungs; and the systemic circuit (the left side of the heart) to the rest of the body
Circulation
Deoxygenated blood from the body enters the right atrium of the heart.
Contraction of the RA, along with GRAVITY, forces the blood into the RV.
The RV contracts to force the blood out through the pulmonary arteries to the lungs.
Oxygen diffuses into the blood out through the capillary networks in the lungs.
Oxygenated blood from the lungs enters the LA through the pulmonary veins.
The LA contracts and squeezes blood into the LV.
The LV contracts and forces blood out through the aorta (the largest blood vessel in the body)
The aorta branches into major arteries that carry blood around the body.
As blood passes through the capillary networks in the body tissues, oxygen diffuses out of the blood into the cells.
The deoxygenated blood enters the venules, which merge to form veins.
These veins merge to form larger veins.
The largest veins, the inferior vena cava (collect blood from the lower parts of the body) and the superior vena cava (collect blood from the upper parts of the body), enter the RA of the heart.
The cycle begins again.
4 valves in the heart ensure that blood flows in only one direction
Pulmonary valve and Aortic valve are semilunar valves (shaped like half moons): prevent blood from flowing back into the ventricles when they relax.
Triscupid valve (3 flaps) and Miral valve (two flaps) are atrioventricular valves (between atrium and ventricle): prevent blood from flowing from the ventricles back into the atria when the ventricles contract.

18. Image from: http://www.smm.org/heart/lessons/heartDiagram.htm

19. Animation The pathway of blood through the heart:

20. Cardiac Cycle
systole = ventricles contracted (blood is pumped from the ventricles)
diastole = ventricles relaxed (blood fills ventricles)
heartbeat “lubb-dubb” caused by the valves closing
Cardiac cycle – a complete heartbeat (a contraction and relaxation of each chamber of the heart)
Normal conditions: takes about 0.8 s.
Cardiac cycle is divided into two basic phases: enter
Lubb-dubb
Lubb sound occurs when the atrioventricular valves close as the ventricles begin to contract
Dubb sound occurs as the ventricles relax and the semilunar valves snap shut

22. Heart Rhythm sinoatrial (SA) node initiates heartbeat; “the pacemaker”
atrioventricular (AV) node carries signal to ventricles
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SA node acts as a pacemaker and set the normal rhythm of the heartbeat
-generates electrical signals causing the muscles to contract
The signals reach AV node, special conducting fibres, called Purkinje fibres, run down through the septum and throughout the muscle cells of the ventricles.

23. Electrocardiograph
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Since the heartbeat is electrically stimulated, it can be indirectly observed by measuring the strength and duration of its electrical signals with electrocardiograph.
Records as an electrocardiogram
Both referred to as an ECG
Abnormalities can be identified only by comparing the potential problem with the normal ECG pattern (see diagram)
P-wave: electrical stimulus from the SA node spreads and causes the contraction of the atria.
QRS complex: electrical stimulus moves via the Purkinje fibres to the tip of the ventricles
T-wave: slight delay as the ventricles recover and prepare for the next contraction.

24. Animation Systole & Diastole Animation: