Cardiovascular Flashcards
heart location
located on left side of the thorax and apex is found at the point of maximal impulse (PMI) which is between the midclavicular line and between the 5th and 6th ribs
what side of the midline is the heart mostly found on?
the left side, because of its tilting action as it contracts
right atrium
receives deoxygenated blood through the superior vena cava and inferior vena cava and the coronary sinus and then sends that blood to the right ventricle through the tricuspid valve.
right ventricle
receives blood from the right atrium, then sends blood out through pulmonary semilunar valves through to the pulmonary arteries towards the lungs to be oxygenated
left atrium
blood enters through the right and left pulmonary veins and into the left ventricle through the bicuspid valve
left ventricle
blood enters through the bicupsid valve and exits out of the aortic semilunar valve and around the rest of the body.
layers of the heart wall
epicardium, myocardium, endocardium
what does the epicardium contain?
visceral pericardium (connects the epicardium to the pericardium), large blood vessels, FCT and adipose tissues
myocardium
makes up most of the thickness of the heart wall and is thicker on the left side because the left ventricle is responsible for pushing more blood around the body, so needs more space
what does the endocardium contain?
is squamous epithelium, FCT, small blood vessels and Purkinje fibres
pericardium
sack around the heart itself that provides protection and for the heart to move around when contracting
structure of pericardium
fibrous pericardium and a parietal layer of the serous pericardium and then the pericardial cavity separates the pericardium from the heart wall
atrioventricular valves
name of valves that bring blood from the aortas into the ventricles
diastole
when blood is moving INTO the heart and atrioventricular valves are open
systole
when blood is moving OUT of the heart; atrioventricular valves are closed but semilunar valves are open
chordae tendinae
attach to the papillary muscles to close the atrioventricular valves during systole; “heartstrings”
papillary muscles
around the atrioventricular valves that close them during systole and open them during diastole; stimulated by built up pressure
function of coronary arteries
pumps blood that is used for the hearts own needs
branches of left coronary artery
circumflex artery and anterior inter-ventricular artery
what layer of the heart wall do all the coronary blood vessels run through?
epicardium
how does blood drain back in the coronary system?
- on the right side, blood drains into the small cardiac vein
- on the left side it drains into the great cardiac vein
- both then drain into the coronary sinus which enters the right ventricle before being reoxygenated.
features of cardiac muscle
- muscle cells in the heart
- centred nuclei
- many mitochondria
- connected with intercalated discs (ICDs) like adhesion belts, desmosomes, gap junctions
intercalated discs
connect cardiac muscle cells; adhesion belts, desmosomes and gap junctions
adhesion belts
link the actin to actin between cells so the cardiac cells contract simultaneously
desmosomes
link cytokeratin with cytokeratin to stabilise the cardiac cells when they contract
conduction pathway function
the pathway that the contraction runs through the heart
what is the conduction pathway?
- starts at SA node in the right atrium which tells the heart when to contract
- then leads down the, right atrium, the interatrial bundle and internodal pathways to the AV node and AV bundle which move the contraction across to the ventricles
- ends with Purkinje fibres
Purkinje fibres
- controls the contraction of the ventricles and used to carry electrical signals and carry a charge.
- are specialised cardiac cells, with glycogen stores, mtiochondria and many gap junctions
major arteries from heart to foot
- common iliac artery
- external iliac artery
- femoral artery
- popliteal artery
- posterior tibial artery
- plantar arch
major veins from the foot to the heart
- plantar venous arch
- posterior tibial vein
- popliteal vein
- great saphenous vein
- femoral vein
- external iliac vein
- common iliac vein
layers of blood vessel wall
tunica intima, tunica media and tunica adventitia
tunica intima
- closest layer of the blood vessel to the lumen
- contains endothelium, sub-endothelium (loose FCT) and internal elastic lamina (IEL) in arteries
internal elastic lamina (IEL)
a condensed sheet of elastic tissue that sits in the tunica intima of arteries NOT in veins; needed so the arteries can expand the most for contractions
tunica media
- second layer of blood vessel
- made of smooth muscle
- thicker in arteries because of increased pressure
tunica adventitia
- last layer of blood vessel
- contains heaps of collagen to prevent the vessel from expanding too much
- includes vaso vasorum in large blood vessels, lymphatics and autonomic nerves
vaso vasorum
the vessels inside of large blood vessels that supply blood to the vessel itself because of how large the vessel is; runs through tunica adventitia
order of classes of blood vessels
aorta - arteries - arterioles - capillaries - venules - veins - venae cavae
do veins or arteries tend to contain more elastin? why’s that?
arteries; to make them more flexible for contractions and blood flow regulation
capacitance vessels
veins that hold extra blood in the body
what prevents the overextension of capacitance vessels?
the thicker tunica adventitia which holds many collagen fibres to stop the vessel growing too massive and
how does blood move in veins?
- valves prevent backflow
- skeletal muscles around veins squeeze the veins to push the blood upwards
capillaries
- the site of exchange between blood and tissues
- spread out into bed to increase SA and have more blood flow through
- thin vessel walls
why are capillaries tight?
to allow RBC’s carrying oxygen to efficiently transfer oxygen from the blood into the tissues
precapillary sphincters
sphincters before the capillaries to regulate blood flow through the capillaries and pressure
vascular shunt
- made up of a metarteriole and thoroughfare channel
- the main passage through a capillary where blood can be shunted if too much heat loss occurs in outer capillaries eg cold hands
continuous capillaries
- not leaky
- most common
- contain basement membrane
fenestrated capillaires
- have same diameter as continuous but have little holes called fenestrations which make it more leaky eg in the kidneys
sinusoidal capillaries
- incomplete basement membrane
- super leaky
vesicles/caveolae in capillaries
assists with the movement of large substances through capillaries
functions of the lymphatic system
- to drain fluid back into the blood and to filter out any foreign material
- also is scanned for immune response
- absorbs fat
lacteal
fatty liquid that travels through lymphatics to reach the veins and be reabsorbed in the blood
functions of cervical, axillary and inguinal nodes
to survey the lymph for any dodgy antigens in case the immune response needs to be activated
lymph nodes
a mesh work of fibers with immune cells hanging off of them which have channels that bring lymph blood into them and out of them to check for antigens in the lymph blood
pulmonary circuit
is the circuit of the CV system that runs through the right side of the heart to send blood to the lungs
systemic circuit
is the circuit of the CV system that runs through the left side of the heart to send blood to the rest of the body
how many times does the heart contract per circuit?
twice
myocytes
muscular fibres in the heart
does the heart activate all myocytes for every contraction?
yes; every myocyte is activated for each contraction but the force produced varies
what makes a ‘strong’ heartbeat?
more actin-myosin cross bridge formations which only occurs when more calcium is released into the muscle cells eg during exercise
what makes muscles go rigid?
lack of ATP; ATP is needed to prime the myosin to release from the actin during cross bridge formations which is why when people die, their bodies tense up because no more ATP is being produced
4 main phases of the cardiac cycle
1) atrial systole
2) isovolumetric contraction
3) ventricular ejection
4) isometric relaxation
atrial systole phase
the atriums contract after the heart has been relaxed for a while
isovolumetric contraction phase
blood pours into the ventricles while the pressure builds up
ventricular ejection phase
ventricles contract to push most of the blood from the ventricles out
isovolumetric relaxation phase
semilunar valves shut, heart relaxes, AV valves open and heart starts filling again
pulse pressure
the pressure you generate in a heartbeat, can be calculated by finding the difference between the highest and lowest point
mean arterial pressure
the average pressure of the heart across a whole cardiac cycle; and is usually lower in systole than diastole because the heart spends more time in diastole
hypertension
having really high blood pressure
hypotension
low blood pressure
hemodynamics
the study of how blood flows in a single vessel
calculating blood flow
pressure difference / resistance
electrical cells in the heart
- Purkinje and AV nodal cells, make up 1% of the cells in the heart
contractile cells
- 99% of cells in the heart
- cause the heart contractions
- contain myosin and actin bridge formations
functional syncytium
how cells communicate and mean they all contract at once
SA node
bundle of cells that tell the heart when to beat
function of AV node
stops the contraction signal received from the SA node so the ventricles and atriums don’t contract at the same time
ECG
is how we visulize and monitor changes in the electrical signaling of the heart, and tells us if something is depolarizing or repolarizing.
P wave
shows the depolarization of the atriums
QRS complex
associated with atrial repolarization and ventricular depolarization
T wave
associated with ventricular repolarization.
heart sounds
first is “lubb” and next is “dubb”
quiescence
when there is no electrical activity happening in the heart, but heart is still filling with blood
electric cycle of heart
- excitation and depolarization spreads from the SA node to the atriums which get fully depolarized and contract
- the atria repolarize and relax, while the AV node sends depolarization signals to the ventricles, so these depolarize and contract
- ventricles then repolarize and relax, and once these have relaxed the heart is back in quiescence.
mean arterial blood pressure (MAP)
cardiac output x total peripheral resistance
cardiac output
stroke volume x heart rate
stroke volume
how much blood is pushed out of the ventricles per beat and the heart rate is how many times your heart beats per minute.
ejection fraction
the amount of blood that leaves the heart compared to how much is left - so if someone has a failing heart, their stroke volume will decrease and ejection fraction decrease, as a result their heartbeat will increase.
locations where baroreceptors are concentrated
- aortic arch (blood pressure in the aorta after each heartbeat)
- carotid sinus in the neck (how much blood is going to the brain at all times)
when blood pressure is too high…
- parasympathetic system activated to tell the SA node through the Vegas nerve to decrease heartbeat thus decrease cardiac output to decrease blood pressure
when blood pressure is too high…
- sympathetic system activated to tell the SA node to make heartbeat faster, and tell the walls of the ventricles to increase the pulling power of the myocytes to create a faster heartbeat
calculation for resistance
= 1/r^4
rule of 16
if we change the size of the lumen by 2, the resistance increases by 16
vascular compliance
a vessel’s stretchiness; found by using the change of volume / change in pressure
sterling’s law of the heart
that the more stretched the muscle fibers are before a contraction, the stronger the contraction will be, so more blood will come out of the heart, and a stronger heartbeat will occur
functions of blood
- transport
- immune response
- coagulation (blood clotting caused by platelets coming in and preventing pathogens from entering)
two categories of blood
plasma and formed elements
what does plasma consist of?
water, solutes and plasma proteins
albumin
most common plasma protein that helps regulate osmotic pressure so the blood cells don’t burst
fibrinogens
plasma proteins that locate where breakage is in the skin and that it needs to be fixed up
hemocytoblasts
foundation for all formed elements in plasma (RBC’s, WBC’s and platelets)
platelets
responsible for finding areas in the body that have some kind of wound and stop the bleeding
hematopoiesis
process by which blood is made, which is done by activating the hemocytoblasts to multiply and produce more red blood cells in the red bone marrow to make more blood.
erythropoietin (EPO)
molecule that stimulates the hemocytoblasts to make more red blood cells.
packed cell volume (PCV) or hematocrit
fraction of blood occupied by the RBC’s
RBC’s have…
- 4 heme groups that can carry four molecules of oxygen each
- men have more RBC’s than women because they have more testosterone
anemic
too few RBC’s
polycythemia
too many RBC’s = chunky blood
