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The Cardiovascular System Flashcards

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1
Q

Blood

A
  • A fluid connective tissue
  • Composed of plasma and cells
  • 4-5 litres in adults
  • 300ml in a new-born baby
  • Alkaline – pH 7.4
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2
Q

Functions of blood

A

-Transports oxygen, nutrients, hormones and enzymes around the body
-Transports carbon dioxide and waste from the body to the excretory organs
- Helps fight infection
-Prevents the loss of body fluids after accidents by clotting
-Regulates body temperature

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3
Q

Blood components - Plasma

A
  • 55% of blood volume
  • Slightly thick, straw-coloured fluid
  • Mostly water (90-92%)
  • Rest is plasma proteins – albumin, globulin, fibrinogen and prothrombin
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4
Q

Functions of plasma

A

Transports essential substances around the body such as:
-Mineral salts sodium chloride, sodium carbonate,
-Nutrients amino acids, fatty acids, glucose,
-Waste e.g. urea
-Hormones
-Enzymes
-Gases oxygen and carbon dioxide are dissolved in plasma
-Antibodies produced by lymphocytes in response to antigens

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5
Q
  • Three types of blood cells
A
  • Erythrocytes
  • Leucocytes
  • Thrombocytes
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6
Q

Erythrocytes

A
  • Small biconcave cells with no nucleus
  • Approx 5,000,000 per ml of blood
  • Produced in the red bone marrow
  • Lifespan of around 120 days
  • Broken down in the spleen and then liver
    *Oxyhaemoglobin gives the blood its red colour
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7
Q

Leukocytes

A
  • Large irregularly shaped cells containing a nucleus
  • Protect the body from infection
  • Approx 8000 per ml of blood in a healthy body
  • Number can increase rapidly when infection is present
  • Produced in bone marrow
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8
Q

The heart

A
  • A muscular structure that contracts in a rhythmic pattern to pump blood
  • A two-sided, 4 chambered structure with muscular walls
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9
Q

in the heart The blood circulation is two closed systems

A

*Pulmonary circulation
*Systemic circulation

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10
Q

Heart structure

A
  • A hollow red organ
  • Positioned in the centre of the thorax
  • Divided into 4 chambers
  • Left and right atria
  • Left and right ventricles
  • Atria and ventricles are connected by the atrioventricular valves
  • The septum separates the left and right sides of the heart
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11
Q

Heart layers

A

1-Endocardium
* Inner layer
* A thin serous membrane composed of endothelial tissue
* Lines the interior of the heart
2- Myocardium
* Middle layer
* The thickest layer
* Composed of cardiac muscle
3- Pericardium
* Outer layer
* A double walled sac containing the heart and
roots of the great vessels
* Outer layer = fibrous pericardium
* Inner layer = serous pericardium Dr S

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12
Q

Cardiac muscle

A
  • Causes the rhythmical beating of the heart, circulating the blood and its contents throughout the body
  • Properties of cardiac muscle include
  • Involuntary
  • Consists of interwoven intercalating fibres
  • Fibres are capable of conducting an impulse
  • Incapable of building up an oxygen debt
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13
Q

Heart functions

A
  • Pump that drives the whole circulatory system
  • Receives and propels blood
  • Rhythmically contracts and forces the blood through a system of vessels
  • Controlled by the autonomic nervous system
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14
Q

The cardiac cycle

A
  • The sequence of contraction and relaxation of heart muscle that ensures the most efficient pumping action of the heart is maintained
  • Atrial Systole. The SAN generates and transmits electrical impulses throughout the atria, which both contract, pumping blood into the ventricles. The ventricles are electrically insulated from the atria, so they do not contract at this time.
  • Ventricular Systole. The electrical impulse passes to the ventricles via the atrioventricular node (AVN), the bundle of His and the Purkinje fibres. These are specialised fibres that do not contract but pass the electrical impulse to the base of the ventricles, with a short but important delay of about 0.1s. The ventricles therefore contract shortly after the atria, from the bottom up, squeezing blood upwards into the arteries.
  • Diastole. The atria and the ventricles relax, while the atria fill with blood. The semilunar valves in the arteries close as the arterial blood pushes against them.
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15
Q

Heart Rate is affected by:

A
  • Exercise – increases the heart rate
  • Age – faster in infants and slows gradually as age increases
  • Size of heart – smaller heart may have a faster heart rate and a larger heart a slower heart rate
  • Emotions and excitement – increase the heart rate. First through nervous stimuli and then through and increase in the level of adrenaline
  • Temperament – a placid, slow heart rate is not easily varied whereas an excitable person will have a quicker heart rate which changes easily
  • Disease – heart rate is quickened by fever, haemorrhage, hyper-thyroidism. Slowed by jaundice, heart blockages and pressure on the brain
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16
Q

Pulmonary and systemic

A

1-Pulmonary
* The circulation from the heart to the lungs and back
* Deoxygenated blood travels from the heart to the lungs in the pulmonary artery
* Blood gets rid of its CO2 and replaces it with O2
* Returns to the heart via the pulmonary vein
2-Systemic
* The circulation of blood from the heart to the body
* Blood leaves the heart by the aorta
* Returns to the heart via the inferior and superior venae cavae

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17
Q

Coronary circulation

A
  • Heart’s own circulatory system
  • Right and left coronary arteries leave the beginning of the aorta
  • Branch within the heart and form a network of capillaries
  • Blood collected back into the coronary veins
  • Empty into the right atrium of the heart
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18
Q

Portal circulation

A
  • Liver has a double blood supply
  • The right and left hepatic arteries carry oxygenated blood to the liver
  • The portal vein carries venous blood from the GI tract to the liver
  • The portal venous blood contains all of the products of digestion absorbed from the GI tract
  • All useful and non-useful products of digestion are processed in the liver
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19
Q

The blood vessels

A
  • Blood vessels consist of concentric layers or “tunics” of different tissue types.
  • The tunica intima is the inner lining, consisting of endothelium and a relatively thin layer of supporting connective tissue.
  • The tunica media is the middle muscular and/or elastic layer, containing smooth muscle and elastic tissue in varying proportions
  • The tunica adventitia is the outer, fibrous connective tissue layer
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20
Q

Types of blood vessels

A
  • Three types of vessels - arteries, veins, and capillaries
  • Both arteries and veins have layers of smooth muscle surrounding them.
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21
Q

deference between Arteries and Veins

A
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22
Q

Arteries and arterioles

A
  • Carry oxygenated blood from the heart
  • Thick walled, hollow tubes
  • Tunics
  • A fibrous outer covering
  • A middle layer of muscle and elastic tissue
  • An endothelial layer of squamous epithelium
  • Elastic artery
  • Close to the heart, arteries have the thickest walls, containing a high percentage of elastic fibres in all three of their tunics.
  • Muscular artery
  • Farther from the heart, the percentage of elastic fibers in an artery’s tunica intima decreases and the amount of smooth muscle in its tunica media increases.
23
Q

Arterioles

A
  • A smaller version of arteries
  • Tunica media is mainly muscle tissue with less elastic tissue than arteries
  • Under normal conditions all arterioles are slightly contracted – helps maintain blood pressure
  • Arterioles relax and dilate to increase blood supply when more oxygen and nutrients are required
  • They contract when an organ is at rest
  • Adrenaline, noradrenaline and vasopressin may cause arterioles to contract
  • In cases of shock all arterioles relax and blood pressure is very low – dangerous condition
24
Q

Veins

A
  • Have 3 layered walls
  • Basic structure similar to arteries
  • Walls much thinner and lumen much larger than arteries
  • Vary in size
  • Venae cavae and pulmonary vein are the largest
  • Skeletal muscles push blood through the vessels
  • Valves present in endothelial layer
  • Prevent backflow of blood
  • Very low blood pressure
  • Carry blood back to the heart
  • All deoxygenated except pulmonary vein
25
Q

Venules

A
  • Small veins
  • Have a thin wall with a large lumen
  • Easily collapsed under pressure
  • Carry deoxygenated blood from the capillaries to the larger veins
26
Q

Capillaries

A
  • The smallest blood vessels
  • Walls are one cell thick
  • Walls are porous allowing passage of gases
  • Water + solutes filters out through the capillary walls and bathes the body tissues
  • Interstitial fluid
  • Distribute oxygen and nutrients to most parts of the body
  • Except the deep brain, hyaline cartilage and epidermis
27
Q

Main arteries of the body

A
  • Aorta
  • Connected to your heart via the aortic valve. It’s formed of the following parts:
  • Ascending aorta - distributes oxygen and nutrients to the heart via the coronary arteries.
  • Aortic arch
  • Has three major branches
  • the brachiocephalic trunk
  • the left common carotid artery
  • the left subclavian artery
  • It sends blood to the upper body, including the head, neck, and arms
  • Descending aorta - Sends blood to the torso, abdomen, and lower body.
  • Also referred to as the thoracic aorta above the diaphragm, below it becomes the abdominal aorta.
28
Q

Head and neck arteries

A

1-Left and right common carotid
* The left common carotid comes directly off the aortic arch, while the right common carotid comes from the brachiocephalic trunk.
2-External carotid
* Paired arteries derived from the common carotid arteries. The external carotid supplies blood to areas like the face, lower jaw, and neck.
3- Internal carotid
* Paired arteries also derived from the common carotid arteries. They’re the primary arteries supplying blood to the brain.
4-Vertebral
* Formed off of the subclavian arteries, these paired arteries travel up the neck, where they also supply blood to the brain.
5-Innominate artery (brachiocephalic artery)
* First vessel off the aortic arch and provides blood to the right arm, neck, and head
Facial artery
* A branch of the external carotid artery that supplies structures of the face

29
Q

Thoracic Aorta

A
  • Gives off many small branches into the thoracic wall and thoracic viscera
30
Q

Abdominal Aorta

A

1-Celiac artery
* Gives rise to left gastric, splenic and hepatic arteries
* Supply upper portions of the digestive tract, spleen and liver
2-Phrenic arteries
* Supply blood to the diaphragm
3-Superior mesenteric
* Branches to many parts of the intestinal tract including the jejunum, ileum, caecum, ascending colon and transverse colon
4-Suprarenal arteries
* Supply blood to the adrenal glands
5-Inferior mesenteric artery
* Branches of lead to the descending colon, sigmoid colon and rectum

31
Q

Arteries to the shoulder and upper limb

A

1-Axillary artery
* Supplies branches to structures in the axilla and chest wall
2-Brachial artery
* Courses along the humerus to the elbow
* Gives rise to the deep brachial artery
3-Ulnar artery
* A terminal branch of the brachial artery
* Supplies the medial aspect of the forearm, wrist, and hand
4-Radial artery
* A continuation of the brachial artery
* Provides a convenient vessel for taking the pulse

32
Q

Arteries to the pelvis and lower limb

A
  • Abdominal aorta divides to form the common iliac arteries.
  • Provide blood to the pelvic organs, gluteal region and lower limbs
33
Q

External iliac artery

A
  • Provides the main blood supply to the lower limbs
  • Branches into the inferior epigastric artery and a deep circumflex iliac artery
  • Supply the muscles and skin in the lower abdominal wall
  • Becomes the femoral artery
  • Main arterial supply to the thigh and leg
34
Q

Venous system

A
  • Returns blood to the heart after gases, nutrients and wastes are exchanged between the blood and body cells
  • Vessels begin with the merging of capillaries into venules, which merge into small veins which in turn merge into larger ones.
  • Larger veins typically follow parallel courses to that of named arteries
35
Q

Veins from the head, neck and brain

A
  • External jugular vein drains blood from the face, scalp and superficial regions of the neck
  • They empty into the right and left subclavian veins
  • The internal jugular veins collect blood from the brain and the superficial parts of the face and neck
  • Internal jugular and subclavian veins form large brachiocephalic veins which merge in the mediastinum and give rise to the superior vena cava
35
Q

Veins from the head, neck and brain

A
  • External jugular vein drains blood from the face, scalp and superficial regions of the neck
  • They empty into the right and left subclavian veins
  • The internal jugular veins collect blood from the brain and the superficial parts of the face and neck
  • Internal jugular and subclavian veins form large brachiocephalic veins which merge in the mediastinum and give rise to the superior vena cava
36
Q

Veins from the upper limb
and shoulder

A
  • The brachial veins are the largest in size, and are situated either side of the brachial artery.
  • The main drainage of the hand and forearm will be directed towards the ulnar and radial veins.
37
Q

Blood pressure

A
  • The force that the blood exerts on the walls of the blood vessels
  • Blood is always under pressure
  • The amount of pressure varies in the different types of blood vessels
  • Heart beat affects blood pressure
  • When the ventricle is contracting it is high –systolic pressure
  • When the ventricle is dilating it is low – diastolic pressure
38
Q

Factors affecting blood pressure

A
  • Cardiac output
  • Determined by the volume of blood pumped out of the heart
  • If cardiac output increases, blood pressure increases
  • Arteriole resistance
  • Vasoconstriction controlled by the vasomotor nerves, adrenaline and noradrenaline
  • The greater the vasoconstriction the higher the blood pressure
  • Total blood volume
  • If circulation blood is reduced = decrease in blood pressure
  • Too much fluid retention = increase in blood pressure
  • Blood viscosity
  • Depends partly on the plasma & plasma proteins & no of
    erythrocytes
  • Lower viscosity = lower blood pressure
  • Elasticity of artery walls
  • Hardening of arteries = loss of elasticity = higher blood pressure
  • Softening of arteries = lower blood pressure
39
Q

Blood pressure

A
40
Q

Blood clotting

A

When a blood vessel is damaged, bleeding occurs
until a clot forms
Clot stops excessive blood loss
No blood clotting causes haemorrhage

41
Q

Requirements for blood clotting

A
42
Q

What affects blood clotting?

A

-Platelet deficiency
-Lack of one of the components - haemophilia
-Absence of fibrinogen
-Lack of vitamin K
-Lack of calcium Excess of
-fibrinogen – may cause thrombosis

43
Q

Rhesus factor

A
44
Q

blood donation

A
45
Q

Varicose veins

A

Often caused by
*Heredity
* Excessive periods of sitting
and standing
*Pregnancy
*obesity

46
Q

Anaemia

A

Reduction in the blood’s ability to carry oxygen
* Decrease in red blood cells
* Decrease in haemoglobin
* Extensive loss of blood
* Lack of iron in the diet
* Failure of bone marrow to produce the normal no of cells
* May be inherited D

47
Q

Sickle cell anaemia

A
  • An inherited form of anaemia
  • Abnormal haemoglobin causes distorted red blood cells
  • Sickled red blood cells are fragile and prone to rupture
  • Sickled cells can also block blood vessels causing tissue and organ
    damage
48
Q

Foetal circulation

A
  • The fetal circulatory system uses 3 shunts
  • These are small passages that direct blood that needs to be oxygenated.
  • The purpose of these shunts is to bypass the lungs and liver because these organs will not work fully until after birth
49
Q

1 – The foramen ovale

A
  • A shunt that bypasses the lungs
  • Moves blood from the right atrium of the heart to the left atrium.
50
Q

2 – Ductus arteriosus

A
  • A large vascular shunt connecting the main pulmonary artery to the descending aorta
  • Allows most of the blood from the right ventricle to bypass the foetus’s fluid-filled nonfunctioning lungs
50
Q

2 – Ductus arteriosus

A
  • A large vascular shunt connecting the main pulmonary artery to the descending aorta
  • Allows most of the blood from the right ventricle to bypass the foetus’s fluid-filled nonfunctioning lungs
51
Q

3- Ductus venosus

A
  • Shunts a portion of umbilical vein blood flow directly to the inferior vena cava
  • Allows oxygenated blood from the placenta to bypass the liver
  • During the second and third trimester, the mean fraction of placental blood shunted through the ductus venosus reduces from 30% to 20%, suggesting a fetal liver priority of circulation
52
Q

fetal circalation

A

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