Download 10. Blood

The Circulatory system is a "closed circulation”
Systemic
Circuit
Pulmonary
Circuit
Systemic
Circuit
Blood
Blood = Plasma + Formed (Cellular) Elements
Plasma
• ~ 55% blood volume
• ~ 92% of plasma is water
• High dissolved O2 content
• Dissolved proteins
Cells
• ~ 45% blood volume
• RBCs (~ 99% of cells)
• WBCs (~ 1% of cells)
Proteins in Plasma
• Albumins
– 60% of plasma proteins (forms lipoproteins).
• Globulins
– 35% of plasma proteins – mostly immunoglobulins.
• Fibrinogen
– For clotting reaction, forms fibrin.
* serum = plasma without clotting proteins
Cellular Components
• RBCs (erythrocytes) ~ 99% of all cells.
Hematocrit = % of blood occupied by cellular components.
(packed RBC volume)
Lacks: nuclei, ribosomes,
and mitochondria.
Anaerobic metabolism
(glycolysis)
Life span = ~120 days
Scanning Electron Micrograph (SEM)
of Erythrocytes or Red Blood Cells (RBCs)
on the tip of a hypodermic needle.
Millions of Hb inside each RBC
Normal Red Blood Cells
Anemia – reduction in O2
carrying capacity of blood.
Sickle Cells
- Sickle Cell Anemia
Anemia
• Hemolytic anemia
– Sickle cell anemia
• Hemorrhagic anemia
– Hemophilia, trauma, ruptured aneurysm
• Inadequate erythropoiesis
– Inadequate nutrition (e.g., iron deficiency)
White Blood Cells
• Neutrophils 70% of circulating leukocytes
– Highly mobile phagocytes.
• Eosinophils much less common
– Attracted to foreign compounds reacted with antibodies.
• Basophils relatively rare
– Migrate to damaged tissue, releases histamine.
• Lymphocytes primary cell of lymphatic system
• T-cells attack foreign cells directly.
• B-cells produce antibodies.
• Monocytes
– Migrate into tissues and differentiate into
Macrophages - highly mobile phagocytes.
• Platelet cells (Thrombocytes)
– Fragments of cells (Megakaryocytes) for clotting.
Never
50-70%
Let
20-30%
Monkeys
Eat
2-8%
Bananas
2-4%
< 1%
Blood Vessels
Blood Vessels
MAP
Type of Blood Vessel
Blood flows down a pressure gradient (P)
Highest at the heart
(driving P), decreases
over distance.
Flow  P / R
Resistance Opposes Flow
3 Factors Influence Resistance of fluid flow in Tube:
1) Length of tube (vessel):  length =  Resistance
2) Viscosity of fluid (blood):
 viscosity
=  Resistance
3) Diameter (radius) of tube (vessel):  radius
=  Resistance
3 Types of Capillary Beds
1. Continuous Capillary Bed
- most common type in the body.
- have tight junctions
- ‘leaky’ capillaries
2. Fenestrated Capillary Bed
- have ‘pores’ or fenestrations.
- more ‘leaky’ than continuous.
- specific locations in body:
e.g., kidney and synovial joints.
3. Sinusoidal Capillary Bed
- open ‘flaps’ in adjacent
endothelial cells.
- ‘leakiest’ capillary bed.
- high degree of exchange.
- highly convoluted (twisting).
- least common in body:
e.g., liver and spleen.
Capillaries
Venule
Ateriole