Chapter 19 The blood Flashcards
Hematology
the study of blood, blood-forming tissues, tissues that make the blood, diseases of blood and treatment of diseases
Blood
a connective tissue with “cells” suspended in plasma
3 General functions of blood
- transport
- regulation of various body parameters
- protection
Blood transport various substances to tissue cells
- from capillary blood to interstitial fluid then across cell plasma membranes into cytosol
- substances include oxygen, nutrients, hormones and regulatory factors, electrocytes, etc.
Blood transport substances from the body’s cells
- substances include secretory products, glucose, cellular waste products
Blood Function: pH regulation
achieved by buffers (ex phosphate and carbonic acid/bicarbonate buffers and plasma proteins)
Blood Function: thermoregulation
Vasoconstriction of dermal blood vessels: decreases loss of body heat
Vasodilation of dermal blood vessels: increases loss of body heat
Blood Function: regulation of osmotic pressure
- osmotic pressure exerted by blood and interstitial fluid determine by salt and protein content
- blood colloidal osmotic pressure due to relative amounts of protein in plasma and interstitial fluid
Blood Function: protection
- blood contains WBCs and proteins which protect the body against foreign cells and particles, cancer cells, and toxins
- hemostasis: protection from exsanguination (bleeding to death) caused by severe traumatic injury
Physical Characteristics of Blood
- avg adult male: about 5-6 liters of blood
- avg adult female: about 4-5 liters of blood
- blood temperature at core = about 37.6 C
- normal blood pH range = 7.35-7.45
Components of blood
- centrifuged whole anticoagulated blood separates into 2 layers: blood plasma and formed elements
Blood plasma
- upper layer
- ECF found within blood vessels
- 92% water, 55% of whole blood volume
- contains nutrients, wastes, electrocytes, buffers, gases, hormones, enzymes and other plasma proteins
- plasma constituents maintain osmotic pressure
Plasma proteins in the blood plasma contain:
- albumins (54%)
- globulins (38%)
- fibrinogen (7%)
- other protein types (>1%)
albumins (54%) of plasma protein
- main colloidal osmotic protein
- function as transport proteins
- made by the liver
globulins (38%) of plasma protein
alpha and beta globins - transport proteins that carry fats, fat-soluble vitamins, and iron (transferrin) - made by the liver gamma globins - mostly antibodies - made by B-lymphocytes and plasma cells - not made by the liver
fibrinogen (7%) of plasma protein
- part of the blood clotting proteins that also include clotting factors VII, IX, and X
- fibrinogen converted to fibrin that forms blood clot meshwork
Formed Elements
- lower layer
- about 45% of whole blood volume
Formed Elements of blood are:
- RBCs = erythrocytes, >99%
- WBCs = leukocytes, true cells
- Platelets = thrombocytes, involved in clotting
Buffy coat
a thin film of WBCs and platelets on the surface of packed RBCs that appear on the hematocrit
Hematocrit
- % of whole blood that is RBCs
- adult Hct > 60% = polycythemia, increased blood viscosity
- adult Hct < 30% = severe anemia
Hemopoiesis
continuous process by which blood cells are formed
fetal hemopoiesis
sites include liver, thymus, spleen and lymph nodes, and eventually red bone marrow
adult hemopoiesis
red bone marrow is the only site
pluripotent stem cells
red bone marrow contains pluripotent stem cells that produce different cell types
