A & P - Cardiovascular system Flashcards
name the three blood vascular systems
systemic
pulmonary
lymphatic
what are the functions of the cardiovascular system?
deliver gases, nutrients and hormones to cells
removes waste products
what does the cardiovascular system consist of?
blood - suspends substances
circulatory systems
the heart - pump
which direction does the blood travel in blood vascular systems?
away from heart via arteries and returns via veins
what connects arteries and veins and what function does it serve?
capillaries - site of gas and nutrient exchange
what does the systemic circulation do?
delivers blood to most body tissues
describe how blood travels around the systemic system and where it is oxygen rich and low
oxygen rich blood travels from left of heart and returns low in oxygen to the right side
the systemic circulation is a high pressure system?
true
what is the arterial pulse?
heart rate
where would you take the arterial pulse?
where a superficial artery can be pressed against bone
- carotid
- radial
- ulna
- facial
- temporal
- dorsalis pedis
- posterior tibial
describe how blood travels around the pulmonary circulation
delivers low oxygen blood from right side of heart to lungs, returns oxygen rich blood to left side of heart
the pulmonary circulation is a low pressure system?
true
name the three layers of the blood vessel, inner to outer
tunica intima - endothelium
tunica media - muscle layer
tunica externa - connective tissue
what is the function of a blood vessel?
to endure changes in pressure
move with surrounding structures
remain open under all conditions
name the three vessels of the blood vascular system
arteries
microcirculation
veins
name three types of artery an it function
elastic
muscular
arterioles
name two types of microcirculation vessels
venules
capillaries - continuous, fenestrated or sinusoid
where can elastic arteries be found?
aorta
brachiocephalic
common carotid
how does the structure of elastic arteries help its function?
thick tunica media with elastic fibres helps withstand continuous changes in pressure
how does the structure of muscular arteries help their function and where are they found?
lots of smooth muscle in tunica media and thick tunica externa helps distribute blood to muscles and organs.
most named arteries are muscular arteries
how does the structure of arterioles help their function?
1-2 layers of smooth muscle in tunica media make arterioles capable of vasoconstriction/dilation
where would fenestrated capillaries be found?
kidneys
where would sinusoid capillaries be found?
liver
what is a capillary bed supplied by?
metarteriole
how many capillaries does a metarteriole contain?
1-10
what is the function of a metarteriole?
connect arterioles with venules
what controls the flow of blood to individual capillary beds?
precapillary sphincter
what forms a direct connection between arterioles and venules?
arteriovenous anastomoses
what is the function of the arteriovenous anastomoses?
to bypass the capillary bed and divert blood flow to venous circulation
what is the function of venules?
to collect blood from capillary beds and deliver to small veins
describe three properties of veins
thin walled
easily distensible
holds 54% of total blood volume
what does the lymphatic system consist of?
network of lymph vessels
lymph
lymphatic tissue and organs
what are the functions of the lymphatic system?
involved in body’s defence mechanism
provides drainage of interstitial fluid
fluid moves in and out of the capillary but how much fluid remains in the interstitial space?
app. 15%
what happens to the excess fluid left in the interstitial space?
enters the lymphatic system via the lymphatic capillary
what happens if the drainage of fluid by the lymphatic system isn’t working properly?
oedema
what is the function of the lymph nodes?
to filter fluid - pick up foreign bodies to produce immune response
which areas of the body drain into the right lymphatic duct?
right side of head and right upper limb
which vein does the right lymphatic duct drain into?
right subclavian vein
which vein does the thoracic duct drain into?
left subclavian vein
where is the heart located?
between 2nd and 5th ribs, in the thorax
name the two types of pericardium which surround the heart
fibrous pericardium
serous pericardium
what is the fibrous pericardium do and what is its structure?
inelastic sac of dense connective tissue around heart
prevents overfill
what is the serous pericardium do and what is its structure?
2 layers - parietal and visceral - separated by pericardial cavity (contains fluid)
prevents friction
name the three layers of the heart from inner to outer
endocardium - endothelium
myocardium - cardiac muscle
epicardium - visceral pericardium
name the four heart valves
pulmonary semilunar valve
aortic semilunar valve
tricuspid (right AV) valve
bicuspid (mitral/left AV) valve
how are the atrioventricular valves opened?
by blood flowing from the atria to ventricles
how are the atrioventricular valves anchored to the papillary muscles and why?
cordae tendinae - to prevent eversion of valves during ventricular contraction
how are the semilunar valves opened?
by blood being pushed from ventricles
how are the semilunar valves closed?
blood in aorta and pulmonary trunk backflows during ventricular relaxation pushing cusps shut
do semi lunar valves have cordae tendinae?
no
which side of the heart pumps blood from the lungs to the systemic circulation? is the blood rich or low in oxygen?
left
oxygen rich
which side of the heart pumps blood from the systemic circulation to the lungs? is the blood oxygen rich or poor?
right
oxygen poor
what does the coronary circulation supply?
the outside of the heart - allows it to contract
how much blood does the coronary circulation receive per minute?
250ml/min
when is the blood supplied to the myocardium?
during ventricular relaxation
what is the position of the left coronary artery (LCA) ?
anterior interventricular and circumflex
what is the position of the right coronary artery (RCA) ?
marginal artery
posterior interventricular
where do most cardiac veins drain into?
coronary sinus then right atrium
where does the anterior cardiac vein drain into?
directly into right atrium
how are cardiac cells interconnected?
by intercalated discs containing gap junctions
what are the function of gap junctions between cardiac muscle cells?
to promote coordinated contraction
cardiac cells act as a functional syncytium, what does this mean?
the cells function as one - contract together
is cardiac muscle auto-rhythmic?
yes - it contracts on its own
what is the function of the conducting system in the heart?
coordinates heart contraction
what does the conducting system in the heart consist of?
non- contractile cells that initiate electrical impulses
name 5 areas of the conducting system
- sinoartrial (SA) node
- artrioventricular (AV) node
- AV bundle (bundle of His)
- right and left bundle branches
- Purkinje fibres
what is the function of the SA node?
sets rhythm of heart
describe the contraction of the heart
SA node spontaneously reaches threshold
impulse spreads through atria
impulse passes through remainder of heart via conducting system
what modifies the rate of the heart?
ANS (would be 100b/p/m but modified to 60-80b/p/m
on an electrocardiogram what does the P wave represent?
depolarisation of atria (contracting phase)
on an electrocardiogram what does the QRS complex represent?
depolarisation of ventricles (contracting phase)
on an electrocardiogram what does the T wave represent?
repolarisation of ventricles (relaxed phase)
describe two differences between foetal circulation and post birth circulation
oxygen and nutrients via placenta and umbilical cord
lungs need bypassing as not functional
name the 3 circulatory shortcuts in foetal circulation
ductus venosus
foramen ovale
ductus arteriosus
what is the function of the ductus venosus?
to connect the umbical vein to the inferior vena cava
what is the function of the foramen ovale?
connects the right and left atria
what is the function of the ductus arteriosus?
connects the pulmonary artery to the arch of aorta - by passing lungs
what causes the foramen ovale to close at birth?
pressure increases in systemic circulation on left side of heart
pressure falls in pulmonary circulation on right side of heart forcing formen ovale closed
why does the ductus arteriosus close?
fall in pressure in pulmonary trunk
what happens when the umbicial vessels close?
rise in pressure in aorta
explain the events of the cardiac cycle during one heart beat
- ventricular filling (passive)
- ventricular filling (atrial systole)
- isovolumetric contraction
- ventricular ejection
- isovolumetric relaxation
what happens during the 1st stage in the cardiac cycle ventricular filling (passive)?
atria and ventricles relaxed
AV valves open
semilunar valves shut
blood flows into atria through AV valves into ventricles
what happens during the 2nd stage in the cardiac cycle ventricular filling (atrial systole)?
atria contract forcing blood into ventricles
what is the diastolic volume at the end of the 2nd stage in the cardiac cycle?
~ 130ml
what happens during the 3rd stage in the cardiac cycle isovolumetric contraction?
atria relax, ventricle contract
AV and semilunar valves closed
blood volume in ventricles unchanged
what does the closure of the AV valve produce?
1st heart sound - lubb
what happens during the 4th stage in the cardiac cycle ventricular ejection?
ventricular pressure exceeds aortic and pulmonary pressure - force semilunar valves open
blood forced into aorta and pulmonary trunk
what is the systolic volume at the end of the 4th stage in the cardiac cycle?
~ 60ml
what happens during the 5th stage in the cardiac cycle isovolumetric relaxation?
ventricles relax
semilunar valves close
AV valve remains closed
volume in ventricle unchanged
what does the closure of the semilunar valve in the 5th stage of the cardiac cycle produce?
2nd heart sound - dubb
what is the cardiac output and how is it measured?
volume of blood expelled by heart per minute
cardiac output = stroke volume * heart rate
CO= SV * HR
how do you calculate the stroke volume?
use the diastolic volume minus the systolic volume to get the stroke volume
eg. 130-60 = 70ml/b (SV)
name three things that affects the stroke volume
degree of stretch in myocytes (preload)
forcefulness of contraction (contractility)
pressure required to eject blood (afterload)
what determines the preload?
end diastolic volume (EDV)
what is end diastolic volume determined by?
venous return (VR)
what is venous return determined by?
volume of circulating blood
what aids venous return?
pressure gradient between veins and heart
respiratory pump
skeletal muscle pump
gravity
what increases forcefulness of contraction in the heart?
noradrenaline
adrenaline
hypercalcaemia
what reduces forcefulness of contraction in the heart?
hyperkalaemia
hypocalcaemia
myocardial hypoxia
myocardial hypercapnia
why must the pressure in the ventricles be higher than in the arteries?
to open semilunar valves
what are the average resting heart rates for a newborn, young adult and adult?
newborn - ~ 120bpm
YA - ~ 64 - 80 bpm
A - ~ 60 bpm
if an adults resting heart rate was above 100bpm what would they be suffering from?
tachycardia
if an adults resting heart rate was below 60bpm what would they be suffering from?
bardycardia
where is the heart rate modified? what would it be without modification?
cardiac centre - medulla oblongata
SA node spontaneously fires at 100bpm
what does the cardioaccelerator centre do to the heart rate?
send sympathetic impulses to increase firing rate at SA node
also increase force of contraction in cardiac muscle
what does the cardioinhibitory centre do to the heart rate?
sends parasympathetic impulses via vagus nerve to reduce firing rate at SA node
what is blood pressure?
the force that blood exerts on the walls of blood vessels
what is systolic blood pressure (SBP)?
max pressure when ventricles contract (~120mmHg)
what is diasystolic blood pressure (DBP)?
max pressure when ventricles relax (~80mmHg)
how do you work out the pulse pressure?
SBP - DBP (~40mmHg)
how do you work out mean arterial pressure?
DBP + 1/3 of pulse pressure
eg. 80+ 40/3 = 93mmHg
what is used to measure blood pressure?
sphygmomanometer
when would you be suffering from hypertension?
chronic resting BP above 140/90mmHg
when would you be suffering from hypotension?
chronic low resting BP
how is blood pressure calculated?
BP = cardiac output * total peripheral resistance (TPR)
(stroke rate HR)
what determines total peripheral resistance?
viscosity - stable
vessel length - unchanged
vessel radius - TPR adjusted by altering vessel radius
what system controls vessel radius?
sympathetic nervous system
in what state are the blood vessels usually maintained in by the SNS?
partial vasoconstriction (sympathetic tone)
which area of the SNS controls vessel radius?
vasomotor in medulla oblongata
name three controls of blood pressure
local control
short term control - neutral
long term control - hormonal
what happens during local control of blood pressure
autoregulation - ability of tissue to regulate own blood supply
which substances control local control of blood pressure and what role do they play?
metabolites - stimulate vasodilation
vasoactive chemicals - stimulate vasodilation
endothelins - stimulate vascoconstriction
name two baroreceptors involved in short term control of blood pressure
carotid sinus
aortic sinus
name three cardiovascular centres which are involved in short term blood pressure control and what they do
vasomotor centre - vasoconstriction to increase TPR
cardiac accelerator centre - increase HR and force of contraction
cardiac inhibitory centre - reduce HR
explain the response of the baroreceptors to increased BP
-increased firing to cardiac and vasomotor
increased PNS activity, reduced HR
-inhibits cardioaccelerator, reduces SNS activity, reduce HR and vasodilation
explain the response of the baroreceptors to decreased BP
reduced firing rate to cardiac and vasomotor centres
