Why are open circulatory systems advantageous to some animals?
- They use less metabolic energy.
- They help the animal move faster.
- They do not need a heart.
- They help large insects develop.
Some animals use diffusion instead of a circulatory system. Examples include:
- birds and jellyfish
- flatworms and arthropods
- mollusks and jellyfish
- none of the above
Blood flow that is directed through the lungs and back to the heart is called ________.
- unidirectional circulation
- gill circulation
- pulmonary circulation
- pulmocutaneous circulation
White blood cells:
- can be classified as granulocytes or agranulocytes
- defend the body against bacteria and viruses
- are also called leucocytes
- all of the above
Platelet plug formation occurs at which point?
- when large megakaryocytes break up into thousands of smaller fragments
- when platelets are dispersed through the bloodstream
- when platelets are attracted to a site of blood vessel damage
- none of the above
In humans, the plasma comprises what percentage of the blood?
- 45 percent
- 55 percent
- 25 percent
- 90 percent
The red blood cells of birds differ from mammalian red blood cells because:
- they are white and have nuclei
- they do not have nuclei
- they have nuclei
- they fight disease
The heart’s internal pacemaker beats by:
- an internal implant that sends an electrical impulse through the heart
- the excitation of cardiac muscle cells at the sinoatrial node followed by the atrioventricular node
- the excitation of cardiac muscle cells at the atrioventricular node followed by the sinoatrial node
- the action of the sinus
During the systolic phase of the cardiac cycle, the heart is ________.
- contracting and relaxing
- filling with blood
Cardiomyocytes are similar to skeletal muscle because:
- they beat involuntarily
- they are used for weight lifting
- they pulse rhythmically
- they are striated
How do arteries differ from veins?
- Arteries have thicker smooth muscle layers to accommodate the changes in pressure from the heart.
- Arteries carry blood.
- Arteries have thinner smooth muscle layers and valves and move blood by the action of skeletal muscle.
- Arteries are thin walled and are used for gas exchange.
High blood pressure would be a result of ________.
- a high cardiac output and high peripheral resistance
- a high cardiac output and low peripheral resistance
- a low cardiac output and high peripheral resistance
- a low cardiac output and low peripheral resistance