Blood Cells Overview

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Questions and Answers

What is the main structural component of large elastic arteries, such as the aorta?

Circular smooth muscle only

Basal lamina

Concentric layers of elastic laminae (correct)

Collagen fibers

Which type of artery is defined as having a relatively thin tunica adventitia and mainly consists of elastic fibers?

Medium-sized arteries

Large (elastic) arteries (correct)

Metarterioles

Arterioles

What type of capillary is characterized by endothelial cells that have no fenestrae?

Fenestrated capillary

Sinusoidal capillary

Discontinuous capillary

Continuous capillary (correct)

Which functional role do pericytes in capillaries potentially serve?

Assist in angiogenesis Signup and view all the answers

Where can sinusoidal capillaries primarily be found?

In the liver, bone marrow, and spleen Signup and view all the answers

What is the typical diameter range of normal red blood cells (erythrocytes)?

6 - 9 microns Signup and view all the answers

Which type of white blood cell constitutes 50-70% of the total leukocyte count?

Neutrophils Signup and view all the answers

What is the primary function of eosinophils in the vascular system?

Antiallergic and antiparasitic response Signup and view all the answers

What is the structure of neutrophils characterized by?

Segmented nucleus formed of 2-5 lobes and specific/non-specific granules Signup and view all the answers

What distinguishes reticulocytes from mature erythrocytes?

Larger diameter and presence of ribosomes Signup and view all the answers

How many millions of red blood cells (RBCs) are typically found in one mm³ of blood?

4.5 - 5.5 million Signup and view all the answers

What type of leukocyte has a nucleus that often appears S-shaped?

Basophils Signup and view all the answers

What characterizes the cytoplasm of eosinophils?

Central crystalline dense core in specific granules Signup and view all the answers

What is the function of heparin secreted by specific granules?

Acts as an anticoagulant Signup and view all the answers

Which type of lymphocyte is primarily responsible for humoral immunity?

B-lymphocytes Signup and view all the answers

What characteristic is used to differentiate large lymphocytes from small lymphocytes?

Amount of cytoplasm Signup and view all the answers

Which layer of blood vessels contains circular smooth muscle cells?

Tunica media Signup and view all the answers

What is a primary function of monocytes?

Phagocytosis Signup and view all the answers

What components are found in the granulomere of blood platelets?

Alpha, delta, and lambda granules Signup and view all the answers

Which structure is considered the innermost layer of blood vessels?

Tunica intima Signup and view all the answers

What type of granules do mast cells contain that is similar to specific granules?

Heparin and histamine Signup and view all the answers

Study Notes

Blood Cells

Red Blood Cells (RBCs or Erythrocytes)
- Shape: Biconcave discs
- Size: 6-9 microns in diameter (average 7.5 µm)
  - Normocytes: Normal size RBCs
  - Macrocytes: RBCs larger than 9 µm (e.g., macrocytic anemia)
  - Microcytes: RBCs smaller than 6 µm (e.g., microcytic anemia)
- Number: 4.5-5.5 million/mm3 of blood
- Structure:
  - Lack nuclei and organelles
  - Contain hemoglobin (Hb) enclosed by cell membrane
- Reticulocytes: Immature RBCs (1% of circulating RBCs)
  - Slightly larger than mature RBCs
  - Contain free ribosomes and a few mitochondria

White Blood Cells (WBCs or Leukocytes)

Total Leukocytic Count: 4,000 – 11,000/mm3 of blood
Differential Leukocytic Count: Percentage of each type of WBC in total WBC count

Granular Leukocytes

Neutrophils (Polymorphs or Polymorphonuclear Leukocytes): 50-70% of WBCs
- Nucleus: Segmented (lobulated) with 2-5 lobes (usually 3)
- Cytoplasm: Contains specific granules (small, numerous) and non-specific (azurophilic) granules (large, less numerous, lysosomes)
- Function: Antibacterial, crucial for acute inflammation
Eosinophils: 1-4% of WBCs
- Nucleus: Bilobed, horse-shoe shaped
- Cytoplasm:
  - Specific eosinophilic granules: Contain antiparasitic and histaminase
  - Non-specific granules: Lysosomes containing hydrolytic enzymes
- Functions: Antiallergic, antiparasitic
Basophils: 0-0.5% of WBCs
- Nucleus: S-shaped
- Cytoplasm:
  - Specific granules: Contain heparin (anticoagulant) and histamine (allergy)
  - Non-specific granules: Lysosomes containing hydrolytic enzymes
- Functions: Secretion of heparin and histamine

Non-Granular Leukocytes

Lymphocytes: 20-40% of WBCs
- Small lymphocytes:
  - Nucleus: Large, rounded, condensed chromatin
  - Cytoplasm: Scanty, few organelles
- Large lymphocytes:
  - Nucleus: Large, rounded with indentation, less condensed chromatin
  - Cytoplasm: Basophilic (due to increased ribosomes)
- Functions:
  - Humoral immunity (B-lymphocytes)
  - Cellular immunity (T-lymphocytes)
Monocytes: 2-8% of WBCs
- Nucleus: Oval or kidney-shaped, eccentrically placed
- Cytoplasm: Contains lysosomes
- Functions: Phagocytosis, production of mononuclear phagocytic system (MPS)

Blood Platelets (Thrombocytes)

Light Microscopy (L/M):
- Peripheral hyalomere (pale)
- Central granulomere (granular)
Electron Microscopy (EM):
- Hyalomere: Contains microtubules, actin, and myosin filaments
- Granulomere: Contains:
  - Dense granules:
    - Alpha granules: Fibrinogen
    - Delta granules: ADP, ATP, epinephrine, and serotonin
    - Lambda granules: Lysosomes

Blood Vessels

Cardiovascular System: Heart + blood vessels
- Arteries: Carry blood from the heart to tissues
- Veins: Carry blood from tissues to the heart
- Capillaries: Arterio-venous connections for exchange

General Structure of Blood Vessels

Tunica Intima (Innermost):
- Endothelium: Simple squamous cells
- Subendothelium: Loose connective tissue
Tunica Media (Middle):
- Smooth muscle cells: Circular arrangement
- Elastic fibers: Variable amounts
Tunica Adventitia (Outermost):
- Loose connective tissue
- Vasa vasorum: Small blood vessels that supply the outer part of the vessel wall

Arteries

Large (Elastic) Arteries: Aorta and its major branches
- Specific Features:
  - Tunica media: Concentric layers of elastic laminae with circular smooth muscle between them
  - Tunica adventitia: Relatively thin
Medium Sized (Muscular) Arteries:
- Specific Features:
  - Tunica media: Predominantly smooth muscle
  - Tunica adventitia: Thicker than in large arteries
Arterioles: Smallest arteries
- Specific Features:
  - Tunica media: One or two layers of smooth muscle
  - Tunica adventitia: Thin
Metarterioles: Connect arterioles to capillaries
- Specific Features:
  - Precapillary sphincters: Regulate blood flow into capillaries

Veins

Large veins:
- Specific Features:
  - Tunica media: Thin with few layers of smooth muscle
  - Tunica adventitia: Thickest layer, contains longitudinal smooth muscle
  - Valves: Prevent backflow of blood
Medium sized veins:
- Specific Features:
  - Tunica media: Thinner than arteries of similar size
Venules: Smallest veins

Capillaries

Smallest channels in the circulatory system
Arise from metarterioles or directly from arterioles
Re-collect to form venules

Structure of Capillaries

Light Microscopy (L/M):
- Endothelial cells: Single layer (1-3 cells)
- Basal lamina:
- Pericytes: Partly surround endothelial cells with long cytoplasmic processes, contain actin and myosin (contractile function), produce new smooth muscle cells after injury

Types of Blood Capillaries

Continuous capillary: No fenestrae (pores)
- Location: Brain
Fenestrated capillary: Large fenestrae in endothelial cells, continuous basal lamina
- Location: Renal glomeruli, endocrine glands
Sinusoidal capillary: Tortuous, wide lumen, multiple fenestrae, discontinuous basal lamina
- Location: Liver, bone marrow, spleen

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Description

This quiz covers the essential characteristics of red and white blood cells, including their structure, types, and functions. Learn about the differences between normocytes, macrocytes, and microcytes, along with the various types of leukocytes and their percentages in blood. Test your understanding of hematology with this informative quiz.