The Circulatory system is a "closed circulation”

PulmonaryCircuit

SystemicCircuit

SystemicCircuit

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)

• 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.

Millions of Hb inside each RBC

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.

Never

Let

Monkeys

Eat

Bananas

20-30%

50-70%

2-8%

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):

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.

Capillaries

Venule

Ateriole