Blood

Characteristics of Blood

Connective tissue Plasma and cells Transports

substances between body cells and the external environment

Blood Volumes

Varies with body size (type), fluid and electrolyte concentrations, and amount of adipose (fat)

Average adult volume – 5 liters (4-5 L for women, 5-6 L for men)

Hematocrit – usually 45%

Blood Cell Types

Erythrocytes – Red blood cells

Leukocytes – White blood cells

Thrombocytes - platelets

Red Blood Cells (RBCs)

Biconcave disks that thin near the centers increased surface

area for transporting gases

Have nuclei early in development, but extrude them

No nucleus – more room for hemoglobin, but cannot reproduce or make proteins

Hemoglobin

Oxygen-carrying protein

1/3 of each RBC Gives blood its color Oxyhemoglobin Deoxyhemoglobin Hypoxia Cyanosis

Red Blood Cell Counts

RBCC – the number of RBCs in 1 mm3 of blood

Adult male average – 4.6 – 6.2 million

Adult female average – 4.2 – 5.4 million

Determines blood’s oxygen carrying capacity

Important diagnostic tool

Blood Cell Production RBCs are normally

flexible, elastic, and able to pass through small blood vessels

More fragile as they age

Macrophages phagocytize and destroy damaged RBCs in the liver and spleen in about 120 days

White Blood Cells (WBCs) Function to protect

against disease Phagocytize bacterial cells Produce antibodies

Move by diapedesis 2 main types:

Granulocytes – neutrophils, eosinophils, and basophils

Agranulocytes – monocytes and lymphocytes

Granulocytes - Neutrophils

Lobed nucleus with 2-5 sections

Dark staining nucleus and pale granules

54-62% of WBCs Contain many

lysosomes – actively phagocytizes bacteria

Granulocytes - Eosinophil

Contains coarse, uniformly sized granules

2 lobes on nucleus Stains red 1-3% of WBCs Kills parasites Helps control

inflammation and allergic reactions

Granulocyte - Basophils

Fewer, more irregular granules than eosinophils

Granules stain deep blue Less than 1% of WBCs Contain heparin (inhibits

blood clotting) and histamine (increases blood flow to injured tissues)

Agranulocytes - Monocytes

Largest blood cells May live weeks to

months 3-9% of WBCs Change to

macrophages in tissue

Agranulocyte - Lymphocytes

Form in red bone marrow and lymphatic system

Slightly larger than RBCs Large, round nucleus with

rim of cytoplasm May live for years 25-33% of WBCs Important for immune

response

White Blood Cell Count (WBCC)

Number of WBCs in 1 mm3 of blood

Adult average – 5000 – 10,000 cells

Leukocytosis – high count

Leukopenia – low count Differential WBCC (DIFF)

More neutrophils – bacterial infection

More eosinophils – parasitic infection, allergic reaction

Leukemia

Platelets Not complete cells Form from

megakaryocytes that fragment

Lack nuclei Half size of RBCs Live 10 days Average count –

300,000/mm3

Help close breaks in damaged blood vessels

Initiate formation of blood clots

Plasma

92% water Functions include:

Transporting nutrients, gases, and vitamins

Regulating fluid and electrolyte balance

Maintaining pH

Hemostasis

Step 1: Vascular spasms

Step 2: Platelet plug formation

Step 3: Coagulation Step 4: Fibroblasts

invade clot Process takes 3-6

minutes

Hemostasis

Normally clots are good, but an embolism is a clot that dislodges and travels elsewhere in the body. This can result in a coronary (heart) or a stroke (brain).

Blood Disorders

Normally clots are good, but an embolism is a clot that dislodges and travels elsewhere in the body. This can result in a coronary (heart) or a stroke (brain).

A brain (cerebral) aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain. In most cases, a brain aneurysm causes no symptoms and goes unnoticed. In rare cases, the brain aneurysm ruptures, releasing blood into the skull and causing a stroke.

Blood Groups

ABO blood group is based on the presence or absence of 2 major antigens (RBC surface molecules)

4 possible combinations: A B AB O

video

Rh Blood Group

85% people are Rh+

Rhesus (Rh) factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you're Rh positive. If your blood lacks the protein, you're Rh negative.