Week 3 Science and Scholarships: Cardiovascular Flashcards
Identify the two types of large arteries
Elastic and Muscular
Examples of large elastic arteries
Aorta and pulmonary arteries
examples of large, muscular arteries
femoral, radial and brachial arteries
large Elastic arteries are made of predominantly
elastic fibres
large muscular arteries are made of predominantly
smooth muscle
function of large arteries
Blood is distributed fast into target areas via large arteries
structure of arteries
tunica intima
tunica media
tunica adventitia
what is tunica intima made up of
endothel, lamina propria, basement membrane, sub endothelial connective tissue
-thinnest layer
what is tunica media made up of
smooth muscle (elastic fibres) and elastic lamellae
-thickest in arteries
what is tunica adventitia/externa made up of
connective tissue , nerve fibres and vasa vasorum
-thickest in veins
-sometimes has smooth muscle in veins ONLY
describe the structure of capillaries
no smooth muscle
only endothelium
sometimes pericytes
erythrocytes are able to squeeze through capillaries
changes in diameter of vessels change what
the pressure of blood
structure of arterioles
small blood vessels (about 30-5 μm in diameter) with 1-4 layers of smooth muscle
structure of valves
-extensions of intima (made of endothelium)
-supported by CT that proveides strength and flexiiblity
function of valves
allow for unidirectional flow of blood through veins i.e blood can flow back towards the heart
location of lymphatic vessels
they start blind (open ended)
structure of lymphatic vessels
contain valves to direct lymph flow
function of arteries
deliver blood to the tissues from the heart
identify types of arteries
muscular
elastic
arterioles
function of veins
return blood from the tissues to the heart
identify types of veins
medium
large
venules
similarities in wall structure of veins and arteries
-both have 3 layers (intima,media,adventitia)
what is endothelium
-simple Squamous epithelium
-smooth
-antithrombogenic
what structure is found between tunica intima and tunica media
IEL
internal elastic lamina
what is vaso vasorum
small vessels supplying O2 and nutrients to outer wall
key features of elastic arteries
-conducting arteries
-large diameter, thick wall and located close to heart
-media has high elastin content organised as numerous concentric elastic laminae
-vasa vasorum in adventitia
key features of muscular arteries
-distributing arteries
-prominent IEL that marks outer of tunica intima
-media has more smooth muscle fibres (many visible nuclei)
-EEL marks outer media
-vasa vasorum in adventitia
EEL means
external elastic lamina
key features of arterioles
-resistance vessels
-small diameter, thin, less complex walls
-thick wall RELATIVE to luminal diameter
-tunica media (smooth muscle) most prominent
function of arterioles
-regulates/slows blood flow & pressure through capillaries
key features of venules
-tunica intima is reduced to endothelium
-tunica media is thin layer of smooth muscle and elastic fibres
-adventitia fuses with connective tissue
-small venules can be surrounded by pericytes
function of venules
collect blood from capillaries
function of medium veins
Blood reservoir due to high capacitance
key features of medium veins
-thin walled
-large and irregular lumen
-intima can form valves
-media has low muscle content is patchy
-adventitia is broadest and has vasa vasorum
function of large veins
act as blood reservoir
key features of large veins
-no valves
-no IEL
-muscular media but thinner than large arteries
-prominent adventitia with lots of collagen
-no EEL
-vasa vasorum in adventitia
Differences between arteries and veins
-arteries are a part of a high-pressure system whereas veins are a part of a low pressure system
-arteries act as a pressure reservoir whereas veins act as a blood reservoir
-arteries are at a full blood capacity whereas veins are at a 30-70% blood capacity
-arteries don’t contain valves whereas veins do (intima)
-arteries contain a circumferential, middle layer of muscle, where is veins contain a patchy and discontinuous layer of muscle
-arteries have thinner adventitia, where is veins have thicker adventitia than their media
-arteries have small lumen, thick walls and circular cross section whereas veins have large lumen, thin walls and collapsed cross section
function of capillaries
sites of exchange between blood vessels and tissues
identify the types of capillaries
continuous ,fenestrated, sinusoidal (discontinous)
wall structure of capillaries
-reduced complexity compared to large vessels
-endothelium
+/- fenestrations
+/- tight junctions
-pinocytotic vesicles
-basal lamina
+/- pericytes
-smallest diameter vessels
Key features of endothelial cells
-have an anti-thrombogenic function
-thin to maximise exchange
-breakdown Lipoproteins to triglycerides and cholesterol
-contain intercellular tight junctions
-contain Pinocytotic vehicles
Features of continuous capillaries
-most widespread
-tight junctions
-many pinocytotic vesicles
-no gaps between endothelial cells
-rapid exchange
more tight junctions means
More selective barrier
if there are more pinocytotic vesicles means
More exchange
Features of fenestrated capillaries
-endothelial cells are pierced by many fenestrations
+/- thin diaphragm
What do fenestrated capillaries allow for
Extensive exchange between blood and tissues, but limited in terms of particle size
If a fenestrated capillary has a diaphragm then …
This makes it more selective
Fenestrated capillaries vs continuous capillaries
Continuous are slower exchange, but are more selective
key features of sinusoidal capillaries?
-large diameter
-tortuous pathway
-incomplete endothelial lining
-large fenestrations
-discontinuous basal lamina
what do sinusoidal capillaries allow for
-maximum exchange between blood and tissues
-gaps in wall, can allow for the movement of whole cells
Outline the functions of blood
- Transport gases, wastes, hormones and nutrients around the body
- Regulates pH and ion concentration in the interstitial fluids by the diffusion of ions and absorption acids
- Restrict fluid loss at the injury site through the clotting process
- Defends against toxins and pathogens via WBC action
- Stabilises body temperature by absorbing the heat produced by skeletal muscles
what is serum
Plasma which has undergone coagulation
identify components of blood
Plasma
-water
-electrolytes
-nutrients eg metabolic wastes, hormones, dissolved gases
-plasma proteins eg albumin
Cellular elements
-RBC + WBC
Lymphocytes
-Monocytes
-Neutrophils
-Eosinophils
-Basophils
-Platelets
Function of water in blood
water provides circulatory volume and medium for dissolved solutes
-transport &distribution, heat loss
function of electrolytes in blood
important in volume regulation osmolarity, pH regulation and membrane potential
examples of plasma proteins
albumin
antibodies
coagulation factors
pH buffering
Function of albumin in blood
drives oncotic/osmotic pressure/
-linked to carrier proteins,
List WBC’s from most to least abundant
Never let monkeys, eat bananas
neutrophil
lymphocyte
monocytes
eosinophil
basophil
outline process of haemostasis
1.vascular spasm
2.circulating platelets are activated by and adhere to exposed collagen at injured vessel
3.activated platelets release ADP and thromboxane
4.these chemicals attract other platelets passing by
5.newly attracted platelets adhere to other platelets and attract even more platelets to form the platelet plug
6.cascading events convert fibrinogen into the fibrin meshwork
7.uninjured endothelium releases nitric oxide and prostacyclin which causes the confinement of the platellet to the site of injury and later promotes fibrinolysis as a means of homeostasis
outline process of haematopoiesis
-low RBC count
-hypoxia
-hypoxia detected by kidneys
-kidneys release erythropoietin
-this stimulates erythropoiesis
-increasing RBC count
-oxygen levels increase
describe the location of the heart
-Thoracic cavity
-Posterior to the sternum
-2nd costal cartilages T4/T5
-anterior to oesophagus
-rests on diaphragm
-pericardial cavity
-slight left
identify the three layers of the heart
epicardium
myocardium
endocardium
what is the parietal pericardium
inner serous and outer fibrous pericardium
what’s the visceral pericardium
epicardium
identify the AV valves
bicuspid and tricuspid
identify semilunar valves
aortic and pulmonary
function of right heart
Right atrium and right ventricle. Receives deoxygenated blood from the body and pumps it towards the lungs
function of left heart
Left atrium and left ventricle. Receives oxygenated blood from the lungs and pumps it into the body
anterior surface of heart
sternocostal
what is posterior surface of heart known as
diaphragmatic
left and right surface of heart
pulmonary
what is meant by base of heart
the posterior side
what is in the base of heart
left atrium and bit of right atrium
where’s apex of heart
-left ventricle
-5th intercostal space (ICS)
trace blood flow of heart
-SVC/IVC
-right atrium
-tricuspid valve
-right ventricle
-pulmonary valve
-pulmonary artery
-lung
-pulmonary vein
-left atrium
-mitral valve
-left ventricle
-aortic valve
-aorta
-body
identify structures in RA
-auricle
-pectinate muscles
-fossa ovalis
-opening coronary sinus
-IVC and SVC
-interatrial spetum
-tricupsid valve
identify structures of RV
-tricuspid valve
* Papillary muscles
* Tendinous cords
* Pulmonary valve
* Interventricular septum
identify structures of LA
- 4 pulmonary veins
-left auricle
-floor oval fossa
identify structures of LV
- Ventricular walls
- Bicuspid valve/Mitral valve
- Aortic valve
- Papillary muscles
where do u listen to aortic valve
right 2nd ICS next to sternum
APT-M 2245
where do u listen to bicuspid valve
left 5th ICS & midclavicular line
where do u listen to pulmonary valve
left 2nd ICS next to sternum
where do u listen to tricuspid valve
left 4/5th ICS next to sternum
describe structure of AV vs SL valves
AV are leaflets whereas SL are cusps
function of valves
support unidirection of blood flow and avoid regurgitation
name two coronary arteries
RCA and LCA
where do coronary arteries originate
from aorta superior to aortic valves
function of RCA
-supplies AV and SA node
-supplies diaphragmatic and more posterior
define BP
pressure exerted on artery walls by blood
describe endocardium
Inner layer of wall that lines chambers
describe myocardium
Middle, thickest wall layer
describe epicardium
Outer layer of wall in contact with pericardial cavity
what makes up pericardial sac
-Inner serous parietal layer of sac
-Outermost fibrous pericardium layer
what walls are thickest out of the 4 chambers
ventricular walls and left side
what makes up inner surface of pericardial sac
mesothelium (simple squamous epithelium )
what is systolic blood pressure
measures the pressure in the arteries when the heart beats eg120
what is diastolic blood pressure
measures the pressure in the arteries between heartbeats. eg80
Normal limits for BP
120/80
what can cause high BP
(external)
-poor diet
-smoking and alcohol
-lack of exercise
-FHx
-co morbidities
-medication
what’s the difference between primary and secondary hypertension
primary (most common) often results from a mixture of causes whereas secondary often occurs from another disease and can be fixed
identify different grades of HTN
normal
elevated
hypertension stage 1
hypertension stage 2
hypertensive crisis
how is HTN diagnosed
using sphygmomanometer with multiple repeats
what may influence accuracy of BP reading
stress
physical activity
time of day
resting or not
posture
caffeine
smoking
define HTN
a condition where the force of blood against the walls of the arteries is consistently too high
what is mean arterial pressure (MAP)
a measure of the average pressure in the arteries during a cardiac cycle
how to calculate MAP
2/3 x diastolic + 1/3 x systolic
how to calculate CO
heart rate x stroke volume
what is total peripheral resistance (TPR)
refers to the resistance to blood flow in the systemic circulation, primarily in the arterioles
where is the main difference in thickness of heart walls
in the myocardium
function of pericardial sac
Keeps heart in place, prevents overexpansion, lubricates (↓ friction with beating), protects against infection & injury
what surrounds the pericardial sac
- Mesothelium (simple squamous epithelium) covers surface facing pericardial cavity
- Fibrous (dense) connective tissue
describe the structure of the epicardium
outermost layer
CT+fat+nerves+mesothelium cells
protects and lubricates heart surface
describe the structure of the myocardium
-thick, middle layer of heart
-Composed of cardiac muscle fibres
-responsible for pumping blood through circulatory system
describe the structure of the endocardium
-inner most layer
-endothelial cells
-provides smooth surface for blood flow within chambers
describe the structure of heart valves
-dense CT core = fibrosa
-covered either side by fibroelastic CT and endothelium
identify the structures of the cardiac conduction system
SA node
AV node
bundle of HIS
bundle branches
purkinje fibres
describe location of SA node
localised in the right atrium near the entry of the superior vena
describe location of AV node
localised in the right atrium , above cardiac skeleton that separates atria and ventricles
describe location of bundle of HIS
normally found distal to the AV node next to tricuspid valve in the atria
describe location of purkinje fibres
run subendocardial and “deliver” the excitation to the cardiomyocytes
Describe how the membrane becomes depolarised and repolarised in cardiac conduction
-resting membrane at -70 m/v
-slow influx of Na+ depolarises membrane
-T-type Ca2+ transient channels open and membrane becomes more depolarised
-then Ca2+ L-type channels open and membrane becomes more depolarised
-threshold reached, action potential fired
-K+ channels open, efflux of K+ initiates hyper polarisation
how does the autonomic NS effect heart beat frequency
-Parasympathetic (vagal) stimulation increases the K+ efflux and causes hyperpolarisation and slows the depolarisation
-decreased vagal influence, Sympathetic stimulation increases the Ca2+ influx and causes faster depolarisation
identify the two broad stages of cardiac cycle
diastole and systole
Outline what happens in diastole
Isovolumetric relaxation (ventricular pressures drop below the aortic and pulmonary pressures)
Rapid inflow into ventricles
Diastasis (reduced inflow into the ventricles)
Atrial contraction (100% full)
(4 phases)
Outline what happens in systole
Isovolumetric contraction
Rapid ventricular ejection
Reduced ventricular ejection
(3 phases)
what valves are open in diastole
mitral and tricuspid open
semilunar closed
what valves are open in systole
aortic and pulmonary open
AV closed
how many phases in cardiac conduction system
7
(4+3)
define cardiac output
volume blood elected from the left ventricle each minute (HR x SV)
define cardiac cycle
rhythmic sequence of events that occur during one complete heartbeat (systole and diastole)
define stroke volume
blood ejected from the left ventricle with each cardiac cycle.
What are the two main factors that influence stroke volume
preload and after load
What is preload?
End-diastolic pressure when the ventricle is filled (at end-diastolic volume)
What is after load?
the resistance or pressure the heart must overcome to eject blood during systole
describe pressure changes in cardiac cycle
1.atrial pressure increases as systole is occurring, contraction causes pressure increase
2.AV valves open, blood flow into ventricles, increasing ventricular pressure
3.Ventricles contract, increasing pressure
4.Ventricle pressure>Atrial pressure so AV valves close
5.Ventricle pressure>Aortic pressure so SL valves open
6.ventricle pressure drops as blood leaves ventricle
7.Aortic pressure>Ventricular pressure, SL valves close
8.Ventricular pressure continues to drop until it goes below atrial pressure, left atrium refills (bc AV valves open) and cycle repeats
Define the frank starling mechanism
the greater the return of venous blood to the heart, the greater the subsequent output that can be achieved
when is aortic pressure high
higher in systole
what is longer diastole or systole
diastole
units for BP
mmHg
identify two factors that impact blood flow
-pressure difference/ gradient along a vessel
-resistance to blood flow through a vessel
blood flows from area of __ to __
high pressure to low pressure
how does measuring BP work
- Cuff inflated above systolic pressure. Arterial inflow ceased.
- Cuff slowly deflated until it drops below arterial pressure. Arterial inflow restored. At this point, first Korotkoff sounds are heard.
- Cuff deflates to below diastolic pressure, at which points Korotkoff sounds disappear.
how does flow/ resistance affect arterial pressure
If flow and/or resistance increase, arterial pressure (particularly systolic pressure)
will increase.
Conversely, if flow and/or resistance decrease, arterial pressure will decline.
define pulse pressure
difference between diastolic and systolic pressure
-indicates elasticity and compliance of arterial walls
define conductance
the measures of blood flow for a given pressure difference
define resistance
the impediment to blood flow in a vessel. Can be
increased with vasoconstriction and decreased with vasodilation
how is acute control of blood flow achieved
achieved primarily through rapid vasoconstriction or vasodilation of resistance arteries
what mechanisms determines where blood flow goes?
Vasodilators released from active tissue.
Endothelial derived factors.
Dampened sympathetic control.
Muscle pump
what term describes blood flow within a capillary
vasomotion
what term describes blood flow through a capillary
intermittent
how do non lipid substances move through capillary
diffuse through intercellular clefts located between endothelial cells.
identify the 4 starling forces
-capillary hydrostaic
-interstital fluid
-plaasma colloid osmotic
-interstitial fluid colloid osmotic
what leads to net outward force in capillary
Elevated capillary pressure at arterial end results in a net outward force
what leads to net inward force in capillary
Lower capillary pressure at venous end, leads to a net inward force
how does arterial pressure influence CO
increase arterial pressure increases CO and ventricular filling
how does exercise influence venous return
Muscle pump promotes increase in venous return.
what is Hypovolemia
Decrease in venous return with severe dehydration or blood loss
how do postural changes influence venous return
Rapid shift in body position may increase (lying down) or decrease (standing up) venous return.
how does muscle length influence influence cardiac muscle active tension
cardiac muscle active tension increased with muscle length.
what does thedifference between active tension and passive tension represent
difference=the force exerted on the volume of blood during contraction.
how do autonomic controls influence CO
- Sympathetic stimulation has both a chronotropic and inotropic effect.
-Increased HR.
-Increased contractility. - Parasympathetic stimulation suppresses HR, slows AV conduction and modestly reduces contractility.
describe sympathetic innervtion of heart
-To increase HR and contractility of the myocardium: cardioacceleratory centre of medulla sends out messages via the sympathetic nerves through the paravertebral ganglion.
-These nerve fibres innervate the SA,AV node and myocardium. -This causes stimulation of adrenal medulla resulting in release of adrenaline and noradrenaline,
-these hormones bind to B1 receptors and cause depolarisation of the nodal cells (threshold is reached) and signals are sent faster, increasing HR and atrial myocardium contractility.
what reflex regulated BP
baroreflex
what is meant by isovolumetric contraction
a phase of the cardiac cycle during which the ventricles of the heart contract, but there is no change in the volume of blood within the ventricles
simply describe starlings law
-more EDV
-more preload
-more SV
-more forceful contraction
what is meant by isovolumetric relaxation
time where all valves are closed and volume of blood in ventricles remains constant
distinguish between hydrostatic and osmotic pressure
hydrostatic pressure pushes fluid out of blood vessels into tissues, while osmotic pressure draws fluid back into blood vessels from the tissues
-osmotic driven by albumin vs hydro driven by plasma volume
large veins are found
closer to surface of body
list two types of blood flow
laminar and turbulent
values for different degrees of HTN
normal 120-129 and 80-84
grade 1: 140-159 and 90-99
grade 2: 160-179 and 100-109
grade 3 180+ and 110+
values for different degrees of HTN
normal 120-129 and 80-84
grade 1: 140-159 and 90-99
grade 2: 160-179 and 100-109
grade 3 180+ and 110+
outline baroreceptor reflex
1.Change in blood pressure detected by baroreceptors in aortic arch and carotid sinus
2.this sensory (afferent) message is sent to cardioregulatory centres of the medulla (AP sent out faster or slower depending) via afferent cranial nerves (9,10)
3.Cardioregulatory centres send out an efferent message that triggers the sympathetic or parasympathetic NS
4. Changes in CO (SV and HR) and constriction/dilation of blood vessels
5.Increase/decrease in BP
normal waist circumferences
- Men: (102 cm or less)
- Women: (88 cm or less)
what causes isolated diastolic hypertension
various factors
-excess salt
-smoking
-alcohol
-lack of exercise
-genetic influence
what are pallor of palmar creases indicative of
anaemia
what is peripheral cyanosis indicative of
poor peripheral perfusion
what are janeway lesions, Osler nodes and splinter haemorrhages indicative of
infective endocarditis (splinter haemorrhages least specific)
what is capillary refill > than 3s indicative of
poor Peripheral perfusion (PVD)
what is tar staining indicative off
smoking
what is tendon xanthomata indicative of
hyperlipidaemia
what is clubbing indicative of
various non specific
-infective endocarditis, CHD
what is scleral jaundice indicative of
severe congestive heart failure leading to hepatic congestion
what is conjunctival pallor indicative of
severe anaemia
what is arcus cornealis indicative of
hyperlipidaemia
what is xanthelasma indicative of
hypercholesterolaemia
what is malar flush indicative of
pulmonary HTN and low CO eg mitral stenosis
what is poor dental hygiene indicative of
increased infective endocarditis risk
what is central cyanosis indicative of
CHF, COPD, cyanotic congenital heart disease
what is high arched palate indicative of
marfan’s : congenital heart disease
what are bruits
turbulent blood flow, atherosclerosis
what is a raised JVP indicative of (>3 cm)
right heart failure
what are thrills and heaves
thrills=palpable murmurs
heaves=right ventricular hypertrophy
pitting sacral oedema and pitting oedema are indicative of
RHF
how to check for mitral stenosis and mitral regurgitation
dynamic manœuvre (left lateral),
-bell for mitral stenosis and diaphragm for mitral regurgitation
-both on expiration
how to check for aortic regurgitation
use diaphragm (patient leans forward)
-check at erbs point on expiration
dullness and crackles when percussing and ausculting lungs respectively indicate
pleural effusion (LHF)
features of continuous capillaries (CNS)
-most widespread
-very tight junctions
-few pinocytotic vesicles
-no gaps between endothelial cells
-restricted exchange
function of heart
-pumps blood and viral nutrients around the body
-some heart cells have endocrine function, releasing signalling hormones
shape of heart
conical, broad based and pointed apex
size of heart
size of human closed fist =14 x 9 cm
outline histology of cardiac muscle
-branched, cylindrical cells, single nucleus
-intercalated discs that allow for synchronised contractions by connecting adjacent cells
-many mitochondria
SA node function
natural pacemaker of heart, generates consistent AP’s
-sets the electrical rythm of heart by firing 60-100 times a minute
AV node function
-cluster of cells
-allow atria to contract before ventricles, by delaying electrical signal briefly
bundle of HIS function
pathway for electrical impulse from AV node to ventricles, allowing coordinated contraction
function of purkinje fibres
specialised cardiac muscle fibres rapidly transmitting electrical pulses, stimulating ventricular muscle contraction for efficient pumping
aortic stenosis murmur
-decrescendo/crescendo sound
-high pitched
-systolic
-radiation to carotid arteries
mitral regurgitation murmur
-blowing
-parasytollic (throughout sytole)
-high pitched
-radiates to axilla
aortic regurgitation murmur
-blowing, decrescendo
-diastolic
-no radiation
mitral stenosis murmur
-mid diastolic
-rumbling
-low pitched
-no radiation
crushing central chest pain, radiating to neck/left arm
MI/angina
tearing chest pain, radiates to back and sudden onset
aortic dissection
pleuritic chest pain that is relieved by sitting forward
pericarditis
factors effecting blood flow through vessel
*Blood Vessel Diameter
*Blood Viscosity
Vessel Length
Pressure Gradient
Turbulence (or laminar)
Elasticity of Blood Vessels
describe parasympathetic innervation of heart
-Parasympathetic messages are sent via vagus nerve from dorsal root ganglion to the SA,AV node only (mostly impacts HR)
-Ach is released, which forces efflux of K+, causing hyperpolarisation
-therefore making it harder for HR to increase
contrast chronotropic vs inotropic
Chronotropic effects refer to changes in heart rate, whereas inotropic effects refer to changes in the strength of heart contractions.
Chronotropic mechanisms influence the rate of depolarization of the sinoatrial (SA) node, whereas inotropic mechanisms influence calcium levels in cardiac muscle fibers.
to increase BP: Positive chronotropic effects increase heart rate, whereas positive inotropic effects increase the force of heart contractions
to decrease BP: Negative chronotropic effects decrease heart rate, whereas negative inotropic effects decrease the force of heart contractions,
what is capillary hydrostatic pressure
-in the capillary
-pressure exerted by fluid inside capillary towards interstitial fluid
whats interstitial fluid pressure
-in the interstitial fluid
-pressure exerted by fluid inside the plasma towards capillary
what is plasma colloid osmotic pressure
-towards capillary
-pressure exerted by proteins such as albumin, pulling fluid towards the capillary
what is interstitial fluid colloid osmotic pressure
-towards the interstitial fluid
-pressure exerted by proteins, such as albumin, pulling fluid towards interstitial fluid
factors effecting resistance (blood flow)
-lumen radius
-viscosity of blood
