Cardiovascular system
1
The circulatory system
The function is to
transport O2 and
nutrients to the cells
of the body and to
carry away CO2 and
other wastes.
To do this, the
system must keep
blood constantly
circulating.
2
The circulatory system
All vertebrates have a closed circulatory system where
blood is transported in vessels, separate from the
interstitial fluid.
In an open circulatory system (as in arthropods) fluids
return to the heart through ostia or open vessels.
3
Single-loop
circulation
Fish have a single-loop
circulatory pathway: the heart
has a single atrium and a
single ventricle.
4
Two-circuits
circulation
Amphibians and most
reptiles have a two-circuits
circulatory pathway, with the
heart divided into two atria
and one ventricle.
5
Two-circuits
circulation
Birds and mammals have a
two-circuits circulatory
pathway with the heart
divided into two atria and two
ventricles.
6
The cardiovascular system
A circulatory system consists of a pump (the heart),
a fluid (the blood) and a series of blood vessels
(the vascular system).
All together those elements form the
cardiovascular system.
7
The heart
The heart has four chambers: two atria and two ventricles.
A cardiac septum separates the heart into right and left
halves.
left atrium
right atrium
left ventricle
septum
right ventricle
8
An artery carries blood away from the heart while a vein
takes the blood to the heart. Cardiac valves keep blood
moving in the correct direction.
superior vena cava
pulmonary
artery
pulmonary veins
aorta
atrioventricular
valve
semilunar
valve
inferior vena cava
9
The heartbeat
Electric rhythmic impulse move the heart. The contraction
is called systole, the relaxation of the chambers is diastole.
10
The cardiac conduction system
The heartbeat starts from
the sinoatrial node (SA),
the impulse-generating
(pacemaker) tissue. The
atrioventricular node
(AV) causes the ventricle
contraction.
11
Blood vessels
Arteries
Blood pressure in arteries and arterioles carries blood
away from the heart.
12
Blood vessels
Veins
Skeletal muscle contractions return blood in veins and
venules to the heart.
13
Blood vessels
Capillaries
Thin-walled capillaries permit exchange of materials and
gas with the tissues.
14
Pulmonary and systemic circuits
Cardiovascular systems includes two circuits.
•Pulmonary circuit: pulmonary arteries take O2-poor
blood to lungs while pulmonary veins return O2-rich blood
to the heart.
•Systemic circuit: left ventricles send O2-rich blood to
aorta; vena cava takes O2-poor blood back to the right
atrium.
15
Pulmonary and
systemic circuits
16
Blood pressure
Blood velocity depends on
pressure and on capillaries
area.
Systolic pressure: is the
pressure in arteries during
ventricular systole.
Diastolic pressure: is the
pressure in arteries during
ventricular diastole.
17
Vascular diseases
A stroke (or cerebral ictus) occurs when a small cranial
arteriole bursts or is blocked by an embolus.
A heart attack occurs when a coronary artery (the artery
that brings O2-rich blood to capillaries of the heart) is
completely blocked.
18
Vascular diseases
Healthy life style can help to prevent
vascular diseases:
•refraining from smoking
•no drugs
•controlling weight
•healthy diet
•monitoring cholesterol
•exercising
19
Vascular diseases
Cholesterol is an essential component of cell
membranes and is carried by plasmic proteins (LDL and
HDL). Anomalies in quantities of LDL or HDL can lead to
the formation of cholesterol plaque in blood vessels.
20
Blood functions
• Transports substances to and from capillaries
where exchanges occur.
• Helps the organism defend against pathogens.
• Helps regulate body temperature.
• Forms clots to prevent hemorrhages.
21
Blood composition
Blood is composed of a liquid portion called plasma and
formed elements: red and white blood cells, and platelets.
Clotting
Blood clotting involves platelets that release clotting
factors at the site of the blood vessel damage.
Fibrin threads provide a meshwork for a blood clot.
23
Blood stem cells
Hematopoietic stem cells (HSCs), are multipotent
stem cells, found in the bone marrow of adults, that can
produce all the blood cell types.
HSCs can be easily transplanted from pelvic bone.
24
Capillary exchange
Between the arterial end and the venus end, substances
diffuse according to the concentration gradient:
•CO2 and waste produced by the cells move in;
•C6H12O6, amino acids and O2 spread out.
25
Capillary exchange
Lymphatic capillaries collect excess tissue fluid (called
lymph) and return it to the vascular system.
26
AB0 classification system
RBC membranes carry specific carbohydrates and
proteins that behave as antigens when transplanted in
incompatible organisms. Those antigens are classified as
A and B and determine the type of blood.
RH factor is another important antigen in matching blood types.
27
AB0 classification system
Agglutination: clumping of RBC in the presence of an
antibody that binds multiple antigens and joins the cells.
No agglutination
Agglutination
28
Online resources
http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_ga
teway/living_growing/circulatoryrev1.shtml
http://www.bbc.co.uk/schools/gcsebitesize/science/21c/keeping
_healthy/heartdiseaserev1.shtml (pages 3, 4, 5)
http://www.abpischools.org.uk/page/modules/heartandcirculatio
n/index.cfm?coSiteNavigation_allTopic=1
Animations
http://media.wwnorton.com/college/biology/discoverbio5/full/
28_01/start.html
http://media.wwnorton.com/college/biology/discoverbio5/full/
28_02/start.html
http://media.wwnorton.com/college/biology/discoverbio5/full/
28_03/start.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter21/animatio
n__cytotoxic__type_ii_hypersensitivity_.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter21/animatio
n__hemoglobin_breakdown.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter22/animatio
n__conducting_system_of_the_heart.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter22/animatio
n__the_cardiac_cycle__quiz_1_.html
30