Chapter 5: The cardiovascular system

Question 1

The cardiovascular system is divided how?

Answer 1

The cardiovascular system ensures a continuous flow of blood to all body cells, and its function is subject to continual physiological adjustments to maintain an adequate blood supply.

• the heart, whose pumping action ensures constant circulation of the blood
• the blood vessels, which form a lengthy network through which the blood flows.

Question 2

How does the heart pump blood into separate systems of blood vessels?

Answer 2

The right side of the heart pumps blood to the lungs (the pulmonary circulation) where gas exchange occurs, i.e., the blood collects oxygen from the air sacs and excess carbon dioxide diffuses into the air sacs for exhalation.
The left side of the heart pumps blood into the systemic circulation, which supplies the rest of the body. Here, tissue wastes are passed into the blood for excretion, and body cells extract nutrients and oxygen.

Question 3

Blood vessels

Answer 3

A tube through which the blood circulates in the body. Blood vessels include a network of arteries, arterioles, capillaries, venules, and veins.

Question 4

Arteries and arterioles

Answer 4

These blood vessels transport blood away from the heart

Question 5

Anastomoses and end-arteries

Answer 5

Anastomoses are arteries that form a link between main arteries supplying an area.
An end-artery is an artery that is the sole source of blood to a tissue, e.g., the branches from the circulus arteriosus (circle of Willis) in the brain or the central artery to the retina of the eye

Question 6

Capillaries and sinusoids

Answer 6

Sinusoids refer to the small, irregularly-shaped blood vessels found in certain organs, especially the liver, while capillaries refer to any of the fine branching blood vessels, which form a network between the arterioles and venules.

Question 7

Capillary refill time

Answer 7

It is a simple test to measure the time taken for color to return to an external capillary bed after pressure is applied, typically by pressing the end of a finger with the thumb and forefinger. Normal capillary refill time is usually 2 seconds or less.

Question 8

Veins and venules

Answer 8

A blood vessel that carries blood that is low in oxygen content from the body back to the heart.
The smallest veins are called venules.

Question 9

Blood supply

Answer 9

The outer layers of tissue of thick-walled blood vessels receive their blood supply via a network of blood vessels called the vasa vasorum. Thin-walled vessels and the endothelium of the others receive oxygen and nutrients by diffusion from the blood passing through them.

Question 10

Control of blood vessel diameter

Answer 10

Blood vessel diameter is controlled by a smooth muscle of tunica media which is supplied by sympathetic nerves of the autonomic nervous system.

Question 11

Blood vessel diameter and blood flow

Answer 11

Resistance to flow of fluids along a tube is determined by three factors: the diameter of the tube; the length of the tube; and the viscosity of the fluid. The most important factor determining how easily the blood flows through blood vessels in the first of these variables, that is, the diameter of the resistance vessels (the peripheral resistance).

Question 12

Local regulation of blood flow

Answer 12

The greatest change in blood pressure and velocity of blood flow occurs at the transition of arterioles to capillaries.
This reduces the pressure and velocity of flow for gas and nutrient exchange to occur within the capillaries.
As such arterioles are the main part of the circulatory system in which local control of blood flow occurs.

Question 13

Capillary exchange

Answer 13

Refers to the exchange of material from the blood into the tissues in the capillary. There are three mechanisms that facilitate capillary exchange: diffusion, transcytosis and bulk flow.

Question 14

Capillary fluid dynamics

Answer 14

Capillary dynamics are controlled by the four Starling forces. The oncotic pressure is a form of osmotic pressure exerted by proteins either in the blood plasma or interstitial fluid. Hydrostatic pressure is a force generated by the pressure of the fluid on the capillary walls either by the blood plasma or interstitial fluid.

Question 15

Heart

Answer 15

The heart is a muscular organ, which pumps blood through the blood vessels of the circulatory system.

Question 16

Position of the heart

Answer 16

The heart is located behind and slightly left of the sternum, between the two lungs, and enclosed in a sac called the pericardium. In the human being the heart lies just behind and slightly to the left of the sternum (breastbone) in a double-layered sac called the pericardium.

Question 17

Organs associated with the heart

Answer 17

Inferiorly – the apex rests on the central tendon of the diaphragm
Superiorly – the great blood vessels, i.e., the aorta, superior vena cava, pulmonary artery, and pulmonary veins
Posteriorly – the esophagus, trachea, left and right bronchus, descending aorta, inferior vena cava, and thoracic vertebrae
Laterally – the lungs – the left lung overlaps the left side of the heart
Anteriorly – the sternum, ribs, and intercostal muscles.

Question 18

Structure of the heart wall

Answer 18

The heart wall is composed of three layers of tissue: pericardium, myocardium and endocardium.

Question 19

Pericardium

Answer 19

The membrane enclosing the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane.

Question 20

Myocardium

Answer 20

the muscular tissue of the heart.

Question 21

Fibrous tissue in the heart

Answer 21

The myocardium is supported by a network of fine fibers that run through all the heart muscle. This is called the fibrous skeleton of the heart. In addition, the atria and the ventricles are separated by a ring of fibrous tissue, which does not conduct electrical impulses.

Question 22

Endocardium

Answer 22

The endocardium is a thin, smooth tissue that makes up the lining of the chambers and valves of the heart. The innermost layer of the heart’s walls, it serves as a barrier between cardiac muscles and the bloodstream and contains necessary blood vessels.

Question 23

Interior of the heart

Answer 23

The right and left sides of your heart are divided by an internal wall of tissue called the septum. The area of the septum that divides the two upper chambers (atria) of your heart is called the atrial or interatrial septum. The area of the septum that divides the two lower chambers (ventricles) of your heart is called the ventricular or interventricular septum.

Question 24

The flow of blood through the heart

Answer 24

The heart has two upper chambers—the left and right atriums—and two larger lower chambers—the left and right ventricles. A series of valves control blood flow in and out of these chambers.
Electrical impulses, controlled by the cardiac conduction system, make the heart muscle contract and relax, creating the rate and rhythm of your heartbeat.

Question 25

Venous drainage

Answer 25

Most of the venous blood is collected into several cardiac veins that join to form the coronary sinus, which opens into the right atrium. The remainder passes directly into the heart chambers through little venous channels.

Question 26

Conducting system of the heart

Answer 26

A cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components of the cardiac conduction system are the SA node, AV node, a bundle of His, bundle branches, and Purkinje fibers.

Question 27

Sinoatrial node (SA node)

Answer 27

A small body of specialized muscle tissue in the wall of the right atrium of the heart that acts as a pacemaker by producing a contractile signal at regular intervals.

Question 28

Atrioventricular node (AV node)

Answer 28

The electrical relay station between the upper and lower chambers of the heart.

Question 29

The atrioventricular bundle

Answer 29

The atrioventricular bundle, also called the bundle of His, is a bundle of cardiac muscle fibers located within the septum of the heart. This fiber bundle extends from the AV node and travels down the septum, which divides the left and right ventricles.

Question 30

Nerve supply to the heart

Answer 30

As mentioned earlier, the heart is influenced by autonomic (sympathetic and parasympathetic) nerves originating in the cardiovascular center in the medulla oblongata. The vagus nerve (parasympathetic) supplies mainly the SA and AV nodes and atrial muscle. Sympathetic nerves supply the SA and AV nodes and the myocardium of atria and ventricles, and stimulation increases the rate and force of the heartbeat.

Question 31

The cardiac cycle

Answer 31

At rest, the healthy adult heart is likely to beat at a rate of 60–80 beats per minute (b.p.m.). During each heartbeat, or cardiac cycle, the heart contracts (systole) and then relaxes (diastole).

Question 32

Stages of the cardiac cycle

Answer 32

A single cycle of cardiac activity can be divided into two basic phases - diastole and systole. Diastole is defined as the phase in which the heart, especially the ventricles, is at rest. The relaxed heart allows for blood to fill the cardiac chambers. Systole is defined as the phase in which the heart, especially the ventricles, is contracting. The contraction allows for blood to flow into the pulmonary circulation and systemic vasculature via the main pulmonary artery and aorta, respectively.

Question 33

Heart sounds

Answer 33

Blood flow creates vibrations in the heart chambers and valves which produce audible sounds that can be heard through a stethoscope. Smooth, low-resistance blood flow is called a laminar flow. When the flow is rough with high resistance it is known as a turbulent flow.

Question 34

First sound

Answer 34

When the two ventricles contract and pump out blood into the aorta and pulmonary artery the mitral and tricuspid valves close to prevent the blood flowing back into the atria. The first sound S1 is generated by vibrations created by the closing of these two valves. Normally the mitral valve closes just before the tricuspid valve, and when the two different sounds are detectable, it is called a “split S1.” A split S1 may be indicative of certain conditions affecting the heart.

Question 35

Second sound

Answer 35

After pumping the blood, the ventricles relax to receive blood from the atria, and the diastole phase starts. The aortic and pulmonic valves close and cause vibrations, giving rise to the second heart sound, S2. The increase in the intensity of this sound may indicate certain conditions. When the aortic valve closes just before the pulmonic valve, it may generate a split S2. This may indicate impairment in heart function.

Question 36

Third sound

Answer 36

The third heart sound is a low-pitched sound audible with the rapid rush of blood from the atrium into the ventricle as it starts relaxing. This may be a normal sound in some people but in people with heart conditions, S3 may indicate heart failure.

Question 37

Fourth sound

Answer 37

The fourth is a low-intensity sound heard just before S1 in the cardiac cycle. The sudden slowing of blood flow by the ventricle as the atrium contracts causes this sound, which may be a sign of heart disease.

Question 38

Electrical changes in the heart

Answer 38

The heart is a pump made up of muscle tissue. Like all muscle, the heart needs a source of energy and oxygen to function. The heart's pumping action is regulated by an electrical conduction system that coordinates the contraction of the various chambers of the heart.

Question 39

Cardiac output

Answer 39

The cardiac output is the amount of blood ejected from each ventricle every minute. The amount expelled by each contraction of each ventricle is the stroke volume. Cardiac output is expressed in liters per minute (L/min) and is calculated by multiplying the stroke volume by the heart rate (measured in beats per minute): Cardiac output=Stroke volume × Heart rate.

Question 40

Stroke volume arterial blood pressure

Answer 40

The stroke volume is determined by the volume of blood in the ventricles immediately before they contract, i.e., the ventricular end-diastolic volume (VEDV), sometimes called preload. Preload depends on the amount of blood returning to the heart through the superior and inferior vena cava (the venous return).

Question 41

Blood volume

Answer 41

This is normally kept constant by the kidneys. Should blood volume fall, e.g., through sudden hemorrhage, this can cause stroke volume, cardiac output and venous return to fall. However, the body's compensatory mechanisms will tend to return these values towards normal, unless the blood loss is too sudden or severe for compensation.

Question 42

Venous return

Answer 42

Venous return is the major determinant of cardiac output and, normally, the heart pumps out all blood returned to it. The force of contraction of the left ventricle ejecting blood into the aorta is not sufficient to push the blood through the arterial and venous circulation and back to the heart.

Question 43

Muscular contraction

Answer 43

Backflow of blood in veins of the limbs, especially when standing, is prevented by valves. The contraction of skeletal muscles surrounding the deep veins compresses them, pushing blood towards the heart. In the lower limbs, this is called the skeletal muscle pump.

Question 44

The respiratory pump

Answer 44

During inspiration, the expansion of the chest creates a negative pressure within the thorax, assisting flow of blood towards the heart. In addition, when the diaphragm descends during inspiration, the increased intra-abdominal pressure pushes blood towards the heart.

Question 45

Heart rate

Answer 45

The heart rate is a major determinant of cardiac output. If heart rate rises, cardiac output increases, and if it falls, cardiac output falls too. The main factors determining heart rate are outlined below.

Question 46

Autonomic nervous system

Answer 46

The intrinsic rate at which the heart beats is a balance between sympathetic and parasympathetic activity, and this is the most important factor in determining heart rate.

Question 47

Circulating chemicals

Answer 47

The hormones adrenaline (epinephrine) and noradrenaline (norepinephrine), secreted by the adrenal medulla, have the same effect as sympathetic stimulation, i.e., they increase the heart rate. Other hormones, including thyroxine, increase heart rate. Hypoxia and elevated carbon dioxide levels stimulate heart rate. Electrolyte imbalances may affect it, e.g., hyperkaliemia depresses cardiac function and leads to bradycardia (slow heart rate).

Question 48

Blood pressure

Answer 48

The pressure of the blood in the circulatory system, often measured for diagnosis since it is closely related to the force and rate of the heartbeat and the diameter and elasticity of the arterial walls.

Question 49

Systolic and diastolic pressures

Answer 49

When the left ventricle contracts and pushes blood into the aorta, the pressure produced within the arterial system is called the systolic blood pressure. In complete cardiac diastole when the heart is resting following the ejection of blood, the pressure within the arteries is much lower and is called diastolic blood pressure. The difference between systolic and diastolic blood pressure is the pulse pressure. Arterial blood pressure (BP) is measured with a sphygmomanometer.

Question 50

The elasticity of arterial walls

Answer 50

An artery with many collagen and elastin filaments, giving it the ability to stretch in response to each pulse

Question 51

Factors determining blood pressure

Answer 51

• Blood pressure is determined by cardiac output and peripheral resistance. Change in either of these parameters tends to alter systemic blood pressure, although the body's compensatory mechanisms usually adjust for any significant change.

Question 52

Cardiac output

Answer 52

Cardiac output is determined by the stroke volume and the heart rate. An increase in cardiac output raises both systolic and diastolic pressures.

Question 53

Peripheral or arteriolar resistance

Answer 53

Is described as blood flow resistance within blood vessels, primarily affected by blood vessel diameter.

Question 54

Autoregulation

Answer 54

Systemic blood pressure continually rises and falls, according to levels of activity, body position, etc. However, the body organs can adjust blood flow and blood pressure in their own local vessels independently of systemic blood pressure. This property is called autoregulation and protects the tissues against swings in systemic pressures.

Question 55

Control of blood pressure (bp)

Answer 55

Blood pressure is controlled in two ways: - short-term control, on a moment-to-moment basis, which mainly involves the baroreceptor reflex, discussed below, and chemoreceptors and circulating hormones - long-term control, which involves regulation of blood volume by the kidneys and the renin-angiotensin-aldosterone system

Question 56

Short-term blood pressure regulation

Answer 56

The cardiovascular center (CVC) is a collection of interconnected neurons in the medulla and pons of the brain stem. The CVC receives, integrates, and coordinates inputs from: - baroreceptors (pressure receptors) - chemoreceptors - higher centers in the brain. - The CVC sends autonomic nerves (both sympathetic and parasympathetic to the heart and blood vessels. It controls BP by slowing down or speeding up the heart rate and by dilating or constricting blood vessels

Question 57

Baroreceptors

Answer 57

A receptor that is sensitive to changes in pressure.

Question 58

Chemoreceptors

Answer 58

A sensory cell or organ is responsive to chemical stimuli.

Question 59

Higher centers in the brain

Answer 59

Input to the CVC from the higher centers is influenced by emotional states such as fear, anxiety, pain, and anger that may stimulate changes in blood pressure. The hypothalamus in the brain controls body temperature and influences the CVC, which response by adjusting the diameter of blood vessels in the skin. This important mechanism regulates conservation and loss of heat so that core body temperature remains in the normal range.

Question 60

Long-term blood pressure regulation

Answer 60

Slower, longer-lasting changes in blood pressure are affected by the renin-angiotensin-aldosterone system and the action of the antidiuretic hormone. Both systems regulate blood volume, thus influencing blood pressure. In addition, atrial natriuretic peptide, a hormone released by the heart itself, causes sodium and water loss from the kidney and reduces blood pressure, opposing the activities of both ADH and the RAAS.

Question 61

Pressure in the pulmonary circulation

Answer 61

Pulmonary blood pressure is much lower than in systemic circulation. This is because although the lungs receive the same amount of blood from the right ventricle as the rest of the body receives from the left ventricle, there are so many capillaries in the lungs that pressure is kept low.

Question 62

Pulse

Answer 62

A rhythmical throbbing of the arteries as blood is propelled through them, typically as felt in the wrists or neck.

Question 63

Factors affecting the pulse

Answer 63

- the arteries supplying the peripheral tissues are narrowed or blocked and the blood therefore is not pumped through them with each heartbeat. - there is some disorder of cardiac contraction, e.g., atrial fibrillation and the heart is unable to generate enough force, with each contraction, to circulate blood to the peripheral arteries.

Question 64

Pulmonary circulation

Answer 64

System of blood vessels that forms a closed circuit between the heart and the lungs, as distinguished from the systemic circulation between the heart and all other body tissues.

Question 65

systemic circulation

Answer 65

The circuit of vessels supplying oxygenated blood to and returning deoxygenated blood from the tissues of the body, as distinguished from the pulmonary circulation

Question 66

Major blood vessels

Answer 66

The aorta is the largest artery of the body. The two largest veins, the superior and inferior venae cava, return blood from all body parts to the heart.

Question 67

Aorta

Answer 67

The main artery of the body, supplying oxygenated blood to the circulatory system. In humans it passes over the heart from the left ventricle and runs down in front of the backbone.

Question 68

Thoracic aorta

Answer 68

The part of the aorta lies above the diaphragm and is described in three parts: - ascending aorta - arch of the aorta - descending aorta in the thorax

Question 69

Ascending aorta

Answer 69

The ascending aorta is the first part of the aorta originating at the left ventricle and leading into the aortic arch

Question 70

Arch of the aorta

Answer 70

Is the portion of the main artery that bends between the ascending and descending aorta. Three branches arise from its upper aspect: -brachiocephalic artery or trunk -left common carotid artery -left subclavian artery

Question 71

Descending aorta in the thorax

Answer 71

The descending aorta (thoracic aorta) | is between the arch of the aorta and the diaphragm muscle below the ribs.

Question 72

Abdominal aorta

Answer 72

The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta (of the thorax).

Question 73

Vena cava

Answer 73

A large vein carrying deoxygenated blood into the heart. There are two in humans, the inferior vena cava (carrying blood from the lower body) and the superior vena cava (carrying blood from the head, arms, and upper body).

Question 74

Superior vena cava

Answer 74

The superior vena cava (SVC) is a large, valveless vein that conveys venous blood from the upper half of the body and returns it to the right atrium.

Question 75

Inferior vena cava

Answer 75

The inferior vena cava (or IVC) is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart

Question 76

Circulation in the head and neck (arterial supply)

Answer 76

The paired arteries supplying the head and neck are the common carotid arteries and the vertebral arteries.

Question 77

Carotid arteries

Answer 77

The carotid arteries extend out from the aorta artery, which transports blood out of the heart and is the body’s largest artery. The carotid arteries carry blood through the neck up to the brain. There are two carotid arteries: one on the left and one on the right.

Question 78

External carotid artery

Answer 78

The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external and internal carotid artery. External carotid artery supplies blood to the face and neck.

Question 79

Internal carotid artery

Answer 79

This is a major contributor to the circulus arteriosus (circle of Willis), which supplies the greater part of the brain. It also has branches that supply the eyes, forehead and nose. It ascends to the base of the skull and passes through the carotid foramen in the temporal bone.

Question 80

Circulus arteriosus (circle of Willis)

Answer 80

The greater part of the brain is supplied with arterial blood by an arrangement of arteries called the circulus arteriosus or the circle of Willis. Four large arteries contribute to its formation: the two internal carotid arteries and the two vertebral arteries Anteriorly, the two anterior cerebral arteries arise from the internal carotid arteries and are joined by the anterior communicating artery. Posteriorly, the two vertebral arteries join to form the basilar artery.

Question 81

Venous return

Answer 81

Venous return is the return of blood to the heart via venules and veins. Venous return to the right atrium is the most important factor determining cardiac output, provided both ventricles and the pulmonary circulation are normal.

Question 82

circulation in the upper limb (The subclavian arteries)

Answer 82

The Subclavian arteries are the large arteries that originate from the aorta near the base of the neck and travel under the collar bones to carry blood to each arm. In the neck region, each Subclavian artery gives off a vertebral artery that supplies blood to the brain.

Question 83

circulation in the thorax (arterial supply)

Answer 83

Branches of the thoracic aorta supply structures in the chest, including: - bronchial arteries, which supply lung tissues not directly involved in gas exchange - esophageal arteries, which supply the esophagus - intercostal arteries, which run along the inferior border of each rib and supply the intercostal muscles, some muscles of the thorax, the ribs, skin, and its underlying connective tissues.

Question 84

Portal circulation

Answer 84

Is the flow of blood from one organ to another, without going through the heart. The term is most often used to refer to how blood moves through the network of veins in the gut and digestive organs, such as the spleen and pancreas, and is carried to the liver.

Question 85

Portal view

Answer 85

vein conveying blood to the liver from the spleen, stomach, pancreas, and intestines.

Question 86

Circulation in the pelvis and lower limb (arterial supply) common iliac arteries

Answer 86

The common iliac artery (CIA) is a short artery transporting blood from the aorta towards the pelvic region and lower extremity.

Question 87

Deep veins

Answer 87

The deep veins accompany the arteries and their branches and have the same names. They are the: - femoral vein, which ascends in the thigh to the level of the inguinal ligament, where it becomes the external iliac vein - external iliac vein, the continuation of the femoral vein where it enters the pelvis lying close to the femoral artery. It passes along the brim of the pelvis, and at the level of the sacroiliac joint it is joined by the internal iliac vein to form the common iliac vein - internal iliac vein, which receives tributaries from several veins draining the organs of the pelvic cavity

Question 88

Superficial veins

Answer 88

The two main superficial veins draining blood from the lower limbs are the small and the great saphenous veins. The small saphenous vein begins behind the ankle joint where many small veins which drain the dorsum of the foot join. The great saphenous vein is the longest vein in the body. It begins at the medial half of the dorsum of the foot and runs upwards, crossing the medial aspect of the tibia and up the inner side of the thigh.

Question 89

Fetal circulation

Answer 89

The developing fetus obtains its oxygen and nutrients, and excretes its waste, via the mother's circulation. To this end, both maternal and fetal circulations develop specific adaptations unique to pregnancy. Because the lungs, gastro­intestinal system and kidneys do not begin to function till after birth, certain modifications in the fetal circulation divert blood flow to meet pre-natal requirements.

Question 90

The placenta

Answer 90

is firmly attached to the uterine wall and consists of an extensive network of fetal capillaries bathed in maternal blood. Whilst the fetal capillaries are in very close proximity to the maternal blood supply, the two circulations are separate. The placenta is attached to the fetus by a cord (the umbilical cord), which is usually about 50 cm long and contains two umbilical arteries and one umbilical vein wrapped in a soft connective tissue coat. The cord enters the fetus at a spot on the abdomen called the umbilicus.

Question 91

Functions of the placenta

Answer 91

Placental functions include exchange of substances, protection of the fetus and maintenance of pregnancy.

Question 92

Exchange of nutrients and wastes during pregnancy

Answer 92

Deoxygenated blood flows from the fetus into the placenta through the umbilical arteries and travels through the network of fetal capillaries in the placenta. Because these capillaries are bathed in maternal blood, exchange of nutrients and gases takes place here and the blood that returns to the fetus in the umbilical vein has collected oxygen and nutrients and lost excess carbon dioxide and other wastes

Question 93

Maintenance of pregnancy

Answer 93

The placenta has an essential endocrine function and secretes the hormones that maintain pregnancy.

Question 94

Progesterone and estrogen

Answer 94

As pregnancy progresses, the placenta takes over secretion of these hormones from the corpus luteum, which degenerates after about 12 weeks. From 12 weeks until delivery, the placenta secretes increasing levels of estrogen and proges­terone. These hormones are essential for maintenance of pregnancy.

Question 95

Aging and the heart

Answer 95

The compliance (stretchability) of the heart falls with age, mainly because the fibrous skeleton of the heart stiffens, increasing the heart's workload. The ability of the heart muscle to respond to adrenaline and noradrenaline lessens, and the contractile strength of the heart and cardiac reserve are reduced. The older heart is therefore more prone to heart failure

Question 96

Shock

Answer 96

Shock (circulatory failure) occurs when the metabolic needs of cells are not being met because of inadequate blood flow.

Question 97

cardiogenic shock

Answer 97

The occurs in acute heart disease when damaged heart muscle cannot maintain an adequate cardiac output, e.g., in myocardial infarction

Question 98

Neurogenic shock

Answer 98

The causes include sudden acute pain, severe emotional experience, spinal anesthesia, and spinal cord damage. These interfere with normal nervous control of blood vessel diameter, leading to hypotension.

Question 99

Thrombosis

Answer 99

is the formation of a blood clot (thrombus) inside a blood vessel, interrupting blood supply to the tissues.

Question 100

Infraction and ischemia

Answer 100

Infraction is the term given to tissue death because of interrupted blood supply. The consequences of interrupting tissue blood supply depend on the size of the artery blocked and the functions of the tissue affected • Ischemic mean tissue damage because of reduced blood supply.

Question 101

Hemorrhoid

Answer 101

a swollen vein or group of veins in the region of the anus.

Question 102

Heart (cardiac) failure

Answer 102

The heart is described as failing when the cardiac output is unable to circulate sufficient blood to meet the needs of the body.

Question 103

Hypertension

Answer 103

The term hypertension is used to describe a level of blood pressure that, taking all other cardiovascular risk factors into account, would benefit the patient if reduced.