Double Circulation in Humans

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Questions and Answers

What is the primary function of white blood cells?

To protect the body from harmful bacteria, viruses and other foreign invaders (correct)

To distribute blood and its contents to body cells

To produce antibodies

To guard against foreign microorganisms

Which type of blood cell does not have a nucleus?

White Blood Cell

Red Blood Cell

Lymphocyte

Platelet (correct)

What is the result of a series of enzyme reactions in the blood clotting process?

Formation of a fibrous mesh (correct)

Release of chemicals that attract platelets

Production of thromboplastin

Formation of fibrinogen

What is the main difference between arteries and veins?

Arteries have thicker walls while veins have thinner walls Signup and view all the answers

What is the function of macrophages?

To clean up bacteria, dead cells, and other debris in the bloodstream Signup and view all the answers

What type of fluid is formed in infected tissue?

Pus Signup and view all the answers

What is the smallest form of blood vessels?

Capillaries Signup and view all the answers

What is the primary function of fibrinogen?

To play a key role in blood clotting Signup and view all the answers

Which component of the blood is responsible for carrying oxygen to the cells?

Red blood cells Signup and view all the answers

What is a key characteristic of double circulation in humans?

Blood flows through two circuits: pulmonary and systemic Signup and view all the answers

During passive transport, molecules move:

From high to low concentration without using energy Signup and view all the answers

Which statement correctly describes active transport?

Energy is used to move molecules from low to high concentration Signup and view all the answers

Why was the development of a circulatory system an important evolutionary adaptation for larger organisms?

It enabled efficient material transport to cells not in direct contact with the external environment Signup and view all the answers

Which blood component helps protect the body against invaders?

White blood cells Signup and view all the answers

What feature of red blood cells increases their surface area for gas exchange?

Their biconcave disk shape Signup and view all the answers

Which chamber of the heart receives deoxygenated blood from the body?

Right atrium Signup and view all the answers

What is the main function of capillary networks in the body?

To supply oxygen and nutrients to body tissues Signup and view all the answers

What is the primary function of white blood cells?

Defending the body against infections Signup and view all the answers

Which type of blood vessel is involved in the exchange of gases and nutrients between the blood and tissues?

Capillaries Signup and view all the answers

What is the correct order of density from least to most dense for blood components separated in a centrifuge?

Plasma, white blood cells and platelets, red blood cells Signup and view all the answers

Study Notes

Circulatory System

The circulatory system consists of two separate circuits: the pulmonary circuit and the systemic circuit.
The pulmonary circuit is responsible for transporting oxygenated blood from the lungs to the heart.
The systemic circuit is responsible for delivering oxygenated blood from the heart to the body and returning deoxygenated blood back to the heart.

Blood Components

Blood is a connective tissue composed of several components, including red blood cells, plasma, platelets, and white blood cells.
Red blood cells (erythrocytes) are the densest component, settling at the bottom of a centrifuge.
Plasma is the least dense component, rising to the top of a centrifuge.
Platelets and white blood cells form a thin layer in the middle.

Red Blood Cells

Red blood cells have no nucleus when mature and are biconcave disks, increasing their surface area for gas exchange by 20-30%.
They are thinner at the center than the edges.
Antibodies (immunoglobulins) help guard against foreign microorganisms.

White Blood Cells

White blood cells (leukocytes) are formed from pluripotent stem cells within bone marrow.
They protect the body from harmful bacteria, viruses, and other foreign invaders.
Unlike red blood cells, white blood cells have a nucleus.

Types of White Blood Cells

Monocytes become enlarged to form macrophages, which clean up bacteria, dead cells, and other debris in the bloodstream.
Lymphocytes produce antibodies that attack invading microorganisms and toxins.

Platelets

Platelets (thrombocytes) have no nucleus.
They are membrane-bound fragments of cells that form when larger cells in the bone marrow break apart.
Platelets play a key role in blood clotting, which prevents excessive blood loss after an injury.

Blood Clotting

When a blood vessel is broken, it releases chemicals that attract platelets.
The platelets then rupture and release chemicals that interact with other nearby chemicals in the plasma to produce enzyme thromboplastin.
A series of enzyme reactions produces fibrin, which forms a fibrous mesh over the site of injury, preventing the loss of blood cells and eventually forming a clot.

Blood Vessels

A complex network of tubes that branch and re-branch to distribute blood and its contents to body cells.
Arteries have thicker walls than veins and are more elastic.
Arteries carry oxygenated blood away from the heart (towards cells), while veins carry deoxygenated blood toward the heart (away from cells).
Capillaries are the smallest form of blood vessels, with walls that are just one cell thick.

Purpose of Circulation

The circulatory system plays a crucial role in delivering nutrients, oxygen, and hormones to cells and removing waste products.
A diffusion membrane is necessary for efficient exchange of oxygen, waste, and nutrients.
There are two types of transport: passive transport, which requires no energy, and active transport, which requires energy to force molecules from a low to high concentration.

Evolution of Circulatory System

The need for a circulatory system is an evolutionary adaptation to increasing body size.
Larger organisms need a network to transport materials throughout the organism because some cells do not have direct contact with the external environment.