Human Physiology(circulatory system)

Circulatory system :The human circulatory system demonstrates the

organisational complexity of the human. It is

made up of a number of different tissues

organised into organs such as the heart, arteries,

arterioles, capillaries, venules and veins.

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Open versus closed circulatory

systems: Open Circulatory System: blood is

pumped from a simple heart and flows out of

blood vessels and around tissue cells of the

organism, e.g. invertebrates, such as insects. The

blood is then returned to the heart via small

pores called ostia.

Closed Circulatory System: blood flows around the body enclosed in blood

vessels and does not leaves the blood vessels, e.g. human.

Structure of the human circulatory system

The human circulatory system consists of: Blood vessels,

Heart, Blood

Blood vessels: Arteries: blood vessels that carry blood away

from the heart in pulses. It has a thick wall and small lumen.

The thick wall of arteries contains a tough outer layer of

collagen that gives strength to the artery that supports the

pressure the blood is under from the heart.

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It also contains a layer of smooth (involuntary) muscle that contracts pushing blood

along. The internal layer of the artery is composed of a layer of cells called the

endothelium.

Veins: blood vessels that carry blood towards the heart in an even flow. They have thin

walls, a large lumen and valves.

Blood pressure in veins is much lower than arteries, hence the thinner wall. They

also have smooth muscle to push blood along in one direction and have valves to prevent

back flow of blood.

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Capillaries: blood vessels with walls one cell thick that carries blood from arterioles to

venules through tissues, releasing nutrients and taking away wastes.

Systemic and pulmonary circuitsThe human circulatory system consists of two blood circuits: the

systemic circuit and the pulmonary circuit. This is why the human

circulatory system is described as a double circulatory system.

The systemic circuit carries blood to all the major organs of the body,

except the lungs.

The lungs have their own blood circuit, called the pulmonary circuit.

The diagram below shows all the arteries and veins emanating from,

and returning to, the heart and internal organs.

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Structure of the heart.

Aorta: largest artery in the body carrying oxygenated blood away

from the left side of the heart to all the major organs of the body

(except the lungs).

Pulmonary artery: carries deoxygenated blood away from the

right side of the heart to the lungs to excrete carbon dioxide and

absorb more oxygen.

Pulmonary vein: carries oxygenated blood towards the right hand

side of the heart from the lungs.

Left atrium: upper left chamber of the heart that receives blood

from the lungs and contracts pumping blood into the left ventricle.

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Inferior vena cava: carries deoxygenated blood from the lower half of the

body back to the heart.

Tricuspid valve: allows one-way flow of blood from the right atrium to the

right ventricle - preventing back-flow of blood.

Right atrium: upper right chamber of the heart that receives blood from the

vena cavae and contracts pumping blood into the right ventricle.

Superior vena cava: carries deoxygenated blood from the upper half of the

body back to the heart.

Semilunar valves: allow one-way flow of blood out of the heart - prevent

back-flow of blood into the heart.

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Pulse and blood pressure

Pulse: alternate contraction and relaxation of an artery as blood passes

through.

Blood pressure: force blood exerts on the walls of blood vessels. Blood

pressure is measured as two values: systolic pressure and diastolic pressure.

Normal blood pressure is 120/80 mmHg, where mmHg stands for millimetres

of mercury. Blood pressure is measured using a sphygmomanometer. Effects

of smoking, diet and exercise on the circulatory system

Smoking: Cigarettes contain many addictive chemicals, of which the most

important is nicotine.

Nicotine raises heart rate and blood pressure putting a strain on the

circulatory system.

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Diet: A diet high in saturated fats increases blood pressure and the risk of atherosclerosis

(or hardening of the arteries).

Salt in the diet also raises blood pressure by increasing thirst and water intake.

Exercise: Exercise stimulates a temporary increase in heart rate and blood pressure.

It strengthens the heart and promotes healthy blood vessels.

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12. HEART RATE AND CARDIAC OUTAPUT

The heart beats about 72 times per minute, i.e., these many cardiac

cycles occur in a minute.

So it could be deduced that the duration of one cardiac cycle is

about 0.8 seconds.

The volume of blood pumped by each ventricle during a cardiac

cycle, is called stroke volume, its is about 70 ml.

The cardiac output refers to the volume of blood pumped out by

each ventricle in a minute, i.e., stroke volume multiplied by number

of cardiac cycles in a minute, which is 70 ml x 72 approximately 5000

ml or 5 litres.

The cardiac output of athletes is much higher than normal people.

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13. ELECTROCARDIOGRAM (ECG)

Electrocardiogram is the graphic record of the electrical potential

differences produced by the excitation of heart muscles as a function

of time.

Electrocardiograph is the machine used to monitor the heart

function. To obtain a standard ECG, the patient is connected to the

machine with three electrical leads, one in each of the wrists and one

to the left ankle, that monitor the heart function.

. By counting the number of QRS complexes formed in a given time

period, one can determine the rate of heart beat of an individual.

Since normal ECG has a fixed pattern, any deviation from it

indicates an abnormality or disorder in the heart functioning.

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15. REGULATION OF CARDIAC ACTIVITY The normal functioning of heart is auto regulated, i.e.,

regulated intrinsically by specialized nodal muscles; hence

the heart is described as myogenic.

A special nerve centre in the medulla oblongata can moderate

the cardiac activity through autonomic nervous system

(ANS).

Hormones of adrenal medulla (adrenaline and

noradrenaline) also increase the heart beat rate and cardiac

output.

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16. LYMPHATIC SYSTEM

Lymphatic system includes the fluid, lymph. lymphocytes and lymph

vessels.

A. Lymph

– As blood is flowing with pressure in the arteries, some water and

dissolved materials seep out into the tissue spaces; this fluid is called

interstitial fluid.

– The part of the interstitial fluid that enters the lymph channels, is

called the lymph.

– Lymph has a composition similar to that of plasma, except that it

has less proteins, as the capillary wall is not permeable to the large

plasma proteins; lymph also has lymphocytes, a type of

agranulocytes.

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B. Circulation of Lymph

– Fine channels arising from the tissue spaces, into which a portion

of the interstitial fluid flows, are the lymph vessels.

– The lymph vessels join and ultimately open into the venous blood

system and reach the heart.

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C. Functions

– It acts as the medium for exchange of gases, nutrients, etc. between

the blood and tissue cells.

– It acts as an accessory route for the flow of interstitial fluid into

the blood.

– The lymphocytes play an important role in the immune system. - It

takes the larger biomolecules into blood for circulation.

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17. DISRDERS OF CIRCULATORY SYSTEM

A. Hypertension

– It is commonly known as high blood pressure, to indicate a blood

pressure that is higher than the normal, i.e., 120/80 mm Hg.

– A sustained high blood pressure of 140/90 mm Hg or higher, is

called hypertension. - It leads to heart diseases and affects the

functioning of vital organs like kidney and brain.

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B. Coronary Artery Disease (CAD)

– It is a disorder which affects the blood vessels (coronary arteries)

that supply blood to the heart muscles. Atherosclerosis is a form of

CAD, which. is caused by the deposition of cholesterol on the wall

lining the lumen of blood vessels.

It makes the lumen narrow and reduces the blood flow to the heart.

– When the cholesterol deposits on the wall of blood vessels become

calcified and hardened, the condition is called arteriosclerosis; such

blood vessels lose their elasticity and become stiff, apart from having

narrow lumen.

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C. Angina pectoris– It is commonly called angina and occurs due to any condition that

affects the blood flow to the heart muscle.

– Due to this, cnough of oxygen is not supplied to the heart muscle

and a symptom of acute chest pain appears.

– It can occur in men and women of any age.

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D. Heart Failure

– It is the condition or state of the heart when it cannot pump

sufficient blood to meet the needs of the body.

– More often the cause for this condition is congestion of lungs;

hence it is called congestive heart failure.

– Heart failure is different from cardiac arrest, where the heart

stops beating and heart attack, where the heart muscle is damaged

suddenly due to insufficient blood supply.

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भानव शयीय- ऩरयसॊचयण तॊत्र

यक्त का सभस्त शयीय भें ऩरयभ्रभण ऩरयसॊचयण तॊत्र कहराता है। भानव के ऩरयसॊचयण तॊत्र भें यक्त नलरकाएॊ (Blood vessels) तथा रृदम भुख्म रूऩ से कामय कयत ेहैं।

रृदम एक ऩॊऩ की तयह काभ कयता है। रृदम एक ऩेशीम अॊग है, जजसका वजन रगबग 280 ग्राभ होता है।

रृदम से यक्त धभननमों द्वाया शयीय के ववलबन्न बागों को जाता है तथा वहाॊ से लशयाओॊ के द्वाया रृदम भें वाऩस आता है।

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इस प्रकाय यक्त, रृदम धभननमों औय लशयाओॊ द्वाया ऩूये शयीय भें जीवनबय रगाताय भ्रभण कयता यहता है।

यक्त नलरकाएॊधभननमाॊ Arteries: मे रृदम से यक्त को शयीय के ववलबन्न अॊगों तक रे जाने का कामय कयती हैं।लशयाएॊ Veins: मे शयीय के ववलबन्न अॊगों से यक्त को रृदम भें वाऩस राती हैं।

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ऩरयसॊचयण Circulation: शुद्ध मा ऑक्सीजनमुक्त (Oxygenated) यक्त पेपडों से रृदम भें आता है। रृदम ऩॊवऩ ॊग क्रिमा द्वाया इस यक्त को धभननमों के द्वाया ऩूये शयीय भें ऩहुॊचाता है। शयीय के यक्त भें लभरा ऑक्सीजन प्रमुक्त हो जाता है औय अशदु्ध मा ऑक्सीजन यहहत (Deoxygenated) यक्त लशयाओॊ द्वाया क्रपय रृदम की ओय आता है। रृदम इस यक्त को ऑक्सीजन प्राप्त कयने के लरए क्रपय से पेपडों भें बेजता है। इस प्रकाय मह चि ननयॊतय चरता यहता है।

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यक्त

यक्त यक्त एक तयर सॊमोजी ऊतक है। मह हल्के मा गहये रार यॊग का अऩायदशी, गाढा, ऺायीम व स्वाद भें नभकीन होता है। मह रृदम एवॊ रुधधय वाहहननमों भें प्रवाहहत होकय सम्ऩूणय शयीय भें ननयॊतय ऩरयभ्रभण कयता यहता है। भनुष्म के शयीय भें यक्त की भात्रा शयीय के बाय का रगबग 7 से 8% होती है। अत् एक स्वस्थ भनुष्म के शयीय भें रगबग 5 से 6 रीटय यक्त होता हैं, जो उसके सम्ऩूणय शयीय के बाय का रगबग 9/13वाॉ बाग होता है। जस्त्रमों के शयीय भें यक्त की भात्रा रगबग 4 से 5 रीटय होती है।

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सॊयचनासॊयचना के आधाय ऩय भनुष्म के यक्त को दो बागों भें ववबक्त क्रकमा गमा है-

प्राज्भा - आमतन के आधाय ऩय रगबग 55 से 60% बाग।

रुधधय कणणकाएॉ मा रुधधयाणु - रगबग 40 से 45% बाग।

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रक्त कणिकाएँप्राज्भा के अनतरयक्त शषे यक्त का रगबग 40-45% बाग रुधधयाणुओॊ का फना होता है। इस बाग को हीभेटोक्रिट कहते हैं। भनुष्म के यक्त भें ननम्नलरणित तीन प्रकाय की रुधधय कणणकाएॉ मा रुधधयाणु ऩाई जाती हैं-

यक्त कोलशका

रार यक्त कणणकाएॉश्वेत यक्त कणणकाएॉयक्त प्रेंटरेट्स

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यक्त सभूह

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रृदमहभाये शयीय का एक अत्मॊत भहत्वऩूणय अॊग है, जो वऺ भें फाईं ओय जस्थत होता है। फॊद भटु्ठी के आकाय के रृदम का बाय रगबग 300 ग्राभ होता है। इसके दोनों ओय दो पेपड ेहोते हैं। रृदम ऩय णझल्री का फना एक आवयण होता है, जजसे ऩेयीकार्ड यमभ कहते हैं। इसकी दो ऩयतें होती हैं- एक ऩयत रृदम के सॊऩकय भें यहती है औय दसूयी इसके फाहय होती है। रृदम वास्तव भें एक भाॊसऩेशी है, जजसके अॊदय यक्त बया यहता है। इस बाग को भामोकार्ड यमभ (Myocardium) कहते हैं। इसके अॊदय की ऩयत, जो यक्त के सॊऩकय भें यहती है, एन्डोकार्ड यमभ (Endocardium) कहराती है।

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रृदम एक िोिरा अॊग है, जो चाय कोष्ठों (Chambers) भें फॊटा होता है। दो कोष्ठ दाहहनी ओय होते हैं, जजनके फीच भें एक ऩयदा (Septum) होता है, जो दाहहने औय फाएॊ ओय के यक्त को लभरने नहीॊ देता। ऊऩय का कोष्ठ अलरॊद (Atrium) औय नीचे का ननरम (Ventricle) कहराता है। इस प्रकाय दोनों तयप दो-दो कोष्ठ होते हैं – दाहहना अलरॊद (Right Atrium) औय ननरम (Ventricle) तथा फामाॊ अलरॊद (Left Atrium) औय ननरमI अलरॊद औय ननरम के फीच भें फड-ेफड ेछेद होते हैं, जजनभें वाल्व (Valve) रगे होते हैं। मे केवर एक ही हदशा भें ननरम की ओय िुरते हैं। इनसे यक्त अलरॊद से ननरम भें तो जा सकता है, रेक्रकन ननरम से अलरॊद भें वाऩस नहीॊ आ सकता। मे वाल्व फॊद होकय उसके जाने का भागय योक रेते हैं।रृदम एक ऩॊऩ की तयह काभ कयता है औय सभस्त शयीय भें यक्त को बेजता है। इसकी दो साइडें एक साथ काभ कयती हैं। एक ओय से इसभें भहालशया (Vena Cava) औय ऩल्भोनयी धभननमों द्वाया यक्त आता है, जो रृदम के ऊऩयी कोष्ठ अलरॊद (Atrium) भें एकत्र हो जाता है। यक्त अलरॊद से ननरम (Ventricle) भें जाता है औय दाहहने ननरम से ऩल्भोनयी धभनी (Pulmonary Artery) द्वाया पेपडों भें ऩहुॊचता है। पेपडों भें ऑक्सीजन के लभरने से वह शुद्ध होकय ऩल्भोनयी लशयाओॊ भें होता हुआ फाएॊ अलरॊद भें रौट आता है। जफ वह अलरॊद से ननरम भें जाता है, तो वह उसको भहाधभनी (Aorta) भें बेज देता है। वहाॊ से मह अऩनी शािाओॊ द्वाया उसको सभस्त शयीय भें ऩहुॊचाती है।

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ह्रदम धडकन Heart Beatsरृदम (Heart) रृदम भानव शयीय का अनत भहत्त्वऩूणय अॊग होता है। मह शयीय भें वऺ बाग भें थोडा फाईं ओय अधय तर की ओय जस्थत होता है। मह जीवनऩमयन्त धडकता यहता है।

स्ऩॊदनभनुष्म का रृदम एक लभनट भें 70-80 फाद स्ऩॊहदत होता है। इसे रृदम स्ऩॊदन की दय कहते हैं।

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1.RBCs की अधधकता (साभान्म से ज्मादा) ऩोरीसाइथीलभमा (Polycythemia)

2. RBCs की कभी (साभान्म से कभ) यक्ताल्ऩता (Anaemia)

3. WBCs की अधधकता (साभान्म से अधधक) ल्मूकलभमा (Leukemia)

4. WBCs की कभी (साभान्म से कभ) ल्मूकोऩीननमा (Leukopenia)

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