Download The Circulatory System

The Circulatory System
Functions of the Circulatory System
• Stabilizes body temperature and pH to
maintain homeostasis
• An organ system which distributes blood
throughout the entire body
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Transports oxygen to body cells
Transports CO2 away from cells
Transportation of hormones
Transportation of immune system components
Contains 3 Major Parts
• The Heart
• Blood Vessels
• Blood
The Heart
The Heart as a Double Pump
• The heart is a double
pump, simultaneously
pumping blood to and
from body cells
through the systemic
circulation and to and
from the lungs in the
pulmonary circulation
Parts of the Heart
• The atria
– Receiving chambers
• The ventricles
– Pumping chambers
• Valves: two atrioventricular and
two semilunar valves
– Control one-way flow
• The interventricular septum
– Separates right and left ventricles
Blood Vessels
Types of Blood Vessels
• Arteries
– Carry blood away from the heart
– Aorta is the largest artery
• Veins
– Carry blood to the heart
– Contain valves
– Vena cava is the largest vein
• Capillaries
– Site of exchange of nutrients, wastes, and gases
between blood and interstitial fluid (fluid surrounding
tissue cells)
Walls of Arteries and Veins
• Tunica externa
– Outermost layer
– Composed of mainly elastic and collagen
fibers
– Strengthens, Anchors
• Tunica media
– Middle layer
– Composed of elastic and
smooth muscle fibers
– Circular Smooth Muscle
– Vaso-constriction/dilation
• Tunica interna
– Innermost layer
– Endothelium
– Minimize friction
• Lumen
Blood
Functions of the Blood
• Carries oxygen from the lungs to all of the cells in
the body
• Carries carbon dioxide from the body cells to the
lungs to be exhaled
• Carries waste to the kidneys to be disposed of
• Carries nutrients to body cells
• Contains immune system cells and molecules that
help fight infection
Components of Blood
• Plasma
– Comprise 55% of
whole blood volume
• Formed Elements
– Comprise 45% of
whole blood volume
Plasma
• 91% water
• Contains dissolved proteins,
glucose, clotting factors,
mineral ions, hormones and
carbon dioxide
Formed Elements
• Red Blood Cells (Erythrocytes or RBCs)
– Contain a large molecule called hemoglobin used to
transport oxygen and carbon dioxide
• White blood cells (Leukocytes or WBCs)
– Cells of the immune system defending the body against
both infectious disease and foreign materials
• Platelets (Thrombocytes)
– Special cell fragments that protect the body by forming
a platelet plug to stop bleeding by ruptured vessels
– Secrete chemicals that aid in blood clotting