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Circulatory system
Premedical
Endothermic way of life require 10x more energy (exothermic).
Cells of body require nutrients, oxygen and exclude carbon
dioxide and wastes.
Cardiovascular system:
• Blood - blood cells and plasma
• Vessels – arteries, veins, capillaries, arterioles, venules,
capillary bed
• Heart – atria and ventricles
Blood pressure
Double circulation : independent body and lung circulatory
system supported by 4 chambered heart of mammals
double circulatory system
lymphatic system
Lungs
the right side of the
the left side of the
system
system
deals with
deals with
deoxygenated
oxygenated
blood.
blood.
Body cells
The Heart
This is a vein. It brings
blood from the body,
except the lungs.
These are arteries.
They carry blood away
from the heart.
2 atria
2 ventricles
Coronary arteries
supply the heart
with blood
first branches
The heart has four chambers
The Heart
artery to lungs
vein from head and body
right atrium
valve
right ventricle
artery to head and body
vein from lungs
left atrium
valve
left ventricle
How does the heart work?
Heartbeat: STEP ONE
blood from the
body
blood from
the lungs
The heart beat begins when the
heart muscles relax and blood
flows into the atria.
How does the heart work?
STEP TWO
The atria then contract and
the valves open to allow blood
into the ventricles.
How does the heart work?
STEP THREE
The valves close to stop blood
flowing backwards.
The ventricles contract forcing
the blood to leave the heart.
At the same time, the atria are
relaxing and once again filling with
blood.
The heartbeat – the cycle repeats itself.
Systole is a phase where the myocardium is contracting
in a coordinated manner in response to an endogenous
electrical stimulus
Diastole is the period of time when the heart fills with
blood after systole.
Cardiac output is the volume of blood being pumped by
the heart, in the time interval of one minute
Puls - frequency of contractions, normal 70 - 75 / minute
Heartbeat - valves close, impact of blood to valves
Heart murmur – defect of valve
Four valves prevent a backward blood flowing.
The AV valve on the right side of the heart is called the
tricuspid valve because it has three leaflets (cusps).
The AV valve on the left side of the heart is called the
bicuspid valve (or mitral valve) because it has two leaflets.
Semiluminar: the pulmonary valve
the aortic valve
Mechanism of heartbeat continuity:
Special cardiomyocytes cells with the ability to
generate the electrical impulses. They have internal
rhythm of contractions.
Pacemaker – Sinoatrial node – right atrium
Atrioventricular bundle - right side
EKG
Blood pressure – hydrostatic pressure
is a force exerted by circulating blood on the walls of blood
vessels. During each heartbeat, BP varies between a
maximum (systolic) and a minimum (diastolic) pressure.
Thoracic cavity
between the lungs and is contained in the
pericardial sac
• Epicardium – outer layer of heart wall
• Endocardium – inner layer that consists of
endothelial cells, which line the heart, covers the
heart valves, and lines the blood vessels.
• Myocardium – middle layer composed of cardiac
muscle.
There are 3 types of blood vessels
a.
ARTERY
b.
VEIN
c.
CAPILLARY
The ARTERY
elastic fibres allow the
artery to maintain a
blood pressure
thick muscle with
elastic fibres
the thick muscle can
contract to push the
blood along.
The VEIN
Veins have valves,
which prevent a
backward blood flow
thin muscle and
elastic fibres
Body muscles surround the veins
so that when they contract to move
the body, they also squeeze the
veins and push the blood along the
vessels.
The CAPILLARY
Basement membrane and
endothel
the wall of a capillary
is only one cell thick
The exchange of materials
between the blood and the
body can only occur through
capillaries.
The CAPILLARY
A collection of capillaries is known as a capillary bed.
artery
vein
capillaries
body cell
The semi-permeable membrane (basement
membrane) of capillary walls allows
nutrients, oxygen, and water
to diffuse from the blood to the tissues.
Waste products, like
carbon dioxide, diffuse from the tissues
into the blood.
Subclavian vein
Superior vena cava
Pulmonary artery
Inferior vena cava
Renal vein
Iliac vein
Femoral vein
Carotid arteries
Subclavian artery
The aorta is
Pulmonary vein
the largest
Aorta
artery in the
body
Renal artery
Iliac artery
Femoral artery
This portion of the systemic circulation is known as
the hepatic portal system.
The gastric vein (stomach), splenic vein (spleen),
pancreatic vein (pancreas), and mesenteric veins
(small intestines) empty into the portal vein that
carries the blood to the liver.
The hepatic vein carries blood to the inferior (caudal)
vena cava.
The lymphatic
system
is part of the immune system and acts as a
secondary (accessory) circulatory
system.
•return water and proteins to blood
• remove excess fluids from body tissues,
• absorb fatty acid and transport fat to circulatory
system, and
• produce immune cells (lymphocytes, monocytes,
and plasma cells).
Flow of Blood & Lymph Within Tissue
As the collecting lymph vessel accumulates lymph from
more and more lymph capillaries in its course, it becomes
larger and is called the
afferent lymph vessel
as
it enters a lymph node. Here the lymph percolates through
the lymph node tissue and is removed by the
efferent
lymph vessel. An efferent lymph vessel may directly
drain into one of the (right or thoracic) lymph ducts
Both
the lymph ducts
return the lymph to the
blood stream by
emptying into the
subclavian veins
Lymph node
Lymph nodes filter foreign substances, such as
bacteria and cancer cells, before it is re-entered into
the blood system through the larger veins.
Lymph nodes act as the body’s first defense against
infection.
Lymph node
has a fibrous outer covering (capsule), a cortex, and a medulla
Photo from U. S. Federal Government courtesy of Wikipedia.
Lymphoid tissue:
spleen, thymus,
bone marrow and the
lymphoid tissue
associated with the
digestive system.
Thank you for your attention
Campbell, Neil A., Reece, Jane
B., Cain Michael L., Jackson,
Robert B., Minorsky, Peter V.,
Biology, Benjamin-Cummings
Publishing Company, 1996 –
2010. chapter 42
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