Vessels physiology. Blood pressure. Pulse. Capillary and venous circulation. Lymphatic supply.

Functional vessels classification:

1. Elastic:

· aorta;

· pulmonary artery;

· other large vessels.

2. Muscular:

· middle arteries;

· shallow arteries.

3. Resistive (vessels of resistance):

· ending arteries;

· arterioles.

4. Of exchange (exchangeable):

· capillaries.

5. Cavitary:

· veins;

· venules.

Blood movements through the vessels obey to some regularities known as hydrodynamics laws. But they are named as haemodynamics laws according to blood vessels.

Factors determining haemodynamics peculiarities (3 first are the main, rest are additional ones):

· pressure;

· resistance;

· velocity;

· vessel diameter and length;

· blood content;

· blood viscosity et al.

Circulation peculiarities:

· one-sided blood traffic through vessels;

· its continuosity;

· laminarity;

· turbulent character.

One-sided movement - is provided by pressure gradient (difference) at the beginning and at the end of vascular system. It is 120-150 mm merc col. in initial circulation part and 5-0 mm merc col - in ending part (veins inflowing into heart).

Circulation continuosity – is linked with vessels elasticity, when blood is pumped in aorta by heart (it possesses elasticity) then all its volume can not come through the vessels at once. More blood part is remained temporarily in dilated (due to elasticity) aorta region and then (in course of dyastole) leaves it due to aorta walls muscular contraction. The more elastic is aorta and other large arteries, the better circulation continuosity is realized. And on the contrary, at elasticity loss (with ageing, at sclerosis and other vessels injuries) circulation continuosity is disturbed.

Laminar or streamline and turbulent character of blood circulation movement character through vessels. Laminar circulation - is blood movement by separate layers in parallel to vessel axis (it is realized practically in all vessels). Turbulent circulation – with blood turbulence – occurs in the places of dilations, constrictions, flexures and pressures on them.

Vessels activity main indexes:

· velocity,

· pressure,

· pulse.

Blood movements velocity types:

1. Volumetric velocity – blood amount flowing through transversal vessel section in time unit. It is expressed in ml/min and depends on pressure gradient at vessel beginning and end as well as on resistance to blood stream. Its size depends on organ state (for instance, in course of muscular activity this velocity increases in them in tens times). This velocity is determined by rheography method.

2. Linear velocity – distance which blood particle passes through time unit. It is determined in m/sec and is under norma:

· in aorta – 0,5-1,0 m/sec,

· large arteries – up to 0,5 m/sec,

· in veins – 0,25 m/sec,

· in capillaries – 0,05 m/sec.

Investigation methods: direct – stains and different substances introduction; indirect – ultrasound.

3. Circulation velocity – blood transport time on circulation circle. Norma: 14-20 sec.

Investigative methods: radioactive.

 

Blood pressure – force whith which blood presses onto vessel walls.

It depends on:

a) heart activity,

b) vessels resistance,

c) their diameter,

d) their length,

e) blood viscosity.

Maximal (systolic) pressure is registrated during heart systole. Its size is equal to 100-130 mm merc col (on brachial artery). There is a tendency to this pressure increasing during last years of practically healthy children even of school age. Its level depends mainly on heart activity.

Minimal (dyastolic) pressure is characterized by size registrated during dyastole. Norma: 65-90 mm merc col. Vascular wall tone is a dominant factor determining this pressure.

Pulse pressure – matematic difference between systolic and dyatolic pressure level. Its maximal size is in arteries near heart. The farther from heart the pressure pulse difference is decreased and beginning from arterioles it disappears.

Middle-dynamic pressure – expresses energy with which blood is moved, it provides blood movement through vessels and it is the average resulting size for all pressure fluctuations (oscillations) alongside all vascular system. Its level is less than systolic but more than dyastolic. Norma: 90-100 mm merc col.

Pressure changings in course of transport through all vessels:

· aorta – 120-130 mm merc col.;

· arteries – 100-120 mm merc col.;

· arteries- 40-80 mm merc col.;

· capillaries – 20-40 mm merc col.;

· veins – 5-10 mm merc col.;

· vena cava - up to 0 mm merc col.

Arterial pulse – or push, arterial wall fluctuation caused by systolic pressure increasing in arteries. Pulse wave appears in aorta when pressure is sharply increased in it and its wall is stretched. This wave is spread with velocity 3-15 m per second from aorta to arterioles. It may be registrated on large, superficially located arteries, by palpation or graphically (sphygmogram). At palpation its necessary to perform on both hands simultaneousely (hands must be at heart level) in one and the same patient location from initial investigation. If one can not determine any difference further pulse investigation should be performed on one hand (at pulse difference on both hands pulse is called different). Different pulse may be diagnostic sign of mitral valve stenosis, aortal aneurisme.

One can differentiate on sphygmogram:

· anacrote (it corresponds to ventricles systole) – curve ascent (rising);

· catacrote (it corresponds to blood slow exile from ventricules in its beginning, rest part – ventricules dyastole) – curve descent (falling down, drop);

· dycrote – there is dycrotic ascent on catacrote, it corresponds to blood return to heart during dyastole ans its shock to semicircular valves.

Pulse clinical characteristics main indexes:

1. Freaquency – shocks (beats) amount per minute. Norma: 60-80 per minute (sometimes it is considered to 90). It may be estimated both on sphygmogram and by palpation.

A) Freaquent pulse (tachycardy, trachysphygmy) – it takes place at hyperthermia, in course of physical loading. At body temperature increasing on 1°C in adults pulse freaquency increases on 8-10 beats, in children – on 15-20 beats per 1 min.

B) Seldom pulse (bradycardy, bradysphygmy) – in sportsmen, in well-trained people.

C) Pulse freaquency is changing in course of ageing:

· new-borns – 130-140 beats per min;

· 1 year – 120-130;

· 7 years – 90-100.

2. Rhythm – is determined both on sphygmogram and by palpation.

A) Rhythmical (regular) pulse – it is observed at equal spaces between pulse waves.

B) Arythmical (irregular) - it is observed at unequal spaces between pulse waves. Physiological arhythmias may be at intensive muscular loading, thermal procedures.

3. Pulse velocity – intensivity with which pressure in artery is increased during pulse wave arising and is reduced in course of its drop (it is determined the best on sphygmogram).

A) Rapid pulse - it may be in course of physical activity, aortal valve insufficiency.

B) Slow pulse – at faint, aortal ostium constriction.

4. Pulse altitude – is determined on sphygmogram.

A) High pulse -it is rapid or fast at the same time.

B) Low pulse – it is slow at the same time.

5. Pulse tension – vascular wall force or resistance degree to its pressure with fingers.

A) Solid pulse – pulse is accelerated and becomes stronger after vessel wall pressure. As a rule, it is observed at elderness due to vascular elasticity reducing; at hypertonic disease.

B) Soft pulse – pulse becomes slower and low-expressed after vessel wall palpation. It is under norma.

Diagnostic value: on tension degree one can tell about maximal blood pressure level. There is direct correlation between these 2 indexes.

6. Pulse filling – consists of pulse altitude and its tension. The higher systolic pressure plus blood volume and pulse altitude, the filling is stronger.

A) Full pulse.

B) Empty pulse – if pulse is small by its size, it is empty, as a rule.

C) Filliformis pulse – it is practically unexpressed - it is observed at strong bleeding, collaps and so on.