the blood clotting mechanism

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The Blood Clotting Mechanism

Introductory Note: Knowledge of the structure and functions of blood and other aspects of

the heart and vascular system are part of training in many therapies, such as Massage,

Aromatherapy, Shiatsu, and others. This page is intended as Revision Notes for Basic / First

Level Courses in these therapies, and some ITEC Diplomas.

Blood Clotting is one of three mechanisms that reduce the loss of blood from broken bloodvessels.The three mechanisms are:

Vascular Spasm - The smooth muscle in blood vessel walls contracts immediately theblood vessel is broken. This response reduces blood loss for some time, while the other

hemostatic mechanisms become active.

Platelet Plug Formation - When blood platelets encounter a damaged blood vesselthey form a "platelet plug" to help to close the gap in the broken blood vessel. (The key

stages of this process are called platelet adhesion, platelet release

reaction, and platelet aggregation)

Blood Clotting (Coagulation) - As described below:

Following damage to a blood vessel, vascular spasm occurs to reduce blood loss while

other mechanisms also take effect:

Blood platelets congregate at the site of damage and amass to form a platelet plug. This is

the beginning of the process of the blood "breaking down" from is usual liquid form in such

a way that its constituents play their own parts in processes to minimise blood loss.

Blood normally remains in its liquid state while it is within the blood vessels but when it

leaves them the blood may thicken and form a gel (coagulation).Blood clotting (technically "blood coagulation") is the process by which (liquid) blood is

transformed into a solid state.

This blood clotting is a complex process involving many clotting factors (incl. calcium ions,enzymes, platelets, damaged tissues) activating each other.

The three stages of this process are:

1. Formation of Prothrombinase Prothrombinase can be formed in two ways, depending of which of two "systems"

or "pathways" apply. These are

Intrinsic

System

This is initiated by liquid blood making contact with a foreign

surface, i.e. something that is not part of the body; or

Extrinsic

System

This is initiated by liquid blood making contact with damaged

tissue.

Both the intrinsic and the extrinsic systems involve interactionsbetween coagulation factors. These coagulation factors have individual names but

are often referred to by a standardised set of Roman Numerals, e.g. Factor VIII

(antihaemophilic factor), Factor IX (Christmas factor).

2. Prothrombin converted into the enzyme Thrombin



Prothrombinase (formed in stage 1.) converts prothrombin, which is a plasma

protein that is formed in the liver, into the enzyme thrombin.

3. Fibrinogen (soluble) converted to Fibrin (insoluble)

In turn, thrombin converts fibrinogen (which is also a plasma protein synthesizedin the liver) into fibrin.

Fibrin is insoluble and forms the threads that bind the clot.

Consequences of Blood Clotting Problems:

If blood clots too quickly/easily then thrombosis may occur. This is blood clotting in an

unbroken blood vessel, which is dangerous and can lead to strokes or heart-attacks.Conversely, if blood takes too long to clot hemorrhage may occur. In this case much blood

may be lost from the blood vessels, which is also dangerous.

The hereditary disorder haemophilia is a condition in which certain coagulation factors

are missing from the blood, as a result of which the blood cannot form clots (without

medical intervention).

The Structure and Functions of BloodNote: Knowledge of the structure and function of blood and aspects of the heart andvascular system are part of training in various therapies, (incl. e.g. Massage, Aromatherapy,

Acupuncture, Shiatsu, etc.). This page is intended to include detail suitable for introductory

courses, and some ITEC Diplomas.

This page is divided into the following sections:

1. The Functions of Blood

(generally - as opposed to the functions of particular components of blood).

2. The Composition of Blood

(incl. the different types of blood cells and their properties and functions).

3. Process of Oxygenation of Tissues due to Circulation of Blood

4. Types of Leucocytes (White Blood Cells)



1. Functions of Blood

1. Transports:

Dissolved gases (e.g. oxygen, carbon dioxide);Waste products of metabolism (e.g. water, urea);

Hormones;

Enzymes;

Nutrients (such as glucose, amino acids, micro-nutrients (vitamins & minerals),

fatty acids, glycerol);

Plasma proteins (associated with defence, such as blood-clotting and anti-

bodies);

Blood cells (incl. white blood cells 'leucocytes', and red blood cells

'erythrocytes').

2. Maintains Body Temperature

3. Controls pH

The pH of blood must remain in the range 6.8 to 7.4, otherwise it begins to damage

cells.

4. Removes toxins from the body

The kidneys filter all of the blood in the body (approx. 8 pints), 36 times every 24hours. Toxins removed from the blood by the kidneys leave the body in the urine.

(Toxins also leave the body in the form of sweat.)

5. Regulation of Body Fluid Electrolytes

Excess salt is removed from the body in urine, which may contain around 10g salt per day

(such as in the cases of people on western diets containing more salt than the body

requires).

2. Composition of Blood

Blood consists of many components (constituents).

These include:

55%Plasma

45%Components, i.e. 'Blood Cells'.

Of these, 99% are erythrocytes (red blood cells) and 1% are leucocytes (white bloodcells) and thrombocytes (blood platelets).

This is summarised in the following diagram, and described in further detail below.



The summary chart above includes: erythrocytes (red blood cells), thrombocytes (blood

platelets) and leucocytes (white blood cells). It also includes categories of leucocytes:

agranulocytes and granulocytes (also known as polymorphonucleocytes), which may alsobe sub-divided into lymphocytes, monocytes, basophils, neutrophils and eosinophils.

The following table includes further general information about the constituents of blood.

Structure Functions

Plasma Normal blood plasma is 90-92 %

water.

This is the straw-coloured fluid in

which the blood cells are

suspended, and consists of:

The medium in which the blood

cells are transported around the

body (by the blood vessels) and

are able to operate effectively.

Helps to maintain optimum bodytemperature throughout the

organism.

Helps to control the pH of theblood and the body tissues,

maintaining this within a rangeat which the cells can thrive.

Helps to maintain an ideal

balance of electrolytes in theblood and tissues of the body.

Dissolved substances including

electrolytes such as sodium,

chlorine, potassiun, manganese,and calcium ions;

Blood plasma proteins (albumin,

globulin, fibrinogen);

Hormones.

Erythrocytes

(Red blood

cells)

Immature erythrocytes have a

nucleus but mature erythrocytes

have no nucleus.

Carry oxygen (process described in

more detail -below).

Haem

Erythrocytes have a "prosthetic



group" (meaning "in addition to"

- in this case, in addition to the

cell). The active component of

this prosthetic group is Haem.

Haem relies on the presence of

iron (Fe).Haem combines with oxygen to

form oxyhaemoglobin:

... continued in section below.

Erythrocytes are eventually

broken down by the spleen into

the blood pigments bilinubin and

bilviridin, and iron. These

components are thentransported by the blood to the

liver where the iron is re-cycled

for use by new erythrocytes, andthe blood pigments form bile

salts. (Bile breaks down fats.)

Have a longevity of approx. 120days.

There are approx. 4.5 - 5.8

million erythrocytes per micro-litre of healthy blood (though

there are variations betweenracial groups and men/women).

Leucocytes

(White blood

cells)

There are different types of

leucocytes (described in moredetail - below), classified as:

Granular: e.g. Neutrophils,

Eosinophils, Basophils.

Agranular (do not contain

granules): e.g. Monocytes,

Lymphocytes.

Major part of the immune system.

Have a longevity of a few hours

to a few days (but some can

remain for many years).

There are approx. 5,000 - 10,000

leucocytes per micro-litre of

blood.



Trombocytes

(Platelets)

Blood platelets are cell

fragments;

To facilitate blood clotting - the

purpose of which is to prevent loss

of body fluids.Disk-shaped;

Diameter 2-4 um(1 micro-metre = 1 um =

0.000001m);

Have many granules but no

nucleus;

Have a longevity of approx. 5-9

days.

There are approx. 150,000 -

400,000 platelets per micro-litreof blood.

3. The Oxygenation of Blood

The oxygenation of blood is the function of the erythrocytes (red blood cells) and takesplace in the lungs.

The sequence of events of the blood becoming oxygenated (in the lungs) then oxygenating

the tissues (in the body) is as follows:

The Right Ventricle (of the heart) sends de-oxygenated blood to the lungs.

While in the lungs:

1. Carbon Dioxide diffuses out of the blood into the lungs, and2. Oxygen (breathed into the lungs) combines with haemoglobin in the blood as it

passes through the lung capillaries.

Oxyhaemoglobin returns to the heart via the pulmonary vein and then enters thesystemic circulation via the aorta.

There is a low concentration of oxygen in the body tissues. They also contain waste

products of the metabolism (such as carbon dioxide).

Due to the high concentration of oxygen in the blood and the low concentration of

oxygen in the tissues,

... the high concentration of carbon dioxide in the tissues diffuses into the blood. (95%

of this carbon dioxide dissolves in the blood plasma.)

Blood returns from the tissues back to the heart via the superior vena cava (from theupper-body) and the inferior vena cava (from the lower-body)



4. Types of Leucocytes (White Blood Cells)

Lymphocytes: Monocytes: *Basophils: *Neutrophils: *Eosinophils:

Approx. 24% of

leucocytes are

lymphocytes.These produce

anti-bodies andinclude:

* T-Cells

* B-Cells

* NaturalKiller Cells

Approx. 4% of

leucocytes are

monoocytes.These are also

known asphagocytes.

They combat

microbes by

the process of phagocytosis.

60-70% of

leucocytes are

basophils.Diameter 10-12

micro-metres.

Phagocytosis.

Destruction of

bacteria withlysozyme and

strong oxidants.

2-4% of

leucocytes are

neutrophils.Diameter 10-12

micro-metres.

Combat the

effects of

histamine inallergic

reactions;

Phagocytize

antigen-antibody

complexes;

Destroy some

parasitic worms.

0.5-1% of

leucocytes are

eosinophils.Diameter 8-10

micro-metres.

Liberate

heparin,

histamine, andseratonin in

allergic

reactions,

intensifying

inflammatory

response.

* It is only possible to observe the differences between these by staining them.

Further notes about the types of leucocytes identified above:

Lymphocytes:

The term "antigen" refers to something that is not naturally present and 'should not be in the body'.

T Cells (lymphocytes) are activated by the thymus

gland.

B Cells (lymphocytes) are activated by other

lymphoid tissue. The 'B' indicates 'bone marrow'

cells.

Both T-cells and B-cells:

Phagocytosis:

A phagocyte is a cell able to engulf and

bacteria, protozoa, cells, cell debris, and

particles. Phagocytes include many leuc

(white blood cells) and macrophages - w

major role in the body's defence system

Phagocytosis is the engulfment and dige

bacteria and other anigens by phagocyt



(1) destroy antigens, and

(2) produce 'memory cells' and anti-bodies.Basophils:

An increased (higher than usual) percentage of

basophils in the blood may indicate an

inflammatory condition somewhere in the body.Neutrophils & Monocytes:

Neutrophils are the first leucocytes to respond to

bacterial invasion of the body. They act by

carrying out the process of phagocytosis (see

opposite), and also be releasing enzymes - such as

lysozyme, that destroy certain bacteria.

Monocytes take longer to reach the site of

infection than neutrophils - but they eventually

arrive in much larger numbers.Monocytes that

migrate into infected tissues develop into cells

called wandering macrophages that canphagocytize many more microbes thanneutrophils are able to.

Monocytes also clear up cellular debris after an

infection.

Eosinophils:

An increased (higher than usual) percentage of eosinophils in the blood may indicate parasitic

infection somewhere in the body.

This is illustrated below.

Blood Vessel

Introductory Note: Knowledge of the structure and function of blood vessels and other

aspects of the heart and vascular system are parts of training in many therapies, such as

Massage (incl. "Indian Head Massage", "Swedish Massage", "Acupressure Massage" etc.),

Aromatherapy, Shiatsu, and others. This page is intended to include the detail required for

most Basic / First Level Courses in these therapies, and some ITEC Diplomas



The main types of blood vessels are:

y Arteries,

y Arterioles,

y Capillaries,

y Venules, and

y Veins.These are described and compared on this page.

1. Diagrams

The following diagram summarises the sequence of blood flow through the heart, arteries,

arterioles, capillaries, venules, veins, then back to the heart:



2. Structure and Functions of Blood Vessels

Structure Functions

Arteries The walls (outer structure) of arteries

contain smooth muscle fibre that

contract and relax under the

instructions of the sympathetic

nervous system.

Transport blood away from the

heart;

Transport oxygenated blood only(except in the case of the

pulmonary artery).

Arterioles Arterioles are tiny branches of arteries that lead to capillaries. These

are also under the control of the

sympathetic nervous system, andconstrict and dialate, to regulate blood

flow.

Transport blood from arteries to

capillaries;

Arterioles are the main regulators

of blood flow and pressure.

CapillariesCapillaries are tiny (extremely

narrow) blood vessels, of

approximately 5-20 micro-metres

(one micro-metre = 0.000001metre)

diameter.

There are networks of capillaries in

most of the organs and tissues of the

body. These capillaries are supplied

with blood by arterioles and drained

by venules. Capillary walls are only

one cell thick (see diagram), whichpermits exchanges of material

between the contents of the capillaryand the surrounding tissue.

Function is to supply tissues with

components of, and carried by, theblood, and also to remove wastefrom the surrounding cells ... as

opposed to simply moving the

blood around the body (in the case

of other blood vessels);

Exchange of oxygen, carbon

dioxide, water, salts, etc., between

the blood and the surroundingbody tissues.

Venules Venules are minute vessels that drain

blood from capillaries and into veins.

Many venules unite to form a vein.

Drains blood from capillaries into

veins, for return to the heart

Veins The walls (outer structure) of veinsconsist of three layers of tissues that

are thinner and less elastic than thecorresponding layers of aerteries.

Veins include valves that aid the

return of blood to the heart by

preventing blood from flowing in thereverse direction.

Transport blood towards the

heart;

Transport deoxygenated blood

only (except in the case of the

pulmonary vein).

3. Comparison between Arteries and Veins

Arteries

Transport blood away from theheart;

Transport blood towards the heart;



Carry Oxygenated Blood(except in the case of the Pulmonary

Artery);

Carry De-oxygenated Blood(except in the case of the

Pulmonary Vein);

Have relatively narrow lumens (seediagram above);

Have relatively wide lumens (seediagram above);

Have relatively more muscle/elastic

tissue;

Have relatively less muscle/elastic

tissue;

Transports bloodunder higher pressure (than veins);

Transports bloodunder lower pressure (than

arteries);

Do not have valves (except for the

semi-lunar valves of the pulmonaryartery and the aorta).

Have valves throughout the main

veins of the body. These are toprevent blood flowing in the wrong

direction, as this could (in theory)return waste materials to the

tissues.

The Structure of the Heart

Introductory Note: Knowledge of the structure and function of the heart and other aspects

of the vascular system, is an essential part of training in many therapies, such as Massage

(in its many forms, "Indian Head Massage", "Swedish Massage", "Acupressure Massage"

etc.), Aromatherapy, Acupuncture, Shiatsu, and others. This page is intended to include the

detail required for most Basic / First Level Courses in these therapies, and some ITEC

Diplomas.

The first diagram (immediately below) is a cut-away section through the heart, showing itsphysical appearance and labelling its major components and blood vessels. The simpler

diagrams below it are line drawings including essential information in a form that is easier

to reproduce in exams.



Illustration of the Physical Form of the Heart

The heart is a muscular cone-shaped organ about the size of a clenched fist of the sameperson.

It is located in the upper body (chest area) between the lungs, and with its pointed end

(called the apex) downwards, forwards, and pointing towards the left.

The main purpose of the heart is to pump blood around the body.

The basic structure of the heart (illustrated above) may be described as follows:

The Heart is divided into separate right and left sections by theinterventricular septum,

or "septum" when the context is clearly that of the heart. Each of these (right and left)

sections is also divided into upper and lower compartments known as atriaand ventricles,

respectively.

The four main chambres of the heart are therefore the:Right Atrium (Labelled "RA" in the diagrams on this page);

Right Ventricle (Labelled "RV" in the diagrams on this page);

Left Atrium (Labelled "LA" in the diagrams on this page);

Left Ventricle (Labelled "LV" in the diagrams on this page).

Deoxygenated blood (from the body) is pumped through the right atrium and the right



ventricle (to the lungs), while oxygenated blood (from the lungs) is pumped through the

left atrium and the left ventricle (to the body).

Deoxygenated blood enters the right atrium from the Superior vena cava and

the Inferior vena cava.

Deoxygenated blood leaves the right ventricle by Pulmonary artery, which

takes blood to the lungs via the right and left brances of the pulmonary artery.Oxygenated blood enters the left atrium from the Pulmonary veins. These may

be labelled as "right pulmonary veins" and "left pulmonary veins".

Oxygenated blood leaves the left ventricle by Ascending aorta, which takes

blood to the body via its system of arteries, arterioles, and capillaries. Major

arteries leading from the heart (via the ascending aorta) includethebrachiocephalic artery, the left common carotid artery, and the left

subclavian artery (illustrated above). These are just a few of the main arteries

of the body.

It is essential that blood flows in the correct direction through the heart so the structure of

the heart includes a series of valves.The Tricuspid valve separates the right atrium from the right ventricle.

The Pulmonic / Pulmonary valve separates the right ventricle from the

pulmonary artery.

The Mitral (also known as the Bicuspid) valve separates the left atrium fromthe left ventricle.

The Aortic valve separates the right ventricle from the ascending aorta.

Line Drawings of the Basic Structure of the Heart

Although Diagram (1) above is a clear illustration of the structure of the heart it may be

difficult to reproduce quickly in examinations. The following diagrams are less detailed andnot as fully labelled (the same information as above applies so more labels could be added),but may be more convenient to sketch rapidly if required to do so.

Diagram (2)a is a simplification of Diagram (1); Diagram 2(b) includes additionalinformation about structures concerned with the system of electical conduction operating

in the heart (which is described on the page about The Functions of the Heart).

The Functions of the Heart

Introductory Note: Knowledge of the structure and function of the heart and other aspects

of the vascular system, is part of training in many therapies, such as Massage (in its many

forms, "Indian Head Massage", "Swedish Massage", "Acupressure Massage" etc.),Aromatherapy, Acupuncture, Shiatsu, and others. This page is intended to include thedetail required for most Basic / First Level Courses in these therapies, and some ITEC

Diplomas.

The physical form and structure of the heart is described and illustrated on the separate

page: The Structure of the Heart

The following diagrams are simple summaries of the main parts of the heart, the functions

of which are described below.



What are the Functions of the Heart ?

The main functions of the heart can be summarised as follows:

Right-Hand Side of the Heart

The right-hand side of the heart receives de-

oxygenated blood from the body tissues (from

the upper- and lower-body via the SuperiorVena Cava and the Inferior Vena Cava,

respectively) into the right atrium. This de-

oxygenated blood passes through the

tricuspid valve into the right ventricle. This

blood is then pumped under higher pressurefrom the right ventricle to the lungs via the

pulmonary artery

Left-Hand Side of the Heart

The left-hand side of the heart receives

oxygenated blood from the lungs (via the

pulmonary veins) into the left atrium. Thisoxygenated blood then passes through the

bicuspid valve into the left ventricle. It is

then pumped to the aorta under greater

pressure (as explained below). This higher

pressure ensures that the oxygenatedblood leaving the heart via the aorta is

effectively delivered to other parts of the

body via the vascular system of bllod

vessels (incl. arteries, arterioles, and

capillaries).

How does the heart perform these functions ?

The pump action performed by the heart is achieved by a sequence of alternating

contraction and relaxation of the heart muscle (illustrated above).

In this context the term "systole" refers to the contraction part of the sequence and the

term "diastole" to the relaxation part of the sequence. Hence, the "systolic" and "diastolic"

pressures may be measured and recorded separately when monitoring blood pressure.



This process is directed by the nervous system, nerve impluses initiating each sequence.

The whole series of actions that cause alternating contractions and relaxations may besummarised in five stages:

1. The vagus nerve stimulates the sinoatrial node (SAN), the pacemaker of the heart.

The sinoatrial node (SAN) is a tiny area of specialised cardiac (meaning "heart")muscle in the upper wall of the right atrium, near the vena cava - as shown above.

The fibres of the SAN contract rhythmically approx. 70 times each minute. After

each of these contractions, the impluse is dispersed across the atrial cardiac muscle,

leading to ...

2. ... simultaneous contraction of both the right and left atria. This movement of the

cardiac muscle pushes blood from the atria into the ventricles (via the tricuspid and

bicuspid valves).

3. The contractions of the atria send impulses down the Purkinje fibers, which in turn

stimulate the atrioventricular node (AVN).

The atrioventricular node is a mass of modified cardiac muscle located in the

lower/central part of the right atrium of the heart.The Purkinje fibres are referred to by various names in different textbooks, so are

also known as "Purkyne Fibres", "Purkynje Fibres", and as the "Bundle of His".This/these are a bundle of modified cardiac muscle fibers that transmit impulses

from the atra, via the AVN, to the ventricles.4. The action potential from the impulse transmitted down the Purkinje fibers reaches

the right and left branches of the Purkinje fibres - as shown in the diagram on the

right. This causes the ...

5. ... ventricles to contract, which pushes blood upwards into the arteries that take the

blood away from the heart (the pulmonary artery taking blood to the lungs, and theaorta taking blood to the body).

Systemic Circulation

Introductory Note: Knowledge of systemic circulation and other aspects of the heart and

vascular system are essential parts of training in many therapies, such as Massage (in itsmany forms, "Indian Head Massage", "Swedish Massage", "Accupressure Massage" etc.),

Aromatherapy, Acupuncture, Shiatsu, and others. This page is intended to include the detail

required for most Basic / First Level Courses in these therapies, and some ITEC Diplomas.

Systemic Circulation is the system of blood vessels and associated tissues that supplies

blood, and hence oxygen, to all parts of the body.

One of the best ways to describe this system is using a diagram:

Diagram summarising Systemic Circulation



This diagram and systemic circulation itself may be summarised in words as follows:



Oxygenated Blood

Oxygenated blood leaves the lungs and enters the Left Atrium (LA) of the heart via

the pulmonary veins.

This oxygenated blood is then pumped from the Left Atrium (LA) of the heart to the

Left Ventricle (LV) of the heart, and then out of the heart to the body tissues via

the aorta, which is the major artery leaving the heart.

The aorta divides into other arteries that serve different parts of the body (as

mentioned on the page about the

structure of the heart ). These can be separated into two categories: blood supply to

the upper-body, and blood supply to the lower-body.

Blood Supply to the Upper-Body:

The aorta leads to the subclavian arteries that take blood to the arms (some of

which eventually reaches the hands),

and also to the carotid artery that carries blood to the head.

Blood Supply to the Lower-Body:

The aorta also leads to the hepatic artery that carries blood to the liver,the mesenteric artery that carries blood to the small intestines,

the renal arteries that carry blood to the kidneys,

and the iliac arteries that carry blood to the legs (some of which eventually reachesthe feet.).

Deoxygenated Blood

Blood is deoxygenated when it leaves the tissues and organs it has supplied with

oxygen and other nutrients, to return back to the pulmonary circulatory system.This can also be summarised for the upper-body and lower-body separately:

Return of Blood from the Upper-Body:

Blood returns from the head via the jugular veins, and from the arms viathe subclavian veins. All of the blood in the major veins of the upper body flows into

the superior vena cava, which returns the blood to the right ventricle of the heart.

Return of Blood from the Lower-Body:

Blood returns from the small intestines by passing through the hepatic portal

vein to the liver.

Blood returns from the liver via the hepatic vein, from the kidneys via the renalveins, and from the legs via the iliac veins. All of the blood in the major veins of the

lower body flows into the inferior vena cava, which returns the blood to the right

ventricle of the heart.

After re-entering the (right atrium of the) heart via the superior vena cava andthe inferior vena cava, deoxygenated blood is pumped into the right ventricle of the

heart and then out of the heart to the lungs via the pulmonary artery.

Deoxygenated blood enters the lungs and is oxygenated before leaving the lungs (as

oxygenated blood), and so the cycle begins again ...

ntroductory Note: Knowledge of the structure and functions of blood and other aspects of

the heart and vascular system are part of training in many therapies, such as Massage,



Aromatherapy, Acupuncture, Shiatsu, and others. This page is intended as Revision Notes

for Basic / First Level Courses in these therapies, and some ITEC Diplomas.Measurement of Blood Pressure

Blood pressure can be measured by an instrument called a sphygmomanometer.

A column of mercury is linked to an inflatable cuff which is wound around the upper arm. A

stethoscope is then used to listen to the sounds of the blood in the brachial artery, at thebend of the elbow.The sounds start at the systolic pressure:

(heart contraction => higher pressure)and finish at the diastolic pressure:

(heart relaxation => lower pressure).

Hence blood pressure is expressed as :"height of column of Hg at systolic pressure "

"height of column of Hg at diastolic pressure".

Normal Blood Pressure is about mm Hg.

The following table summaries key causes, effects, and symptoms of both "High" and "Low"

Blood Pressure:



Causes of Condition Effects / Symptoms

High Blood Pressure May be of unknown cause

(essential hypertension,

or hyperpiesia)

May result from kidney disease,

including narrowing of the

renal artery (renal

hypertension)

Or endocrine diseases (such as

Cushing's disease or

phaeochromocytoma)

Or disease of the arteries (such

as contraction of the aorta) -

which is known as secondary,

orsymptomatic hypertension.

More general contributory factorsare :

Stress; Obesity; Age; Social

Class; Smoking; Lack of

exercise; Poor diet.

Damage to arteries &

veins.

Holes get blocked up bycolesterol.

Hypertension is symptomlessuntil the symptoms of its

complications develop.

These include :

Atherosclerosis

Heart failure,

Cerebral haemorrage,

Kidney failure.

Low Blood Pressure Can occur following:

Excessive fluid loss (e.g.through diarrhoea, burns or

vomiting),

Severe blood loss(haemorrage) from any cause.

Other causes may include:

Myocardinal infarction,

Pulmonary embolism,

Severe infections,

Allergic reactions,

Arrhythmias,

Acute abdominal conditions(e.g. pancreatitits),

Addisons disease, and

Drugs (e.g. an overdose of the

drugs used to treat hypertension).

Temporary Hypotension :

Simple faint (syncope)

Light-headed

Sweats

Impaired conciousnessSevere Hypotension :

Peripheral circulatoryfailure (cardiogenic shock)

Unrecordable blood

pressure

Weak pulses

Suppression of urine

production

the blood clotting mechanism

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