Dyspnoea This article discusses different causes of dyspnoea, stages of dyspnoea, and more. Keywords : Psychometric | 5-point Likert Scale (5PLS) | MRC breathlessness scale| COPD| Table of contents 1. Introduction 2. Causes 3. Stages and severity 4. Treatment 5. Prognosis About’ total physiology.com.’ This article is part of my mission to provide trustworthy, recent health information to support the general public, patients, and professionals globally. Here you will find human Physiology and health-related topics. This article is intended for all learners and medical care providers. This activit...
Know
your blood vessels|Channel of blood flow|
Keywords: Tunica intima|Tunica media|Tunica
adventitia|Internal elastic lamina|External elastic lamina|windkessel artery|Distributing
artery|Angiogenesis|Vasculogenesis|
Table of contents
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Sr.no |
Contents |
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1. |
Definition |
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2. |
Types of blood vessels |
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3. |
Structure of blood vessels |
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4. |
Artery |
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5. |
Types of capillaries |
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6. |
Functions a blood vessels |
The blood vessel is the essential part that
transports blood throughout the human body in the circulatory system. It transports
blood from the heart to the body's tissues, collects it, and returns it to
the heart.
The blood vessels carry blood and provide the tissues with nutrition, hormones, and oxygen. In
addition, they transport waste metabolites and carbon dioxide from the tissues to
the heart. Therefore, the blood vessel is vital to maintain life.
Types
of blood vessels
An artery carries blood from the heart, and the
capillaries distribute and exchange water and chemicals between the blood and
the tissues. Then, venules and veins carry blood from the capillaries back
toward the heart.
The word vascular is derived from the Latin ‘vas’, which means vessels, And vascular denotes blood vessels.
The vascular organs or structures that contain
blood vessels are known as vascular organs, and
Avascular organs or structures do not have blood
vessels some organs, for example, cartilage, epithelium, and the lens and
cornea of the eye.
Structure
of blood vessels
The blood vessels have three layers except
for the capillaries, a single layer. The layers are:
1. The inner layer is tunica intima. It is a
single layer of ‘simple squamous epithelium.’The tunica interna are attached by
a polysaccharide intercellular matrix surrounded by a thin layer of subendothelial
connective tissue with multiple circular elastic bands. This is the internal
elastic lamina. A thin membrane of elastic fibers in the tunica intima run
parallel to the vessel is the internal elastic lamina.
2. Tunica media is the middle layer of the vessel wall,
which is separated from the tunica interna by the internal elastic lamina. Tunica
media is the thickest layer and consists of circularly arranged elastic fiber,
connective tissue, and polysaccharides. In the arteries, the tunica media is
rich in vascular smooth muscle that controls the caliber of the vessels. This layer
is separated from the outer layer by external elastic lamina. The external
elastic lamina is a thick elastic band.
The veins are not rich in vascular smooth muscle and
do not have external elastic lamina. However, the internal elastic lamina is present.
3. Tunica adventitia is the outermost layer of
a blood vessel. lt is thick in veins and contains connective tissues with
nerves and capillaries in larger blood vessels-‘Vasa vasorum’. The blood vessel
supplying the blood vessel is ‘Vasa vasorum.’
Capillaries consist of a single layer of
endothelial cells, with the supporting endothelium consisting of a basement
membrane and connective tissue.
Anastomosis: A diffuse network of the blood vessels to
supply blood is known as anastomosis and plays a vital role in maintaining
blood supply in case of blockage.
Valves are present in the upper and lower
extremities. In leg veins, it is well developed and allows blood to flow
towards the heart, preventing blood from flowing in the reverse direction in
normal conditions.
The blood vessels are divided into arteries
and veins according to the direction of blood flow in the vessels.
In the arteries,
the blood flows away from the heart.
And in the veins, it flows toward the heart.
The artery carries 98-100% oxygenated or pure blood,
but the exception is the pulmonary artery, which carries blood with 75% oxygen-deoxygenated (impure)
blood.
The vein carries blood with75% oxygen-deoxygenated (impure)
blood, but the pulmonary vein carries 98-100% oxygenated or pure blood.
Artery
1. Distensible artery =windkessel: Aorta and
Pulmonary artery and their large branches.
2. Distributing arteries, arterioles, and
metaarterioles with precapillary sphincters.
3. Exchange vessels: capillaries, and
4. Capacitance vessels, veins and venules
Arteriovenous shunts or shunt vessels: or Thoroughfare
vessels:
They do not have capillaries. So the arterial
blood will go directly to the veins. These shunts are mainly present in the
skin of exposed body parts, such as the legs, toes, fingers, palms, chicks, and
lips.
They have a significant role in the temperature regulation
of the body. When the temperature rises, these vessels will dilate and increase heat loss.
In the cold, these vessels will constrict and
reduce heat loss that is preserved heat in the body.
Types
of capillaries
1. In Continuous or non-fenestrated capillaries,
the endothelial cells are tightly attached.
2. Fenestrated capillaries and
3. Discontinuous capillaries are also known
as Sinusoids.
Functions
of blood vessels
Transport: Oxygenated blood from the lungs to multiple
organs and deoxygenated blood from the body to the lungs.
Endothelial cells of the endothelial layer of blood vessels perform many essential metabolic and endocrinal functions.
In the blood vessels, blood circulates
throughout the circulatory system.
The blood vessels are not actively engaged in blood
transportation. Instead, the blood is propelled through the arteries, in a cyclic-pulse
fashion, due to pressure generated by the heart. But the blood vessels maintain
blood flow at a constant rate.
In the veins, blood moves toward the heart due to the following:
Milking effect of the muscles
Presence of valves in veins, and
Respiratory movements.
Endothelial permeability is vital in releasing
nutrients to the tissue.
Arteries and veins regulate their diameters, and the
blood flows through them by autoregulation. Autoregulation is mainly by metabolic
end-products and the autonomic nervous system. For example, the sympathetic
nervous system causes vasoconstriction.
The blood vessels channel delivers blood to all body
parts because the Rt.and Lt. sides of the heart work together to allow
continuous blood flow to the lungs and other parts of the body.
The capillaries distribute oxygen and
nutrients to the tissues and remove carbon dioxide and metabolic end products.
The
blood pressure in blood vessels
The blood pressure is expressed in millimeters of mercury.
(1 mm of
mercury is equal to 133 Pascal).
Blood
pressure in the arterial system is usually systolic, 120 mm of mercury, and diastolic,
about 80 mm of mercury. But in the venous system, it is almost constant and never
exceeds 10 mm of mercury.
The role of blood vessels is critical in all
medical conditions. For example, cancer cannot progress unless new blood
vessels are formed by angiogenesis.
|
Angiogenesis: blood vessels
develop from the existing blood vessels. |
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Vasculogenesis: blood vessels develop from the angioblast |
Accumulation of plaque in blood vessels, especially
coronary arteries, may cause heart attacks or cardiac arrest.
Blood vessel permeability increases in
inflammation.
Vasculitis is inflammation of the blood vessels
due to infection for autoimmune disease.
Damage to the blood vessels by trauma or spontaneously
causes bleeding or hemorrhage.
Blood vessel occlusion leads to downstream ischemia
or infarction.
Hashtags: Windkesselartery #Distributingartery # Angiogenesis #Vasculogenesis #
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