Cardiovascular System
Structure, Function & Response to
Acute & Long Term Exercise
Cardiovascular System
- Referred to as the Circulatory System
- Consist of Heart, Blood Vessels & Blood
- Major transport system which carries food &
oxygen to body tissues
- Carbon Dioxide is carried from cells to the
lungs
Basic Structure
Located on the left hand side of the chest beneath
the sternum
Weighs approx. 255 grams and is the size of a
closed fist
Basic function is a hollow muscular pump that
drives blood into and through arteries in order to
deliver to the workings muscles and tissues in the
body
Basic Structure
- Heart is surrounded by a two layered sac known as the pericardium
- The cavity between the layers is filled with pericardial fluid, the
purpose is to prevent friction when the heart beats
- The heart is made of three layers
Epicardium – Outer Layer
Myocardium – Strong Middle Layer
Endocardium – Inner Layer
The septum is the wall that separates the left from the right. This
prevents blood from the right coming into contact with the left
Pathway of Blood
-The heart can be thought of as two pumps, the two
chambers on the right and the left function separately
-The chambers on the right supply blood at a low
pressure to the lings via the pulmonary arteries,
arterioles and capillaries where gaseous exchange
takes place.
- Carbon dioxide passes through the blood to alveoli of
the lungs and oxygen is taken on board. This blood is
then returned to the left side of the heart via the
capillaries, venules and veins
Pathway of Blood
- When the chambers of the left side are full it contracts
simultaneously with the right, acting as a high pressure
pump
- This supplies oxygenated blood via the arteries,
arterioles and capillaries to the tissues and muscle cells
- Oxygen passes from the blood to the cells and carbon
dioxide (Waste Product) is taken on board
- Blood returns to the right atrium of the heart via the
capillaries, venules and veins04152
Blood Vessels
• As the heart contracts blood flows around the body
• Around 96,000km of arteries, arterioles, capillaries, venules
and veins maintain circulation
• The function of each of these is determined by their
structure and pressure of blood within them
• Blood flowing through the arteries appears bright red, due
to oxygenation. As it moves through the network it drops of
oxygen and picks up carbon dioxide, resulting in blood
appearing in veins as much bluer
Arteries
•
Carry blood away from the heart, and other than the pulmonary artery carry
oxygenated blood
•
Thick muscle walls, and expand when blood is ejected into them
Arterioles
• Thinner walls than arteries
• Control blood distribution
Capillaries
• Form and extensive network
• Smallest of the vessels and are very thin
Veins
• Facilitate return of deoxygenated blood to the
heart
• Branch into smaller vessels called venules
Venuoles
• Branches off the vein and are also linked to
the capillaries
Definitions
Arteries carry oxygenated blood away from the
heart
Veins carry deoxygenated blood back to the
heart
Capillaries connect the veins and arteries
Superior
Vena Cava
Aorta
Pulmonary
Artery
Left Atrium
Pulmonary
Valve
Pulmonary
Veins
Right Atrium
Tricuspid
Valve
Right
Ventricle
Inferior
Vena Cava
Aortic Valve
Left
Ventricle
Bicuspid
Valve
Atria
- Upper chambers of the heart
- Receive blood returning to your heart from either
body or lungs
- Right Atrium receives deoxygenated blood from
superior and inferior vena cava
- The left atrium receives oxygenated blood from
the left and right pulmonary veins
Ventricles
- The pumping chambers of the heart
- Thicker walls than Atria
- Right ventricle pumps blood to the pulmonary
circulation for the lungs
- Left ventricle pumps blood to the systemic
circulation for the body
Bicuspid (Mitral) Valve
- One of the four valves in the heart between
the left atrium and the left ventricle
- It allows blood to flow in one direction only,
from the left atrium to the right ventricle
Tricuspid Valve
- Situated between the right atrium and the
right ventricle
- Allows blood to flow from the right atrium to
the right ventricle
Aortic Valve
- Situated between the left ventricle and the
aorta
- Prevents backflow from the pulmonary aorta
Aorta
- The body's main artery
- It originates in the left ventricle and carries
oxygenated blood to all parts of the body
except the lungs
Superior Vena Cava
- A vein that receives deoxygenated blood from
the upper body to empty into the right atrium
of the heart
Inferior Vena Cava
- A vein that receives deoxygenated blood from
the lower body to empty into the right atrium
of the heart
Pulmonary Vein
- Carries oxygenated blood from the lungs to
the left atrium of the heart
Pulmonary Artery
- Carries deoxygenated blood from the heart
back to the lungs
- it is the only artery that carries deoxygenated
blood
Functions of The CV System
•
•
•
•
•
•
Delivery of Oxygen & Nutrients
Removal of Waste Products
Thermoregulation
Vasodilatation & Vasoconstriction
Function of Blood
Oxygen Transport, Clotting & Fighting
Infection
Delivery of Oxygen & Nutrients
• A key function is to supply oxygen and
nutrients to the tissues of the body via the
bloodstream
Removal of Waste Products
• As well as providing oxygen and nutrients to
all tissues in the body, the circulatory system
carries waste products from the tissues to the
kidneys and the liver returns carbon dioxide
from the tissues to the lungs
Thermoregulation
Increased energy expenditure during exercise
requires adjustments in blood flow that affect
the CV system
The CV system is responsible for the distribution
and redistribution of heat with your body to
maintain thermal balance during exercises
Vasodilatation
During exercise the vascular portion of active
muscles increase through dilation of
arterioles. This is known as vasodilatation
Vasodilatation causes an increase in the
diameter of blood vessels to decrease
resistance to the flow of blood to the area
supplied by the vessels
Vasoconstriction
• Vasoconstriction is the narrowing of the blood vessels
resulting from contraction of the muscular wall of the
vessels, particularly the large arteries and small arterioles.
The process is the opposite of vasodilatation, the widening
of blood vessels. The process is particularly important in
staunching haemorrhage and acute blood loss. When blood
vessels constrict, the flow of blood is restricted or
decreased, thus, retaining body heat or increasing vascular
resistance. As a result, this makes the skin turn paler
because less blood reaches the surface, reducing the
radiation of heat. On a larger level, vasoconstriction is one
mechanism by which the body regulates and maintains
mean arterial pressure
Function of Blood
•
Blood provides the fluid environment for cells and acts as transport
•
Each person has approx 4 – 5 litres of blood
•
Four principles components (Plasma/Red Blood Cells/White Blood Cells/Platelets)
•
Has a function of distribution, regulation and protection
•
Maintains body temperature
•
Life sustaining nutrients are transported from the intestines, and waste products
transported to the kidneys
•
Hormones, medicines & antibodies including white blood cells are all transported
by blood
Oxygen Transport
• As a result of exercise the demand for oxygen
increases
• Blood transports oxygen from the lungs to the
parts of the body that require it
Clotting
• Clotting is enabled by white blood cells
forming solid clots
• A damaged blood vessel wall is covered by a
clot to repair the damaged vessel
Fighting Infection
• Blood contains antibodies and white blood
cells which help defend against viruses and
bacteria