Cardiorespiratory System

Question 1

Cardiorespiratory System

Answer 1

The cardiorespiratory system is made up of:
The cardiovascular system, which contains the heart, blood vessels and blood
The respiratory system, which contains the trachea, bronchi, alveoli and lungs

The cardiorespiratory system provides the body with oxygen and nutrients required to perform work, and removes waste products, like carbon dioxide, from the body. It also regulates body temperature and maintains fluid balance.

Question 2

Oxygen transport

Answer 2

1. Inhalation
   Upon inhalation, oxygen diffuses from atmospheric air, across alveolus tissue and into deoxygenated blood that’s been pumped there by the heart. Here, oxygen is bound to iron on hemoglobin and transported through the blood.
2. Journey to the muscles
   Oxygenated blood enters the arterial system, is transported via hemoglobin to the muscle and is absorbed into the mitochondria. There, oxygen is used to produce ATP through the aerobic oxidation energy pathway. Carbon dioxide, a byproduct of energy metabolism, diffuses out of the cells into venous blood.
3. Exhalation
   The carbon dioxide in venous blood acts as the primary driver for the respiratory response and is a critical component to controlling blood pH during exercise.
   The delivery of oxygen to the working muscle is dependent upon all parts of the cardiorespiratory system working in concert together—lungs, heart, blood and vessels.

Question 3

Training effects - Resting heart rate

Answer 3

New vasculature, particularly in the capillary beds of working muscle, acts to decrease resting blood pressure. The result is more blood pushed through the working tissue, a lower resting heart rate and lower heart rate at submaximal exercise intensities.

Question 4

Training effects - Stroke Volume

Answer 4

The amount of blood pumped from the left ventricle in a single contraction is known as stroke volume.

Cardiovascular training increases the size of the left ventricle, increasing stroke volume.

Endurance training also increases plasma volume, which in turn increases total blood volume.

Question 5

Training effects - Cardiac Output

Answer 5

Cardiac output is the volume of blood per minute pumped by the heart. The calculation is as follows:

Heart rate x Stroke volume = Cardiac output

The increase in total blood volume along with the increase in cardiac output means that the heart can pump more oxygen and nutrients to the skeletal muscle, as well as more carbon dioxide away from working skeletal muscle.

The maximal cardiac output in trained individuals is higher than in untrained individuals because of the larger stroke volume. This means more blood is being pumped to the muscles and more oxygenated blood is delivered to the active tissues, permitting a greater reliance on oxidative ATP resynthesis.

Question 6

Training Effects: Oxygen Consumption

Answer 6

Proper and effective cardiovascular training also improves the body’s oxygen consumption.

As exercise intensity increases, so does the demand for oxygen and the creation of carbon dioxide.

Cardiovascular training improves an athlete’s ability to transport oxygen and to use it as well.

The more oxygen the athlete can consume, the more energy they are capable of producing.

Question 7

Measuring Cardiovascular Fitness:

VO2 Max

Answer 7

VO2max is the maximal rate of oxygen consumption that can be achieved during physical exertion. It is one factor that can determine an athlete’s capacity to perform sustained exercise and is linked to aerobic endurance.

VO2max is determined via a graded exercise test, usually in a lab, in which exercise intensity is gradually increased while oxygen consumption is being measured.

When oxygen consumption remains steady, despite an increase in workload, an athlete has reached his or her VO2max

Question 8

Measuring Cardiovascular Fitness: Lactate Threshold

Answer 8

The blood lactate levels in response to exercise have been used as a performance indicator.

Energy demand is a function of exercise intensity and is met by the oxidation of fat and carbohydrates.

If the demand for energy increases, then a greater portion of ATP resynthesis shifts from the aerobic to anaerobic metabolic pathways and lactate begins to accumulate in the blood.

The point at which lactate production outmatches its clearance is known as the lactate threshold.

The lactate threshold (LT) is determined most accurately via a blood test, but can also be determined via field tests.

Question 9

Summary

Answer 9

• The cardiorespiratory system provides the body with oxygen and nutrients required to perform work, and removes waste products, like carbon dioxide, from the body. It also regulates body temperature and maintains fluid balance.
• Cardiovascular training effects include: decreased Resting Heart Rate (RHR), decreased resting blood pressure, lower heart rate at submaximal exercise intensities, increased plasma volume, increased total blood volume, increased cardiac output, improved oxygen consumption, a shift in fuel utilization to spare glycogen, change in blood composition, increased motor neuron recruitment and improved temperature regulation.
• The ability to transport oxygen efficiently contributes to optimal performance for the endurance athlete. The more oxygen the athlete can consume, the more energy they are capable of producing.
• Measures of cardiovascular fitness include VO2max (the highest rate of oxygen transport and use that can be achieved at maximal physical exertion) and lactate threshold (the intensity beyond which any further contributions to total energy supply comes from oxygen-independent sources).