Transcript Circulatory system

Circulatory System Consists of…
• Blood
Vessels
• Blood
• Heart
What are the 3 types of circulation?
• System – between heart to body systems
• Pulmonary – between heart & lungs
• Coronary – between heart & heartS
Two Pathways
• Pulmonary Circulation
– Carries blood to lungs and back
• Systemic Circulation
– Carries blood to body and back
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,
the hearts own
blood supply
The heart has four chambers
now lets look inside the heart
How does the Heart work?
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 cycle then repeats itself.
Coronary Circulation
 Blood in the heart chambers does not
nourish the myocardium
 The heart has its own nourishing
circulatory system
 Coronary arteries
 Cardiac veins
 Blood empties into the right atrium via the
coronary sinus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
What is coronary circulation?
• The flow of blood to and from the tissues
of the heart
• When the coronary circulation is blocked,
oxygen and nutrients cannot reach all the
cells of the heart. This can cause a heart
attack
Trace the pathway of blood
from heart to lungs and back.
A. Blood, high in
carbon dioxide
and low in oxygen,
returns from the
body to the
heart. It enters
the right atrium
through the
superior and
inferior vena
cava.
Trace the pathway of blood
from heart to lungs and back.
B. The right atrium
contracts, forcing the
blood into the right
ventricle. When the right
ventricle contracts, the
blood leaves the heart
and goes through the
pulmonary artery to the
lungs. The pulmonary
arteries are the only
arteries that carry blood
that is high in carbon
dioxide
Trace the pathway of blood
from heart to lungs and back.
C. Oxygen-rich blood
travels from the
lungs through the
pulmonary vein and
into the left atrium.
The pulmonary veins
are the only veins
that carry oxygenrich blood.
Trace the pathway of blood
from heart to lungs and back.
D. The left atrium
contracts and forces
the blood into the
left ventricle. The
left ventricle
contracts, forcing
the blood out of the
heart and into the
aorta.
There are 3 types of
blood vessels
a.
ARTERY
b.
VEIN
c.
CAPILLARY
Arteries:
carries blood Away from heart
–
–
–
–
Large
Thick-walled, Muscular
Elastic
Oxygenated blood
•
Exception Pulmonary Artery
– Carried under great pressure
– Steady pulsating
Arterioles: smaller vessels, enter tissue
The ARTERY
Arteries carry blood away from the heart.
the elastic fibres allow
the artery to stretch
under pressure
thick muscle and
elastic fibres
the thick muscle can
contract to push the
blood along.
•
Arteries: Built for high pressure
pump
Arteries
– thicker walls
• provide strength for high pressure
pumping of blood
– narrower diameter
– elasticity
• elastic recoil helps
maintain blood
pressure even
when heart relaxes
The VEIN
Veins carry blood towards from the heart.
veins have valves
which act to stop the
blood from going in
the wrong direction.
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 vessel.
Veins: Built for low pressure
flow
Blood flows
• Veins
– thinner-walled
– wider diameter
toward heart
Open valve
• blood travels back to heart
at low velocity & pressure
• lower pressure
– distant from heart
– blood must flow by skeletal muscle contractions
when we move
Closed valve
» squeeze blood through veins
– valves
• in larger veins one-way valves
allow blood to flow only toward heart
Veins:
Carries blood to heart
–
Carries blood that contains
waste and CO2
•
–
–
Exception pulmonary vein
Blood not under much
pressure
Valves to prevent much
gravity pull
Venules: larger than capillaries
The CAPILLARY
Capillaries link Arteries with Veins
they exchange materials
between the blood and
other body cells.
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.
Capillaries
–
–
–
–
Smallest vessel
Microscopic
Walls one cell thick
Nutrients and gases diffuse here
Capillaries: Built for exchange
• Capillaries
– very thin walls
• lack 2 outer wall layers
• only endothelium
– enhances exchange
across capillary
– diffusion
• exchange between blood
& cells
The CAPILLARY
A collection of capillaries is known as a capillary bed.
artery
body cell
vein
capillaries
Blood Pressure
 Measurements by health professionals
are made on the pressure in large
arteries
 Systolic – pressure at the peak of
ventricular contraction
 Diastolic – pressure when ventricles relax
 Pressure in blood vessels decreases as
the distance away from the heart
increases
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
Cardiac cycle
• 1 complete sequence of pumping
– heart contracts & pumps
– heart relaxes & chambers fill
– contraction phase
• systole
• ventricles pumps blood out
– relaxation phase
• diastole
• atria refill with blood
systolic
________
diastolic
pump
(peak pressure)
_________________
fill (minimum pressure)
110
____
70
Congestive Heart Failure (CHF)
• Decline in pumping efficiency of heart
• Inadequate circulation
• Progressive, also coronary atherosclerosis, high
blood pressure and history of multiple
Myocardial Infarctions
• Left side fails = pulmonary congestion and
suffocation
• Right side fails = peripheral congestion and
edema
Stephen Taylor
http://sciencevideos.wordpress.com