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Flashcards in Circulatory system Deck (60):
1

Describe the heart and position

The Heart•Hollow coned shaped muscular organ -approximately size of the owners fist•It lies in the thoracic cavity, obliquely in the mediastinum, behind the sternum.•2/3 lies to the left of the midline,•Base above, apex below, resting on the diaphragm.

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Three layers of the walls of The Heart

Three layers of the walls of The Heart •Pericardium – fibrous outer sac –2 layers •Myocardium – muscle layer, thickest in the left ventricle, has its own intrinsic stimulus, coronary arteries found here •Endocardium – smooth inner lining continuous with blood vessels

3

Pericardium

Pericardium•Consists of two sacs–an outer fibrous sac (Fibrous pericardium)–a double inner layer of serous membrane •The outer layer of serous membrane, called the parietal pericardium adheres to the outer fibrous pericardium•The innermost layer of serous membrane, called the visceral pericardium adheres to the myocardium

4

Myocardium

MyocardiumIs the muscle layer of the heart. It is thickest around the left ventricle and has a unique characteristic, called Automaticity.This means the heart can contract without an outside stimulus

5

Endocardium

EndocardiumThe innermost lining of the heart and its valves, it is composed of endothelium, providing a smooth lining and preventing local blood clotting

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Three  main components of the circulatory system + what

Three Main Components •

The heart •

Blood vessels •

Blood

and control mechanisms

7

Heart chambers

Heart ChambersFour chambers •Left and right atria •Left and right ventricles •Left and Right sides are divided by muscular partition called the septum

8

Heart valves

Heart ValvesFour valves: •Pulmonary valve •Aortic valve •Two atrioventricular valves–Right or tricuspid valve–Left or mitral valve

9

Pulmonary & Systemic circulation

Pulmonary & Systemic Circulation •Pulmonary – involves pumping deoxygenated blood to the lungs and returning re-oxygenated blood to the heart •Systemic – involves circulating oxygenated blood throughout the body to the tissues and returning deoxygenated blood to the heart

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Types of blood Vessel

The heart pumps blood into vessels that vary in structure, size, and function, and there are several types:• arteries• arterioles• capillaries• venules• veins

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Structure of Blood Vessels

Structure of Blood Vessels

All vessels are structured in three layers: •

Tunica Adventicia (Outer fibrous sheath) •

Tunica Media (middle layer of muscle and elastic tissue)

•Tunica Intima (Inner layer of smooth endothelium)

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Portal circulation

Portal Circulation•A branch of the systemic circulation•Carries blood to and from the liver•Hepatic artery supplies oxygenated blood•Hepatic portal vein carries blood rich in nutrients from the digestive tract to the liver•Hepatic Veins carry deoxygenated blood from Liver to Inferior Vena Cava

13

Spleen

Spleen•Lies in the left hypochondrial region of the abdominal cavity, between fundus of the stomach and the diaphragm •Size varies but usually approx. 12cm long, 7cm wide and 2.5cm thick •Weighs approx. 200g

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Function of the spleen

Functions of the Spleen •Produce new white blood cells •Store red blood cells •Destroy old red blood cells

15

Composition of blood

Composition of Blood Blood is composed of 55% liquid, 45% solids and contains four main elements: •Plasma (Liquid) •Red cells (erythrocytes) •White cells (leukocytes) •Platelets (thrombocytes)

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Principle functions of blood

Principle Functions of Blood•Carry oxygen and carbon dioxide•Carry nutrients and water •Carry waste products to excretory organs •Distribute secretion of glands (Enzymes and hormones) Protect the body from infection •Distribute heat •Seal wounds by clotting

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Plasma

Plasma

Plasma is a straw coloured transparent fluid made up of approximately 90% water and 10% dissolved substances like proteins, mineral salts, and nutrients like fats and carbohydrates .

It is responsibile for carrying the solid constituents of blood around the body in order for them to carry out their specific function.

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Red blood cells (erythrocytes)

Red blood cells (erythrocytes)

Red blood cells are bi-concave discs. There are approximately 5.5 million per cubic millimetre of blood and they are produced within the red bone marrow of some bones.

They contain a protein called haemoglobin, made up of two substances, globin and haem. Haem is an iron containing pigment that gives the cell its colour, globin is a protein.

Haemoglobin has a great affinity for oxygen, and this helps to carry the gas around the body. In an oxygen-enriched state it is called oxyhaemoglobin.

When the oxygen is given up at the tissue level, the haemoglobin attracts carbon dioxide from the tissues and then carries it back to the lungs for exhalation from the body. Haemoglobin in this state is called carbaminohaemoglobin.

Red blood cells have a life span of approximately 120 days, after which they are destroyed by the spleen or liver.

 

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White blood cells (leukocytes)

White blood cells (leukocytes)

These cells are larger than red blood cells and consequently there are less of them - approximately 9,000 per cubic millimetre of blood.

It is possible to divide this group of cells into five sub groups, but for the purpose of this course we will treat them all as one.

White cells as a whole have two major functions:

To fight infection

To provide the body with immunity

20

Platelets (thrombocytes)

Platelets (thrombocytes)

Platelets are small colourless bodies that react with enzymes, proteins and mineral salts when an injury occurs to form a blood clot, thus preventing the escape of too much blood.

This process can be faulty in some illnesses such as haemophilia

21

What are blood vessels?

What are blood vessels?

Blood is transported around the body in tube-like vessels. There are several different types of blood vessel and they differ in structure according to location and function.

Arteries carry blood away from the heart. As these arteries become smaller they are called arterioles. In turn, as arterioles become smaller they become capillaries. Capillaries have extremely thin walls through which the oxygen and nutrients are delivered to the tissues.

The walls of the capillaries only allow certain size molecules to pass through, this is why blood plasma and other blood cells (large molecules) remain within the circulation while oxygen and nutrients move on to the tissues.

Waste products of tissue metabolism are returned to the capillaries and on, back to the heart. The return journey is via the venous system. Capillaries begin to get larger and their walls thicker at which stage they are called venules. They continue to enlarge and become known as veins. Veins always carry blood back to the heart.

In order to aid the return of blood to the heart, some veins, especially those of the lower extremities and the arms, possess tiny valves that prevent backflow and maintain the forward momentum of the blood returning to the heart.

22

What is the capillary network?

What is the capillary network?

Capillaries surround and penetrate whatever tissue or organ they are supplying, forming what is termed a capillary network or bed. The exchange of gases and nutrients for waste products takes place within and through this network.

The smooth muscle within the construction of the arterioles and venules is responsible for maintaining the correct blood pressure within the capillary network.

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Systemic circulation

Systemic circulation

Systemic circulation is made up of those vessels that supply the major organs and systems of the body and emanate from the left ventricle of the heart, via the aorta , and drain back into the right atrium of the heart via the superior and inferior vena cava .

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Pulmonary circulation

Pulmonary circulation

Pulmonary circulation is made up of those vessels that take deoxygenated blood from the right ventricle of the heart, via the pulmonary artery to the lungs, and oxygenated blood from the lungs, via the pulmonary veins back to the left atrium of the heart

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Circulation through the heart

Circulation through the heart

This is considered to be part of the systemic circulation, however the heart maintains its own circulatory system, being fed by the first two branches of the ascending aorta, the right and left coronary arteries .

The left coronary artery divides into the anterior ventricular branch, which supplies the anterior aspects of both ventricles , and the circumflex branch, which supplies the left atria and the left ventricle.

The right coronary artery divides into the marginal branch, which supplies the right atria and the right ventricle, and the posterior inter-ventricular branch, which supplies the posterior aspect of both ventricles.

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Portal circulation

Portal circulation

Portal circulation is usually classified within the systemic circulation.

It is basically made up of those vessels that gather nutrients from the digestive organs and pass them into the circulation and back on to the heart.

The hepatic artery feeds the liver with oxygenated blood and the hepatic vein carries that blood back to the inferior vena cava rich in nutrients and food stuffs. The hepatic portal vein carries nutrients from the small intestines to the liver ready for transportation to the heart.

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The pulse

The pulse

Every time the heart contracts, a surge of blood is pumped into the circulation. This surge is palpable (seen and felt) as a pulse.

A pulse can be palpated at any point where an artery is close to the surface of the skin. There are several pulse areas:

Radial - the wrist

Brachial - the inside of the elbow

Cartoid - either side of the neck

Pedal - front of the foot

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Functions of the heart

Functions of the heart

The right and left sides of the heart act as two totally separate pumps, but their action is always simultaneous.

The right side of the heart is responsible for dealing with deoxygenated blood. Deoxygenated blood returning from the circulation enters the right atrium via two major veins :

Superior vena cava
Drains blood from the head, neck and upper limbs

Inferior vena cava
Drains blood from the trunk, abdominal and pelvic cavities and lower limbs

When the atria contract, this deoxygenated blood is pushed through a one-way valve (the tricuspid valve) in the atrioventricular septum and into the right ventricle . The ventricle contracts and pumps the blood to the lungs via the pulmonary artery, which divides into the right and left pulmonary arteries soon after leaving the heart. The blood returns to the heart from the lungs reoxygenated, via four pulmonary veins that enter the left atrium. This is known as the pulmonary circulation.

The reoxygenated blood is then passed through another one-way valve (the bicuspid or mitral valve) in the atrioventricular septum into the left ventricle.

That ventricle contracts causing the blood to leave the left ventricle via the aorta. This is the main artery of the body, which leads to all other vessels of the circulation, feeding all tissues and organs with oxygenated blood.

Once the tissues and organs have used the oxygen within the blood, the deoxygenated blood is returned to the heart via the venous system, entering the right atrium again, via the superior and inferior vena cava. This part of the circulation is called the systemic circulation.

Some vessels branch off the systemic circulation and supply the digestive organs with oxygenated blood. This blood passes through organs like the stomach and the intestines where it picks up nutrients from digestion and carries them to the liver and then back to the heart. The nutrients are then delivered to the tissues of the body to help metabolism. The portal vein is the main vessel carrying nutrient-enriched blood from the gut to the liver.

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What are the control mechanisms of circulation?

What are the control mechanisms of circulation?

The myocardial tissue contracts in response to nervous stimuli from the cardiac centre in the medulla oblongata. This stimulus is part of the autonomic nervous system and either speeds up the heart rate and force of contraction by sympathetic impulses, or slows it down by parasympathetic impulses.

The cardiac centre is stimulated by receptors (baroreceptors) activated by changes in blood pressure. These baroreceptors are sited in three locations:

  1. Within the wall of the carotid arteries (carotid sinus reflex)
  2. Within the walls of the arch of the aorta (aortic reflex)
  3. Within the walls of the right atria (right heart reflex)

If all cardiac centre stimulation were removed, myocardial tissue would still rhythmically contract due to an intrinsic capability to generate electrical impulses that stimulate the heart muscle. These specialised cells form a conductivity pathway that originates in the right atrium and continues through the myocardium until the whole heart is stimulated to contract.

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Autonomic nervous system

Autonomic nervous system

The subdivision of the nervous system that controls involuntary body functions. It comprises the parasympathetic and sympathetic nervous systems.

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Conductivity pathway

Conductivity pathway

The pacemaker site is a cluster of specialised nervous tissue (the sinoatrial node) situated in the right atrial wall near the entrance of the superior vena cava . The tissues of the node create 60-100 beats per minute, but this can vary under autonomic stimulus.

How?
Electrical impulses pass across both atria causing them to contract and forcing blood into the ventricles . The atrioventricular septum forms an insulated wall stopping the impulses from stimulating the ventricles. Another cluster of tissue in the lower portion of the right atrium (the atrioventricular node) collects the impulses and passes them through the atrioventricular septum via a bundle of fibres known as the "bundle of his".

The impulse continues down the bundle of his closely following the interventricular septum where the bundle divides into the right and left bundle branches. The impulse then travels along these bundle branches to their termination in minute fibres called purkinje fibres deep in the ventricular myocardium, causing contraction

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Incised wound

Incised

This is usually a clean cut made by a sharp edge, eg a knife blade or broken glass.

This type of wound normally bleeds freely but heals relatively quickly. Be aware however that there may be damage to underlying organs or structures, eg tendons, blood vessels etc.

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Lacerated

Lacerated

Normally results from ripping or snagging of the tissues by jagged metal or the like.

This type of wound may not bleed quite so profusely, but there is more likely to be damage to the surrounding area, including some bruising.

Contamination from foreign matter and debris resulting in infection is likely in this type of wound, and this can result in a longer healing time.

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Abrasion (graze)

Abrasion (graze)

This is merely a superficial wound in which the upper layers of the skin are scraped off, leaving a tender raw area behind.

Abrasions usually contain foreign particles which carry a very high risk of causing infection to the wound

35

Contusion (bruise)

Contusion (bruise)

A contusion is caused by the rupture of the underlying blood vessels by a blow from a blunt source, eg a kick or punch.

A contusion can sometimes mask an injury to an underlying organ, like the spleen, kidneys or brain

36

Puncture wound

Puncture

This type of wound is caused by a pointed object. The wound usually has a small entry site, but the major damage is caused to the organs or tissues much deeper in the body along the penetration track.

Depending on the instrument used to initiate the wound, bacteria can be transported deep into the wound causing a very high risk of infection

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Gunshot wound

Gunshot

This type of wound is caused by a bullet, shot or shrapnel. The wound associated with the entry site can be relatively small, but the exit wound, if there is one, may be large and ragged depending on the calibre and velocity of the projectile.

Due to the nature of the wound, damage to underlying organs and the risk of infection is huge

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signs symptoms shock

 

 

Signs and symptoms

The following list is by no means complete and any one patient may not exhibit all of them:

  1. Rapid pulse
  2. Sweating
  3. Cold clammy skin
  4. Pale grey skin
  5. Thirst
  6. Nausea
  7. Weakness
  8. Lowered level of consciousness

Anaphylactic shock may exhibit signs of swelling around the eyes, face and throat, with associated breathing problems. Skin colour may appear flushed due to the

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Cardiogenic shock

Cardiogenic shock

One of the more common types of shock, this is caused by the heart ceasing to function properly due to chronic or acute heart disease. 

Insufficient heart activity will result in a drop in blood pressure reducing the amount of oxygenated blood circulating around the body

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Hypovolaemic shock

Hypovolaemic shock

This happens when blood is lost from the system due to either internal or external haemorrhage, or loss of other body fluids in the case of severe burns, diarrhoea or vomiting.

This lack of fluid is compensated for by the body automatically closing down the blood vessels on the periphery of the body, forcing the excess blood inwards to the core.

This process gives the patient a pale grey appearance with cold clammy skin. The heart rate will increase to circulate the remaining blood more quickly. 

41

Anaphylactic shock

Anaphylactic shock

This type of shock is the result of an extreme allergic reaction. Some people are more susceptible than others to insect bites or certain foods.

The reaction will produce chemical substances, which are secreted into the blood stream causing a massive dilation of blood vessels.

This process will create a situation where there is not enough circulating blood to fill the system. The major organs receive less oxygen causing shock to develop.

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Angina pectoris signs symptoms

Angina pectoris

This is a condition where the patient suffers severe to moderate central chest pain due to inadequate oxygen supply to the heart muscle. The patient also has a feeling of suffocation sometimes accompanied by shortness of breath.

Angina usually occurs in middle to late life and can be brought on by any number of factors. The most being:

Exertion

Anxiety

Stress

Lack of exercise

Hypertension (high blood pressure)

High cholesterol

Over-eating

Family history

It is not uncommon for the patient to recover quite quickly from an attack, once they have rested for a short time, or taken their medication. This is usually small white tablets put under the tongue, or an inhaler; both will most likely contain glyceryl trinitrate .

Some patients may experience the pain of angina for no reason and may even be woken from sleep as a result of it. This type of angina is called unstable angina and will seldom go away with ordinary medication. It is a dire emergency and immediate hospitalisation must be sought. There is a very high risk of this condition deteriorating into a myocardial infarction and you must be ready to resuscitate if necessary.

The inadequate supply of oxygen to the heart muscle, the myocardium, is caused through a progressive narrowing of the blood vessels that supply it. This is called atherosclerosis and is similar to the furring up of water pipes. The progressive narrowing is caused by lesions of a fatty substance building up on the walls of the blood vessels supplying the heart. As the lesions grow they trap mineral salts and begin to harden; so the lumen of the vessel gets smaller and smaller until the bore is so small that blood can no longer pass through

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Left ventricular failure The major signs and symptoms are:

Left ventricular failure

Left ventricular failure happens when the left ventricle is unable to pump all the blood that is delivered to it by the right ventricle at a satisfactory rate. This decreases the amount of oxygenated blood circulating around the body supplying the brain and heart. This inability to pump properly is due to damage of the heart muscle caused by myocardial infarct or atherosclerosis .

Blood backs up from the left ventricle into the left atrium causing distension and gorging of the pulmonary veins. This back-pressure causes fluid from the blood to be forced through the walls of the alveoli resulting in fluid in the lung (pulmonary oedema ).

The right ventricle which usually pumps blood through the lungs will experience problems because of the build up of fluid and pressure in the alveoli, and will inevitably then fail itself. This combination of left and right ventricular failure is called complete congestive heart failure (CCF).

The major signs and symptoms are:

Difficulty in breathing

Noisy wheezy breathing

Tachycardia

Distended neck veins

Blood stained sputum

Lowered level of consciousness

Orthopnoea (difficulty breathing while lying down)

Sweating

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Signs and symptoms are Myocardial infarct

Myocardial infarct

When the atherosclerosis reaches the stage when no blood can pass through the lumen of the blood vessels, the tissues usually supplied by that vessel will die. This area of dead tissue is called an infarct. When this process happens within the heart muscle it is called a myocardial infarct.

The layman's term for this condition would be a heart attack.

The signs and symptoms of both angina and myocardial infarct are very similar. The only difference under normal circumstances is that the pain of angina will be relieved by medication (except unstable angina).

Signs and symptoms are:

Gripping chest pain

Shortness of breath

Radiating pain down arms (usually left arm)

Pins and needles in hands and fingers

Nausea

Weakness

Sweating

Orthopnoea (difficulty breathing while lying down)

Feeling unwell

Yellowish - pale grey complexion

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Describe the heart and position

The Heart•Hollow coned shaped muscular organ -approximately size of the owners fist•It lies in the thoracic cavity, obliquely in the mediastinum, behind the sternum.•2/3 lies to the left of the midline,•Base above, apex below, resting on the diaphragm.

46

Three layers of the walls of The Heart

Three layers of the walls of The Heart •Pericardium – fibrous outer sac –2 layers •Myocardium – muscle layer, thickest in the left ventricle, has its own intrinsic stimulus, coronary arteries found here •Endocardium – smooth inner lining continuous with blood vessels

47

Pericardium

Pericardium•Consists of two sacs–an outer fibrous sac (Fibrous pericardium)–a double inner layer of serous membrane •The outer layer of serous membrane, called the parietal pericardium adheres to the outer fibrous pericardium•The innermost layer of serous membrane, called the visceral pericardium adheres to the myocardium

48

Myocardium

MyocardiumIs the muscle layer of the heart. It is thickest around the left ventricle and has a unique characteristic, called Automaticity.This means the heart can contract without an outside stimulus

49

Endocardium

EndocardiumThe innermost lining of the heart and its valves, it is composed of endothelium, providing a smooth lining and preventing local blood clotting

50

Three main components of the circulatory system

Three Main Components •The heart •Blood vessels •Blood

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Heart chambers

Heart ChambersFour chambers •Left and right atria •Left and right ventricles •Left and Right sides are divided by muscular partition called the septum

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Heart valves

Heart ValvesFour valves: •Pulmonary valve •Aortic valve •Two atrioventricular valves–Right or tricuspid valve–Left or mitral valve

53

Pulmonary & Systemic circulation

Pulmonary & Systemic Circulation •Pulmonary – involves pumping deoxygenated blood to the lungs and returning re-oxygenated blood to the heart •Systemic – involves circulating oxygenated blood throughout the body to the tissues and returning deoxygenated blood to the heart

54

Types of blood Vessel

The heart pumps blood into vessels that vary in structure, size, and function, and there are several types:• arteries• arterioles• capillaries• venules• veins

55

Structure of Blood Vessels

Structure of Blood VesselsAll vessels are structured in three layers: •Tunica Adventicia (Outer fibrous sheath) •Tunica Media (middle layer of muscle and elastic tissue) •Tunica Intima (Inner layer of smooth endothelium)

56

Portal circulation

Portal Circulation•A branch of the systemic circulation•Carries blood to and from the liver•Hepatic artery supplies oxygenated blood•Hepatic portal vein carries blood rich in nutrients from the digestive tract to the liver•Hepatic Veins carry deoxygenated blood from Liver to Inferior Vena Cava

57

Spleen

Spleen•Lies in the left hypochondrial region of the abdominal cavity, between fundus of the stomach and the diaphragm •Size varies but usually approx. 12cm long, 7cm wide and 2.5cm thick •Weighs approx. 200g

58

Function of the spleen

Functions of the Spleen •Produce new white blood cells •Store red blood cells •Destroy old red blood cells

59

Composition of blood

Composition of Blood Blood is composed of 55% liquid, 45% solids and contains four main elements: •Plasma (Liquid) •Red cells (erythrocytes) •White cells (leukocytes) •Platelets (thrombocytes)

60

Principle functions of blood

Principle Functions of Blood•Carry oxygen and carbon dioxide•Carry nutrients and water •Carry waste products to excretory organs •Distribute secretion of glands (Enzymes and hormones) Protect the body from infection •Distribute heat •Seal wounds by clotting