Human Blood and Its Functions Quiz

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Questions and Answers

What percentage of total body weight does blood constitute in an adult human?

10%

12%

8% (correct)

Which type of blood cell is primarily responsible for transporting oxygen in the body?

Plasma cells

Platelets

White blood cells

Red blood cells (correct)

What is the primary study of blood called?

Physiology

Hematology (correct)

Pathology

Cardiology

Which of the following is NOT a function of blood?

Digestion of food Signup and view all the answers

What color is blood typically described as being?

Bright red Signup and view all the answers

How does blood help in temperature regulation?

By adjusting body temperature Signup and view all the answers

What type of blood cells are primarily involved in protection against disease?

Leukocytes Signup and view all the answers

Which component of blood is classified as non-cellular?

Plasma Signup and view all the answers

What happens to the phagocytic vesicle when lysosomes come in contact with it?

It becomes a digestive vesicle. Signup and view all the answers

Which enzymes are specifically found in the lysosomes of macrophages but not in neutrophils?

Lipases Signup and view all the answers

What role do oxidizing agents play in the process of phagocytosis?

They produce bactericidal effects. Signup and view all the answers

What is the composition of the reticuloendothelial system?

Monocytes, mobile macrophages, fixed tissue macrophages, and specialized endothelial cells. Signup and view all the answers

Which bactericidal agent is formed by the enzyme myeloperoxidase?

Hypochlorite Signup and view all the answers

What mechanism allows tissue macrophages to become mobile again?

They receive a signal for mobility. Signup and view all the answers

In response to local infection, what do local tissue macrophages in subcutaneous tissue do?

They undergo mitosis to create more macrophages. Signup and view all the answers

Which condition describes the state of monocytes that become fixed tissue macrophages?

They remain attached for long periods unless stimulated. Signup and view all the answers

What role do macrophages play in inflammation?

They become mobile and migrate to the injury site. Signup and view all the answers

Which substances are released during tissue injury and contribute to inflammation?

Bradykinin and serotonin Signup and view all the answers

What is a key characteristic of the capillaries in the spleen?

They allow whole blood to pass into the reticular meshwork. Signup and view all the answers

How do macrophages respond shortly after inflammation begins?

They begin phagocytic actions and may become mobile. Signup and view all the answers

What is the purpose of the 'walling off' phenomenon during inflammation?

To prevent the spread of bacteria or toxins. Signup and view all the answers

What characterizes the trabecular meshwork in the red pulp of the spleen?

It is lined with numerous macrophages. Signup and view all the answers

What is likely the first immune response to invading organisms?

Phagocytosis by macrophages. Signup and view all the answers

What role do venous sinuses play in the spleen?

They are lined with macrophages for filtration. Signup and view all the answers

What role do eosinophils primarily play in the immune response?

Attaching to parasites and releasing toxic substances Signup and view all the answers

Which substance is NOT released by basophils and mast cells during allergic reactions?

Major basic proteins Signup and view all the answers

What percentage of blood leukocytes do eosinophils normally constitute?

2% Signup and view all the answers

What is one of the primary functions of platelets in the immune response?

Forming a temporary plug to stop bleeding Signup and view all the answers

How do eosinophils contribute to allergic reactions?

By detoxifying substances released by mast cells Signup and view all the answers

Which statement accurately describes basophils?

Basophils release heparin to prevent blood coagulation. Signup and view all the answers

Which of the following describes a function of platelets during inflammation?

Digesting bacteria Signup and view all the answers

Eosinophils are particularly important in response to which type of infection?

Parasitic infections Signup and view all the answers

What is the primary function of macrophages in the lymph nodes?

To phagocytize foreign particles Signup and view all the answers

Which type of macrophages are found in the liver sinusoids?

Kupffer cells Signup and view all the answers

How do large particles that macrophages cannot digest get managed?

They are encapsulated by giant cells Signup and view all the answers

What happens to lymph fluid as it passes through the lymph nodes?

It flows through sinuses lined with macrophages Signup and view all the answers

What role do alveolar macrophages play in the lungs?

They phagocytize particles trapped in alveoli Signup and view all the answers

What is the fate of bacteria that enter the portal blood from the gastrointestinal tract?

They are trapped and phagocytized by Kupffer cells Signup and view all the answers

Where do macrophages in the spleen and bone marrow mainly provide defense?

Against invading organisms in general circulation Signup and view all the answers

What is the primary route for foreign particles to enter the lymphatic system?

Transport via the gastrointestinal tract Signup and view all the answers

What triggers the influx of neutrophils to the inflamed tissue during the initial phase of inflammation?

Chemotactic products present in the inflamed tissue Signup and view all the answers

How much does the number of neutrophils increase in the first few hours of acute inflammation?

By four to five times Signup and view all the answers

What is the primary reason for slower macrophage accumulation compared to neutrophils during inflammation?

Limited storage pool of monocytes in the bone marrow Signup and view all the answers

Which cells become the dominant phagocytic cells weeks after inflammation begins?

Macrophages Signup and view all the answers

How long does it typically take for newly formed granulocytes and monocytes to leave the bone marrow?

3 to 4 days Signup and view all the answers

What is formed by the accumulation of dead neutrophils, dead macrophages, and necrotic tissue?

Pus Signup and view all the answers

Which of the following factors is NOT involved in the feedback control of the macrophage and neutrophil response?

Cytokine interleukin-6 (IL-6) Signup and view all the answers

Which cell type is primarily responsible for the initial rapid response to inflammation?

Neutrophils Signup and view all the answers

Study Notes

Blood Composition and Functions

Blood is the major circulating fluid in the human body
Hematology is the study of blood
Blood is a fluid connective tissue derived from mesoderm
Blood is bright red, slightly alkaline (pH 7.4), salty, and heavier than water
An adult has about 5 liters of blood, which constitutes about 8% of total body weight

Blood Constituents

Blood is divided into two main components: cellular and non-cellular components
Cellular components include red blood cells (RBCs), white blood cells (WBCs), and platelets
Non-cellular components include plasma

Cellular Components

Red Blood Cells (RBCs):
- Circular, biconcave, and enucleated cells
- Transport oxygen from the lungs to tissues using hemoglobin
- In healthy men, about 5,200,000 RBCs per cubic millimeter of blood
- In healthy women, about 4,700,000 RBCs per cubic millimeter of blood
White Blood Cells (WBCs):
- Mobile units of the body's protective system
- Travel to areas of infection or inflammation
- Types include granulocytes (e.g., neutrophils, eosinophils, basophils) and agranulocytes (e.g., monocytes, lymphocytes, plasma cells)
- Granulocytes and monocytes are formed in the bone marrow
- Lymphocytes, and plasma cells are produced in various lymphogenous tissues (e.g., lymph glands, spleen, thymus).
- Granulocytes circulate in the blood for 4-8 hours and another 4-5 days in tissues, (shorter life span if infection).
- Monocytes circulate in the blood 10-20 hours and swell to be macrophages in tissues, (longer life span).
- Lymphocytes have a lifespan of weeks or months.
- Platelets are replaced about once every 10 days.
- Neutrophils and tissue macrophages attack and destroy invading bacteria, viruses, and other injurious agents.
- Concentrations of WBCs in an adult: neutrophils (62%), eosinophils (2.3%), basophils (0.4%), monocytes (5.3%), and lymphocytes (30%)
Platelets:
- Small fragments of bone marrow cells
- Involved in vasoconstriction, forming temporary platelet plugs to stop bleeding, secreting procoagulants to promote clotting, digesting and destroying bacteria, secreting chemicals to attract neutrophils and monocytes to the site of inflammation, and secreting growth factor to maintain blood vessel lining.

Non-Cellular Component (Plasma)

Straw-colored, slightly alkaline, viscous fluid
Primarily composed of water (90-92%)
Contains proteins (albumin, globulin, fibrinogen, prothrombin), nutrients (glucose, amino acids, glycerols), nitrogenous wastes (urea, uric acid), gases (O2, CO2, nitrogen), and inorganic substances (bicarbonates, chlorides, phosphates, sulfates, Na, K, Ca, Mg ions).

Phagocytosis by Neutrophils and Macrophages

Neutrophils and macrophages employ phagocytosis to ingest foreign particles.
First, neutrophils attach to the particle; then they extend pseudopodia around it, and form a chamber to contain the phagocytized particle.
Next, this chamber invaginates to form a free-floating phagocytic vesicle or phagosome.
A single neutrophil engulfs 3-20 bacteria; neutrophils then inactivate and die.
Macrophages are much more powerful phagocytes and can digest larger particles, even whole red blood cells.
After digesting particles, macrophages extrude residual products and often survive and function for months.

Digestion of Phagocytized Particles

Lysosomes and other cytoplasmic granules (in neutrophils or macrophages) release digestive enzymes and bactericidal agents.
The digestive vesicle now becomes a digestive vesicle where digestion of the phagocytized particle beings immediately.
Macrophages also contain Lipases that digest thick lipid membranes of bacteria such as tuberculosis bacillus.
Neutrophils and macrophages have bactericidal agents that kill most bacteria even when their lysosomal enzymes don't digest them.

Role of Macrophages and Neutrophils in Inflammation

Tissue injury release substances that cause secondary changes in tissue, increasing local blood flow and permeability of capillaries.
Resulting fluid leakage causes interstitial swelling, tissue spaces are blocked by fibrinogen clots, delaying spread of bacteria and toxic products.
The intensity is proportional to the degree of tissue injury.
Macrophages, the first line of defense, begin phagocytosis within minutes after inflammation.
Many sessile macrophages break free and become mobile in response to chemotaxis.
Neutrophils arrive as a second line during the first hour.
Large numbers of neutrophils invade the inflamed area as a result of tissue products that attract them. They cause chemotaxis.
Within a few hrs, many neutrophils increase by about four to five-fold.
Inflammatory products are transported to the bone marrow, where neutrophils are mobilized and move into the bloodstream.
A second wave of macrophages arrive, monocytes from the blood enlarge to become macrophages.
Macrophage buildup is slower than for neutrophils.

Pus Formation

When neutrophils and macrophages engulf large numbers of bacteria and necrotic tissue, essentially all of the neutrophils and many macrophages die.
The combination of dead neutrophils, dead macrophages, portions of necrotic tissue, and tissue fluid is called pus.
If infection is suppressed, the cells in the pus autolyze (themselves digest) over several days and are absorbed, so tissue damage can reverse

Other Blood Cells

Eosinophils: High numbers in parasitic infections; attach to parasites to release substances (e.g., enzymes, oxygen, proteins) that kill parasites
Basophils: Circulating mast cells, release heparin (anti-coagulation), histamine, bradykinin, serotonin (inflammation) that support allergic reactions. IgE antibodies become attached to mast cells and basophils to release histamine, bradykinin, serotonin, and heparin.

Blood Platelets

Platelets are small fragments of bone marrow cells involved in vasoconstriction, platelet plug formation, blood clotting, digesting bacteria, attracting neutrophils, and monocytes to the inflamed area.

Macrophage Systems

Monocyte-Macrophage System/Reticuloendothelial System: A system of monocytes that enter tissues, become macrophages, remain attached for weeks/months fulfilling local protective functions.
Other tissue macrophages, such as alveolar macrophages, Kupffer cells, and macrophages found in the spleen and bone marrow, also perform various phagocytic and protective roles (alveolar macrophages in the lung, Kupffer in the liver, spleen/bone marrow).
In the lymph nodes, macrophages in the lymph sinuses trap and phagocytize foreign particles entering the node.
Macrophages in the spleen/bone marrow, are entrapped by the reticular meshwork of the organs

Factors Involved in Feedback Control

Factors including TNF, IL-1, granulocyte-monocyte colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and monocyte colony-stimulating factor (M-CSF).

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Description

Test your knowledge on various aspects of human blood, including its composition, functions, and the types of cells involved in its processes. This quiz covers essential topics such as oxygen transport, temperature regulation, and immune responses. Perfect for biology students or anyone interested in human physiology!