KEY KNOWLEDGEKEY SKILLS The structure and function of the heart and lungs The way the...

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.

© Cengage Learning Australia 2011

The cardiovascular system is made up of the heart, blood vessels and blood.

The heart is made up of:Two upper chambers – the atriaTwo lower chambers – the ventricles


The cardiac cycle

• 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.


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.

Blood – functions• Transportation of gases,

fuels, and minerals• Protection• Maintaining the body’s state

of equilibrium (homeostasis) via enzyme and hormone regulation

Cardiac Output (Q) = stroke volume (SV) x heart rate (BPM)


• 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 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.


Blood pressure is the force exerted by blood against the blood vessel walls


Respiratory structures


Breathing in = InspirationActive• 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 = ExpirationPassive• 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


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 haemoglobin (Hb) and when the two combine they form oxyhaemoglobin:

haemoglobin + oxygen = oxyhaemoglobin

Hb + O 2 = HbO2

Transfer & transport of gases


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.

Arteriovenous oxygen difference – (a-vO2 diff)


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