Red blood cells transport respiratory gases

Most of the cells in the blood are erythrocytes, or red blood cells. Mature red blood cells are biconcave, flexible discs packed with hemoglobin. Their function is to transport respiratory gases. Their shape gives them a large surface area for gas exchange, and their flexibility enables them to squeeze through narrow capillaries. There are 5 to 6 million red blood cells per cubic milliliter of blood (about one drop).

Red blood cells, as well as all the other cellular components of blood, are generated by stem cells in the bone mar-

Blood is withdrawn from the arm, placed in a test tube, and centrifuged.

100%

50% Hematocrit

100%

50% Hematocrit

Plasma portion

49.15 The Composition of Blood Blood consists of a complex aqueous solution (the plasma), and of numerous cell types and cell fragments.The hematocrit (arrow) is a measure of the cellular portion as a percentage of the total blood volume.

Components

Sodium, potassium, calcium, magnesium, chloride, bicarbonate

Plasma proteins Albumin Fibrinogen Immunoglobulins

Functions

Solvent

Osmotic balance, pH buffering, regulation of membrane potentials

Osmotic balance, pH buffering, clotting, immune responses

Cellular portion

Components

Erythrocytes (red blood cells)

Leukocytes (white blood cells) y Basophil Eosinophil Neutrophil Lymphocyte Ä

Number per mm3 of blood

5-6 million

5,000-10,000

Functions

Transport oxygen and carbon dioxide

Destroy foreign cells, produce antibodies; roles in allergic responses

Transported by blood:

Nutrients

Waste products of metabolism

Respiratory gases

Hormones

Heat

Transported by blood:

Nutrients

Waste products of metabolism

Respiratory gases

Hormones

Heat

Platelets

250,000400,000

Blood clotting row, particularly in the ribs, breastbone, pelvis, and vertebrae. Red blood cell production is controlled by a hormone, erythropoietin, which is released by cells in the kidney in response to insufficient oxygen (hypoxia) in the tissues. Many tissues respond to hypoxia by expressing a transcription factor called hypoxia-inducible factor 1 (HIF-1). When it reaches the kidney, HIF-1 activates the gene encoding erythropoietin.

Under normal conditions, your bone marrow produces about 2 million red blood cells every second. Developing, immature red blood cells divide many times while still in the bone marrow, and during this time they produce hemoglobin. When the hemoglobin content of a red blood cell approaches about 30 percent, its nucleus, endoplasmic reticu-lum, Golgi apparatus, and mitochondria begin to break down. This process is almost complete when the new red blood cell squeezes between the endothelial cells of blood vessels in the bone marrow and enters the circulation.

Each red blood cell circulates for about 120 days. As it gets older, its membrane becomes less flexible and more fragile. Therefore, old red blood cells can rupture as they bend to fit through narrow capillaries. One place where they are really squeezed is in the spleen, an organ that sits near the stomach in the upper left side of the abdominal cavity. The spleen has many venous cavities, or sinuses, that serve as a reservoir for red blood cells, but to get into the sinuses, the red blood cells must squeeze between spleen cells. When old red blood cells are ruptured by this squeezing, their remnants are taken up and degraded by macrophages.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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Responses

  • McKenzie
    When red blood cells transport respiratory gases?
    8 years ago
  • ross
    How does red blood cell function in the transportation of respiration gases?
    8 years ago
  • longo
    How red blood cells are transported in the plasma?
    8 years ago
  • liisa
    How are respiratory gases transported by blood?
    7 years ago
  • uwe
    When red blood cells transport respiratory gases quizlet?
    7 years ago
  • Uwe
    When red blood cells transport respiratory gasses both?
    7 years ago
  • Biniam
    What type of blood cell transports gases?
    7 years ago
  • theodoric
    Is a function of the blood to transport gases to the cells?
    7 years ago
  • RICKY STEVENSON
    When red blood cells transport respiratory gases oxygen binds?
    7 years ago
  • dirk
    Do platelets transport respiratory gases?
    5 years ago
  • lois
    What thpe of respiratory gases transport rbc?
    3 years ago
  • Kristian
    What happens when red blood cells transport respitory gases?
    3 years ago
  • Carolyn
    Which component in the red blood cells carries respiratory gase?
    3 years ago
  • Saba
    Which component in the red blood cells carries respiratory gases?
    3 years ago
  • Beverly
    Which cell help in transport of gases?
    2 years ago
  • robert
    Which blood component transport most of the gasses?
    1 year ago

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