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Title: Human Transport
Description: Biology notes for the circulatory system, parts of blood such as plasma, red blood cells, etc functions of the blood and parts of the circulatory system, the blood and heart, types of circulation, blood vessels and cardiac cycles. Very Comprehensive
Description: Biology notes for the circulatory system, parts of blood such as plasma, red blood cells, etc functions of the blood and parts of the circulatory system, the blood and heart, types of circulation, blood vessels and cardiac cycles. Very Comprehensive
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Human Transport Notes
The circulatory system is a system that permits
blood and lymph
circulation to transport nutrients
(e
...
amino acids
and electrolytes
), oxygen arbon dioxide ormones
,
c
,
h
etc
...
The transport system consists of a series of blood vessels, blood that flows through the vessels and a
heart to ensure that blood flows through the vessels
...
Simple diffusion is not enough to bring enough oxygen
and food materials to these cells nor can it remove waste products with sufficient speed as some cells
are situated deep in the body, far from the external environment
...
g
...
It is composed of
blood cells
and platelets
(45%) suspended in
plasma
(55%)
...
g
...
Fibrinogen and prothrombin play
an important part in the clotting of blood
...
Antibodies help to
fight diseases
...
g
...
●
Mineral salts E
...
Hydrogencarbonates, chlorides, sulphates and phosphates of calcium,
sodium and potassium
...
Calcium is essential for blood
clotting
...
g
...
●
Waste Products E
...
Urea, uric acid, carbon dioxide and creatinine
...
They
absorb oxygen in the
lungs and release it while squeezing through blood
capillaries
...
Mature red blood cells are flexible and oval biconcave disks
...
It is elastic and can turn bellshaped in
order to squeeze through blood capillaries smaller than itself in diameter
...
The lifespan of red blood cells is about 34 months and the spleen destroys it when
it’s worn out
...
White blood cells or leukocytes are
cells of the
immune system
involved in defending the body against
infectious disease
s/invasive pathogens and foreign materials
...
The ratio of red blood cells to white blood cells is 700:1
...
High numbers of leukocytes in
the
blood are often an indicator of
disease
...
It has an
irregular shape and contains a nucleus
...
White blood cells can be lymphocytes
and phagocytes
...
Lymphocytes tend to be nearly round in shape and show only limited
movements
...
Phagocytes take in and digest foreign materials during photosynthesis, e
...
bacteria
...
Blood Platelets, or thrombocytes, are small, irregularly shaped clear cell fragments (i
...
cells that do not
have a
nucleus
), 2–3 µm in diameter, which are derived from fragmentation of certain bone marrow
cells
...
The average lifespan of a platelet is normally just 5 to 9
days
...
Such clumps block up small blood
vessels and obstruct the flow of blood
...
Agglutination clots blood in bleeding wounds, where agglutination blocks the blood from flowing
out
...
These antigens
may be
proteins arbohydrates lycoproteins
,
c
,
g
, or glycolipids
, depending on the blood group
system
...
Antibodies against antigens A and B
may be represented by small letters ‘a’ and ‘b’ respectively
...
There are 4 types of blood groups
...
When a transfusion is carried out, the effect the recipient’s
plasma has on the antibodies has to be considered
...
E
...
Digested Food is carried from the intestines to other parts of the body and excess mineral salts
are transported to the kidneys for excretion; Excretory products are carried from all parts of the
body to the kidneys for nitrogenous wastes and the lungs for carbon dioxide; Hormones are
transported from the glands to the target organs; Heat is transported from respiring body tissues
to all parts of the body to maintain a uniform body temperature; Oxygen is transported from the
lungs to all parts of the body for respiration
...
Haemoglobin has a great affinity for oxygen and haemoglobin
binds with oxygen, forming oxyhaemoglobin
...
As blood passes through tissues containing very little oxygen, the
oxyhaemoglobin releases its oxygen and the oxygen diffuses into the tissue cells
...
o
Blood Clotting Blood exposed to air will soon clot (form a solid lump)
...
The clot also prevents foreign particles from
entering the bloodstream
...
When blood
vessels are damaged, damaged tissues and blood platelets release an enzyme called
thrombokinase
...
Thrombin is also an enzyme
and this catalyses the conversion of the soluble protein fibrinogen to insoluble threads
of fibrin
...
The clot
seals the wound
...
This is due to
the presence of an anticlotting substance called heparin, which is produced in the liver
...
When blood clots, serum is left behind
...
o
Phagocytosis Phagocytes can destroy foreign particles entering the blood, e
...
bacteria
...
Ingested bacteria will be digested and in the process, the phagocyte might be killed,
forming pus
...
These protect our bodies against diseases, e
...
destroying bacteria by
attaching to it and rupturing its surface membrane; causing the bacteria to agglutinate
so they can be easily ingested by the phagocytes and neutralising harmful substances
...
Some types of dead bacteria are
sometimes injected into the bodies of certain animals to induce the formation of
antibodies in the blood
...
Antibody production can be
directly induced by exposing the person to dead or weakened forms of the pathogen
...
o
Organ Transplant and Tissue Rejection A person’s damaged tissue or organ can be
replaced by a healthy tissue or organ
...
The organ to be
transplanted must not be rejected by the recipient’s immune system as the recipient’s
lymphocytes may respond by producing antibodies to destroy the transplanted organ
...
A tissue
match is necessary to reduce risk of rejection
...
Immunosuppressive drugs which
inhibit the response of the recipient’s immune system also help reduce risk of tissue
rejection but this may lower resistance to infection and the recipient has to continually
take drugs
...
It comprises of the heart, the arteries, the arterioles,
blood capillaries the venules and the veins
...
This blood is normally
oxygenated, except the
pulmonary
arteries (from the heart to the lungs)
...
T
pressure
portion of the circulatory
system
...
They are thick, muscular and elastic, allowing them to withstand the high pressure
...
The elasticity enables the artery wall to stretch and roil or
spring back, enabling the artery wall to stretch and recoil or spring back, pushing the blood in
spurts and rising pulse levels
...
When an artery constricts, its lumen become narrower and
blood flows slower
...
Arteries also aid the heart in pumping blood
...
he aorta is the
T
largest
artery
in the
human body
, originating from the
left ventricle
of the
heart and extending
down to the
abdomen
, where it
bifurcates
into two smaller arteries (the
common iliac arteries
)
...
Most veins carry
deoxygenated blood except the
pulmonary
veins, which carry oxygenated blood to the heart
...
Hence, veins need not be as thick and muscular as the arteries’ walls
...
Valves are folds of the inner walls, called semilunar valves
...
The movement of blood along the veins is
assisted by skeletal muscles along the veins
...
The arterioles branch out
and ultimately become capillaries
...
They have walls made up of a single layer of flattened cells called the
endothelium
...
It enables certain substances to diffuse
quickly through the capillary walls
...
The numerous branches
provide a large surface area to volume ratio for the exchange of substances between the blood
and the tissue cells
...
This lowers the blood pressure in the capillaries
...
●
Venules Capillaries unite to form small veins called venules when they leave an organ
...
Dissolved food substances and
oxygen diffuse from the blood in the blood capillaries into the tissue fluid and then into the cells into the
tissue fluid and then through the blood capillary walls into the blood
...
Since the blood capillaries are narrow, the red blood cells can only move
through the lumen of the blood capillaries in a line
...
It increases its surface area to speed up
absorption or release of oxygen
...
The double circulatory system of blood flow references two distinct systems, where blood passes
through the heart twice for every complete circuit of the body
...
Most animals living above the water require a double circulatory
system to allow the added benefit of direct oxygenation from a developed pulmonary circuit
...
Types of Circulation
●
Pulmonary Deoxygenated blood flows from the heart to the lungs via the pulmonary arteries
and oxygenated blood flows from the lungs to the heart via the pulmonary veins
...
The heart is a hollow uscle
m
that pumps
blood through
blood vessels
by repeated, rhythmic
contractions
...
The vertebrate
heart is principally composed of
cardiac muscle
and connective tissue
...
The average
human heart
, beating at 72 beats per minute, will beat approximately 2
...
It weighs approximately 250 to 300 grams in females and 300 to 350
grams in males and is about the size of a fist
...
The heart is surrounded by a bag called the pericardium
...
The inner membrane is in contact with the tissues making up the
heart
...
Parts of the Heart
●
Atriums The atriums are the two upper chambers in the heart and they have thin muscular walls
since they only force blood into the ventricles and this does not require high pressure
...
●
Ventricles The ventricles have thick muscular walls especially the left ventricles as it has to
pump blood through the arterioles, at a high pressure round the whole body
...
Blood
leaves the heart here
...
It prevents the mixing of deoxygenated
blood with oxygenated blood, which can cause a reduction in the amount of oxygen carried to
tissue cells
...
Deoxygenated blood from the body flows via the superior vena cava (blood vessel from upper
parts of body) and the inferior vena cava (blood from lower parts of body) into the right atrium
...
The blood is then pumped through the
tricuspid valve
into the
right ventricle
, whose subsequent
contraction forces it out through the
semilunar valve
into the
pulmonary arteries
leading to
the
lungs
...
The tricuspid valve consists of three flaps, which are attached
to the walls of the right ventricles by cordlike tendons called chordae tendineae
...
3
...
It leaves the heart and divides into two, one to each lung
...
Semilunar valves in the pulmonary artery
prevent backflow of blood into the right ventricle
...
Blood in the pulmonary arteries is at a lower pressure than blood in the aorta so that gaseous
exchange can take place efficiently in the lungs
...
Meanwhile, oxygenated blood returns from the lungs through the
pulmonary veins
into the
left
atrium
...
This causes the bicuspid valve to open and blood enters the left
ventricle
...
This is
similar in structure and function to the tricuspid valve except that it has two valves not three
...
The left ventricle has a thicker wall than the right ventricle as
blood must be pumped at a high pressure to reach all parts of the body efficiently
...
From the aorta, blood is distributed to all parts of the body (except the lungs)
...
It also possesses semilunar valves to
prevent backflow of blood to the left ventricle
...
Two small coronary arteries emerge from the aorta that brings oxygen and nutrients to
the heart muscles
...
The atrium contract, forcing blood into the relaxed ventricles
...
After a short pause, the ventricles contract
...
The semilunar valves open
...
3
...
The right atrium receives blood from the
venae cave while the left atrium receives blood from the pulmonary veins
...
The ventricles then relax
...
The AV valves also open
and blood flows from the atria into the ventricles
...
The atria contract again and the whole cycle repeats
...
Both
make up one heartbeat and lasts for about 0
...
There is a short pause between two heartbeats
...
Blood pressure is the force that blood exerts on the walls of blood vessels
...
The blood pressure in the arteries is highest during the
ventricular systole and decreases during ventricular diastole
...
A slight change in the ventricular pressure due to the contraction of the left atrium, forcing blood
into the relaxed ventricle
...
The ventricle begins to contract, the bicuspid valve closes and the pressure increase
...
The pressure in the ventricle continues to rise as it contracts
...
The pressure in the left ventricle becomes higher than that in the aorta
...
5
...
The aortic valve closes to prevent backflow of the blood into the
ventricle
...
The pressure in the ventricle continues to decrease as it relaxes
...
The bicuspid valve opens as the pressure in the ventricle becomes lower than that of the atrium
...
The pressure in the ventricle gradually increases as blood continues to enter the ventricle from
the atrium
...
The cycle repeats
...
Arteries Aorta to Head, neck and arms
...
●
Inferior Vena Cava Lower Body to Heart
...
The veins from the gut unite to form the hepatic portal vein, which enters the liver and branches into
numerous capillaries there
...
The lymphatic system is part of the
circulatory system
, comprising a network of
lymphatic vessels
that
carry a clear fluid called
lymph
directionally towards the heart
...
Roughly 17 litres of the filtered plasma get reabsorbed directly into the blood vessels,
while the remaining 3 litres are left behind in the
interstitial fluid
...
The other main function is that of defence in the
immune system
...
It also contains waste products and debris of cells
together with bacteria and protein
...
Lymphocytes are concentrated in the
lymph nodes
...
Coronary Heart Disease is the most common heart disease
...
Blood supply to the heart muscles
can be greatly reduced due to the occlusion or blockage of the coronary arteries, causing a heart attack
...
Extensive heart damage is often fatal as the blood cannot pump blood now
...
This is called
atherosclerosis
...
Such an
affected artery develops a rough inner surface
...
If it occurs in the coronary arteries, the supply of blood and oxygen
may be completely cut off
...
Without oxygen, the heart muscle cells may be damaged, and a heart attack occurs
...
A proper diet of polyunsaturated fats, proper stress management, smoking abstinence and regular
physical exercise helps lower risk of coronary heart disease and helps strengthen the heart
Title: Human Transport
Description: Biology notes for the circulatory system, parts of blood such as plasma, red blood cells, etc functions of the blood and parts of the circulatory system, the blood and heart, types of circulation, blood vessels and cardiac cycles. Very Comprehensive
Description: Biology notes for the circulatory system, parts of blood such as plasma, red blood cells, etc functions of the blood and parts of the circulatory system, the blood and heart, types of circulation, blood vessels and cardiac cycles. Very Comprehensive