Transcript Circulation - onlinebiosurgery

Objectives:
* Describe one way flow of blood around the body.
** Describe the structure and function of a heart
*** Describe the cardiac cycle
Starter:
1.What components make up the circulatory system?
2. What are the substances carried by this system ? Name the route
of each substance.
1.Blood, heart and blood vessels.
2. Oxygen from lungs to cells digested food from small intestine to
cells CO2 from cells to lungs waste materials from cells to kidneys.
Double circulation
• Like all mammals,
humans have a double
circulation
• The right side of the
heart sends blood to the
lungs (pulmonary
circulation)
• Blood returns from the
lungs to the left side of
the heart which pumps it
into the systemic
circulation supplying
the rest of the body.
• Blood passes twice
through the heart.
Double circulation
• What is the
advantage of a
double circulation?
Double circulation
• A double circulation has the
advantage of providing all
body organs with oxygenated
blood at high pressure and
at low pressure to the lungs
as they are spongy tissue.
In the single circulation of a fish, blood is pumped
Heart
Organs
Gills
Most of the pressure generated by the heart is lost
in the gills, and the organs receive low pressure
oxygenated blood.
Double circulation
• Double circulation is
made possible by
the complete
division of the heart
into separate left
and right sides
Pulmonary
circulation
• The left side receives
oxygenated blood(red)
from the lungs, and
pumps it to the
systemic circulation;
the right side receives
deoxygenated blood
(dark red) from the
body, and pumps it to
the lungs.
Lungs
Heart
Systemic
circulation
Body
Blood circulation
The heart pumps blood to the blood vessels. Arteries take blood away from the
heart to different organs and veins bring them back to the heart. The smallest
blood vessels that connect arteries to veins are capillaries. The circulatory
system allows one way blood flow. The capillaries has very thin walls so to
reduce the pressure of blood flow small muscular blood vessels called arterioles
receive the blood to reduce the pressure before blood enters capillaries.
Most arteries contain oxygenated blood and most vein deoxygenated blood
but not all.
You can get instructions for a heart
dissection here
• http://heartlab.robarts.ca/dissect/dissection
.html
Structure of the heart
Remember your rt is the
body’s left
Pulmonary
artery
Superior vena
cava
The diagram shows the heart at
diastole – relaxed, between
contractions.
Semilunar valves( has 3 pockets and half
moon shaped)
Pulmonary
veins
Aorta
Right atrium
Right atrioventricular valve
(tricuspid valve)
Inferior vena
cava
Left atrium
Left atrioventricular valve
(bicuspid valve)
Right ventricle
Septum
Tendon
Papillary muscle
Left ventricle
The cardiac cycle
At
systole
At
Atventricular
atrial
diastole
systole
(0.4
s):
(0.1 s):(0.3 s):
the
contract;
the
theventricles
atria
heartcontract;
muscle
is relaxed;
ventricular
pressureare
rises
the
thevein
atrioventicular
openings
valves
above
atrial,and
closing
constricted,
are open,
preventing
blood the
flows
atrioventicular
valves;
backflow
passivelyinto
from
theatria
veins
into
ventricles; pressure rises
ventricular
blood is forced
from atria into
above
arterial,
opening
the
ventricles
the semilunar
through
valves
the open
are
semilunar
valves;
atrioventicular
closed, because
valves;
arterial
pressure
is higher
blood
is forced
fromthan
ventricles
the semilunar
valves
remain
ventricular
pressure.
into
the because
pulmonary
artery and
closed,
arterial
aorta.
pressure is still higher than
ventricular pressure.
Papillary muscles adjust tension
in valve tendons
Animation of the cardiac cycle
Try to identify the three stages of the
cardiac cycle in this animation.
Note which valves are open and closed
at each stage.
The cardiac cycle
1. Heart muscle relaxed; ________ valves open,
allowing blood flow from ________ to ________.
Semilunar valves ________ to prevent backflow
from ________ to ________.
2. ________ contract, opening ________ valves and
forcing blood from ________ into ________ .
3. ________ contract, closing ________ valves and
opening ________ valves: blood pumped from
________ into ________ .
1. Deoxygenated
blood (i.e. blood
without oxygen)
enters through the
vena cava into the
right atrium
2. It’s then pumped
through the tricuspid
valve into the right
ventricle
3. It’s then pumped
through the semi-lunar
valve up to the lungs
through
the pulmonary
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artery
The Heart
4. Oxygenated blood
from the lungs enters
through the pulmonary
vein into the left atrium
5. It’s then pumped
through the bicuspid
valve into the left
ventricle
6. It’s then pumped
out of the aorta to
the rest of the body
Blood Vessels
Objectives:
*Name blood vessels and describe their
structure
** Explain how structures are related to their
functions
*** Explain the role of valves in heart and
blood vessels
Lesson 2: starter questions
A
B
1. Identify the stage of the cardiac
cycle shown in the diagram.
Give two reasons for your
answer.
C
(3 marks)
2. Identify the blood vessels
labelled A, B and C.
(3 marks)
X
Y
3. Explain the difference in
thickness of the muscular wall at
X and Y.
(2 marks)
The Circulatory system
The circulatory system is responsible for pumping
______ around the body. We need blood to be taken
around the body because blood contains ________ and
_______. These are needed so that all the ____ in our
bodies can produce _____ through _________.
The main organs in the circulatory system are the
_____, the lungs and the kidneys.
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Words – energy, heart, blood, glucose, respiration,
oxygen, cells
Blood vessels
• Arteries carry blood from the heart
towards capillary beds, veins carry blood
from capillary beds towards the heart
• Arteries do not always carry oxygenated
blood, nor veins deoxygenated: the
pulmonary and umbilical arteries carry
deoxygenated blood, the pulmonary and
umbilical veins oxygenated blood
Arteries
Arteries characteristically have:
a narrow lumen, maintaining
high pressure
a thick wall to withstand high
pressure
a corrugated inner lining
(endothelium), allowing stretching
during systole
extensive elastic tissue, which
absorbs some of the energy given
to the blood at systole and then
returns it by recoiling during
diastole
muscle fibres, allowing the
artery to be constricted or dilated
to control the amount of blood
flowing through it (NB this muscle
does not propel the blood)
Veins
Veins characteristically have:
a wide lumen, giving minimum
resistance to low pressure flow
a smooth endothelium, again
giving minimum resistance
little elastic or muscular tissue
valves to prevent backflow of low
pressure blood
Arteries, veins and capillaries
Arteries carry high pressure blood away
from the heart. They have smaller lumen
and no valves.
Capillaries have thin walls (one cell
thick) to allow glucose and oxygen to
pass through. Also used to connect
arteries to veins.
“Lumen”
Veins carry low pressure blood back to the heart. They have
thinner, less elastic walls and have valves to prevent backflow of
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blood.
Animation of the cardiac cycle
Try to identify the three stages of the
cardiac cycle in this animation.
Note which valves are open and closed
at each stage.
Action of valves in veins
Looking at valves in veins
Try this simple experiment to
show valves in the veins of your
hand.
Hold your arm down by your
side. This helps to fill the veins in
your hand with blood and make
them easier to see.
Find the vein shown in the picture
that runs down the middle of the
back of your hand.
With your other hand, gently
press your index finger onto the
top of the vein and push it
downwards, towards your
knuckles. This forces the blood in
the vein against the direction it
normally flows.
Notice that the vein
does not fill up with
blood from higher in
your arm. This is
because the vein
contains a valve by
your wrist. This valve
prevents blood from
the section of vein
higher up in your arm
from flowing back
down and refilling the
section of the vein in
your hand.
When you stop
pressing with your
finger the vein refills
with blood flowing from
your fingers.
Arteries, capillaries and veins
As arteries branch and become smaller, their muscle and elastic layers are reduced.
Arterioles still have muscle and a nerve supply, and control the blood supply to capillary
beds
Capillaries have no muscle or nerve supply, only a single cell layer (the endothelium)
As capillaries rejoin they form venules, which reunite to form veins
Capillary structure
The capillary wall is a single layer of very flat cells.
It is highly permeable, with gaps between cells and holes through cells: capillary
beds are where exchange occurs between blood and tissues.
The lumen of a capillary is about
5 mm in diameter: red blood cells
(diameter 7 mm) pass through in
single file, squashed against the
capillary wall.
Nucleus of squamous epithelial
cell
Capillary lumen
Red blood cell
Basement membrane of
squamous epithelial cell – allows
small molecules through, keeps
plasma proteins in
Name the most important
arteries and veins
Vessel
O
R
Heart
Bringing blood
to organ
Taking blood
away from
organ
Vena cava
to rt atrium
pulmonary
vein to lt
atrium
From rt
ventricle to
pulmonary
artery from
lt ventricle
to aorta
G
A
Lungs
Liver
pulmonary
artery
pulmonary
vein
Hepatic
artery,
hepatic
portal vein
Hepatic
vein
N
S
Kidneys
Renal
artery
Renal vein
Coronary Heart Disease(CHD)
Objectives:
* State and explain the effect of physical activity on pulse rate
**Describe the nature of coronary heart disease
***Describe the possible causes and preventative measures of CHD
Practice questions
The micrograph shows a blood vessel in transverse
section
1. Identify the type of blood
vessel shown and give
two reasons for your
answer.
(3 marks)
2. Name two kinds of tissue
you would expect to find
in the layer labelled X,
and state one function for
each.
X
(2 marks)
Investigating pulse rate( the number of pulse beat /min=heart
rate)
1. Sit still and get you partner to measure you pulse rate
2. Try doing step ups for 1 min (light exercise)and sit down and count the
pulse rate again.
3. Wait till your pulse rate comes to the resting rate
4. Do step ups for 3 mins (heavy exercise) and sit down and count the
pulse rate again.
5. You can repeat and calculate an average but wait for 5 mins before
each repeat.
6. Ensure the same person is doing the exercise.
7. Explain your results in terms of supplying substances to your muscles
and removing the wastes.
During exercise your muscle needs more energy from respiration to
contract. Do heart beats faster and arteries supplying muscles dilate.
These increase the blood flow to muscles resulting in:
1.An increase in supply of oxygen and glucose
2.An increase in removal of carbondioxide
Coronary circulation
Aorta
The muscular wall atria
and ventricles of the heart
is provided with highpressure oxygenated
blood by the coronary
arteries, arising from the
base of the aorta just
above the semilunar
valves.
Slow Flow
Healthy arteries has smooth lining letting the blood flow easily. However
c………… which is made in the liver can stick to the wall making it
n……….. Which will slow down the flow. This condition is known as
atherosclerosis. The artery walls can become rough which can cause the
blood to c……… and block the vessel. The blockage is called
thrombosis.
These conditions can cause chest pains especially when the heart is
working hard. This condition is called angina when enough o………… does
not get to the heart muscle. Angina or thrombosis can lead to a heart
attack. Parts of the heart can be damaged or it may stop beating altogether
causing cardiac arrest.
Risk fcators
Factors that can be avoided:
1. Diet with too much saturated (animal)fat increases concentration of
cholesterol in the blood.
2. Overweight
3.Smoking
4.Taking little or no exercise
5. Stress
Factors cannot be avoided:
1. Genes that control the metabolism of fat and cholesterol
2. Age increases with age
3. Sex men are more likely than women
Taking care
1.Diet – Eat more poultry and fish fresh fruit and
vegetables. Cut down on fried foods, red meat.
2.Take regular exercise
3.Do not smoke