9. Transport in animals

These components work together: the heart moves blood into vessels, the vessels connect the circulation, and valves stop blood reversing direction.

The complete fish pathway is: heart → gills → body → heart.

Together the two loops give the route heart → lungs → heart → body → heart.

The key causal chain is: two circuits → pressure can be adjusted and blood kept separate → efficient oxygen delivery to body tissues.

First locate the atria and ventricles, then use wall thickness to orient left and right; finally identify the septum, valves and surface coronary arteries.

Apply the direction rule before considering oxygen concentration: a vessel leaving a ventricle is an artery, and a vessel entering an atrium is a vein.

Each method provides a different observable signal of repeated heart activity; pulse rate is convenient for simple investigations.

Describe the pattern with direction and data where available: starting value, peak or post-exercise value, and recovery over time.

Possible risk factors include diet, lack of exercise, stress, smoking, genetic predisposition, increasing age and sex.

The strongest conclusion is conditional: sustained healthy diet and regular exercise reduce risk, while individual risk also depends on smoking, stress and inherited or demographic factors.

Trace blood from atrium → ventricle → artery: it crosses an AV valve first and a semilunar valve second.

For every comparison link destination and resistance to the pressure required, then link pressure to muscular-wall thickness.

Separation supports efficient oxygen delivery and therefore aerobic respiration in body tissues.

Valves open or close because pressure differs on their two sides; they do not contract actively.

Nervous signals and adrenaline can increase the rate of heart contraction. After exercise, heart rate stays elevated briefly while transport demand returns towards resting level.

In cross-section, an artery keeps a smaller, more regular lumen inside a thick wall; a vein has a larger lumen and thinner wall; a capillary is only wide enough for cells to pass close to its wall.

Capillaries connect the small branches of arteries to the small branches of veins, allowing exchange throughout tissues.

Use artery = away from the heart and vein = towards the heart, then attach the organ name for pulmonary and renal vessels.

An explanation must link each structural difference to high or low pressure, rather than merely list features.

These features allow useful substances to leave blood and wastes to enter it efficiently by diffusion or fluid movement.

On a diagram, find the vessel from the intestine to identify the hepatic portal vein; the remaining inflow is the hepatic artery and the outflow is the hepatic vein.

Plasma is the transport medium; the three formed components travel within it.

First find the numerous small pale-centred discs: these are red cells. Larger cells with dark nuclei are white cells.

Match the substance or process to its carrier: oxygen mainly with haemoglobin in red cells; the listed dissolved substances and cells in plasma.

Both roles follow from closing the break in the skin and blood vessel.

In a blood image, first confirm the cell is a nucleated white cell, then use the round-versus-lobed nucleus distinction.

Antibody production is a chemical defence by lymphocytes; engulfment is a cellular process carried out by phagocytes.

The fibrin mesh produces the physical barrier that reduces blood loss and pathogen entry.