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Cardiovascular System Flashcards

1
Q

What is pulmonary circulation?

A

Vessels connecting heart to lungs

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2
Q

What is systemic circulation?

A

Vessels connecting heart to other tissues

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3
Q

What is the pathway for deoxygenated blood to be oxygenated and sent to other tissues? Include all structures

A

SYSTEMIC
Right atrium -> tricuspid valve -> right ventricle
PULMONARY
-> pulmonary valve -> pulmonary artery -> capillaries in lungs -> pulmonary veins
SYSTEMIC
-> left atrium -> mitral valve -> left ventricle -> aortic valve -> aorta -> elastic arteries ->arteriole with variable radius -> exchange of material with cells
Deoxygenated blood returned back to right atrium via venules
->expandable veins -> venae cavae

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4
Q

What are microscopic structures of blood vessels?

A

Tunica Intima- endothelium and internal elastic lamina
Tunica Media- smooth muscle and external elastic lamina
Tunica Externa- connective tissue and vaso vasorum

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5
Q

What are capillaries made of and mean thickness and diameter?

A

Endothelium
Diameter- 8µm
Thickness- 0.5µm

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6
Q

What are venules made of and mean thickness and diameter?

A

Endothelium and fibrous tissue
Diameter- 20µm
Thickness- 1µm

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7
Q

What are arterioles made of and mean thickness and diameter?

A

Endothelium and smooth muscle
Diameter- 30µm
Thickness- 6µm

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8
Q

What are arteries made of and mean thickness and diameter?

A

Endothelium, elastic tissue, smooth muscle, fibrous tissue
Diameter- 4mm
Thickness- 1mm

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9
Q

What are veins made of and mean thickness and diameter?

A

Endothelium, elastic tissue, smooth muscle, fibrous tissue
Diameter- 5mm
Thickness- 0.5mm

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10
Q

What are the components of blood?

A

Plasma- 3 litres liquid (water, ions, proteins, nutrients, wastes, gases)
Formed elements- 2.5 litres cells and cell fragments (erythrocytes, leucocytes, platelets)
Haematocrit (or packed cell volume (PCV)) = % blood volume made of RBC’s
45% males
42% females

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11
Q

Where is blood flow rate highest?

A

Pressure is generated from heart (expressed in mmHg). Pressure decreases as the distance from the heart increases. Flow rate expressed as ml/min or litres/min

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12
Q

What is vessel length?

A

Vessel length (L)- longer vessel = greater resistance. Slows flow. Huge changes at birth -> maturity. Constant in adults, can increase due to weight gain or tumour growth. Flow rate 1/L

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13
Q

What is vessel radius?

A

Vessel radius (r)- flow slower near vessel wall, flow faster near centre. Smaller vessel = greater resistance. Flow rate r^4. Small changes in radius = large change in flow.
Inc radius -> dec resistance -> inc flow
Dec radius -> inc resistance -> dec flow
Changes in radius produced by vascular smooth muscle (vasodilation and vasoconstriction). Vessels get smaller as further away from heart

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14
Q

What is viscosity?

A

Viscosity (η)- degree which a fluid resists flow. Caused by friction between formed elements, proteins, liquid. Flow rate 1/η
Inc viscosity -> inc resistance -> dec flow
Dec viscosity -> dec resistance -> inc flow
Haematocrit affects viscosity. Inc erythrocytes or dec plasma decreases flow.
Haematocrit altered by
Erythropoietin (EPO)- hormone secreted by kidneys in response to hypoxia, stimulates erythrocyte production
Recombinant EPO- Dramatically increases erythrocyte production (dec plasma), causes stroke or heart failure
Blood Doping- Collect own blood and store, retranfuse when needed
Polycythaemia vera- Red blood cell disease, excessive red blood cells

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15
Q

What is Poiseuille’s Equation?

A

F= ΔP x πr4 / 8ηL

F- blood flow rate (mL/min)
ΔP- pressure gradient
r- radius
L- length of vessel
η- viscosity

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16
Q

Which ventricle of the heart is thicker?

A

Left- pumps blood all the way around the systemic circulation

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17
Q

What are heart wall layers from outermost to innermost?

A

Pericardium (pericardial space with pericardial fluid separates pericardium from other layers) -> epicardium -> myocardium -> endocardium

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18
Q

What are 4 valves of heart?

A

Tricuspid valve, pulmonary semilunar valve, bicuspid valve, aortic semilunar valve
Inc pressure- valves open
Dec pressure- valves close

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19
Q

What maintains blood supply of heart muscles?

A

Coronary arteries- supply blood to the heart muscle
Coronary sinus- VEIN, drain deoxygenated blood from the heart muscle into the right atrium

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20
Q

What are cardiomyocytes?

A

Cardiac muscle fibres. Involuntary, autorhythmicity, striated due to myofibrils alignment, branched cell with single nucleus, held together by intercalated discs (desmosomes- junction between adjacent cells, hold adjacent cardiomyocytes together) (gap junctions- aligned in adjacent cardiomyocytes so there is electrical continuity). Sarcolemma (plasma membrane of cell) Sarcoplasm (has nucleus, myofibrils ect). Forms functional syncytium

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21
Q

What are conducting-system cells?

A

Derived from cardiomyocytes but few myofibrils so non-contractile, initiates and spreads electrical activity. Found at sinoatrial (SA) node at right atrium, spreads to atrioventricular (AV) node between atria and ventricles then to single branch at ventricles called bundle of His and then to Purkinje fibres further down ventricles (2 bundles)

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22
Q

What is the direction of action potentials in electrical activity of heart?

A

SA node -> atria (communicate with non contractile cells and cardiomyocytes to trigger contraction of atria) -> AV node -> bundle of His -> purkinje fibres -> ventricles (non contractile cells and cardiomyocytes trigger contraction)

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23
Q

How does the action potential in a cardiomyocyte differ from an action potential in a normal cell?

A

RMP slightly lower (-90mV instead of -80mV), plateau phase (0mV) between depolarising and repolarising phase where Na+ channels close and L-type Ca2+ channels open for long period of time where Ca2+ influx happens. This influx of positive charge maintains depolarised state of cardiomyocyte. In repolarising phase these L-type Ca2+ channels close and K+ channels open and K+ leaves cardiomyocyte

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24
Q

Describe the action potential in a pacemaker cell

A

RMP -60mV (much less -ve), very slow depolarisation (curved depolarisation into repolarisation). At pacemaker potential F-type channels open which allows Na+ to enter and K+ to exit at the same time but concentration and electrical gradient help Na+ more. T-type Ca2+ channels open which allows Ca2+ to enter. Both these channels open very slowly which means slow depolarisation. L-type Ca2+ channels open at depolarising phase and Ca2+ enters which is mainly responsible for depolarisation. At repolarising phase, L-type Ca2+ channels close and K+ channels open (K+ flows out)

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25
What determines basic rhythm of heart rate?
SA node (pacemaker potential in SA node shortest)
26
What is heart rate in SA node, AV node and Purkinje fibres?
SA = 100bpm AV = 50bpm Purkinje = 30bpm
27
What is an absolute refractory period?
Period of time in cardiac muscle fibres where another action potential cannot start (approx 250ms). Set by SA node. Due to ion channel inactivation. Prevents ectopic excitation of ventricles
28
What does parasympathetic and sympathetic divisions of autonomic nervous system do to modify heart rate?
Parasympathetic: Innervates SA node, acetylcholine binds to muscarinic receptors, increase duration of pacemaker potential (decrease heart rate). At rest this predominates (can be blocked eg through vagus nerves), decreased rate of depolarisation Sympathetic: noradrenaline binds to beta-adrenergic, decrease duration of pacemaker potential (increase heart rate) similar to adrenaline, increased rate of depolarisation Both spontaneously active Duel innervation of most organs (dynamically opposing effects)
29
Describe an ECG
Synchronous activity of electrical activity in heart able to be recorded. Exposed to conducting medium which allows heartbeat to be recorded. ECG is sum of all these action potentials. Electrodes record these on body surface
30
What is Einthoven triangle? Draw this
Limb lead placement: Lead 1: RA to LA (across base of heart) Lead 2: RA to LL (from base to apex of heart) Lead 3: LA to LL (along left side of heart)
31
What are the complexes/waves seen on an ECG and what does each mean?
P wave: atrial depolarisation QRS complex: ventricular depolarisation T wave: ventricular repolarisation
32
What are alterations in electrical signalling that can be detected with an ECG?
AV Conduction disorder- action potential delayed or blocked in AV node Long QT syndrome- congenital disorder, mutation of K+ channels (delayed repolarisation), results in fainting, cardiac arrest, death
33
What is electrical and mechanical event of these waves/complexes: P wave QRS complex T wave
P wave- atrial depolarisation, atrial contraction QRS complex- ventricular depolarisation, ventricular contraction T wave- ventricular repolarisation, ventricular relaxation
34
What is largest wave and why?
R wave as ventricular depolarisation. Ventricles have largest muscle mass of heart therefore require more electrical activity to activate
35
Which lead has largest R wave and why?
Lead 2 as electrical activity in ventricular depolarisation runs from middle of heart down to bottom left of heart which lead 2 runs parallel to
36
What 2 variables determine height of waves/complexes?
-size of muscle -angle of electrical activity relative to direction of electrode
37
What is instantaneous heart rate when there is 19 divisions between 2 R waves?
0.04 x 19 =0.76s (for 1 beat) 60/0.76= 79 beats.min^-1
38
What is average heart rate when there is 94.5 divisions between 5 heart beats?
94.5 x 0.04 =3.78s (for 5 beats) In 60s- (60/3.78) x 5 =79.35 beats.min^-1
39
Why is average heart rate better than instantaneous heart rate?
Instantaneous heart rate is measure between 2 beats. Not accurate as there can be variances in heart rate over time (sinus arrhythmia) which isn't taken into account. Average heart rate accounts for potential variances in time between heartbeats, accounts for sinus arrhythmia
40
How is sinus arrhythmia different in deep breathing compared to normal breathing and why?
Heartrate increased in deep breathing. This is because more stretch receptors are activated therefore more inhibition to parasympathetic tone which increases heart rate more. This sinus arrhythmia is primarily during inspiration
41
What is excitation-contraction coupling in cardiomyocytes with contraction?
Initiated by action potential travelling along sarcolemma and comes across T-tubules which are deep in cardiomyocyte and allow rapid transmission of action potential. This allows L-type Ca2+ channels to open (Ca2+ influx into sarcoplasm) which opens Ryanodine Receptor (RyR) Channel in sarcoplasmic reticulum. The SR releases large concentration of Ca2+ (calcium induced calcium release) which triggers myofibril shortening
42
What is excitation-contraction coupling in cardiomyocytes with relaxation?
Calcium pumped back into sarcoplasmic reticulum (requires ATP) and also out of cell across sarcolemma (pumped out and engages in exchange system for Na+). Decrease in sarcoplasm Ca2+ concentration allows lengthening of myofibrils
43
What is systole?
Systole- blood ejected from heart. At start ventricles relaxed (pressure low). Isovolumetric ventricular contraction phase is initiated by depolarisation (contraction) of ventricles (QRS wave). Pressure in ventricles increased, bicuspid and tricuspid AV valves closed (1st heart sound). No change in volume in ventricles. Ventricular ejection phase initiated by ventricular pressure > aortic pressure. Aortic valve opens, blood ejected (stroke volume), aortic pressure increases so ventricular volume (and pressure) decreases, ventricular relaxation (T wave)
44
What is diastole?
Diastole- refilling of heart. Isovolumetric ventricular relaxation phase started by ventricular pressure decrease, aortic and pulmonary semilunar valves closes (2nd heart sound), no changes in volume in ventricles. Ventricular filling phase initiated by atrial pressure > ventricular pressure, AV valve opens, ventricular volume increases (until 80% full), atrial contraction (systole, P wave) completes ventricular filling (remaining 20%)
45
What is stroke volume?
Volume of blood ejected from the ventricle during each contraction. Controlled by: End-diastolic volume (EDV)- volume of blood in ventricles after filling is complete at end of single cardiac cycle (diastole). Greater EDV means greater stroke volume (Frank-Starling law of heart). As venous return increases, blood in ventricles increases which stretches myofibrils which increases opportunity for cross bridge interactions (interactions between thin and thick myofilaments). Increased force of contraction of heart during ventricular contraction Sympathetic nervous system- sympathetic neurones innervate ventricles, noradrenaline increases force of cardiac muscle fibre contraction. Increases stroke volume due to noradrenaline from sympathetic postganglionic neurones interacting with beta adrenergic receptors on cardiac muscle fibres. Targets L-type calcium channels and RYR channels (Ca2+ influx). Sarcoplasmic Ca2+ increased therefore increases force of contraction and stroke volume (NO PARASYMPATHETIC INNERVATION OF VENTRICLES) Afterload- heart has to move blood against arterial pressure. Afterload higher if arterial pressure is high which decreases stroke volume. In chronic hypertension afterload is a consideration
46
What is venous return?
Volume of blood entering right atrium (from systemic circuit). Venous pressure low (2mmHg in RA). Venous circulation has low resistance to flow and vessels are compliant (distend easily). Increased volume with little change in pressure. Veins can store large volumes of blood. Orthostatic tension is consequence of venous pooling (due to sitting/lying down). When standing quickly, amount of blood returned to heart reduced (decreased cardiac output and decreased blood supply to brain). Causes dizziness. Can be affected by: Muscular pump and valves- contraction of skeletal muscles compress veins. Pumps blood toward heart, valves in veins prevent backflow. Significantly increases venous return Respiratory pump- heart in thoracic cavity, during inspiration intrapleural pressure decreased. Pressure in atria decreased (pressure gradient increased). Increases venous return Sympathetic tone- smooth muscle of veins innervated by sympathetic postganglionic neurones. Noradrenaline binds to alpha adrenergic receptors, venous constriction. Blood returns to heart therefore increased venous return
47
What is cardiac output?
Volume of blood pumped by each ventricle in a minute. Cardiac output (CO) = heart rate x stroke volume (in ml/min) Exercise increases cardiac output by 4-5 times (20-25L/min), even 7x output (35L/min) in athletes. Controlled by: CHANGES IN HEART RATE- referred to chronotropic effects CHANGES IN STROKE VOLUME- referred to as inotropic effects HORMONES: Adrenaline- increases heart rate, increases stroke volume Thyroxine- increases heart rate, increases stroke volume Glucagon- increases stroke volume DRUGS: Ivabradine- acts on F-type channels (responsible for pacemaker potential), prolongs pacemaker potential therefore decreases heart rate Sympathomimetics- beta adrenergic receptor agonists, increase heart rate and stroke volume Beta blockers- beta adrenergic receptor antagonists, reduce sympathetic tone, decreases heart rate and stroke volume Cardiac glycosides- purified extract of foxglove plant, digitalis (treatment of heart failure), inhibits Na+/K+ exchange pump (reduces amount of sodium available to exchange with calcium, increases sarcoplasmic Ca2+). Increased force of contraction. Slows AV node conduction (decreased heart rate, increased EDV, increased stroke volume).
48
How many layers can be seen in a haematocrit tube after centrifugation? What does each of these layers contain?
Plasma- water, proteins, nutrients, hormones Buffy coat- white blood cells, platelets Haematocrit- red blood cells
49
What is haematocrit a measure of?
Ratio of red blood cells to total volume of blood
50
What is a normal haematocrit?
40-50%
51
What can cause an increase in haematocrit?
Polycythaemia, dehydration, heart disease, kidney disease
52
What can cause a decrease in haematocrit?
Anaemia, overhydration, iron deficiency, haemorrhage, bone marrow suppression
53
How to calculate mean flow rate given a time and a volume in a blood viscosity test? eg find mean flow rate of sample that took 14 seconds for 5mL to exit the tube
(60/average time) x volume eg (60/14) x 5 = 21.43 ml/min
54
What is the relationship between haematocrit and flow rate? How does this relate to viscosity? What is the physiological reason behind this?
Increased haematocrit (more rbc's in blood volume) means a decreased flow rate (increased viscosity) Rbc's interact with each other more than plasma, causing collisions with each other and therefore slowing the flow rate
55
What effect does taking EPO have on haematocrit and hence blood flow? Why do athletes use EPO? Why might this be dangerous?
Increases haematocrit hence decreases blood flow. Stimulates erythrocyte production by bone marrow therefore increasing oxygenation to muscles, increasing performance. Dangerous as decreased blood flow rate increases risk of stroke or heart failure
56
Which of the following will increase mean arterial blood pressure? 1. Increased heart rate. 2. Decreased stroke volume 3. Increased vasoconstriction of the systemic arteries.
1 and 3
57
What is the difference in resting membrane potential between cardiac muscle cells and pacemaker cells?
30mV
58
The pressure in the heart when the ventricles are relaxed is known as which of the following? systolic pressure hydrostatic pressure mean aortic pressure diastolic pressure driving pressure
diastolic pressure
59
Frank-Starling’s law states which of the following? stroke volume is proportional to cross-sectional area blood flow is proportional to pressure differences stroke volume is inversely proportional to resistance stroke volume is inversely proportional to pressure stroke volume is proportional to end-diastolic volume
stroke volume is proportional to end-diastolic volume
60
Which of the following best describes the function of the tricuspid valve? it prevents backflow of blood between the left atrium and left ventricle it prevents backflow of blood between the right atrium and right ventricle it prevents backflow of blood between the right and left atria it prevents backflow of blood between the right atrium and the pulmonary artery it prevents backflow of blood in veins
it prevents backflow of blood between the right atrium and right ventricle
61
The stage of the cardiac cycle where the pressure is the greatest within the heart is which of the following? atrial systole ventricular diastole the isovolumetric ventricular relaxation phase the isovolumetric ventricular contraction phase the ventricular ejection phase
the ventricular ejection phase
62
Most of the blood volume in the body is contained within which of the following? heart arterioles veins capillaries arteries
veins
63
The T wave of an electrocardiogram is associated with which of the following electrical events? atrial depolarisation ventricular repolarisation atrial contraction ventricular depolarisation ventricular contraction
ventricular repolarisation
64
During the early phase of systole, which of the following events occur? Ventricular pressure rises. Ventricular volume decreases. The ventricles contract.
1 and 3
65
The conduction velocity of action potentials in the heart is reduced as they pass through which of the following structures? the bundle of His the sinoatrial node the Purkinje fibres the atrioventricular node the interventricular septum
the atrioventricular node
66
The second heart sound corresponds with which of the following mechanical events? Closing of the aortic valve. Closing of the tricuspid valve. Closing of the pulmonary valve.
1 and 3
67
Which of the following is/are a function of arterioles? The control mean arterial pressure. The regulation of blood flow to different regions of the body. The transport of blood to capillaries.
All 3
68
Why is haematocrit often low in patients with kidney disease? because these patients do not produce sufficient erythropoietin because these patients do not produce sufficient haemoglobin because these patients do not produce sufficient iron because these patients are anaemic because these patients retain excess fluid
because these patients do not produce sufficient erythropoietin
69
The first and second heart sounds represent which of the following (in order)? closure of the atrioventricular valves and closure of the semilunar valves closure of the atrioventricular valves and opening of the semilunar valves closure of the semilunar valves then closure of the atrioventricular valves turbulent blood flow during filling of the atria and then the ventricles closure of the pulmonary valve then closure of the aortic valve
closure of the atrioventricular valves and closure of the semilunar valves
70
If cardiac output is 18 L/min, and heart rate is 150 beats per minute, what will the stroke volume be?
SV= CO/HR 18/150= 0.12L or 120mL
71
Venous return to the heart is assisted by which of the following? low resistance of veins low pressure in the right atrium valves in veins the skeletal muscle pump
All 4
72
Oxygenated blood passes through which of the following? Pulmonary veins. Pulmonary arteries. Left atrium.
1 and 3
73
What is blood pressure?
Pressure in blood vessels created by the heart. Varies within cardiac cycle. Systole pressure 120mmHg. Diastole 80mmHg (maintained by elastic arteries). Very little change as blood flows through major arteries as arteries have large radius which causes low resistance. In arterioles blood pressure drops significantly as arterioles have small radius which causes high resistance.
74
How is pulse pressure calculated?
Systolic pressure - diastolic pressure
75
How is mean arterial blood pressure calculated?
diastolic blood pressure + 1/3 of pulse pressure
76
How is blood pressure controlled?
Blood volume- determined by fluid intake and fluid loss (regulated by kidneys) Cardiac output- effectiveness of heart as a pump. Heart rate and stroke volume alter this Diameter of veins- stores a lot of blood. Blood pressure reduced if a lot of blood is in venous system. Blood pressure increased if venous system is constricted and blood is in arterial system Diameter of arterioles- regulated by smooth muscles, contraction reduces diameter of arterioles (vasoconstriction), when smooth muscle relaxes diameter of arterioles widens (vasodilation).
77
How is the smooth muscle state in arterioles regulated?
INTRINSIC (LOCAL) CONTROL- self regulation of arteriole resistance to control blood flow. No neural or hormonal input. Ensures adequate blood supply to tissues. In metabolically active tissues, O2 decreases, CO2 increases, Adenosine levels elevated, K+ ion build up, increased temperature. Causes vasodilation, decreases arteriole resistance, increased blood flow EXTRINSIC CONTROLS- sympathetic division of autonomic nervous system, noradrenaline as neurotransmitter, sympathetic postganglionic neurones bind to alpha adrenergic receptors on arterioles. Increased sympathetic tone (vasoconstriction), decreased sympathetic tone (vasodilation). Changes regional (rather than local) blood flow eg during exercise blood flow to skeletal muscles increased while blood flow to digestive tract decreased. Reinforced by adrenaline from adrenal medulla REFLEX CONTROL OF BLOOD PRESSURE- rapid short term control, ensure enough pressure to generate adequate blood flow, especially to brain and heart. Arterial baroreceptors: stretch sensitive nerve-endings found in carotid arteries (carotid sinus) and aortic arch. Spontaneously active at normal blood pressure. Detect changes in blood pressure. High BP increases action potentials, low BP decreases action potentials. Relays this info to brainstem. Medullary cardiovascular control centre- in medulla oblongata, collects information from arterial baroreceptors, determines appropriate response, alters sympathetic and parasympathetic tone affecting heart, arterioles and veins. eg orthostatic hypertension, blood pools in venous system and standing up quickly gives transient decrease in blood pressure. Detected by carotid and aortic baroreceptors, respond by decreasing action potentials which cardiovascular control centres in medulla decrease parasympathetic tone to the SA node (to increase heart rate) and sympathetic tone is increased to arterioles and veins, ventricles and the SA node (to cause vasoconstriction, increase force of contraction and increase heart rate). Vasoconstriction increases peripheral resistance and the force of contraction and heart rate increases cause increased cardiac output. These 2 things increase blood pressure back to normal
78
What is capillary exchange?
In peripheral circulatory system, movement of materials between blood and tissues, capillaries well adapted for function (single layer of flat endothelial cells), small diameter and slow blood flow, high density (50,000 miles of capillaries), most cells 0.1mm away from capillary, 6300m2 SA, Intercellular spaces between endothelial cells which allows materials to move easily from blood to tissues
79
What are the mechanisms that move materials across walls of capillaries?
Diffusion- movement down concentration gradient, across plasma membrane, lipid soluble materials move by simple diffusion, others by facilitated diffusion. Gases, nutrients and metabolic end products move by simple diffusion Transcytosis- process which materials endocytosed into cell and exocytosed out of cell. Non-lipid soluble macromolecules Bulk flow- mass movement of water and small solutes through intercellular spaces. Hydrostatic pressure (pressure inside capillary pushing fluid out of capillary) drives this. Osmotic (oncotic) pressure opposes this by sucking fluid back into capillary. Due to large MW proteins stuck in plasma of capillary. Referred to as Starling forces. Capillary Hydrostatic Pressure (HPc) and Interstitial Fluid Hydrostatic Pressure (HPi), pressure gradient moves water and solutes. Capillary Oncotic Pressure (OPc) high, Interstitial Fluid Oncotic Pressure (OPi) low, fluid from interstitial fluid moves back into capillary. Direction of bulk flow determined by net filtration pressure (NFP) which is the difference between the hydrostatic and the oncotic pressure gradients
80
What is net filtration pressure (NFP)?
Direction of bulk flow determined by NFP which is the difference between the hydrostatic and the oncotic pressure gradients NFP= (HPc - HPi) - (OPc - OPi) Formula will determine which way fluid will flow, normally most fluid is reabsorbed however changes in blood pressure and osmolarity can alter this. Soft tissue injuries can cause plasma proteins to leak into interstitial fluid which increases OPi which increases filtration and decreases reabsorption causing oedema (swelling)
81
At arterial end of capillary, HPc is 35mmHg, OPc is 28mmHg, HPi is 0mmHg and OPi is 3mmHg. What is net filtration pressure? What is the direction of flow?
NFP= (HPc - HPi) - (OPc - OPi) NFP= (35 - 0) - (28 - 3) =10mmHg Therefore fluid will move from the capillary to interstitial space
82
At venous end of capillary, HPc is 16mmHg, OPc is 28mmHg, HPi is 0mmHg and OPi is 3mmHg. What is net filtration pressure? What is the direction of flow?
NFP= (HPc - HPi) - (OPc - OPi) NFP= (16 - 0) - (28 - 3) = -9mmHg Therefore fluid will move from interstitial space back into capillary
83
A patient's blood pressure is 160/90mmHg. What is the patient's pulse pressure?
70mmHg (160-90)
84
Which of the following will NOT increase cardiac output? a) increased parasympathetic stimulation b) increased venous return c) increased heart rate d) increased sympathetic stimulation e) increased force of ventricular contraction
a
85
Which side of the heart has the greatest stroke volume?
Stroke volume of right and left sides of heart is the SAME. Systemic and pulmonary circulations are connected in 'series'. If one side of the heart were to output more than the other, circulatory system would fail
86
Why is it important that blood pressure cuff is placed at the same level as the heart?
Pressure of blood increased if cuff is lower than heart and pressure of blood is decreased if cuff is higher than heart. Heart is reference point. Due to hydrostatic pressure
87
What noises are heard from stethoscope over brachial artery if: -cuff isn't inflated -cuff is inflated above systolic pressure -pressure in cuff is reduced to systolic pressure
Not inflated: Only laminar flow, no pressure placed upon artery Above systolic: artery is too constricted, no flow Systolic: Korotkoff sounds are heard as blood flow is turbulent and irregular as artery is opening and blood is passing through again
88
What factors can cause variation in blood pressure between individuals?
Age, height, fitness, stress, medications
89
Why does blood pressure increase with age?
Arteries and arterioles lose elasticity and stiffen. Plaque build up
90
Why is Harvard step test useful in measuring heart rate post exercise to assess fitness?
Assesses how quickly heart rate can recover post exercise (how quickly heart rate can return to rest) and how much it increases by during exercise. Good score is result of HR1-HR3 being low. Depends on fitness and physiological features.
91
What happens to blood pressure during exercise?
Blood vessels dilate and cardiac output is greater. Little change in blood pressure therefore greater force of contraction
92
What happens to cardiac output during exercise?
Increases as more oxygen required to stimulate muscles therefore heart must work faster to supply oxygenated blood

Med Phys 2 (6 decks)

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