The Circulatory system is a "closed circulation” Pulmonary Circuit Systemic Circuit Systemic Circuit.
Post on 13-Dec-2015
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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)
• Albumins– 60% of plasma proteins (forms lipoproteins).
Proteins in Plasma
• 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.
Lacks: nuclei, ribosomes,
and mitochondria.
Hematocrit = % of blood occupied by cellular components.
(packed RBC volume)
Life span = ~120 days
Anaerobic metabolism
(glycolysis)
Scanning Electron Micrograph (SEM)
of Erythrocytes or Red Blood Cells (RBCs)
on the tip of a hypodermic needle.
Normal Red Blood Cells
Sickle Cells
- Sickle Cell Anemia
Anemia – reduction in O2
carrying capacity of blood.
Anemia• Hemolytic anemia
– Sickle cell anemia
• Inadequate erythropoiesis – Inadequate nutrition (e.g., iron deficiency)
• Hemorrhagic anemia – Hemophilia, trauma, ruptured aneurysm
• 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.
White Blood Cells
• Monocytes
– Migrate into tissues and differentiate into Macrophages - highly mobile phagocytes.
• Lymphocytes primary cell of lymphatic system
• T-cells attack foreign cells directly.
• B-cells produce antibodies.
• Platelet cells (Thrombocytes)
– Fragments of cells (Megakaryocytes) for clotting.
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):
2) Viscosity of fluid (blood):
3) Diameter (radius) of tube (vessel):
length = Resistance
viscosity
= Resistance
radius
= Resistance
3 Types of Capillary Beds
1. Continuous Capillary Bed
- have tight junctions
- ‘leaky’ capillaries
- most common type in the body.
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.
- least common in body: e.g., liver and spleen.
- highly convoluted (twisting).
- high degree of exchange.
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