1. The Mammalian Circulatory System

2. Components of a CLOSED Circulatory System
Pump:
to circulate blood (i.e. heart)
Vessels:
along which fluid travels (arteries, veins, capillaries)
Fluid:
to carry substances around body (blood)

4. Flow of Blood in Circulatory System
Divided into three main pathways:
Pulmonary (lungs)
Coronary (heart)
Systemic (rest of body)

5. Coronary (Cardiac) Circulation
Feeds heart muscle
If blocked, leads to heart attack (cardiac infarction)

6. Structure of Heart

7. ELECTRICAL CONDUCTION
Stimulation of the S.A. node causes the AV node to contract.
From the AV node, impulses run through the Bundle of His to the Purkinje Fibres  these impulses cause ventricles to contract

8. CARDIAC CYCLE & ECG

9. Normal electrocardiograph
The change in voltage produced by these electrical signals can be measured using a device called an electrocardioGRAM (ECG)
The tracing produced by an electrocardiogram is called an electrocardioGRAPH
Normal electrocardiograph
Depolarization = contraction
Repolarization = relaxation

10. Let’s play Doctor

11. Artificial Pacemakers
They are useful if the SA node cannot transmit regular impulses
It consists of: battery, timer and electrode
These are inserted into heart region where the pacemaker would normally be
Electrode sends out impulses at timed intervals to either speed up a slow heart or correct an erratic heart beat

12. Measurement of blood pressure
Artery
Rubber cuff inflated with air
Artery closed
120 70
Pressure in cuff above120
Pressure in cuff below 120
Pressure in cuff below 70
Sounds audible in stethoscope
Sounds stop
Blood pressure
Reading: 120/170

13. Blood Pressure Systolic pressure Diastolic pressure
Is the pressure in the arteries during ventricular systole
Is the highest pressure in the arteries
Diastolic pressure
Is the pressure in the arteries during diastole
Is lower than systolic pressure

14. Blood pressure Blood pressure is determined partly by cardiac output
C.O. = H.R. x S.V.
And partly by peripheral resistance due to variable constriction of the arterioles

15. Mammalian Heart Each side of the pump has 2 chambers: atrium
at the top; receive blood from veins
ventricle (thick-walled)
at the bottom; pump blood away from heart through arteries

16. Mammalian Heart Size of a fist Located between lungs
Consists of cardiac muscle tissue
Covered by pericardium (sac)
Heartbeat is created by the pulling of the muscles in the organ against each other
In an adult, 80 mL of blood is pumped at each beat
Heart is divided into 4 chambers: 2 atria; 2 ventricles (i.e., two parallel pumps) separated by a thick partition called a septum

17. Structure of heart

18. Blood Flow through the heart
The right atrium receives deoxygenated blood from the body via the vena cava
The blood goes to the right ventricle and pumps to the lung (through the pulmonary artery)

19. Blood Flow through the heart
The left atrium receives oxygenated blood from lungs (from pulmonary vein)
The blood goes to the left ventricle, which pumps blood away from heart through the aorta to the rest of the body

20. Valves Maintain one-way flow of blood through heart 4 valves in total
Atrioventricular (Atria  ventricles)
tricuspid valve: from R.A. R.V.
bicuspid (mitral) valve: from L.A. L.V.
Semi-lunar valves (Ventricles  arteries)
pulmonary SLV: R.V. pulmonary artery
aortic SLV: L.V.  aorta

21. Valves

22. Sounds of the Heart
Lub—AV valve close
Dub—SL valve close

23. Systole vs. Diastole Systole Diastole contraction of heart chambers
relaxation of heart chambers

24. VESSELS