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Transport In Humans(Circulatory System as known as Cardiovascular System)
Transport In Humans(Circulatory System as known as Cardiovascular System)
Blood Vessels
Veins
Veins carry blood to the heart from all parts of the body
Blood pressure in veins is much lower than the blood pressure
Venules in turn join to form bigger veins
Blood flows more slowly and smoothly in the veins
Thin wall with less elastic tissue
Contain less elastic tissue
Carry deoxygenated blood
(except pulmonary vein carries oxgenated blood)
Pulmonary veins brings oxygenated blood back to the heart
Capillaries
Microscopic blood vessels that are found between the cells of almost all the tissues
Walls made up of only a single layer of flattened cells called the
endothelium
branch repeatedly
Endothelium is partially permeable
have a large surface area for the exchange of substances between the blood and the tissue cells
Arteries
Carry blood away from the heart
need to be able to withstand the immense pressure of the blood
The thick elastic walls help to withstand the high blood pressure in the artery
Have walls which are
thick , muscular
and
elastic
Elasticity enables the artery wall to stretch and
recoil
or spring back
Pulmonary artery brings deoxygenated blood away from heart to lungs
Heart
The Main Vein is the
Vena Cava
Two larger lower chambers
Ventricles
Left ventricle requires high pressure
Right ventricle has thinner walls
Have thick muscular walls,especially the
left ventricle
Right and left ventricle are separated by a muscular wall called ----
Median Septum
If
deoxygenated blood are mixed with oxygenated blood,it will reduce the amount of oxygen being carried to the tissue cells
It prevent the mixing of oxygenated blood and deoxygenated blood
The Main Artery is the
Aorta
.
Two upper chambers
auricles(part of atria)
does not require high pressure
thin muscular walls
Inferior is also known as
posterior
Surrounded by a 'bag' called the
pericardium
Superior is known as
anterior
.
Made up with
muscle tissue
Coronary Heart Disease
Causes
Coronary heart disease (CHD) is usually caused by a build-up of fatty deposits (atheroma) on the walls of the arteries around the heart (coronary arteries).
The build-up of atheroma makes the arteries narrower, restricting the flow of blood to the heart muscle. This process is called atherosclerosis.
Your risk of developing atherosclerosis is significantly increased if you:
smoke
have high blood pressure (hypertension)
have a high blood cholesterol level
did not take regular exercise
have diabetes
Other risk factors for developing atherosclerosis include:
being obese or overweight
having a family history of CHD - the risk is increased if you have a male relative under the age of 55, or a female relative under 65, with CHD
PREVENTIVE MEASURES
There are several ways you can help reduce your risk of developing coronary heart disease (CHD), which include the following:
Eat a healthy, balanced diet
Be more physically active
Keep to a healthy weight
Give up smoking
Reduce alcohol consumption
Keep blood pressure under control
Keep diabetes under control
a waxy substance called plaque builds up inside the coronary arteries.
These arteries supply oxygen-rich blood to your heart muscle.
When plaque builds up in the arteries, the condition is called atherosclerosis. The buildup of plaque occurs over many years.
Blood
PLASMA
Dissolved mineral salts,example,hydrogencarbonates,chlorides,sulfates and phosphates of calcium,sodium and potassium.All these occur as ions in the plasma.Calcium is essential for blood clotting.
Food substances,example:glucose,amino acids,fats and vitamins.
Soluble proteins such as
fibrinogen
,
prothrombin
and
antibodies
.Fibrinogen and prothrombin help to fight diseases that involves in blood clotting.They are proteins made in the liver.
Excretory products,for example :
urea
,
uric acid
and
creatinine
.Carbon dioxide is present as hydrogencarbonate ions.
Plasma is about 90% of water and the rest is a complex mixture of various dissolved substances.
Hormones = Insulin
A pale yellowing liquid
RED BLOOD CELLS / ERYTHROCYTES
It contains the pifment haemoglobin which is a special kind of iron-containing protein.Haemoglobin combinds reversibly with oxygen.This enables red blood cells to transport oxygen from the lungs to all cells in the body.
Mammalian red blood cells has these features:
It is a circular,flattened biconcave disc.The centre of the cell is thinner than its edge.This increases the cell's surface area to volume ratio.The cell can thus absorb and release oxygen at a faster rate.
There are about
five millions
of red blood cells(erythrocytes) in each cubic millimetre of blood
It does not possess a nucleus,enabling it to carry more haemoglobin and oxygen.
It is elastic and can turn bell-shaped in order to squeeze through blood vessels smaller than itself in diameter (less than 0.01mm)
Red blood cells are produced by the bone marrow.The lifespan of red blood cells is about
3-4 months
WHITE BLOOD CELLS
Irregular in shape and contains a nucleus
Have two main kinds of tissue cells :
lymphocytes
and
phagocytes
Keeps the body healthy by fighting diseases
Are larger than red blood cells but are few in number
They contain a nucleus but their normal lifespan in the bloodstream is only a few days
Colourless and does not contain haemoglobin
Can move,change its shape and squeeze the walls of the thinniest blood capillaries into the spaces among tissue cells
BLOOD PLATELETS/THROMBOCYTES
Blood platelets or
thrombocytes
are not true cells
Play part in the clotting of blood