In terms of the distribution of blood within the circulatory system at rest, most of the blood in our bodies (60-70%) is contained in the:

• Lungs

• Capillaries

• Systemic Veins

• Systemic arteries

• Heart

Answer explanation

Small veins and venules hold more blood than the larger veins.

True or False: Blood pressure in the veins is much higher than in the arteries.

• True

• False

Answer explanation

Blood pressure in the arteries is much higher than in the veins, in part due to receiving blood from the heart after contraction, but also due to their contractile capacity.

The ______ is the contractile unit of muscle.

To help veins of the lower limbs return blood to the heart, the veins pass between skeletal muscle groups called _______ which provide contractions to help move blood back.

When breathing in, your chest ______ and your diaphragm ______.

• contracts, contracts

• expands, relaxes

• expands, contracts

• contracts, relaxes

When breathing out, your chest ______ and your diaphragm ______.

• contracts, contracts

• expands, relaxes

• expands, contracts

• contracts, relaxes

Veins have thinner, less muscular walls than do arteries; thus, they have a lower compliance

• True

• False

Answer explanation

Veins have thinner, less muscular walls than do arteries; thus, they have a higher compliance (higher stretchability) They expand a lot under pressure, and are not very resistant (blood pools in veins)

True or False? The capillaries lack smooth muscle and connective tissue.

• True

• False

Answer explanation

The capillaries lack smooth muscle and connective tissue which makes it easier to exchange materials between blood and tissues.

True or False: The lungs are very elastic and resist distension (stretching)

• True

• False

Answer explanation

The lungs are normally stuck to the chest wall, so they are always in a state of elastic tension.

This tension increases during inspiration when the lungs are stretched, and is reduced by elastic recoil during expiration.

True or False? The lungs are normally stuck to the chest wall, so they are always in a state of elastic tension.

• True

• False