1. © Cengage Learning Australia 2011

2. The structure and function of the heart and lungs
KEY KNOWLEDGE
KEY SKILLS
The structure and function of the heart and lungs
The way the cardiovascular and respiratory systems work together in bringing oxygen to working muscles including breathing, gaseous exchange and the transportation of blood around the body.
Participate in, analyse and report on physiological changes occurring under rest and different exercise conditions at the cardiovascular, respiratory and muscular systems.
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4. The cardiovascular system is made up of the heart, blood vessels and blood.
The heart is made up of:
Two upper chambers – the atria
Two lower chambers – the ventricles
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5. The cardiac cycle Stage 1 – atrial diastole
Stage 1 – atrial diastole
Stage 2 – ventricular diastole
Stage 3 – atrial systole
Stage 4 – ventricular diastole
Stage 1 – the atria of the heart fill with blood returning from two key areas. Blood from the body returns via the vena cava into the right atrium and blood from the lungs returns via the pulmonary vein into the left atrium. At this time the heart valves remain shut.
Stage 2 – the bicuspid and tricuspid valves open because of the pressure build up in the atria and blood flows into the ventricles, and then the valves shut again
Stage 3 – the atria now contract and blood is forced into the ventricles and pressure increases to be greater than that in the aorta and pulmonary artery.
Stage 4 – the semi-lunar valves open and the ventricles contract forcing blood into the aorta to go the rest of the body or the pulmonary artery to go to the lungs.
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6. = stroke volume (SV) x heart rate (BPM)
Cardiac Output (Q)
= stroke volume (SV) x heart rate (BPM)
Blood – functions
Transportation of gases, fuels, and minerals
Protection
Maintaining the body’s state of equilibrium (homeostasis) via enzyme and hormone regulation
Blood – composition
Red blood are produced in bone marrow and contain hemoglobin, which carries oxygen to body tissues and muscles .
White blood cells fight infection. They are produced in bone marrow, lymph tissue and the spleen.
Platelets are cells that help form blood clots to stop bleeding. They are produced in bone marrow.
Blood plasma carries nutrients and also removes waste products.
Plasma is 90% water and contains fibrinogen, which assists platelets in blood clotting.
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7. Blood vessels
Arteries carry blood away from the heart (oxygenated blood)
Veins return blood to the heart (deoxygenated blood)
Capillaries “connect” arterioles and venules &
are the smallest blood vessels
Blood flow through capillaries is controlled by small muscular rings known as pre-capillary sphincters and these can stop blood flowing into capillaries and redirect it to other parts of the body.
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8. Blood pressure is the force exerted by blood against the blood vessel walls
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9. Respiratory structures
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10. Breathing in = Inspiration
Active
intercostals and diaphragm both contract
ribs move upwards and outwards
diaphragm moves downwards
lung space increases causing decreased lung pressure
air moves into the lungs.
Breathing out = Expiration
Passive
intercostals and diaphragm relax
ribs drop and diaphragm return to dome-like relaxed state
lung space decreases causing increased lung pressure
air moves out of the lungs.
Tidal volume = amount of air inhaled and exhaled per breath
Respiratory rate = breath taken per minute
Minute ventilation (VE) = respiratory rate x tidal volume
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11. haemoglobin + oxygen = oxyhaemoglobin
Transfer & transport of gases
Pulmonary diffusion occurs in the lungs and as having two main functions:
to provide blood with oxygen before being transported to muscles and other cells
to remove carbon dioxide from blood returning from the muscles and other cells
Movement of gases at the alveoli is two-way:
oxygen moves from the alveoli into the blood
and
carbon dioxide moves from the blood to the alveoli.
Most oxygen is transported by the red blood cells combined with hemoglobin (Hb) and when the two combine they form oxyhaemoglobin:
haemoglobin + oxygen = oxyhaemoglobin
Hb O = HbO2
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12. Arteriovenous oxygen difference – (a-vO2 diff)
Is the difference in oxygen concentration between arterial and venous blood
At rest, the a-vO2 diff is approximately 5 mL of oxygen per 100 mL of blood and this reveals the amount of oxygen used by muscles.
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