Anatomy of the Internal Heart Flashcards
what are the 2 layers of the pericardium?
fibrous and serous
what is the fibrous layer of the pericardium like?
-tough and inelastic
-rests on/attached to diaphragm
-open end fused with adventitia of great vessels
what is the serous layer of the pericardium like?
-parietal layer fused to fibrous pericardium
-visceral layer continuous/part of epicardium
-pericardial cavity space between parietal and visceral layers contains pericardial fluid
where is the pericardial fluid found?
in the pericardial cavity between the parietal and visceral layers
which layer is more superficial, fibrous or serous ?
fibrous
generally how much pericardial fluid do we have?
between 10 and 50ml
what is the 3 layers of the heart wall?
outer - epicardium
middle - myocardium
inner - endocardium
what is the epicardium?
visceral serous pericardium
what is the myocardium?
cardiac muscle
what os the endocardium?
continuous with endothelium of large vessels of heart
what are the opening points into the right atrium?
superior + inferior vena cava (deoxygenated blood from the body)
coronary sinus (deoxygenated blood from the heart walls)
where does the superior vena cava bring blood back from?
head and neck
where does the inferior vena cava bring blood back from?
the rest of the body
what is the crista terminalis?
boundary that distinguishes the boundary between the two:
-smooth wall sinus centrum posteriorly
-rough wall pectinate muscled anteriorly
where do the pectinate muscles originate from?
crista terminalis
what do the rough wall pectinate muscles do?
aid strong contraction of the atria when they are operating at maximum capacity
what is the fossa ovalis?
remnant of opening between L and R atria
-allows blood to bypass lungs during development
where is the fossa ovalis?
circular feature in the posterior wall of the sinus centrum
how Many pulmonary veins do we have?
4, smaller than the vena cava openings as they are smaller
is the fossa ovalis prominent in both atrium?
no generally just in the right atrium
what is the tricuspid valve?
prevents back flow of blood into right atrium during systole
what are the chordae tendineae?
attaches cusps of valves to the papillary muscles
what are the papillary muscles?
contract to prevent cusps everting into atria during systole and hold the valve shut
what is the pulmonary valve?
prevents back flow of blood into right ventricle during diastole
what are the trabeculae carneae?
muscular ridges in wall of ventricle
projections of muscle
what structures can be found on the internal right ventricle?
tricuspid valve
chordae tendinae
papillary muscles
pulmonary valve
trabeculae carneae
what are the internal structures of the left ventricle?
mitral (bicuspid valve)
chordae tendineae
papillary muscles
aortic valve
trabeculae carneae
how much thicker is the muscular wall In the left ventricle than the right?
2-3 times thicker
what is the reason for trabeculae carneae?
to aid in making the surface of the internal heart rough
maximise surface area
to decrease surface tension and greater capacity to expand the wall
prevent the sides of the ventricles from sticking together
do all valves have chordae tendineae?
no only the AV valves
what are the great vessels?
superior vena cava
pulmonary arteries
pulmonary trunk
inferior vena cava
aortic arch
pulmonary veins
ascending aorta
where do the coronary arteries branch off the aorta?
around the aortic valve
what are the branches of the aortic arch?
- brachiocephalic (branching to right subclavian and right common carotid)
- left common carotid
- left subclavian
where does the common carotid artery feed to?
right up towards the neck
where does the right subclavian artery go?
goes underneath clavicle and turns into brachial artery of right arm
what is hemodynamics?
dynamics of blood flow
in which system is the pressure higher?
systemic circuit
why do we not want the pressure in the pulmonary circuit to be that high?
-dont want blood flowing quickly as we want to Give it Time to get oxygen
when do we get a drop in blood pressure?
then the blood reaches the arterioles because rhwy are the resistance vessels of the circulation
what happens to capillary beds if pressure is top high?
damage the walls
generally what is the pressure of blood in the pulmonary circuit?
10-25mmHg
generally what is the pressure of blood in the systemic circuit?
110/70 mmHg
generally what is the pressure of blood in the capillary beds?
10-25mmHg
generally what is the pressure of blood in the venous system
5-10mmHg
what is the foetal circulation of blood?
-oxygenated blood enters through the umbilical vein
-some blood enters the liver and the rest enters the ductus venous to bypass the liver and enter the inferior vena cava
-The IVC enters the right atrium and most of the blood passes through the foramen oval to the left atrium, left ventricle and aorta.
-blood entering the right atrium from the superior vena cava is poorly oxygenated as blood returning from the lungs
-this passes through the ductus arterioles and reduces the oxygenation of the blood in the aorta
what are the important rules of the cardiac cycle?
atria contract first
followed by ventricles (0.1 second delay)
both left and right ventricle eject the same volume
if not blood pooling and back up can occur very quickly
resting HR is 70bpm
therefor each beat takes 0.85s
where are the pacemakers located?
right atrium
what causes the delay between the nodes?
the annulus fibrosis as it acts as am electrical insulator
where does the ventricular depolarisation and repolarisation begin?
the apex of the heart
what are the 4 main phases of the cardiac cycle and generally how long to they last?
ventricular filling - 0.5s
isovolumetric contraction - 0.05s
ejection - 0.3secs
isovolumetric relaxation -0.08s
what happens during diastole?
-AV valves open
-SL valves closed
-driven by venous pressure
-ventricle walls expand as they fill
-atria contract and add 10-20% extra at rest (more during exercise)
generally what is the end diastolic volume?
120ml
when do the AV valves shut?
as soon as ventricular pressure exceeds atrial pressure
what happens during isovolumetric contraction?
all valves are closed
pressure in ventricles now begins to climb rapidly
what happens during the ejection phase?
-AV valves closed
-SL open
-when V pressure> A pressure SL valves open
-3/4 blood is ejected in the first 0.15s
-this causes bulging of elastic arteries
-only 2/3rds of EDV is ejected
when does the pressure in the ventricles fall?
when the rate at which blood is transported to the peripheral arteries exceeds the blood leaving the ventricles so pressure in ventricles falls
therefor SL valves close
what happens during isovolumetric relaxation?
all valves are closed
until ventricular pressure falls below atrial pressure
AV valves are pushed open and blood begins to fill ventricles again
-atria have been filling
what makes up the SA node/why can it beat at 100bpm?
it is a collection of myocytes that spontaneously depolarise at regular intervals
not governed by extrinsic nerves
what controls the rate at which myocytes depolarise?
extrinsic nerves mainly the ANS
what is the basal tonic rate of the heart?
parasympathetic does this via the vagal motor nuclei in the brain stem (vagus nerve)
-right side - SA node
-left side - AV node
NT - acetylcholine binds to muscuranic receptors
how does the parasympathetic NS decrease rate of SA node?
makes the membranes hyperpolarized gives them a larger starting point (-70mV down to -90mV)
how does the sympathetic branch speed up HR?
-fibres exit at T1-T5
-long nerve fibres that run along the great vessels
right supply atria
left supply ventricles
NT- noradrenaline acts on B1 adrenoreceptors
where are the bronchopulmonary lymph nodes located in the thorax?
surrounding the principle bronchi
where does the thoracic duct drain into the venous system?
left venous angle
what effect would aortic stenosis have on the function of the heart?
left ventricular hypertrophy
where is the Sino atrial node located?
right atrium
what is the crista terminalis?
forms the boundary between the sinus venarum and pectinate muscles
what are chordae tendinae?
cord like tendons that connect the valves to papillary muscles
which vein arches over the hilum of the right lung to drain into the superior vena cava?
azygous
What is a defining property of glyceryl trinitrate?
Is a pro-drug that requires bioconversion to the active principle, nitric oxide
Which vein can act as an alternative route for blood to the heart if either superior vena cava or inferior vena cava are occluded?
azygous
What are the anatomical features of cardiac muscle cells?
What are the anatomical features of cardiac muscle cells?
Which part of the conducting system is usually responsible for transmitting electrical signals from the atria to the ventricles?
bundle of HIS
How does diltiazem work to reduce the symptoms of angina?
Blocks L-type calcium channels
how does warfarin work?
inhibits the synthesis of vitamin K dependant clotting factors
Which anticoagulant works by directly inhibiting thrombin (factor IIa)?
dabigatran exilate
