Transcript Circulatory system - PA

What is the circulatory system?

The circulatory system carries blood and dissolved
substances to and from different places in the body.

The Heart has the job of pumping these things around
the body.

The Heart pumps blood and substances around the
body in tubes called blood vessels.
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The Heart and blood vessels together make up the
Circulatory System.
Our circulatory system is a double circulatory system.
This means it has two parts parts.
Lungs
the right side of
the left side of
the system
the system
deals with
deals with
oxygenated
deoxygenated
blood.
blood.
Body cells
Two circulatory paths
Systemic
Pulmonary
The double pump
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
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
II.Circulatory System Components
• Heart - divided into four chambers
– right atrium, right ventricle, left atrium,
left ventricle
Heart Chambers and Valves
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.
Right Heart Chambers: Pulmonary Circuit
• Right Atrium (forms
most of posterior of
heart)
– Receives O2-poor
blood from body via
IVC, SVC,
• Right Ventricle
– Receives O2-poor
blood from right atrium
through tricuspid valve
– Pumps blood to lungs
via Pulmonary
Semilunar Valve in
pulmonary trunk
Left Heart Chambers: Systemic Circuit
• Left Atrium
– Receives O2-rich blood
from 4 Pulmonary
Veins
• Left Ventricle (forms
apex of heart)
– Receives blood from
Left Atrium via bicuspid
valve
– Pumps blood into aorta
via Aortic Semilunar
Valve to body
Heart Valves: Lub*-Dub**
•
•
•
*Tricuspid Valve: Right AV valve
– 3 Cusps (flaps) made of
endocardium and CT
– Flow of blood pushes cusps open
– When ventricle in diastole (relaxed),
cusps hang limp in ventricle
– Ventricular contraction increases
pressure and forces cusps closed
*Bicuspid (Mitral) Valve: Left AV
valve
– 2 cusps anchored in Lft. Ventricle
by chordae tendinae
– Functions same as Rt. AV valve
**Semilunar valves: prevents backflow
in large arteries
– Pulmonary Semilunar Valve: Rt
Ventricle and Pulmonary Trunk
– Aortic Semilunar Valve: Left
Ventricle and Aorta
blood from the heart gets around
the body through blood vessels
There are 3 types of blood vessels
a.
ARTERY
b.
VEIN
c.
CAPILLARY
• Three types of blood vessels
– arteries carry blood away
• thicker walls to withstand the pressure of blood
being pumped from heart
– veins - toward heart
• lower pressure
• one-way valves to prevent blood from flowing
backwards away from heart
– capillaries
• tiny links b/w arteries and veins where oxygen
and nutrients diffuse to body tissues
• smallest of blood vessels, are only visible by
microscope ten capillaries lying side by side are
barely as thick as a human hair.
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.
The VEIN
Veins carry blood towards 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.
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.
• Arteries, veins, and capillaries - divided
into two systems:
– Systemic - carries oxygenated blood from
heart to all tissues in body except lungs and
returns deoxygenated blood carrying waste
products, such as carbon dioxide, back to
heart.
• oxygen-rich blood ejected under high pressure out of
heart's main pumping chamber (L. ventricle) through
largest artery (aorta)
• smaller arteries branch off from aorta to various parts of
the body
• smaller arteries in turn branch out into even smaller
arteries (arterioles)
• arterioles become progressively smaller eventually
forming capillaries - blood pressure is greatly reduced
•
interstitial fluid fills the gaps between the cells of
tissues or organs
– dissolved oxygen and nutrients then enter the cells
from interstitial fluid by diffusion
– carbon dioxide and other wastes leave the cell via
interstitial fluid, cross capillary walls, and enter
blood.
•
after delivering oxygen to tissues and absorbing
wastes, deoxygenated blood in capillaries then
starts the return trip to heart
• capillaries merge to form tiny veins, called
venules
• venules join together to form progressively larger
veins
• veins converge into two large veins:
– inferior vena cava-brings blood from the lower half of
body
– superior vena cava-brings blood from upper half
– Both join at the right atrium of heart
FYI
– Varicose Veins
• pressure is dissipated in arterioles and capillaries
• blood in veins flows back to heart at very low
pressure, often running uphill when a person is
standing
• Flow against gravity allowed by one-way valves
– several centimeters apart in veins
• Veins with defective valves (allow the blood to
flow backward) become enlarged or dilated to
form varicose veins
Varicose
veins
– Pulmonary Circulation
• deoxygenated blood returning from organs and
tissues travel from R. atrium to R. ventricle.
• pushed through pulmonary artery to lung
• pulmonary artery divides forming pulmonary capillary
region
• microscopic vessels pass adjacent to alveoli (air sacs)
- gases are exchanged across thin membrane
• oxygen crosses membrane into blood while carbon
dioxide leaves blood through same membrane
• newly oxygenated blood then flows into pulmonary
veins and is collected by L. atrium of the heart
(collecting pool for L.ventricle)
• contraction of L. ventricle sends blood into aorta
completing circulatory loop
SUP. VENA CAVA
AORTIC ARCH
L. LUNG
PUL. ARTERY
R. LUNG
HEART
INF. VENA CAVA
PUL. VEINS
AORTA
Artery/Vein differences
Arteries (aa.)
Direction Blood Away from
of flow
Heart
Pressure Higher
Veins (vv.)
Blood to Heart
Walls
Lumen
THICKER: Tunica
media thicker than
tunica externa
Smaller
THINNER: Tunica
externa thicker
than tunica media
Larger
Valves
No valves
Valves (see next)
Lower
what’s in
digested food
red blood cells
white blood cells
oxygen
waste (urea)
platelets
carbon dioxide
plasma
hormones
The Blood
red blood cell
platelets
white blood cell
plasma
Red Blood Cells
a biconcave disc that is
round and flat without a
nucleus
contain haemoglobin, a
molecule specially designed
to hold oxygen and carry it
to cells that need it.
can change shape to an
amazing extent, without
breaking, as it squeezes
single file through the
capillaries.
White Blood Cells
`
there are many different types and
all contain a big nucleus.
the two main ones are the
lymphocytes and the macrophages.
macrophages ‘eat’ and digest microorganisms .
some lymphocytes fight disease by making antibodies to destroy
invaders by dissolving them.
other lymphocytes make antitoxins to break down poisons.
Platelets
Platelets are bits of cell
broken off larger cells.
Platelets produce
tiny fibrinogen
fibres to form a net.
This net traps other
blood cells to form a
blood clot.
Plasma
It also contains useful
things like;
• carbon dioxide
A strawcoloured
liquid that
carries the
cells and the
platelets
which help
blood clot.
• glucose
• amino acids
• proteins
• minerals
• vitamins
• hormones
• waste materials
like urea.
Heart Chambers and Valves