In a closed circulatory system, how many times does blood pass through the heart in a double circulatory system?

• A) Once

• B) Twice

• C) Three times

• D) Four times

Fill in the blank: Tissue fluid contains dissolved ______ and nutrients.

• Carbon dioxide

• Oxygen

• Nitrogen

• Hydrogen

Fill in the blank: The potential of the tissue fluid is ______ compared to the blood.

• More positive

• Less negative

• More negative

• Less positive

Which blood vessels have thinner and less muscular walls?

• A) Arteries

• B) Arterioles

• C) Capillaries

• D) Veins

Fill in the blank: Closed circulatory systems in mammals have a heart with ______ chambers.

• Two

• Three

• Four

• Five

Which component of the blood vessel allows it to stretch and recoil?

• Valves

• Elastic tissue

• Smooth muscle

• Endothelium

Which type of node acts as the pacemaker of the heart?

• A) Atrioventricular node

• B) Sinoatrial node

• C) Purkyne fibres

• D) Bundle of His

What is the function of the atrioventricular valves during ventricular systole?

• To open

• To close

• To contract

• To relax

Fill in the blank: The bundle of His branches into ______ fibres which carry the wave upwards.

• Sinoatrial

• Atrioventricular

• Purkyne

• Lymphatic

Fill in the blank: The heart is referred to as ______ because of its ability to initiate its own contraction.

• Myogenic

• Neurogenic

• Cardiogenic

• Lymphogenic