أحياء لغات الباب الثانى 3ث شرح بالفيديو Measuring the blood pressure حصريا

Due to the heart beating, the heart pushes the blood to the body through arteries and veins easily.

The blood is a viscous liquid can't move easily through the
microscopic blood capillaries, so the blood need a pressure to move
through it therefore, it causes resistance.

The resistance increases the blood pressure in the network of the arteries.

Systolic blood pressure is the maximum blood pressure in the
arteries that close to the heart during the contraction of the
ventricles.

Diastolic blood pressure is the minimum blood pressure in the
arteries that close to the heart during the relaxation of the
ventricles.

The blood pressure reading is expressed as two figures the
first (Systolic blood pressure) higher than the second Diastolic blood
pressure.



Measuring the blood pressure

Sphygmomanometer

It is an instrument that used to measure

the blood pressure.

Sphygmomanometer give 2 numbers

as 120/80 mm Hg in normal youth.

The no.120 indicate Systolic

blood pressure but 80 indicate the

Systolic blood pressure is the maximum

blood pressure in the arteries that close to the heart
during the contraction of the ventricles 120 mm Hg but it decrease until
reach 10 mm Hg in blood capillaries and veins therefore the presence
of the internal valves of vein help the blood to return back to the
heart .

The blood pressure increase gradually in old ages so, it needs to treat before it reaches the dangerous cases.

The structure of Mercurial sphygmomanometer

• It consists of mercury tube connected

to graduated scale.

• The blood pressure is measured

according the height of mercury column.

• A cuff is connected to the instrument

and placed around the upper arm.

• By using a Stethoscope the doctor can

hear the contraction of the ventricles

and distinguish the point of the systolic

blood pressure and distinguish diastolic

blood pressure when the sound disappear.

• The blood pressure can be measured when the heart beat and
between beat and the next and also by the digital instruments but
the mercury instrument is more accurate.


The blood circulation

1- Pulmonary circulation 2- Systematic circulation 3- Hepatic circulation

1. Pulmonary circulation

It starts from right ventricle & ends at left atrium.

When the right ventricle contracts,

the tricuspid valve shuts & the deoxygenated

blood rushes into the pulmonary artery and

the Simi-lunar valve is closed preventing the

returning back of the blood to the heart

The pulmonary artery divide into two branches, each

branch divides again into small branches till it ends

at blood capillaries around alveoli.

• Through the blood capillaries water vapour & CO2

come out the blood & O2 get into the blood

This is called exchange of gases so, the blood now become oxygenated.

• The blood returns from the lungs to the left atrium through the 4 pulmonary veins.

• The left atrium contracts pushing the blood down to the left ventricle through the bicuspid valve.


2- Systematic circulation

• It starts from the left ventricle

& ends at the right atrium.

• When the left ventricle contracts the bicuspid

valve shuts & Oxygenated blood rushes into

the aorta & does not go back to the heart.GR

• The aorta branches into arteries. Each artery

enters to an organ of the body and endat a

network of blood capillaries distributed

between the body tissues & cells

• Exchange of material between the blood &

the cells takes place where the cells receive

O2 & foodstuffs from the blood & the blood

receives CO2 , H2O & wastes.

• Exchange of substance takes place by

diffusion & active transport through the walls

of the blood capillaries.





The 2 sides of the heart, right & left contract at the
same time, so that pumping of the oxygenated & deoxygenated
blood takes place at the same time.







3- Hepatic portal circulation

The blood capillary of the villi, carrying digested food
stuffs, collect to form larger venules, These venules form a large vein
called hepatic portal vein that enters into the liver The hepatic portal
vein also receives other veins coming from the pancreas, the spleen
& the stomach.

The hepatic portal vein branches into smaller venules that end
at blood capillaries distributed between the hepatic cells, Through the
blood capillaries sugars & amino acids diffuse into the hepatic
cells where some changes occur.

The blood leaves the liver through the hepatic vein to join the
upper part of the inferior vena cava just before it opens at the right
atrium.



NB.


The hepatic portal vein is the only vein begins & ends by blood capillaries.

The liver is the only organ that receives an artery as well as a vein.

The hepatic portal vein and the hepatic vein are the only veins connected

together by blood capillaries



Summary:

1- Pulmonary circulation

Rt. Ventricle pulmonary artery Lungs 4pulmonary vein Lt Atrium

2- Systematic circulation

Lt. ventricle aorta body organs superior & inferior VC. Rt. atrium

3- Hepatic portal circulation

Villi blood capillaries hepatic portal V. hepatic V. Inf.V.C Rt. Atrium


Formation of the blood clotting

• The blood clots if it is exposed to the air or the cells are exposed to rough surface.

The mechanism of the blood clotting

• When the blood is exposed to air or to rough surface, as
damaged blood vessels & cells, the blood platelets with the
damaged cells form a protein substance named thromboplastin.

• In the presence of Ca++ ions, thromboplastin activates inactive
prothrombin into active thrombin (prothrombin is formed inside the
liver by the help of vitamin K It is then passed directly to the blood)
.

• Thrombin catalyses the conversion of soluble protein found in the blood named fibrinogen into Insoluble fibrin.

• Fibrin precipitates as a network of fibers, the blood cells
aggregate at that network forming the clot, which blocks damaged area at
the vessel, so that bleeding stops.



1- Blood platelets + destroyed cells clotting factors thromboplastin.


2 -Prothrombin Thromboplastin +clotting factors, Ca++ thrombin



3- Fibrinogen thrombin Fibrin


Why blood does not clot inside blood vessels?

Because:

1. Blood runs inside blood vessels in a regular speed and does not slow down.

2. Blood platelets slide easily and smoothly inside the blood vessels in order not to be broken.

3. The liver secretes a substance called heparin that prevents the conversion of thrombin into thrombin


N.B

During blood clotting the action of heparin stops


The lymphatic system is the immunity system of the body because
it has the ability to protect the body against the harmful bacteria and
the foreign particles and produce the antibodies which responsible for
the body immunity.