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Blood pressure regulation by baroreceptors

 

Reports or information related to blood pressure variations in the arterial system (the level, volume and chemical composition of the blood) can be sensed and gathered through specific receptors. There are the following receptors: baroreceptors, chemoreceptors and receptors from heart atrium chambers and chambers (A, B and C type, natriuretic peptide).



Picture 1. Anatomic picture of aortal /carotid nerves. Main nerves connecting the area of the baroreceptors with the hypothalamus through spinal chord with Nervus Glossopharygeus (IX nerve) and Nervus Vagus (X)

There are two types of baroreceptors shown in the Picture. One type is found in the carotidal sinus at the point of forking of the carotidal artery, and the other type is in the aortal wall. There are also receptors scattered between these "main" receptors. Baroreceptors are terminal part of nerve fibrils, which forks in adventitia and meiya of the carotidal sinus and the above mentioned part of the aorta.

In which way does the increased blood pressure stimulate baroreceptors?

Increased blood pressure in the arterial system causes the stretching of the blood vessel wall, and even of the receptor itself. It means that the increased blood pressure causes the stretching of elastic blood vessel. When stretched, the receptor reacts and has effects on the newly generated situation. The activity of baroreceptors is continuous, or we could better say they are always "awake" and continuously responding to blood pressure variations. Received stimuli due to blood pressure variation, its increase or drop, are sent to corresponding brain centres. These "centres" are also continuously active, sending the received "information" toward parasympaticus or sympaticus. If the influence of sympaticus is decreased, the heart rhythm slows down and the diameter of blood vessels increases, resulting in the drop in blood pressure in the arterial system.
When the blood pressure reaches 220 mmHg, the frequency of impulses from corresponding nerve is close to the maximum response. Normal heart (provided that also CNS is balanced) imposes to the receptors alternately the systolic and diastolic pressure. During variation of the blood pressure, when it is in the phase of dropping, the receptors stop their activity, even when the pressure is above the threshold when their intervention normally begins. It means that the receptors are sensitive not only to medium arterial pressure, but also to the speed of arterial pressure variations
The hypothalamus, as the emotion centre, may cause the increase in the blood pressure, by sending gathered information (impulses) through the sympaticus in case of: anger, fear or uneasiness (feelings that the modern man goes to bed and wakes up with). Over a certain period of time a chronic hypertension will appear. This is, to some extent, an explanation of the mass occurrence of hypertension in our region.



When will we write the diagnosis: dg hypertensia arterialis?
 

Systolic pressure

Diastolic pressure

Normal - increased- 130 - 139 mmHg

Increased- 9o mmHg and more

Normal - increased- 130 - 139 mmHg

Normal - increased - 85 – 89 mmHg

Ideal 129 or lower

Ideal 84 or lower

 

A physician will write the diagnosis hypertensia arterialis if the blood pressure measurements made during more than two visits to the physician, show the values exceeding the ideal pressure values.

PHISIOLOGIC STATUS

PATOLOGIC STATUS

HABITS, LIFESTYLE

- Age
- Sex
- Heredity
- A type personality

- Hypertension
- Dyslipidemia
- Diabetes mellitus

- Smoking
- High fat nutrition
- Sedentary job

 

Risk factors for cardiovascular diseases (RFCD) can be divided into three categories: physiologic, pathologic and those depending on lifestyle and habits.

Some states of pain, or suffering, which may be increased by worry, or strong desire which cannot be realized (in case of poverty, struggle for survival, unfair competition, constant psychic tension), cause the increased secretion of cateholamines. Cateholamines have effects on the pancreas (on beta cells), which causes the decreased secretion of insulin. Insulin suppression increases the activity of the cyclic AMP, which increases FFA (free fatty acids) in the plasma. They cause damage to the metabolism of myocardium.

Cateholamines produce bad effects also to the liver. They cause in the liver the glycogenolisis increasing in this way the content of glucose in the blood. It also causes disorders of the metabolism of myocardium (the heart muscle). Decreased quantity of insulin causes additional metabolic disorders. The increased blood pressure and obesity occurs with most of these patients. This is still the realistic picture of our everyday survival and the cause of the occurrence of the hypertension disease.
 

 

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