Download The Cardiorespiratory System

The Cardiorespiratory System
Notes adapted from Exercise Science and
Foundations of Human Movement
Components of the Cardiovascular
System
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Heart – size of closed fist
Blood – RBC, WBC, plasma
Blood vessels – arteries, veins, capillaries
Lungs
The Primary Roles of the Cardiovascular System
1. To transport oxygen from the lungs to the tissues and to
transport carbon dioxide from the tissues to the lungs
2. To transport nutrients from the digestive system to other
areas in the body and transport waste products from sites of
production to sites of excretion.
3. Maintain body temperature (thermoregulation)
4. Prevent infections (immune system)
The Heart’s Linings
• Myocardium  is term used
to describe cardiac tissue
• Pericardium  sac filled with
fluid to reduce friction
• Epicardium  outer lining of
heart that lies against
pericardium
• Endocardium  lines the
inside of the heart
The Heart
Structure
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comprised of cardiac muscle that serves to pump blood
through the human body.
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consists of four chambers:
- two ventricles (left and right)  pump blood through the
body,
- two atria (left and right)  receive blood from peripheral
organs and pump blood into the ventricles
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Left ventricle  pumps blood through the entire body (are
larger and with stronger muscle walls than the right ventricles)
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Right ventricle  pumps blood a short distance to the lungs
Chambers of the Heart
• Two Atria
– Right atrium gets deoxygenated blood
from the superior and inferior vena cava
– Left atrium gets oxygenated blood from
pulmonary veins
• Two Ventricles
– Left has thicker wall and pumps to the
body
– Right pumps blood to lungs to get
oxygenated
– Separated by interventricular septum
The Four Valves of the Heart
• Valves prevent the backflow of blood.
• Atrioventricular valves (gateway to
ventricles)
– Right = tricuspid
– Left = bicuspid/mitral
– Valves attach to special muscular
extensions of ventricle walls –
PAPILLARY MUSCLE – by strands
of strong specialized tissue called
CHORDAE TENDINAE
• Semilunar valves (gateway to lungs
and aorta)
– Pulmonary and aortic
Structures of the Heart
Right Side
• Superior and inferior vena
cava
• Right atrium
• Right ventricle
• Pulmonary artery
• Tricuspid valve
• Pulmonary valve
Left Side
• Aorta and thoracic
(descending) aorta
• Left atrium
• Left ventricle
• Pulmonary vein
• Bicuspid (mitral) valve
• Aortic valve
Common structures of both: chordae tendinae, papillary muscles, and the interventricular
septum
Internal Structures of the Heart
The Heart
Pathway of blood flow:
Inferior vena cava
Superior vena cava
RIGHT ATRIUM
Tricuspid valve
RIGHT VENTRICLE
Veins
Pulmonary semilunar valve
Pulmonary arteries
Capillaries
Lungs
Pulmonary veins
Arteries
LEFT ATRIUM
Bicuspid valve
LEFT VENTRICLE
Aortic semilunar valve
Aorta
Deoxygenated
Oxygenated
The Heart
Function
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The heart contracts in a constant rhythm that may speed up or slow
down depending on the need for blood (and oxygen) in the body.
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The beating of the heart is governed by an automatic electrical impulse
generated by the sinus node (sinoatrial node)
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The sinus node is a small bundle of nerve fibers that are found in the
wall of the right atrium
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The sinus node generates an electrical charge called an action
potential. The action potential causes the muscle walls of the heart to
contract. This action potential travels through the two atria and the two
ventricles via the a-v node and the Purkinje fibres.
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The atria contract before the ventricles contract, which allows for the
blood to be quickly pumped into the ventricles from the atria
Excitation of the Heart
• The heart conduction system includes:
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Sinoatrial (SA) node
Internodal pathways
Atrioventricular (AV) node
Bundle of HIS
Right and left bundle branches
Purkinje fibres
Electrical Conduction System of the Heart
The Heart
Blood Pressure
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This is an important measure of cardiac function.
There are two components to the measure of blood
pressure:
1. Diastole - It is used to describe the pressure in the heart
when the ventricles are relaxed and are being filled with
blood. Indicator of peripheral blood pressure (the blood
pressure in the body outside the heart).
2. Systole - It is the pressure in the ventricles when they are
contracting and pushing blood out into the body.
FYI: The normal range of pressure in the atria during diastole is
about 80 mmHg, and during systole is about 120 mmHg.
Systole and Diastole
• Cardiac cycle  the series of
events that occur through one
heart beat
– Systole when ventricles
contract (heart empties)
– Diastole when ventricles relax
(heart fills)
• Heart sounds heard through a
stethoscope
– Lub - closing of the
atrioventricular valves
– Dup - closing of the semilunar
valves
The Finely Tuned Cardiac Cycle
(a) As the heart relaxes in diastole, both
atria simultaneously fill with blood.
(c) As the ventricle compartments
fill with blood, they contract, thereby
ejecting blood to the lungs and body.
(b) The mitral (bicuspid) and tricuspid valves
open, and the atria, squeezing into systole,
force blood into the ventricles.
(d) The atria again relax and refill
with blood.
Electrocardiogram
Coronary Circulation
• Right and left coronary arteries nourish the myocardium
• Left and right cardiac veins remove waste from the
myocardium
The Vascular System
Venules and Veins
– Carries blood towards the heart
– Usually carries deoxygenated
blood except for the pulmonary
vein
– Major properties
• limited contractibility and
elasticity
• One-way valves (varicose
veins)
Arteries and Arterioles
– Carries blood away from the
heart
– Usually carries oxygenated blood
except for the pulmonary artery
– Thick smooth muscle wall
– Major properties
• Contractibility
• Elasticity
Capillaries
The Vascular System
– Permit exchange of nutrients and gases; walls are one cell thick
– Capillaries connect arterioles and venules
Skeletal Muscle Pump
Bringing Blood Back to the Heart
• Three main ways:
– Thoracic pump
– Venoconstriction
– Skeletal muscle pump
• muscle contraction
• one-way valves
Properties of Blood
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Erythrocytes - Red blood cells
Leukocytes - White blood cells
Plasma
Thrombocytes - Platelets
Color (hemoglobin)
– Arterial (red blood)
– Venous (blue blood)
• Volume
The Role of Erythrocytes
(Red Blood Cells)
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Carry oxygen
Carry carbon dioxide
Carry nutrients
Remove waste
Characteristics of Erythrocytes
(Red Blood Cells - RBC)
• Made in bone marrow
• Hemoglobin is a specialized protein located on the
RBC
• Transport nutrients and waste
Characteristics of Leukocytes
(White Blood Cells)
• Destroy foreign elements
• Critical in the function of the immune system
• Help in the healing of bone and multiple other cellular activity
Characteristics of Plasma
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Fluid component of blood
Transport medium
mostly water
Makes up 55 percent of blood
Other dissolved substances in plasma
– Gases
– Nutrients (protein)
– Ions (electrolytes)