1. The Cardiorespiratory System
PSK 4U1

2. Functions of the Cardiorespiratory System
Each cell of the body requires water and energy and the disposal of waste.
Approximately 100 trillion cells
These materials are carried by blood through arteries, capillaries and veins.

3. The Path of Blood Along Vessels
Artery Arteriole Capillary Venule Vein
Arteries have muscular walls.
Veins have valves to prevent
backflow. (c.n. atherosclerosis,
aneurisms, varicose
veins)

4. Circulation is the pumping of blood through the entire body by the heart
Coronary circulation is the circulation of blood within the heart. (c.n. MI)
Pulmonary circulation is the flow of blood between the heart and lungs. (c.n. hemo/pneumo)
Systemic circulation is the flow of blood between the heart and the cells of the body.

5. A Comparison of the Cardiovascular and Respiratory Systems
Cardiovascular System
Assists in gas transport.
Delivers nutrients, hormones, and antibodies.
Removes waste products from the cells
Assists in temperature regulation
Assists in balancing body fluids and helps prevent dehydration
Respiratory System
Transports gases (O2 and CO2) to and from the lungs and body tissues.
O2 is inhaled and transported, in blood, to the tissues.
CO2, a by product of metabolism, is picked up at the tissue level and transported, in blood, back to the heart and lungs.

6. Structure and Function of Cardiorespiratory System
The two atria receive blood into the heart; the two ventricles send blood from the heart to the rest of the body.
The left ventricle has a thicker myocardium due to hypertrophy resulting from the force with which it must contract.
Cardiac tissue has its own conduction system through which it initiates its own pulse without neural control (A-V node & S-A node)

7. The Heart

8. Circulation in the Heart

9. Myocardium—The Cardiac Muscle
Thickness varies directly with stress placed on chamber walls.
Left ventricle is the most powerful of chambers and thus, the largest.
With vigorous exercise, the left ventricle size increases.
Due to intercalated disks—impulses travel quickly in cardiac muscle and allow it to act as one large muscle fibre; all fibres contract together. (c.n. heart murmurs)
􀂊 􀂊 􀂊 􀂊.

10. The Cardiac Cycle
Systole: when the ventricles contract and the atria fill.
Diastole: when atria contract and the ventricles fill.
Blood pressure: is measured in millimeters of mercury (mmHg) and reflects the difference in pressure in the arteries between the systolic and diastolic phases of the cardiac cycle, e.g., 120/80 mm/Hg (c.n. High BP)

11. Measures of the Cardiorespiratory System
AT REST
Heart rate: 50–90 beats/minute
Breathing rate: 12–20 breaths/minute
Blood pressure: 110/70
Cardiac output: 5L/min.
Blood distributed to muscles: 15–20%
DURING EXERCISE
Heart rate: 170–210 beats/minute
Breathing rate: 40–60 breaths/minute
Blood pressure: 175/65
Cardiac output: 20-40L/min.
Blood distributed to muscles: 85–90%

12. Measures of the Cardiorespiratory System (cont.)
Stroke Volume (SV): The volume of blood pumped per contraction
End-diastolic volume (EDV): The volume of blood in ventricle before contraction
End-systolic volume (ESV): The volume of blood in ventricle after contraction
SV = EDV – ESV
Cardiac Output (Q): The total volume of blood pumped by the left ventricle per minute

13. Stroke Volume Increases During Exercise
Frank Starling mechanism more blood in the ventricle causes it to stretch more and contract with more force.
Increased ventricular contractility (without end-diastolic volume increases).
Decreased total peripheral resistance due to increased vasodilation of blood vessels to active muscles

14. Cardiac Output (Q) also increases
Resting value is approximately 5.0 L/min.
Increases directly with increasing exercise intensity to between 20 to 40 L/min.
Value of increase varies with body size and endurance conditioning.
When exercise intensity exceeds 40% to 60%, further increases in Q are more a result of increases in HR than SV

15. Blood
A complex mixture of cells, water, and various proteins and sugars.
Fifty-five percent is plasma (liquid).
Forty-five percent is solid.
(c.n. hemophilia)

16. Hemoglobin (Hb) and O2
Hemoglobin is the O2-carrying molecule in our blood. It contains iron (Fe) and binds with O2 in the alveoli. As Hb circulates through the body, it drops off O2 in tissues that are metabolically active, and picks up CO2, which it drops off at the alveoli on its return.

17. Hemoglobin (Hb) and O2 (cont.)
The affinity or “stickiness” of O2 to Hb is inversely proportional to temperature and acidity. Therefore, when muscle temp. rises, and pH decreases as muscles contract, O2 is preferentially dropped off. (c.n. anemia, sickle cell anemia, CO poisoning)

18. Arterio-venous O2 Difference (A-V O2 diff)
At rest, approximately 75% of the O2 that is bound to Hb returns to the alveoli after circulating through the body. As you exercise, the demand for O2 increases. Therefore, less O2 returns to the alveoli after circulating through the body. The (A-V O2 diff) is the difference in [O2] between arteries and veins
VO2 (max) is the amount of O2 a person can take in and use in 1 minute. It is an important determinant of cardiovascular fitness.
Fick Equation

19. Increasing [Hb] Blood doping Sleeping in a hypobaric chamber
Training at altitude.
Taking iron supplements (for some)
O2 supplementation in athletes
O8 water
EPO