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MBChB1 Phase 1 > Week 9 > Flashcards

Week 9 Flashcards

1
Q

What is the circulatory system?

A

organ system transporting oxygen, carbon dioxide, nutrients etc

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2
Q

What is the cardiovascular system made up of?

A
  • heart
  • blood vessels aka arteries, veins, capillaries
  • blood
  • lymphatic system
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3
Q

what is the lymphatic system?

A

network of tissues, vessels and organs working together to move lymph back into circulatory system

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4
Q

what is the pulmonary circulation?

A

oxygen depleted blood passes from heart to lungs
returns oxygenated blood to heart

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5
Q

what is the systemic circulation?

A

oxygen rich blood passes from heart to lungs
returns deoxygenated blood to heart

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6
Q

what are the boundaries of the superior mediatinum?

A

T1
superior manubrium (chest wall)
sternal angle
T4/5

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7
Q

What is in the superior mediastinum?

A

thymus
aortic artery
pulmonary artery

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8
Q

what are the boundaries of the inferior mediastinum?

A

sternal angle
skeletal muscle of diaphragm

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9
Q

what is in the anterior portion of the inferior mediastinum?

A

fat and some thymus

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10
Q

what is in the middle portion of the inferior mediastinum?

A

heart

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11
Q

what is in the posterior portion of the inferior mediastinum?

A

aorta
oesophagus

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12
Q

function of trabeculae in heart?

A

increase flow and contractility of blood and heart

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13
Q

what is the endocardium?

A

the iner layer of the heart

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14
Q

2 layers of pericardium?

A

fibrous and serous

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15
Q

function of fibrous pericardium? problem with this?

A

tough outer layer anchoring heaart to diaphragm
prevents rapid overfilling of heart
can restrict if theres an accumulation of fluid aka pericardial effusion compressing the heart, especially in right side reducing cardiac output

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16
Q

function of serous pericardium? 2 layers?

A

helps lubricate heart
inner visceral and outer parietal

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17
Q

function of serous fluid?

A

reduces friction of layers during beating of heart

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18
Q

function of superior vena cava?

A

takes deoxygenated blood from head and neck and upper limbs to RA

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19
Q

function of inferior vena cava?

A

takes deoxygenated blood from below level of heart e.g. abdomen, pelvis, lower limbs to RA

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20
Q

pathway of blood from SVC and IVC?

A

Right atria then right ventricles, to pulmonary valve then pulmnary trunk then to lungs via pulmonary arteries

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21
Q

Where does oxygenated blood from lungs pass to?

A

pulmonary veins then to LA then mitral valve then LV then aorta then several other blood vessels

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22
Q

Function of coronary arteries?

A

first branch of aorta
pass blood to heart muscle

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23
Q

function of braciocephalic trunk?

A

passes blood to right subclavian artery and right carotid artery
first branch of aorta

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24
Q

function of right carotid artery?

A

supplies head and neck with blood

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25
Q

function of right subclavian artery?

A

supplies right upper limb

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26
Q

function of ductus venosus? how much blood is taken to IVC here?

A

allows maetrnal blood to bypass fetal liver to go to IVC
30%

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27
Q

what does the ductus venosus become at birth?

A

ligamentum venosum

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28
Q

function of foramen ovale?

A

allows blood to flow between the right and left atrium

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29
Q

function of ductus arteriosus

A

links pulmonary trunk with aorta to allow blood to flow into systemic circulation of fetus
prevents blood going to non breathing lungs in utero

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30
Q

function of umbiical arteries

A

carry deoxygenated blood back to placneta

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31
Q

what is 70% of maternal blood used in fetus?

A

liver

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32
Q

what is the fossa ovalis?

A

embryological remenant of forman ovale

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33
Q

function of aortic sinuses and location?

A

above aortic valve
3 of these, 2 from left and right coronary arteries
give rise to coronary arteries

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34
Q

significance of right atrial appendage?

A

additional part of right atrium
site for external pacemaker to be positioned

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35
Q

where is crista terminalis, function?

A

at opening of right atrial appendage
site of origin for pectinate muscles

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36
Q

function of pentinate muscles?

A

allow strecth in RA and improve volume capacity

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37
Q

what is the orifice of the coronary sinus?

A

where venous blood from heart enters

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38
Q

function of pulmonary veins?

A

carry oxygenated blood to left atrium

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39
Q

which heart chamber is thicker?

A

left as it has to pump blood through systemic circulation

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40
Q

what are trabeculae carnae?

A

rounded muscular collumns in heart ventricles
contraction pulls on chordae tendinae

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41
Q

what happens when you have atrial or ventricular septal defects?

A

present at birth
holes between ventricles or atria
small holes close themselfs
compromise lungs and heart by increasing BP
may require surgery

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42
Q

what are symptoms of atrio ventricular septal defect? requires?

A

breathing problems
heart racing
cyanosed
tired easily
surgery

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43
Q

which heart valve is tricuspid?

A

right between atria and ventricles

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44
Q

which heart vakve is bicuspid?

A

left between LA and LV

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45
Q

what are chordae tendinae?

A

heart strings connecting to papillary muscles
prevent mitral and tricuspid valves flipping back into atria during ventricular contraction

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46
Q

WHat arteries supply heart muscle?

A

coronary arteries

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47
Q

Which coronary arteries does left coronary arteries give rise to?

A

circumflex artery
anterior and posterior interventricular arteries

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48
Q

what arteries does right coronary artery give rise to?

A

marginal artery

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49
Q

name the cardiac veins?

A

small anterior cardiac veins
small cardiac vein
middle cardiac vein
great cardiac vein

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50
Q

where do blood from the heart drain into right atrium?

A

coronary sinus

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51
Q

what are end arteries?

A

supply oxygenated blood to specific portion of tissue

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52
Q

where are end arteries found?

A

spleen
liver
intestines
ends of digits
ears
nose
penis

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53
Q

what happens if end arteries are blocked?

A

heart attack

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54
Q

what is ischaemia, what can it cause? what does it present with?

A

reduction in blood oxygen
colateral circulation develops
angina

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55
Q

what is colateral ciruclation?

A

new blood vessel growth to pass around area of reduced blood supply

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56
Q

what is infarction?

A

death of a tissue due to a lack of blood supply

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57
Q

which coronary arteries are usually affected by infarction?

A

anterior interventricular branch of LCA 40-50%
RCA 30-40%
circumflex branch of LCA 15-20%

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58
Q

what can be used in a coronary artery bypass graft?

A

saphenous vein (longest vein in body)
internal mammary artery
internal thoracic artery

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59
Q

what is the pacemaker of the heart? how? what does this mean?

A

sinoatrial node
generates electrical signals
controls heart rate

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60
Q

what is the moderator band of the heart?

A

allows more rapid contraction across to anterior papillary muscle
helps with conduction times

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61
Q

what are purkinje fibres and their functions?

A

specialised conducting fibres
create contraction across ventricles
maintain regular heart rate

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62
Q

what is the pathway of nerve impulses in the heart?

A

pass from Sinoatrial node to atrioventricular node
pass down interventricular septum through atrioventricular bundle
through walls of left and right ventricles
then into purkinje fibres

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63
Q

what makes up the upper respiratory tract?

A

nasal cavity
pharynx
larynx

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64
Q

what makes up the lower respiratory tract?

A

trachea
primary bronchi
lungs

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65
Q

functions of the respiratory tract?

A

conducts air (warms and humidifies)
respiration (gas exchange)
mucus protects against pathogens

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66
Q

what is the nasopharynx?

A

base of skull to soft palate

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67
Q

what is oropharynx?

A

soft palate to epiglottis

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68
Q

what is the laryngopharynx?

A

epiglottis to where bifurcation occurs to oesophagus and trachea

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69
Q

difference between right and left bronchus?

A

right - vertical, greater diameter and short so foreign body more likely to go here. Right has superior, middle and inferior lobe bronchus

Left - has suberior and inferior lobe bronchus

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70
Q

what type of epithelia is respiratory epithelium?

A

pseudostratified ciliated columnar epithelium with goblet cells

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71
Q

what is lamina propira?

A

thin layer of connective tissue forming part of mucus membrane

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72
Q

function of brush cells in bronchi?

A

can detect bacteria proteins

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73
Q

what is different in each level of bronchi?

A

epithelium type

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74
Q

what happens in type I pneumocytes?

A

gas exchange

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75
Q

what is secreted by type II pneumocytes? function?

A

surfactant
increases lung compliance/expandability and prevents atelectasis/collapse of lungs at end of expiration

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76
Q

when is surfactant produced?

A

weeks 24-28

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77
Q

how many lobes are in each lung?

A

left - 2
right - 3

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78
Q

what is contained in the hilum?

A

bronchus
pulmonary arteries
veins

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79
Q

what does the base of the lungs join with?

A

diaphragm

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80
Q

what does the costal urface of lungs connect to?

A

ribs

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81
Q

what 2 fissures exist in right lung?

A

horizontal fissure
oblique fissure

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82
Q

what fissure exists in left lung?

A

oblique fissure

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83
Q

what 3 lobes are in right lung?

A

superior, middle, inferior lobe

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84
Q

what is a drug?

A

chemical entity altering body function
prevents or treats disease

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85
Q

features of small molecule drugs?

A

synthetic and chemical derived
low molecular weight
simple structure
stable
cheap

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86
Q

how do drugs work?

A

drug must get to site of action
bunds to target/receptor
exhibits required response

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87
Q

what are biologics drugs? what disease are they involved in?

A

recombitant processes
target soecific
side effects
expensive
autoimmune disease

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88
Q

example of biologic drug and how it works?

A

etanercept
recombitant antibody molecule blocks TNF alpha
treats autoimmune disease

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89
Q

what is a drug target?

A

macromolecular component of a cell where a drug interacts to produce a response

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90
Q

what are drug targets usually and what do they change?

A

usually a protien
change activity of cellular enzymes

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91
Q

what may happen to cellular enzymes when drug interacts with protein?

A

inhibited or activated

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92
Q

what siganl acts on ligand gated ion channels? where?

A

neurotransmitters in nerve or muscle cell

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93
Q

when is suxamethonium used and how..?

A

used in anaesthesia as a muscle relaxant
binds to acethycholine receptor at neuromuscular junction
depolarisation occurs

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94
Q

which molecule do catecholamines activate?

A

b adrenoreceptors
activates adenylyl cyclase
actuvates camp

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95
Q

what is bisoprolol used for? which type of drug id it? how does it work? speed?

A

heart conditions
beta blocker
blocks stimulation of b1 receptors , which would usually increase heart rate
seconds to minutes

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96
Q

what are targets for peptide hormones in protein kinase inhibitors involved in? how long does this take…

A

cell growth and differentiatiin
release of inflammatory mediators
hours

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97
Q

where are cytosolic receptors foind? what do they do?

A

inside the cell
regulate dna trabscription and protein synthesis
hours to days

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98
Q

4 mechanisms of drug action?

A

ligand gated ion channels
gpcrs
protein kinase receptors
cytosolic receptors

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99
Q

what is prednisolone used for? which type of drug is it?

A

allergies
corticosteroid
inhibits inflammation
slow process

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100
Q

Role of the lungs?

A

Bring in oxygen rich air to the body
Expel waste gas produced from cells in the body

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101
Q

What process is movement in and out the lungs coupled with?

A

Cellular respiration

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102
Q

Which type of homeostasis does breathing maintain?

A

Blood gas homeostasis

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103
Q

What is the partial pressure of oxyegn at rest?

A

100mm hg

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104
Q

What is the partial pressure of carbon dioxode at rest?

A

40mm Hg

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105
Q

How many liters of ventilation happens in the lungs at rest per minute, how many breaths?

A

6L/min
12
500ml/breath

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106
Q

How many mls carbon dioxide expired and oxygen consumer per minute?

A

250ml/min consumed
200ml/min expired

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107
Q

What is the barometric pressure?

A

Sea level atmospheric pressure
760 mmHg

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108
Q

How do you work out the partial pressure of a gas?

A

Fraction of gas in gas mixture x barometric pressure

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109
Q

What is the water vapour partial pressure at body temperature?

A

47mmHg

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110
Q

What is the partial pressure of oxygen in the trachea?

A

150mmHg

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111
Q

WhT is the primary muscle for respiration?

A

Diaphragm

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112
Q

What happens to the disphragm and exteranl intercostals in quiet breathing?

A

Inspiration: active
Diaphragm contracts downwards and pishes abdominal contents outwards
External intercostals pull ribs upwards and outwards
Expiration: passive
Elastic recoil

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113
Q

What happens in inspiration in strenuous breathinf?

A

Greater contraction of diaphragm (10cm compared to 1cm in quiet) and external intercostals

Inspiratory accessory muscles active e.g. sternocleidomadtoud, alae nasi, genioglossus

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114
Q

What happens in expiration in strenuous breathing?

A

Abdominal muscles active
Internal intercostals oppose external by pushing ribs down and inwards

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115
Q

What is pleural pressure?

A

Pressure between albeolar lining and chest wall

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116
Q

What is transpulmonary pressure?

A

Difference in pressure between pleural and alveolar pressure

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117
Q

What is alveolar pressure?

A

Pressure within alveolar sacs

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118
Q

What is the alveolar pressure at the start of inspiration?

A

The same as barometric pressure

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119
Q

What increases when inspiratory muscles contract? What decreases?

A

Thoracic volume
Transpulomary pressure
Alveolar volume

pleural pressure decreases
Alveolar pressure decreases below barometric pressure

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120
Q

Where does air flow into in inspiration? From which pressure?

A

Alveoli
From high to low pressure

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121
Q

How does inspiration end?

A

Muscles stop contracting
Thorax and alveoli stop expanding

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122
Q

What happens in expirstion?

A

Thoracic volume decreases
Pleural pressure increases
Transpulmonary pressure decreases
Alveolar pressure becomes greater than barometric pressure

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123
Q

Function of the nasal cavities?

A

Filters warms and humidifies air
Detects smells

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124
Q

Function of the pharynx?

A

Conducts air to larynx

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125
Q

Function of larynx?

A

Protects opening to trachea
Contains vocal cords

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126
Q

Function of trachea? What jeeps the airway open?

A

Filters air
Traps particles in mucus
Cartilages keep airway ipen

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127
Q

Functions of bronchi?

A

Filters air
Traps paritcles in mucus

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128
Q

Fucntion of alveoli?

A

Act as sites of gas exchange between air and blood

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129
Q

Function of upper airways?

A

Consucts air to lungs
Humidifies air - saturates with water
Warms to body temp
Filter

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130
Q

How do upper airways filter air?

A

Inhaled particles stick to mucus
Mucus move to mouth by beating cilia

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131
Q

Function of coughing?

A

Protective reflex gets rid if offending material

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132
Q

What receptors activate the cough reflex?

A

Rapidly adapting pulmonary strech receptors in epithelium of respiratory tract

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133
Q

What are RARs activated by?

A

Dust
Smoke
Amnonia
Odeoma

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134
Q

What are RARs afferents of?

A

Vagus nerve

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135
Q

How is afferent information from RARs sent to brain?

A

Via vagus nerve

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136
Q

describe the cough reflex

A
  • stimulation of rapidly adapting pulmonary strecth receptors by irratant e.g. dust
  • afferent information sent via vagus nerve to brain
  • brain sends information to diaphragm via phrenic nerve
  • external intercostals induce strong contraction
  • air rushes into lungs
  • abdominal muscles contract to induce expiration
  • glottis opens to forcefully expel air and irritants
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137
Q

what do trachea branch into? what happens with branching?

A

bronchi
non respiratory brinchioles
respiratory bronchioles
alveolar ducts

increase in number, decrease in diameter, increase in surface area

138
Q

what are conducting airways ? where aree these? what do they form?

A

do not participate in gas exchange, only conduct air into body
form anatomic dead space
brinchi containing cartilage and non respiratory bronchioles

139
Q

how much volume is in conducting airways?

A

150mls
30 percent of average breath

140
Q

what are respiratory airways? where are they?

A

bronchioles with alveoli where gas exchange occurs
from terminal bronchioles to alveoli

141
Q

how long is the region of respiratory airways! how much volume is in these..

A

5mm long
2500ml volume

142
Q

what is a respiratory unit? what does it consist of?

A

gas exchanging unit
basic physiological unit of the lung
consists of respiratory bronchioles, alveolar ducts, alveoli

143
Q

how many alveolar sacs are in an adult?

A

300-400 million

144
Q

what shape are alveoli? what is their dismeter?

A

250 microns

145
Q

what type of cells are in alveoli?

A

type 1 and 2 epithelial cells

146
Q

what are type one epithelial cells? how much surface area does this take up?

A

site of gas exchange in alveoli
97%

147
Q

what are type 2 epithelial cells?

A

produce pulmonary surfactant to relieve surface tension

148
Q

what are septal cells?

A

type 2 epithelial cells

149
Q

what are alveolar macrophages?

A

remove debris

150
Q

why are alveoli designed for gas exchange?

A

large surface area
very thin walls
good diffusion characteristics

151
Q

surface area of alveoli?

A

100metres squared

152
Q

how thin are alveolar walls?

A

0.5 microms

153
Q

function of pulmonary circulation in lung?

A

brings deoxygenated blood from heart to lung and oxygenated blood from lung to heart

154
Q

function of bronchial circulation in lung?

A

brings oxygenated blood to lung parenchyma

155
Q

how much blood is in the pulmonary circulation?

A

500mls so 10 pervent

156
Q

how much blood is in the alveolar capillary network at rest? what does this increase to and how?

A

75mls
150-200mls due to recruitment of new capillaries and increased pressure and flow in exercise

157
Q

how long does it take for RBCs to pass through capillaries..

A

less than 1 second

158
Q

what is the pulmonary circuit in gas exchange?

A

oxygen enters blood from alveoli down pressure gradient
carbon dioxide leaves blood to alveoli down pressure gradient

159
Q

what is the systemic circuit of gas exchange?

A

oxygen leaves blood to go to tissues down pressure gradient
carbon dioxide enters blood via tissues down concentration gradient

160
Q

what is partial pressure of oxygen in alveoli compared to venous blood?

A

alveoli - 100mmHg
venous blood - 40 mmHg

161
Q

what is the partial pressure of co2 in alveoli compared to venoud blood?

A

alveoli - 40mmHg
venous blood - 46mmHg

162
Q

what is the partial pressure of co2 in tissues compared to arterial blood?

A

tissue - 46mmHg
arterial blood - 40mmHg

163
Q

what is the partial pressure of oxygen in tissues compared to arterial blood?

A

tissues - 40mmHg
arterial blood - 100mmHg

164
Q

what processes near ro a cell can drugs act on?

A

inhibition/induction of transporter processes that carry substances in or out of cells
incorporation into larger molecules
altering metabolic processes unique to microorganisms e.g. penicillin

165
Q

how can drugs act on processes outside a cell?

A

direct chenical interaction
chealating agents

166
Q

what are agonist drugs?

A

binds to receptor binding site
activates it the same way as the endogenous chemical messenger would

167
Q

2 types of agonist drugs?

A

full- an agonist with maximum efficacy
partial - a drug with less than maximal efficacy

168
Q

function of antagonist drugs?

A

interact with receptor but do not activate it
affinity but no efficacy

169
Q

example of partial agonist?

A

buprenorphine used to treat opiod addiction

170
Q

2 types of antagonist drug?

A

competitive
non competitive

171
Q

what is a competitive antagonist?

A

competes with agonist for receptor
reduces apparent affinity of the agoist

172
Q

what happens to dose response curve in competitive antagonists?

A

dextral shift - displaced to the right
loss of potency of agonist

173
Q

what is a non competitive antagonist?

A

drug binds irreveribly to receptor
producds slight dextral shift
as more receptors are bound by non competitive agonists it is impossible for agonist to elicit maximum effect

174
Q

what is affinity?

A

how strongly a drug binds to a receptor

175
Q

what is efficacy?

A

a measure of the maximum biological effect resulting ffom a drug binding to its target

176
Q

what is drug potency?

A

measure of the amount of drug required to produce a defined biological effect

177
Q

example of drug potency?

A

morphine is more potent than aspirin
less morphine is required to achieve a large analgesic effect than aspirin

178
Q

what is a drug adverse affect?

A

response to a drug which is noixus and unintended
occurs at normal doses
used for therapy of a disease

179
Q

how common are drug adverse effects? who is more at risk?

A

1 in 16 patients in hospital
older adults and those on multiple prescribed medication

180
Q

two types of drug adverse affects?

A

type a; related to intended pharmalogical action if the drug
type b: effects unrelated to known pharmacological function

181
Q

characteristics if type a drug adverse affect?

A

common
predictable
dose related usually
usually not life threatening
e.g. drug for lowering blood pressure may cause low blood pressure in patients

182
Q

characteristics of type b adverse drug effects?

A

uncommon
unpredicstbel
usually not dose related
usually life threatening
e.g. severe allergy causing anaphyaltic shock afyer penicllim

183
Q

what is theraputic efficacy?

A

capacity of a drug to produce an effect and refers to maximum such effect

184
Q

what is median effective dose 50 ED50?

A

dose at which 50 percent of the population or sample manifests a given effect

185
Q

what is median toxic dose 50 TD50?

A

dose at which 50 percent of population manifests given toxic effect

186
Q

what is median lethal dose 50 LD50?

A

dose which kills 50 percent of subjects

187
Q

what is drug toleramce? example?

A

continuous or repeated administration of a drug accompanied with gradual diminuation of the effect it produces
must increase dose to get required effect of previous smaller dose

188
Q

examples of drug tolerance?

A

alcohol - accellerated metabolism by enzyme induction
opiates

189
Q

3 concepts of drugs crossing the cell membrane?

A

phsiochemical properties of the drug
properties of membrane
type of transport

190
Q

3 phsiochemical properties of drugs?

A

molecular size
concentration gradient
pharmacokinetics

191
Q

properties of the cell membrane affecting drugs?

A

thickness
surface area
permability
ph of cell

192
Q

3 types of drug transport?

A

paracellular - diffuses through extracellular fluid
diffusion through memrbanes
active transport/transport protoens

193
Q

2 types of diffusion across cell memrbaen for drugs?

A

passive and facilitated diffusion

194
Q

3 types of passive diffusion?

A

paraceullar diffusion
intracellular diffusion (lipid)
membrane diffusion

195
Q

2 types or faciliated diffusion?

A

channel protein
carrier protein

196
Q

what influences drug diffusion?

A

drug molecule size and shape
concentration gradient
membrane thickness
membrane surface area
pharmacokinetics
ph of solution

197
Q

3 time courses of drug effects

A

immediate
delayed
cumulative

198
Q

example of delayed drug effect?

A

warfarin

199
Q

what is warfarins drug action? effect? response?

A

inhibition of vit k recycling
decreased synthesis of clotting factors
prolonged cosgultion time

200
Q

what is cumulation of a drug?

A

blood levels of a drug build ip and inreases its theraptuic and toxic effects

201
Q

example of cumulative drug? action? effect? response?

A

omeprazole

action - inhibits gastric acid pump
effect - decreased acid secretion and increased pH
response - ulcer healing

202
Q

how exactly does omezaprole block proton pumps?

A

irreveribly binds to them

203
Q

when do first order kinetics occur? what is the rate of elimination proportional to?

A

when a constant proportion of the drug is eliminated per unit time
rate of elimination proportionsl to amount of drug in body - each half life of the drug halfs the concentration

204
Q

how are most drugs eliminated?

A

first order kinetics
every half life that passes eliminates half drug concentration

205
Q

what are zero order kinetics? examples of drugs?

A

a constant amount of drug is eliminated per unit time
e.g. 10mg drug eliminated per hour
ethanol, phenytoin, salicylates

206
Q

what are non linear kinetics due to?

A

saturation in a pharmacokinetic mechanism
protein binding, hepatic metabolism, active renal transport of drug

207
Q

what is theraputic drug minitoring?

A

monitors level of medication within blood

208
Q

what is a loading dose? when is it used? what do you need to calculate this?

A

brings the concentration of a drug to the target range in a single dose
used when rapid onset of action is needed
volume of distribution

209
Q

when is oral loading dose used?

A

when drug will take a long time to reach a steady state concentration e.g. digoxin

210
Q

what are the functions of the cardiovascular system?

A
  • transport of nutrients, oxygen, waste products around the body
  • transfer of heat (core to skin)
  • buffers body pH
  • transport of hormones e.g. adrenaline
  • asissts in infection response
  • assists in formation of urine
211
Q

what is opening/closing of a valve determined by?

A

pressure gradients across the valve

212
Q

what is calcification of valves? what can this cause?

A

calcium deposits form on aortic valve of heart causing narrowing of valve
lv hypertrophy, heart failure

213
Q

what is the first heart sound?

A

sound of AV valves closing

214
Q

what is the second heart sound?

A

sound of pulmonary and aortic valves closing

215
Q

why might a third heart sound be heard?

A

due to oscillation of blood flow into the ventricle

216
Q

what is preload?

A

force from volume of blood present that stretches cardiac muscle prior to contraction

217
Q

what is afterload?

A

the force the heart must work against to eject blood during contraction

218
Q

what is end diastolic volume?

A

volume of blood left after ventricular contraction

219
Q

what is stroke volme?

A

amount of blood ejected per beat

220
Q

how is cardiac output calculated? average volume?

A

CO = SV x HR
5L / min

221
Q

what determines heart rate in the heart? why?

A

sinoatrial node
has fastest intrinsic rate

222
Q

which part of the heart slows contraction and can act as a secondary pacemaker?

A

av node

223
Q

what is excitation contraction coupling?

A

purkinje fibres interdigitate with myocyte to spread impulse across ventricles

224
Q

what can problems with pacemakr cells cause?

A

arythmias
tachycardia
brachycardia

225
Q

what does an ecg detect?

A

phasic change in potential difference between 2 electrodes

226
Q

where are 2 electrodes placed in ecg? what is the role of the body in this?

A

on surface of heart
on limbs
volume conductor

227
Q

what device is used in an ecg?

A

oscilloscope

228
Q

what is the p wave in ecg?

A

atrial depolarisation

229
Q

what is the qrs complex in an ecg?

A

ventricular depolarisation

230
Q

what happens in the t wave in ecg?

A

ventricular repolarisation

231
Q

what happens in pr interval of ecg?

A

delay through av node

232
Q

what happens in st interval of ecg?

A

plateau phase of ap

233
Q

what triggers action potential in sinoatrial node? what causes deplarisation? what causes repolarisation?

A

calcium ions in and reduced potassium ions out (both positive)
calcium in
potassium leaves and calcium channels closed

234
Q

what happens if potassium permability increases in the sinoatrial node?

A

more potassium leaves so there is a longer time to thereshold therefore fewer bpm so HR decreases
due to ach from vagal nerve

235
Q

what happens in calcium permeability increases in the sinoatrial node?

A

shorter time to thereshold so more bpm so HR increases
due to noradrenaline

236
Q

what is the resting membrane potential in purkinje fibres?

A

-90mV

237
Q

how is a purkinje action potential caused?

A

positive sodium moves in
calcium ions move in
potassium moves out

238
Q

why is there a plateau phase in purkinje action potential? what is this on an ECG?

A

positive calcium is moving in but positive potassium is moving out at the same time
ST segment

239
Q

why is plateau phase of AP important?

A

elongastes phase of action potential by creating a refractory period
this allows the heart to relax

240
Q

what triggers contraction in cardiac muscle?

A

calcium entry

241
Q

where does calcium come from to trigger contraction in muscles?

A

outside of myocyte
sarcoplasmic reticulum inside cell

242
Q

function of calcium induced calcium release in myocytes?

A

allows greater contraction for a small calcium movement
acts as amplifier

243
Q

how do some drugs increase heart contraction?

A

increase intracellular calcium

244
Q

what is starlings law?

A

force of contraction increases as muscle was streched in response to increased filling of heart chambers
otherwise circulation would fail

245
Q

where are b1 adrenoreceptors found in the heart?

A

nodal tissue
conducting system
myocardium

246
Q

what do b1 adrenoreceptors bind?

A

noradrenaline by sympathetic nerves
adrenaline in circulation

247
Q

effects of b1 adrenoreceptors binding adrenaline/noradrenaline?

A

positive inotropy
positive chronotropy
positive lusitropy
positve dromotropy

248
Q

what is positive inotropy?

A

increases contraction of the heart

249
Q

what is positive chronotropy?

A

increases heart rate

250
Q

what is positive lusitropy?

A

relaxing the heart muscle

251
Q

what is positive dromotropy?

A

increases rate of conduction

252
Q

effect of beta agonists on the heart?

A

bind to beta adrenoreceptors
support with cardiogenic shock/arrest

253
Q

what happens if you use a drug for asthma that acts on b1 and b2 agonists?`

A

causes inotropy etc causing increased HR/contraction/conduction

254
Q

where does the left and right vagus nerve terminate?

A

R - SA node
L - AV node

255
Q

how does ACh released by vagus nerve affect m2 receptors?

A

activates them to reduce HR
by increased K+ permeability

256
Q

what do vagolytic drugs (inhibits vagal nerve activity) do in bradycardic patients?

A

increase heart rate

257
Q

how can you stimulate the vagal reflex?

A

breath holding

258
Q

what are changes in cardiac output detected by? where is this information taken to?

A

baroreceptors
brain

259
Q

arteries function?

A

carries oxygenated blood away from the heart around the body

260
Q

function of arterioles?

A

small blood vessel branching off arteries which link to capillaries

261
Q

function of capillaries?

A

gas exchange

262
Q

function of venules?

A

drains blood from capillaries into veins

263
Q

function of veins?

A

blood vessel carrying deoxygenated blood back to heart

264
Q

where do endothelial cells line?

A

all vessels and inside of heart chambers

265
Q

how are endothelial cells important to heart function?

A

regulates blood pressure
prevents platelet aggregation and formation of blood clots
angiogenesis +vessel remodelling
can express molecules which tether inflammatory cells

266
Q

what barrier do endothelial cells form?

A

permeability barrier for nutrients/fluid between plasma and interstitial fluid

267
Q

what do endothelial cells release?

A

vasoconstrictors: endothelin, thromboxane
vasodilators: nitric oxide, prostacyclin
free radicals

268
Q

function of free radicals?

A

oxidise ldl cholestrol

269
Q

where is vascular smooth muscle found?

A

all vessels apart from smallest capillaries

270
Q

function of vascular smooth muscke? what does it secrete? what happens when it multiplies?

A

determines vessel radius by contracting/relaxing
secretes ecm to give vessels elastic properties
hypertension

271
Q

why is arterial elasticity (compliance) important?

A

allows large arteries to act as pressure reservoir
prevents pressure falling to 0 as blood leaves arteries in diastole
allows expansion of arteries without having pressure too high

272
Q

why does calcification occur in arteries? what happens?

A

healing response to precense of dead cells
reduces elasticity of vessel
affects blood prssure
more likely for plaques to form

273
Q

when does blood pressure fall?

A

blood circulating from left to right ventricle in systemic circulation
right to left in pulmonary

274
Q

what is the normal blood pressure?

A

120/80
systolic/diastolic

275
Q

how is mean arterial pressure caculated?

A

diastolic bp + 1/3 pulse pressure
or
co x tpr

276
Q

what is the mean arterial pressure?

A

average pressure pushing blood round the system

277
Q

where does blood to the arteries come from?

A

ventricles forcefully

278
Q

what happens to arteries walls and why?

A

elastic wall stretched by raised pressure

279
Q

how do aorta/arteries structures relate to their function?

A

small amount of blood at high pressure
very thick walled/elastic

280
Q

how do arterioles structures relate to their function?

A

variable resistance system distributing blood
dissipates most of pressure

281
Q

how do capillaries structures relate to their function?

A

interchange of substances with extracellular fluid of tissues
large surface area, one cell thick

282
Q

how do venules/veins/vena cava structures relate to their function?

A

contains most of blood at low pressure
very distensible

283
Q

how much blood is in capillaries?

A

5%

284
Q

why are capilaries one cell thick?

A

rapid exchange with tissues

285
Q

what does flow in capillaries depend on?

A

supply from arterioles

286
Q

what is hydrostatic pressure?what movement does this pressure favour?

A

blood in capillaries exerts pressure on capillary wall
movement out of the capillary

287
Q

what is colloid pressure? what movement does this pressure favour?

A

plasma has instrinsic osmostic pressure due to plasma proteins
movement of fluid into the capillary

288
Q

hydrostatic pressure at arterial end of capillary opposed to venous end?

A

35mmHg at arterial
15mmHg at venous

289
Q

what prevents pulmonary oedema?

A

pulmonary hydrostatic pressure much lower than systemic pressure

290
Q

what pressure increases in heart failure? where does this happen in particular? symptoms?

A

capillary hydrostatic pressure increases
in extremities
pitting oedema, pulmonary oedema

291
Q

what is pulmonary oedema caused by?

A

high altitude
left heart failure

292
Q

what symptoms happens in right heart failure?

A

jugular distension

293
Q

what drugs reduce capillary hydrostatic pressure?

A

nitrates
ace inhibitors
vaso dilators

294
Q

what is the net filtration of tissue fluid a day?

A

4 litres not including kidneys

295
Q

what does build up of fluid in tissues cause? how does the body stop this?

A

oedema
moves fluid back into blood with lymph vessels and capillaries

296
Q

how do lymph vessels aid movement of fluid?

A

contraction

297
Q

where is the carina found in the lungs?

A

where the trachea bifurcates

298
Q

which parts of the lung are especially sensitive to irratants and create a cough?

A

larynx and carina

299
Q

what are the main arterial baroreceptors in the body detecting changes in blood vessels

A

carotid sinus
aortic arch

300
Q

how do nasal hair protect against infection?

A

trap foreign particles

301
Q

how can you change total peripheral resistance to lower blood pressure?

A
  • nerve varicosities from sympathetic nervous system release noradrenaline
  • activates alpha 1 adrenoreceptors on blood vessels
  • blood vessels constrict
  • tpr raised and raises bp
302
Q

name a selective alpha adrenoreceptor antagonist? what is its function?

A

prazosin, doxazosin
decreases total peripheral resistance

303
Q

name a non selective alpha adrenoreceptor antagonist? why are they not used theraputically?

A

phentalomine
blocks a1 and a2 adrenoreceptors
a2 adrenoreceptors act as negative feedback to prevent excessive noradrenaline release
more noradrenaline is released when a2 adrenoreceptor bound to so more competition for a1 receptor

304
Q

how does prazosin work?

A

blocks a1 adrenoreceptor
reduces noradrenaline binding
reduces constriction of blood vessels
total peripheral resistance decreases

305
Q

how do nasal decongestants work?

A

vasoconstrict mucosal blood vessels by releasing endogenous noradrenaline

306
Q

which channel does menthol cool and act as a local anasthetic?

A

TRPM8

307
Q

what can dilate arterioles? what happens?

A

changes in o2/co2/cellular metabolites
active hyperaemia

308
Q

what is reactive hyperaemia induced by?

A

blocking blood flow temporarily

309
Q

how is flow maintained? what is this?

A

flow autoregulation
blood flow in vascular bed reamins constant during varied arterial arterial pressure

310
Q

what can reduced blood flow cause?

A

coronary artery disease = MI
critical limb ischaemia
reynaud’s

311
Q

what are factors controlling blood flow?

A

length of tube
viscosity of liquid aka blood
pressure gradient across tube
cross sectional area of tube

312
Q

what is assumed about flow?

A

flow is laminar
flow is non pulsatile
flow is through a uniform straight pipe

313
Q

what problems can be caused by viscosity of blood?

A
  • deep vein thrombosis
  • immobility due to venous pooling
  • dehydration increases blood viscosity so flow increases
314
Q

how to decrease thickened blood viscosity?

A

movement increases venous return
hydration
reduce alcohol
compression socks for dvt

315
Q

how is flow determinded?

A

pressure gradient
resistance

316
Q

what is resistance proportional to?

A

diameter

317
Q

what happens as branching increases down the arterial tree (arteries, arterioles, capillaries)?

A

resistance increases
flow reduced

318
Q

function of valves in veins?

A

prevents backflow of blood

319
Q

what happens when theres too much blood in the veins?

A

increases capillary hydrostatic pressure
increases fluid in tissue
oedema

320
Q

how does skeletal muscle aid in venous return?

A

in exercise it compresses veins
moves venous blood back to heart
acts as a pump

321
Q

what 3 things aid venous return?

A

skeletal muscle pump
respiratory muscle contraction
sympathetic nerves

322
Q

how do sympathetic nerves aid in venous return?

A

noradrenaline constricts veins
increased bp increases venpus return to heart

323
Q

what is preload? what happens if it increases?

A

venous return to the right ventricle
heart has to work harder to pump blood out - probem in heart failure and coronary artery disease

324
Q

what does cerebral dilation by glyceral nitrate cause?

A

headache

325
Q

effect of nitrates on the circulatory system?

A

primary venodilation
reduces preload on the heart so reduces cardiac work

326
Q

what does venodilation do to the cardiovascular system?

A

decreases central venous pressure
precreases preload
decreases cardiac outpit
decreases cardiac work/oxygen consumption

327
Q

what is reflex tachycardia and what is it caused by? what does this maintain?

A

blood pressure decrease causes chronotropy
maintains arterial blood pressure

328
Q

where does aortic arch baroreceptors take information?

A

brain via vagus nerve 10

329
Q

where does carotid sinus take information to the brain?

A

nerve IX

330
Q

which baroreceptor is most sensitive? when?

A

carotid receptor so more importnat
most sensitive around mean arterial pressure

331
Q

where do baroreceptors inpit information?

A

nts - nucleus tractus solaris

332
Q

which pressure is baroreceptors sensitive to?

A

60-180mmHg

333
Q

what does decreased arterial pressure do in baroreceptors, parasympathetic and sympathetic systems?

A

decreased arterial baroreceptors firing
decreased parasympathetic outflow to heart so heart rate increases
increased sympathetic outflow to heart, arterioles veins to increase HR

334
Q

which reflex decreases parasympathetic outflow to heart?

A

medullary cardiovascular centre

335
Q

how is blood pressure lowered by the nucleus tractus solaris?

A

alpha 2 adrenoreceptor
inhibits bulbar circulatory centres to lower noradrenaline release to decrease tpr
activates vagus nerve to release ach to lower cardiac input

336
Q

how is blood pressure increased by the nucleus tractus solaris?

A

beta 1 adrenoreceptor
activates bulbar circulatory centres to release noradrenaline to increase tpr
inhibits vagal nerve releasing ach to increase cardiac output

337
Q

function of clonidine? problem?

A

alpha 2 agonist
decreases blood pressure
activates presynaptic receptors in brain vasomotor centres to lower sympathetic output

rebound hypertension

338
Q

function of methyldopa? problem? when is it used?

A

used as central a2 adrenoreceptor agonist
decreases bp
decreases dopamine
used in hypertension in pregnancy

339
Q

what is local control of bp?

A

modulation of local blood pressure/flow and can override central control systems
independent of nerves/hormones

340
Q

what is involved in the local control of bp?

A

metabolites
blood gases
endothelium derived factors

341
Q

how does nicorandil treat angina?

A

opens potassium channels
hyperpolarises smooth muscles
closes calcium channels
reduces muscle contraction

MBChB1 Phase 1 (12 decks)

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