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Anatomy and Physiology > Cardiovascular system > Flashcards

Cardiovascular system Flashcards

1
Q

What is blood?

A

part of the extracellular fluid (ECF) contained within blood vessels
consists of plasma (55% of total volume) and blood cells (45% of total volume)

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2
Q

What is plasma?

A

straw-coloured transparent fluid
consists of 90-92% water and dissolved substances (plasma proteins, enzymes, hormones, gases, electrolytes and waste products)

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3
Q

What are the three main types of plasma proteins?

A

albumins - help to create osmotic pressure to draw fluid back into capillaries from the interstitial fluid
fibrinogen and prothrombin - major proteins used in blood clotting
globulins - essential for immunity

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4
Q

What are the three main types of blood cells suspended in the plasma?

A

erythrocytes (red blood cells), leucocytes (white blood cells), thrombocytes (platelets)

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5
Q

Where are erythrocytes formed?

A

red bone marrow

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6
Q

What is the structure of an erythrocyte?

A

biconcave shape to increase SA for gas absorption and access to small spaces
no nuclei, ribosomes or mitochondria (cell has a short life span of about 120 days)
no mitochondria means no aerobic respiration (cell obtains energy via anaerobic respiration so does not use the oxygen carried)

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7
Q

What is haemoglobin?

A

pigment contained within erythrocytes

transports oxygen and carbon dioxide to and from cells

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8
Q

What is the structure of haemoglobin?

A

composed of globin (a protein) and a haem group which contains an iron ion
quarternary structure with 4 globin chains and 4 haem groups
oxygen attaches to haem, which means each haemoglobin molecule carries 4 oxygen molecules

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9
Q

What is erythropoiesis?

A

formation of new erythrocytes

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10
Q

What are the stages of erythropoiesis?

A

kidneys detect hypoxia
erythropoietin released by the kidney into the blood
bone marrow increases erythropoiesis
increase in erythrocytes in the blood with the capacity to carry oxygen
decrease in tissue hypoxia due to increased oxygen availability

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11
Q

What happens as erythrocytes age?

A

cell membrane becomes fragile from wear and tear
cell membrane lacks flexibility to pass through narrow channels in the spleen
cells are trapped and destroyed with fragments engulfed by macrophages in the spleen and liver

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12
Q

What is haemoglobin broken down into?

A

globin - recycled into amino acids
haem - further split into iron (stored by the liver or reused in bone marrow to make more haemoglobin) and biliverdin (converted to bilirubin, combined with albumin, removed by the liver and excreted in bile)

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13
Q

What are the two major systems of blood groups?

A

ABO system and Rhesus (Rh) system

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14
Q

What is the ABO system?

A

A antigen - blood type A/anti-B antibodies
B antigen - blood type B/anti-A antibodies
A and B antigens - blood type AB/no anti-A or anti-B antibodies (universal recipient)
no antigens - blood type O/anti-A and anti-B antibodies (universal donor)

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15
Q

What is the Rhesus (Rh) system?

A

Rh positive - carry RhD antigen
Rh negative - do not carry RhD antigen
Rh negative people do not normally carry Rhesus antibodies
if they are exposed to Rh positive blood through transfusion or pregnancy they will produce anti-D (anti-Rhesus) antibodies

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16
Q

What are the two basic types of leucocytes?

A

granulocytes - have visible granules (organelles) in cytoplasm
agranulocytes - have no granules (organelles) in cytoplasm

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17
Q

What are the three types of granulocytes?

A

neutrophils, eosinophils, basophils

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18
Q

What is the function of neutrophils?

A

to engulf bacteria and cell debris or use chemical agents to destroy foreign bodies

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19
Q

What are the functions of eosinophils?

A

to engulf antigen-antibody complexes, allergens and inflammatory chemicals
to weaken or kill parasites by secreting chemical agents

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20
Q

What is the function of basophils?

A

to secrete histamine (to increase blood flow by vasodilation) and heparin (anticoagulant)

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21
Q

What are the two types of agranulocytes?

A

lymphocytes - B-cells, T-cells, natural killer cells

monocytes

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22
Q

What is the function of B cells?

A

to recognise specific antigens and produce antibodies

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23
Q

What are the functions of T cells?

A

to secrete immunologically active compounds and assist B-cells
cytotoxic (can destroy foreign cells directly)
to self-regulate other T-cells by preventing overactivity
to release interleukins which stimulate other lymphocytes and macrophages

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24
Q

What is the function of natural killer cells?

A

to provide rapid response to virally infected cells and respond to tumour cell growth

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25
Q

What are the functions of monocytes?

A

to differentiate into macrophages
to engulf pathogens and dead neutrophils, clear debris from dead or damaged cells and present antigens to activate other immune cells

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26
Q

What are thrombocytes?

A

small discs without nuclei

lifespan of 8-11 days

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27
Q

What are the functions of thrombocytes?

A

involved in blood clotting, secreting clotting factors (procoagulants), vasoconstricting agents to induce vascular spasm, and clumping together in platelet plugs
dissolve old blood clots
destroy bacteria by phagocytosis
secrete chemical agents
attract neutrophils and monocytes to infected sites by chemical messengers
promote mitosis in fibroblasts and smooth muscle

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28
Q

What are the three stages in haemostasis?

A

vasoconstriction, platelet plug formation, coagulation

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29
Q

What happens in vasoconstriction?

A

pain receptors stimulate smooth muscle in blood vessels to constrict to reduce blood flow
thrombocytes release serotonin for longer lasting vasoconstriction

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30
Q

What happens in platelet plug formation?

A

collagen fibres are exposed and thrombocytes adhere to collagen using pseudopods (temporary projections of cell cytoplasm)
these enable them to adhere to other platelets, causing a mass accumulation that forms a platelet plug
pseudopods contract to bring vessel walls closer and form a temporary seal

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31
Q

What is coagulation?

A

a complex series of reactions enhanced by positive feedback which forms a blood clot

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32
Q

What happens in the extrinsic pathway?

A

activated when proteins are released by damaged blood vessels and perivascular tissue (tissue close to/surrounding blood vessels)
factor III combines with factor VII and, in the presence of calcium, activates factor X

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33
Q

What happens in the intrinsic pathway?

A

triggered when thrombocytes release factor XII (through degranulation), leading to activated factor XI, IX and VIII in that order, each triggering the next
factor VIII activation requires the presence of calcium and platelet factor 3
factor VIII also activates factor X

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34
Q

What happens in the final common pathway?

A

factor X combines with factors III and V in the presence of calcium and platelet factor 3 resulting in prothrombin activator
this converts factor II (prothrombin) to thrombin, which converts factor I (fibrinogen) to fibrin
fibrin reacts with factor XIII and calcium to produce the structural framework of the blood clot
thrombin speeds up process by accelerating production of prothrombin activator by interacting with factor V

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35
Q

What is the difference between procoagulants and anticoagulants?

A

procoagulants (e.g. fibrinogen and calcium) promote clot formation
anticoagulants (e.g. heparin and plasmin) cause clot breakdown/fibrinolysis

36
Q

What happens after the clot has formed and damaged vessels heal?

A

fibrinolysis prevents further clot formation

37
Q

What is the heart?

A

the organ which pumps blood around the body
right side of heart pumps blood through pulmonary circulation
left side of heart pumps blood through systemic circulation
the myocardium in the left side of the heart is thicker than in the right as the force required for systemic circulation is much greater than for pulmonary circulation

38
Q

Where is the heart positioned?

A

in the thoracic cavity and mediastinum, just behind and to the left of the sternum
it is well protected by the sternum and ribcage

39
Q

What are the three layers of the heart?

A

pericardium (outer layer), myocardium (middle layer), endocardium (inner layer)

40
Q

What is the structure of the pericardium?

A

consists of dense connective fibrous tissue that prevents the heart from overstretching
inner layer has two serous membranes
outer membrane is the parietal pericardium
inner membrane is the visceral pericardium
serous fluid between the two layers provides lubrication

41
Q

What is the structure of the myocardium?

A

consists of thin filaments (actin) and thick filaments (myosin)
these fibres pass over each other when the heart contracts, shortening the muscle which pumps blood out of the chambers
the thickness of the myocardium varies depending on how strong that area needs to be

42
Q

What is the structure of the endocardium?

A

lines the heart and heart valves
consists of a single layer of epithelial cells continuous with the innermost layer of blood vessels
this ensures the smooth inner nature of blood vessels continues inside the heart
the anterior and inferior walls of the right ventricle, the lower two thirds of the septum, and a large amount of the left ventricle are lined by rough muscle bundles (trabeculae carneae) involved in contraction

43
Q

What is the structure of cardiac muscle?

A

striated
contracts involuntarily via the ANS
own pacemaker cells (autorhythmic)
cardiomyocytes contain many mitochondria

44
Q

How does blood flow through the heart?

A

deoxygenated blood enters the right atrium via the superior and inferior vena cava
blood is pumped via the tricuspid valve into the right ventricle
blood is pumped via the pulmonary valve into the pulmonary trunk, which divides into the right and left pulmonary arteries
blood is pumped to the lungs for gas exchange via the pulmonary arterioles and capillaries
capillaries bring oxygenated blood into pulmonary venules and veins to the left atrium
blood is pumped via the bicuspid valve into the left ventricle
blood is pumped via the aortic valve into the aorta

45
Q

What is the function of the septum?

A

to divide the right and left sides of the heart

46
Q

What are the two types of heart valves?

A

atrioventricular (tricuspid and bicuspid) valves - between the atria and ventricles
semilunar (pulmonary and aortic) valves - at the entrances to the major arteries from the heart

47
Q

What are the functions of the heart valves?

A

to ensure blood flows in one direction

to prevent backflow of blood

48
Q

What happens to the heart valves when the ventricles relax?

A

semilunar valves close and AV valves open

blood is pumped from the atria into the ventricles

49
Q

What happens to the heart valves when the ventricles contract?

A

AV valves close and semilunar valves open

blood is pumped from the ventricles into the pulmonary trunk and aorta (not back into the atria)

50
Q

What is coronary circulation?

A

blood supply to the heart via the right and left coronary arteries
cardiac veins collect venous blood
most join to form the coronary sinus which empties into the right atrium
others empty directly into the right atrium

51
Q

What are the three main types of blood vessels?

A

arteries - carry blood away from the heart
capillaries - enable exchange of water, nutrients and waste products between the blood and the tissues
veins - carry blood towards the heart

52
Q

What are the three structural layers found in arteries and veins?

A

tunica externa - an outer fibrous layer
tunica media - a middle layer of smooth muscle, elastic fibres and collagen
tunica intima - an inner lining of endothelium

53
Q

What is the structure of the tunica externa?

A

consists of collagen fibres, varying in thickness between vessels
this layer anchors blood vessels to nearby organs, nerves and other blood vessels and provides a passage for nerves and small lymphatic/blood vessels
large blood vessels require their own blood supply (the vasa vasorum)
other layers are nourished by the blood through diffusion

54
Q

What is the structure of the tunica media?

A

smooth muscle allows vasoconstriction and vasodilation which alters the blood flow and pressure
elastic fibres allow for expansion and recoil
collagen provides structural support

55
Q

What is the structure of the tunica intima?

A

consists of a thin layer of squamous epithelium covering a basement membrane and some fibrous tissue that lines arteries and veins
it is in direct contact with blood and is smooth to enhance flow and prevent coagulation
this layer is partially permeable and can secrete vasoactive substances

56
Q

What are the distinct adaptations of arteries and arterioles that support their role in the CVS?

A

walls of larger arteries (nearer the heart) contain more elastic tissue to withstand blood pressure
as arteries get smaller, muscle tissue increases
tunica media of arterioles consists entirely of smooth muscle for vasoconstriction/dilation

57
Q

What are the distinct adaptations of capillaries that support their role in the CVS?

A

consist of a single layer of endothelial cells

this forms a partially permeable membrane that separates the blood and interstitial fluid

58
Q

What are the distinct adaptations of venules and veins that support their role in the CVS?

A

tunica media of veins is thinner

some veins have valves to prevent backflow of blood as it returns to the heart

59
Q

How does fluid move between the capillary membrane?

A

freely permeable to water and small molecules (e.g. oxygen, electrolytes, glucose)
not freely permeable to large molecules (e.g. plasma proteins) which remain in the plasma

60
Q

How does fluid move between the cell membrane?

A

freely permeable to water

other small molecules move in by active transport

61
Q

What is hydrostatic pressure?

A

the pressure exerted by the blood against the arterial wall by the force exerted by the heart pumping
this pressure forces fluid and small molecules out of the capillary at the arterial end

62
Q

What is osmotic pressure?

A

the pressure exerted by plasma proteins and some electrolytes in the plasma inside the capillaries

63
Q

What is the difference in pressure at the two ends of the capillary termed?

A

net filtration pressure (NFP)

64
Q

What does the conduction system consist of?

A 
sinoatrial node (SAN)
atrioventricular node (AVN)
atrioventricular bundle (AVB)/bundle of His
right and left bundle branches
Purkyne fibres
65
Q

How is a heartbeat initiated and coordinated?

A

SAN initiates a wave of excitation across the atria causing atrial systole
the non-conducting tissue stops ventricular systole
AVN delays the impulse whilst the blood leaves the atria and fills the ventricles
AVN sends a wave of excitation down the Bundle of His causing ventricular systole from the apex up

66
Q

What is the cardiac cycle?

A

one complete heartbeat

67
Q

What is an electrocardiogram (ECG)?

A

a record of the electrical changes in the heart muscle during a cardiac cycle

68
Q

What is the PQRST complex?

A

ECG trace of a healthy person
wave P - atrial systole
wave QRS - ventricular systole
wave T - diastole

69
Q

What is cardiac output?

A

the volume of blood pumped out of the heart per minute

70
Q

How do you measure cardiac output?

A

stroke volume x heart rate

71
Q

What is blood pressure?

A

the pressure exerted by the blood against the arterial walls by the pumping force of the heart

72
Q

How do you measure blood pressure?

A

cardiac output x peripheral resistance

73
Q

What are the two control systems in the body that regulate blood pressure?

A

short-term/fast-acting control - autonomic division of the nervous system
long-term/slow-acting control - renin angiotensin aldosterone system (RAAS) of the endocrine system

74
Q

How does the nervous system detect rises and falls in blood pressure?

A

chemoreceptors respond to changes in concentration of chemicals (e.g. chemicals affected by respiration)
baroreceptors (in the arch of the aorta and carotid sinuses) respond to changes in pressure

75
Q

How do chemoreceptors respond to high carbon dioxide concentration/low oxygen concentration?

A

relay to cardiovascular centre
sympathetic nervous system relays to SAN to increase heart rate (and the rate of breathing to increase gas exchange)
increase cardiac output and blood pressure

76
Q

How do chemoreceptors respond to low carbon dioxide concentration/high oxygen concentration?

A

relay to cardiovascular centre
parasympathetic nervous system relays to SAN to decrease heart rate
decrease cardiac output and blood pressure
carbon dioxide and hydrogen ions stimulate arterial/arteriole vasodilation

77
Q

How do baroreceptors respond to a decrease in blood pressure?

A

relay to cardiovascular centre
sympathetic nervous system relays to SAN to increase heart rate and cause vasoconstriction of smooth muscle in arterial walls
catecholamines and adrenaline stimulate alpha-adrenergic and beta-adrenergic receptors which cause vasoconstriction

78
Q

How do baroreceptors respond to an increase in blood pressure?

A

relay to cardiovascular centre
parasympathetic nervous system relays to SAN to decrease heart rate and cause vasodilation of smooth muscle in arterial walls

79
Q

How does the endocrine system respond to a decrease in blood pressure?

A

blood flow through glomerulus in the nephron of the kidney is reduced
renin released from the afferent arteriole
renin converts angiotensinogen (a plasma protein) produced by the liver to angiotensin I (a variant plasma protein)
the lungs and PCTs produce angiotensin converting enzyme (ACE)
when ACE comes into contact with angiotensin I, it converts it to angiotensin II (the active form of this hormone)

80
Q

How many pathways are triggered by angiotensin II to increase blood pressure?

A

five

81
Q

What happens in pathway 1?

A

angiotensin II stimulates the adrenal cortex to release aldosterone
this hormone triggers the reabsorption of sodium and water back into the blood stream from the kidney nephrons
this increases blood volume and blood pressure by increasing cardiac output and peripheral vascular resistance

82
Q

What happens in pathway 2?

A

angiotensin II stimulates the release of ADH from the posterior pituitary gland
ADH increases permeability of the DCTs and collecting ducts
this increases water reabsorption leading to an increase in blood volume and blood pressure

83
Q

What happens in pathway 3?

A

angiotensin II stimulates the thirst centre in hypothalamus

a person may drink more fluids, leading to an increase in blood volume and blood pressure

84
Q

What happens in pathway 4?

A

angiotensin II stimulates vasoconstriction of the smooth muscle in arterial walls
this increases blood pressure and peripheral vascular resistance

85
Q

What happens in pathway 5?

A

angiotensin II causes cardiac and vascular hypertrophy

this raises blood pressure by reducing the elasticity of heart and arterial walls

86
Q

What is the atrial natriuretic peptide?

A

a hormone released by the heart when raised blood volume causes stretching of the atrial wall beyond what is expected
acts on PCTs and collecting ducts to decrease reabsorption of sodium and water
this reduces blood pressure as more water is lost from the body through urine formation

Anatomy and Physiology (13 decks)

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