The Circulatory System
“ A Transport Service”
Circulatory System Consists of…
• Heart
• Blood Vessels
• Blood
HEART: The Vital Pump
On average, the
heart contracts
72 times a
minute, pumping
about 5 quarts
of blood.
Structure and Function
• Keeps blood moving
• Large organ
composed of
– cardiac muscle,
– rich in mitochondria
– Enclosed by a
PERICARDIUM sac
Structure of Heart (cont)
• Four chambers :
– Two upper (Atria)
– Two lower (Ventricles)
Structures of the Heart
Aorta
Superior Vena Cava
Large vein that brings oxygen-poor blood from the upper
part of the body to the right atrium
Pulmonary
Arteries
Pulmonary Veins
Bring oxygen-rich blood from each of
the lungs to the left atrium
Bring oxygen-poor blood
to the lungs
Left Atrium
Pulmonary Valve
Aortic Valve
Prevents blood from flowing back
into the right ventricle after it has
entered the pulmonary artery
Right Atrium
Prevents blood from flowing back
into the left ventricle after it has
entered the aorta
Mitral Valve
Tricuspid Valve
Left
Prevents blood from flowing back into
Ventricle the left atrium after it has entered the
left ventricle
Prevents blood from flowing back into
the right atrium after it has entered
the right ventricle
Right Ventricle
Inferior Vena Cava
Vein that brings oxygen-poor blood
from the lower part of the body to
the right atrium
Brings oxygen-rich blood from the left
ventricle to the rest of the body
Septum
Blood Flow Through the Heart
©COPY 1997 HeartPoint
Blood Flow Through the Heart
STEP 1
• Both Atria fill at same time
– Right atrium receives oxygen POOR blood from body
through vena cava
– Left atrium receives oxygen RICH blood from lungs
through four pulmonary veins
STEP 2
• After filled with blood atria contract, pushing
blood into ventricles
STEP 3
•Both ventricles contract
Right ventricle contracts and pushes oxygen-poor blood
toward lungs,
-against gravity
-through pulmonary arteries
Left ventricle contracts and forces oxygen rich blood
• out of heart through aorta (largest vessel)
This creates the “lub” sound of the heartbeat.
STEP 4
• As the ventricles relax, the valves snap shut.
This creates the “dub” sound, finishing the heartbeat.
• Blood start filling the atria, and the cycle begins
again.
Heart - as two separate pumps:
• Circulation of blood
between the heart and
the lungsPULMONARY
circulation
• Circulation of blood
between the heart and
the rest of the bodySYSTEMIC circulation
Circulatory System
BLOOD VESSELS
Blood Vessels:
Pathway of Circulation
•
3 types of vessels
– Arteries
– Capillaries
– Veins
Arteries:
carry blood Away from heart
–
–
–
–
Large
Thick-walled, Muscular
Elastic
Oxygenated blood
•
–
–
Exception -Pulmonary
Artery
Carried under great
pressure
Steady pulsating
Capillaries
-
Smallest vessels
–
–
–
Microscopic
Walls one cell thick
Nutrients and gases diffuse here
Endothelium
Capillary
Artery
Arteriole
Venule
Vein
Connective
tissue
Connective
tissue
Smooth
muscle
Endothelium
Smooth
muscle
Endothelium
Valve
Veins:
Carry blood to heart
–
Carry blood that contains
waste and CO2
•
–
–
Exception -pulmonary vein
Blood not under much
pressure
Valves to prevent much
gravity pull
Circulatory System
BLOOD
The Blood
• Body contains 4-6 L
• Consists of
–
–
–
–
Water
Red Blood Cells
Plasma
White blood cells and
platelets
Plasma
Platelets
White blood
cells
Red blood
cells
Whole Blood Sample
Sample Placed in Centrifuge
Blood Sample That
Has Been Centrifuged
Parts of the Blood
Blood: Fluid Transport
Liquid Portion Carries
• Blood cells
– red blood cells
– white blood cells
• Platelets (non cellular particles)
• Proteins
– Enzymes
– Hormones – Endocrine System
• Nutrients - Digestive System
• Gases - Respiratory System
• Inorganic salts
Carbon Dioxide in the Blood
• CO2 is a waste product of
cellular work
• 70% of CO2 combines with
water
• The rest travels to the lungs
RBC
• Transporters of
– Oxygen
– Carbon Dioxide
• RBC
– Lack a nucleus
– Contain hemoglobin
– Disk-shaped
• RBC are produced in red bone
marrow of
–
–
–
–
ribs,
humerus,
femur,
sternum, and other long bones
• Lives for 120 days
• Old RBC are destroyed in liver
and spleen
WBC
•
WBC fight infection
–
•
•
•
Less abundant
Large cells
Some live for
months
–
•
•
Attack foreign
substances
Most just a few days
Several types
ALL contain nuclei
Platelets
•
•
•
•
•
PLATELETS are for CLOTTING blood
Cell fragments
Produced in bone marrow
Short life span (1 week)
Fibrin (sticky network of protein fibers)
– Form a web trapping blood cells
Blood Clotting
Break in Capillary Wall
Clumping of Platelets
Clot Forms
Blood vessels injured.
Platelets clump at the site
and release thromboplastin.
Thromboplastin converts
prothrombin into thrombin..
Thrombin converts
fibrinogen into fibrin, which
causes a clot. The clot
prevents further loss of
blood..
Blood Types
• Massive loss of blood
requires a transfusion
• Four Types
–
–
–
–
A
B
AB
O
• Inherited from your
parents
Blood Pressure
• Blood against the blood vessel’s walls
– The systolic pressure refers to
• the pressure recorded while the ventricles pump
the blood.
– The diastolic pressure refers to
• the pressure recorded as the ventricles fill with
blood.
• A normal blood pressure is 120/80
Disorders (cont)
• Hypertension
– High blood pressure
– Hearts works harder than necessary
– Increases risk of heart attack or stroke
Disorders (cont)
• Heart Attack
– Atherosclerosis in coronary artery
– Heart muscle begins to die
• Symptoms
– Nausea
– Shortness of breath
– Severe chest pain
IMMEDIATE MEDICAL ATTENTION NECESSARY
Disorders (cont)
• Stroke
– Blood clot gets stuck in blood vessels leading
to brain
– Brain cells die due to lack of oxygen
• Or blood vessel burst
– Can lead to paralysis,
• loss of ability to speak
• death
Current PREVENTION
Recommendations
•
•
•
•
•
Regular exercise
Weight control
Well balanced diet
Do not smoke
Diet low in saturated
fat