32 Questions
What is the total length of blood vessels in an average human adult compared to the Earth's circumference at the equator?
Twice the Earth's circumference
What is the primary function of arterioles?
To convey blood to capillaries
What is the purpose of capillary beds?
To exchange gases and chemicals with the interstitial fluid
In which type of blood vessel does the exchange of dissolved gases and other chemicals occur?
Capillaries
What is the direction of blood flow in arteries?
From the heart to organs
How are arteries and veins distinguished?
By the direction in which they carry blood
What is the primary function of the atria in the heart?
To receive blood entering the heart
What is the term for the circulation of blood in sharks, rays, and bony fishes?
Single circulation
What is the primary advantage of double circulation over single circulation?
It provides a more vigorous flow of blood to the brain and muscles
Which of the following is an example of a portal vein?
Hepatic portal vein
What is the term for the circulation of blood in the lungs, where gas exchange takes place?
Pulmonary circuit
What is the main difference between the circulatory systems of vertebrates and those of invertebrates?
Number of chambers in the heart
What is the purpose of the ventricles in the heart?
To pump blood out of the heart
What is the result of the drop in blood pressure in the gills of single-circulation animals?
Decreased blood flow to the body
What is the term for the circulation of blood in the body, excluding the gas exchange organs?
Systemic circuit
Which of the following animals has a double-circulation system?
Human
What is the primary function of the hepatic portal vein?
To carry blood from capillary beds in the digestive system to capillary beds in the liver
What is the main difference between the hearts of vertebrates and invertebrates?
The number of chambers in the heart
In which type of circulation does blood flow through two capillary beds before returning to the heart?
Single circulation
What is the primary advantage of double circulation over single circulation?
Double circulation provides a more vigorous flow of blood to the brain, muscles, and other organs
Which of the following is a characteristic of single circulation?
The heart has two chambers
What is the term for the circulation of blood in the lungs, where gas exchange takes place, in most vertebrates?
Pulmonary circuit
In which type of circulation does the heart repressurize the blood after it passes through the capillary beds of the lungs or skin?
Double circulation
What is the primary function of the atria in the heart?
To receive blood entering the heart
Which type of circulation is found in sharks, rays, and bony fishes?
Single circulation
What is the primary difference between the pulmonary circuit and the pulmocutaneous circuit?
The type of gas exchange tissues involved
What is the primary function of capillaries in the cardiovascular system?
To exchange dissolved gases and other chemicals between the blood and interstitial fluid
What is the direction of blood flow in veins?
Toward the heart from capillaries
What is the name given to the network of vessels that infiltrate tissues and are involved in the exchange of gases and other chemicals?
Capillary beds
What is the purpose of arterioles?
To convey blood to capillaries
What is the characteristic that distinguishes arteries from veins?
The direction in which they carry blood
What is the total length of blood vessels in an average human adult compared to the Earth's circumference at the equator?
Twice the Earth's circumference
Study Notes
Organization of Vertebrate Circulatory Systems
- The term cardiovascular system refers to the heart and blood vessels in vertebrates.
- The total length of blood vessels in an average human adult is twice Earth's circumference at the equator.
- There are three main types of blood vessels: arteries, veins, and capillaries.
- Blood flows in only one direction within each type of vessel.
- Arteries carry blood from the heart to organs throughout the body, branching into arterioles that convey blood to capillaries.
- Capillaries are microscopic vessels with thin, porous walls where dissolved gases and other chemicals are exchanged by diffusion between the blood and interstitial fluid.
- Capillaries converge into venules, which converge into veins, carrying blood back to the heart.
Blood Circulation
- Single circulation occurs in sharks, rays, and bony fishes, where blood travels through the body and returns to the heart in a single circuit.
- The heart consists of two chambers: an atrium and a ventricle.
- Blood entering the heart collects in the atrium before transfer to the ventricle, which pumps blood to a capillary bed in the gills.
- Blood that leaves the heart passes through two capillary beds before returning to the heart.
- Blood pressure drops substantially in the gills, limiting the rate of blood flow in the rest of the animal's body.
Double Circulation
- Double circulation occurs in amphibians, reptiles, and mammals, with two circuits of blood flow.
- The pumps for the two circuits are combined into a single organ, the heart.
- The right side of the heart pumps oxygen-poor blood to the capillary beds of the gas exchange tissues (pulmonary circuit in most vertebrates or pulmocutaneous circuit in amphibians).
- The left side of the heart pumps oxygen-enriched blood from the gas exchange tissues to capillary beds in organs and tissues throughout the body (systemic circuit).
- Double circulation provides a vigorous flow of blood to the brain, muscles, and other organs due to the heart repressurizing the blood after it passes through the capillary beds of the lungs or skin.
Learn about the cardiovascular system, its components, and blood flow direction in vertebrates. Discover the extent of blood vessels in an average human adult. Understand the functions of arteries, veins, and capillaries.
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