physiology - 2 blood

what are the main components of blood

plasma (~55%) and cells (~45%)

what are the 3 types of blood cells?

RBC’s, WBC’s and Platelets

what is the approximate blood volume in a normal adult male?

about 5 liters

what is plasma?

the fluid part of blood, making up about 55%

what is plasma mainly composed of?

about 90% water, plus proteins and dissolved substances

what substances are dissolved in plasma?

proteins, electrolytes, nutrients, gases, hormones, and metabolic wastes

what are examples of plasma electrolytes?

Na⁺ and Cl^-

what are examples of plasma nutrients?

Glucose and amino acids

which gases are dissolved in plasma?

O₂ and CO₂

which metabolic wastes are found in plasma?

urea and creatinine

what is plasma oncotic pressure?

the pulling force that draws water back into vessels

what does oncotic pressure balance?

the outward push of hydrostatic pressure

what are the major plasma proteins?

albumin, fibrinogen, prothrombin, α/β globulins and y-globulin

where are most plasma proteins produced?

the liver

which cells produce y-globulin?

B lymphocytes and plasma cells

what are the functions of albumin?

maintains oncotic pressure and transports many substances

what is the function of fibrinogen?

forms fibrin during blood clotting

what is the function of prothrombin?

it is involved in clotting

what is the function of α and β globulins?

adaptive immunity; it includes antibodies

what are RBC’s also called?

Erythrocytes

what is the shape of RBC’s?

biconcave discs

why are RBC’s biconcave?

to squeeze through small capillaries without rupturing

which major organelles do RBC’s lack?

a nucleus, mitochondria, and other major organelles.

what is the most important content of RBCs?

hemoglobin

what is the normal RBC count in adult males

about 5-5.5 million/mm³

what is the normal RBC count in adult females?

about 4.5-5 million/mm³

why is the RBC count higher in adult males?

due to androgens

when is RBC count higher than normal?

in newborns and at high altitudes due to hypoxia (lack of oxygen)

what is the RBC count in old age?

lower

what is the lifespan of an RBC?

about 120 days

what is hemoglobin?

the red oxygen-carrying pigment of RBCs

what is the normal Hb range in adults males?

about 14-18 g/dL

what is the normal Hb range in adult females?

about 12-16 g/dL

what is the normal Hb level in neonates?

about 19g/dL or more

what are the functions of hemoglobin?

O₂ transport, contribution to CO₂ transport, and intracellular H⁺ buffering

what is erythropoiesis?

the process of formation of new RBCs

where does erythropoiesis begin in the fetus?

the yolk sac

where does fetal erythropoiesis occur after the yolk sac?

mainly the liver, with contribution from the spleen, then bone marrow

where does erythropoiesis occur after birth?

bone marrow

where does erythropoiesis occur in adults?

axial skeleton bone marrow and proximal humeri and femora

which bones of the axial skeleton are involved in adult erythropoiesis?

vertebrae, sternum, ribs and pelvis

what hormone mainly stimulates RBC production?

erythropoietin (EPO)

where is EPO mainly produced?

the kidney

which organ contributes a smaller amount of EPO?

liver

what is the main stimulus for EPO production?

hypoxia, or decreased O₂ supply to tissues

why does hypoxia increase RBC production?

less oxygen = more EPO and more erythropoiesis

which dietary factors are needed for erythropoiesis?

iron, vitamin B12. folate and proteins

what other hormones support erythropoiesis?

androgens and thyroid hormones

how do androgens and thyroid hormones support erythropoiesis?

by enhancing EPO action and bone marrow activity

what is anemia?

Hb concentration is below the appropriate reference for age and sex

how is anemia classified?

by RBC size and Hb content

what are the 3 types of anemia?

microcytic hypochromic, normocytic normochromic, and macrocytic

what is an example of microcytic hypochromic anemia?

iron deficiency

what is an example of normocytic normochromic anemia?

acute blood loss

what can cause macrocytic anemia?

vitamin B12 or folate deficiency

what does microcytic mean?

RBCs are smaller than normal

what does hypochromic mean?

RBC Hb content is less than normal

what does macrocytic mean?

RBCs are larger than normal

what is polycythemia?

an increased number of RBCs

what are the 2 types of polycythemia?

primary polycythemia (vera) and secondary polycythemia

what is the primary polycythemia (vera)?

a bone marrow disorder causing excessive RBC production

what causes secondary polycythemia?

hypoxemia and high altitude

what is the mechanism of secondary polycythemia at high altitude?

Hypoxemia = more EPO = more RBCs

what is the normal WBC count?

about 4,000-11,000/mm³

what is the main function of WBCs?

immunity and defense

what is leukocytosis?

when WBC count >11,000/mm³

what are the causes of leukocytosis?

infection and leukemia

what is leukopenia?

when WBC count <4,000/mm³

what are the causes of leukopenia?

viral infections and bone marrow suppression

what are platelets also called?

thrombocytes

what is the structure of platelets?

small, non-nucleated, granulated bodies

what is the normal platelet count?

150,000-450,000/mm³

what is the main function of platelets?

primary hemostasis and platelet plug formation

what are the steps of platelet primary hemostasis?

adhesion, activation, aggregation and platelet plug formation

how do platelets support coagulation?

they provide a surface for coagulation reactions

what is thrombocytosis?

platelet count >450,000/mm³

what are the causes of thrombocytosis?

inflammation, infection, iron deficiency, and blood loss

how do inflammation, infection, iron deficiency and blood loss cause thrombocytosis?

they stimulate bone marrow to produce platelets

what is thrombocytopenia?

platelet count<150,000/mm³

what are causes of thrombocytopenia?

bone marrow depression, drugs and viral infection

what is an example of bone marrow depression causing thrombocytopenia?

irradiation