Download Transport in Humans

Transport in Humans
Candidates should be able to:
(a) name the main blood vessels to and from the heart, lungs, liver and kidney
(b) state the functions of blood
• red blood cells – haemoglobin and oxygen transport
• white blood cells – phagocytosis, antibody formation and tissue rejection
• platelets – fibrinogen to fibrin, causing clotting
• plasma – transport of blood cells, ions, soluble food substances, hormones,
carbon dioxide, urea, vitamins, plasma proteins
(c) relate the structure of arteries, veins and capillaries to their functions
(d) describe the structure and function of the heart in terms of muscular
contraction and the working of valves (histology of the heart muscle, names of
nerves and transmitter substances are not required)
(e) describe coronary heart disease in terms of the occlusion of coronary
arteries and list the possible causes, such as diet, stress, smoking, and the
possible preventative measures
© Nur Huda (2012)
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Main blood vessels
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Heart
Pulmonary artery
(to the lungs)
Vena cava
(from the body)
Semi-lunar valve
Aorta (to the body)
Pulmonary vein
(from the lungs)
Left atrium
Right atrium
Tricuspid valve
Bicuspid valve
Left ventricle
Right ventricle
Thick muscular wall
of left ventricle
deoxygenated
oxygenated
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Heart
Right atrium
• Receives deoxygenated blood from vena cava
• Right atrium contracts, force blood to enter right
ventricle
Superior
vena cava
Pulmonary
artery
Triscupid valve
• Prevents backflow of blood to right atrium
Right ventricle
• Right ventricle contracts and pumps deoxygenated
blood to the lungs via pulmonary artery
Semi-lunar valve
• Prevents backflow to right ventricle
Right
atrium
Inferior
vena cava
Triscupid
valve
Right
ventricle
Semi-lunar
valve
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Heart
Left atrium
• Receives oxygenated blood from the lungs via
pulmonary vein
• Left atrium contracts, forces blood to enter left
ventricle
Aorta
Pulmonary vein
Biscupid valve
• Prevents backflow of blood to left atrium
Left atrium
Biscupid
valve
Left ventricle
• Left ventricle contracts and pumps oxygenated
blood to the rest of the body via the aorta
Semi-lunar valve
• Prevents backflow to left ventricle
Left ventricle
Semi-lunar
valve
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Common exams questions
• Why does left ventricle has muscular wall than the right ventricle?
– Left ventricle pump blood to the rest of the body, a greater distance
compared to right ventricle which pump blood into the lungs. Hence, it has a
thicker muscle wall to produce strong force to pump blood over longer
distance.
• Function of septum
– Prevent mixing of oxygenated and deoxygenated blood
• Function of valve
– To prevent backflow of blood and ensure blood flow in one direction
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Blood vessels
Heart  Artery  Arteriole  Capillary  Venule  Vein  Heart
heart
vein
blood
flowing
back to
the heart
veins
artery
a capillary
network links
arteries and veins
capillaries
venules arterioles
blood flowing
from the heart
arteries
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Blood vessels
Artery
Structure
Function
Blood Flow
Vein
Capillary
•
Thick and muscular
wall
•
Thin and less
muscular wall
• Very thin wall
(One-cell thick/
one layer of cells)
•
Elastic tissue
•
Not elastic
•
Not elastic
•
Narrow lumen
•
Wide lumen
•
Very small lumen
•
Valves absent
•
Valves present
•
Valves absent
•
Carries blood away
from heart
•
Carries blood
towards the heart
•
Allows exchange of
materials between
blood and body cells
•
Transport
oxygenated blood
except pulmonary
artery
•
Transport
deoxygenated blood
except pulmonary
vein
--
•
•
Very fast flow
Highest pressure
•
Slow and smooth
flow
Lowest pressure
•
•
•
Slow and smooth
flow
Pressure is between
artery and vein
Blood vessels
Artery
- Thick muscular wall to withstand
the pressure of blood exerted on
the walls because artery receive
blood directly from the heart and
the blood is under high pressure.
- Elastic to enable the artery wall to
stretch and recoil to push the blood
forward
- Small lumen to maintain the high
pressure
- Artery receive blood directly from
the heart and the blood is under
high pressure, hence no valve to
impede the flow
Vein
- Thin outer wall and wide lumen as
blood pressure is the lowest
- Valve ensure blood flows in one
direction back to the heart because
blood in veins is under low
pressure and there is no direct
force to push the blood forward.
Capillary
- Thin wall of one layer of cells to
allow higher rate of diffusion of
substances
- Permeable walls to allow diffusion
of substances
- Branching of capillaries to
increase the surface area to
volume ratio for diffusion of
substances
- Slow blood flow gives more time
for the diffusion of substances
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Coronary Heart Disease
Narrow artery
Fatty deposit
• Coronary artery becomes hardened and narrow due to fatty
deposits in the innermost lining of coronary artery.
• More resistance for blood to flow and the heart will overwork
to pump blood.
• Blood clot of coronary artery will prevent blood flow to the
muscle tissues in the heart. Blood and oxygen supply to the
cardiac muscles is reduced.
• Heart muscles becomes deprived of oxygen and die. When
too much heart muscles tissues is damaged, it leads to heart
attack and even death.
(myocardial infarction= heart attack)
(Occlusion = blood clot)
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(atherosclerosis: fatty deposits on the inner arterial walls)
Coronary Heart Disease
Causes
High saturated fats diet
- Increases the cholesterol level in
the blood and build up fatty
deposits.
Smoking
- Nicotine increase risk of blood
clotting in arteries
- Carbon monoxide increases the
risk of fatty deposits on the inner
surface or arterial wall
Lack of exercise
- Result in unfit heart which slows
down blood circulation and may
allow fatty substances to deposit
easily in the arteries
Stress
Preventive measure
Reduce intake of high saturated fats
Quit smoking
Exercise regularly
Manage stress
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Blood
Parts
Plasma
Function
Transport dissolved substances (e.g blood cells,
ions, soluble food substances, hormones,
carbon dioxide, urea, vitamins, plasma proteins)
Appearance
Pale yellow
fluid
White
- Destroy harmful bacteria by phagocytosis
blood cells - Produce antibody
- Defend the body against infection
- Involve in tissue rejection after organ
transplant
Platelets
Fibrinogen converted into fibrin, causing blood
clot
Red blood
cells
- contain a red pigment called haemoglobin
which binds to oxygen
- transport oxygen from the lungs to other parts
of the body
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Blood clot
red blood cell
fibrin thread
Fibrin threads entangle red blood cells
red blood cell
fibrin thread
clot
• When blood vessels are
damaged, platelets release an
enzyme that catalyses the
conversion of the soluble
protein fibrinogen to insoluble
threads of fibrin
• Fibrin threads entangle blood
cells which forms a clot
• Blood clot prevents entry of
foreign particles through
open wound or cuts
Red blood cells entangled in fibrin
threads, forming a blood clot
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