Outcome 9 - Cardiovascular System Flashcards
what are the layers of the pericardium?
- fibrous pericardium
- serous pericardium
what is the purpose of the pericardium?
- it surrounds and protects the heart
- it allows for vigorous and rapid contractions
- it holds the heart in the mediastinum
the serous pericardium is double layered, what are they called?
- parietal layer
- visceral layer (epicardium)
what is the fibrous pericardium composed of?
- tough, inelastic, dense irregular connective tissue
what is the pericardial cavity?
the space between the parietal and visceral layer
what are the three layers of the heart wall?
- epicardium
- myocardium
- endocardium
What are the two layers of the epicardium made out of?
- visceral serous layer (outermost layer) - mesothelium
- adipose and fibroelastic tissue (inner layer)
describe the myocardium.
- it is a cardiac muscle tissue
- it has involuntary movements – pumping action
- 95% of the heart wall
describe the endocardium.
- it is a thin layer of connective tissue with a thin layer of endothelium
- they provide smooth lining for chambers and over valves
what are the external chambers of the heart?
- auricle
- sulci
what is an auricle?
it is the wrinkled “pouch-like” structure on the anterior surface of the atria
what is the sulci?
- they are grooves that hold the coronary blood vessels and fat
- they mark the boundary between 2 chambers
what are the 3 sulci?
- coronary sulcus
- anterior inter ventricular sulcus
- posterior inter ventricular sulcus
where do you find the coronary sulcus?
it is deep in the heart, and it separates the atrium from the ventricles
where do you find the anterior interventricular sulcus?
ANTERIORLY between the right and left ventricles, shallowly
where do you find the posterior interventricular sulcus?
POSTERIORLY between the right and left ventricles, shallowly
what are the four chambers of the heart?
right and left atria
right and left ventricles
what separates the right and left atrium?
interatrial septum
what is the fossa ovalis?
an oval depression on the septum
what is the valve separating the RIGHT atrium from the RIGHT ventricle?
tricuspid valve
aka R atrioventricular valve
the right atrium receives blood from _____, ______, and the _________.
from the superior vena cava, inferior vena cave and the coronary sinus
so right side - deoxygenated blood
where do you find the pectinate muscles?
on the internal surface, anterior surface and the auricle
what are the cardiac muscle ridges found in the right ventricle called?
trabeculae carneae
chordae tendineae attaches the cusps of the valves to ______.
papillary muscles
what is the name for the septum that separates the right ventricle from the left ventricles?
interventricular septum
what is the valve that separates the right ventricle from the pulmonary trunk?
pulmonary valve
the left atrium receives blood from _____ by the ________ ______.
from the lungs by the pulmonary veins
what is the valve called between the LEFT atrium and LEFT ventricle?
bicuspid valve (2 cusps)
aka mitral or L atrioventricular valve
what is the ligament arteriosum?
- it connects the arch of the aorta and pulmonary trunk
what is the largest part of the heart?
the left ventricle
what is the blood flow after blood leaves the L ventricle?
Left ventricle –> aortic valve –> ascending aorta –> arch of the aorta –> descending aorta –> rest of the body
what carries the blood from the aorta to the heart wall?
coronary arteries that branch from the ascending aorta
what does the fibrous skeleton do for the heart?
- it provides a structural foundation and prevents the overstretching of valves
- it also provides a point of insertion for bundles of cardiac muscle fibres
- acts as an electrical insulator
the 4 dense CT rings that surrounds the valves, fuse together by _______. These fuse rings then become a part of _______.
fuse together by trigones
fused rings become part of the interventricular septum
what is an important role of the fibrous rings?
they prevent the valves from overstretching and becoming leaky
what are the two types of valves in the heart?
- atrioventricular valve
- semilunar valve
what are the two kinds of atrioventricular valve?
- triscuspid (RA and RV)
- bicuspid/mitral (LA and LV)
what are the two kinds of semilunar valves?
- aortic valve
- pulmonary valve
when do the semilunar valves close?
during ventricular relaxation
what are the two coronary arteries?
- L coronary artery
- R coronary artery
what does the left coronary artery divide into?
- the anterior interventricular branch aka the left anterior descending branch
- circumflex branch
where does the LAD supply blood to?
walls of both VENTRICLES
what does the circumflex branch supply blood to?
walls of the left atrium and ventricle
what does the right coronary artery branch into?
- posterior interventricular branch
- marginal branch
where does the posterior interventricular branch supply blood to?
the right and left VENTRICLES
where does the marginal branch supply blood to?
RIGHT ventricle
during ____, blood is shunted into the right and left coronary artery.
relaxation
what does the deoxygenated blood from the myocardium drain into?
coronary sinus
what drains into the great cardiac vein?
both right and left ventricles + left atrium
what drains into the middle cardiac vein?
both right and left ventricles
what drains into the small cardiac vein?
the right atrium and right ventricle
what drains into the anterior cardiac vein?
right ventricle
what is myocardial infarction (MI)?
the death of cardiac muscle tissue due to interrupted blood supply
*complete blood flow obstruction
what is ischemia?
the reduction of blood flow to the cardiac muscle tissues
- hypoxic state which weakens tissue cells
what is angina?
it describes chest pain that could radiate to the t-spin, shoulder, arm, jaw, neck
- associated with MI and ischemia
what is the short axis plane?
oblique coronal
what is the horizontal long axis?
oblique transverse
(heart oriented towards you, and you cut anteriorly/posteriorly)
what is the vertical long axis?
oblique sagittal
how does ATP production occur in skeletal muscles? cardiac muscles?
skeletal - can occur anaerobically
cardiac - almost exclusively on aerobically
what are autorhythmic fibres?
“self-exciting” muscle fibres
- meaning they generate AP without stimulus
what are the autorhythmic fibres composed of?
~1% cardiac muscle fibers
99% contractile muscle fibers
what does the autorhythmic fibers do?
- act as a pacemaker - setting rhythm of excitation for the heart beat
- forms conduction systems - gives pathways for ap to travel
what are the 5 different autorhythmic fibers?
- sinoatrial node (SA node)
- atrioventricular node (AV node)
- bundle of his (aka av bundle)
- right and left bundle branches
- purkinje fibers
what is the sa node?
- it is known as the pacemaker of the heart
- it creates an ap of the fastest rate
what is the role of the av node?
- it slows down the ap from the sa node
- will fire ap if the something were to happen to the sa node –> rate is much slower than the sa node’s (40-60 bpm)
where do you find the sa node? av node?
sa - right atrium next to the opening for the inferior vena cava
av - in the wall of the septum between atrium and ventricle; anterior to the coronary sinus opening
what are internodal tracts? where are they found?
myocytes extending from the sa node to the av node
- found throughout right atrium
what are Bachman’s bundles? where are they found?
myocytes extending from sa node to av node
- found throughout the left atrium
when does the atria contract?
follow an ap that is triggered by the sa node
when ap travels from the sa node to the av node, what is happening?
- the ap slows down/slight pause due to the fewer gap junctions here (0.1 sec delay)
- this will allow for the atria to empty their blood into the ventricles
what are the 5 steps to ap propagation?
- sa triggers ap: atrial contraction
- ap from sa to av: ventricle filling
- av node to av bundle
- av bundle into right and left bundle branch
- right and left bundle branch into purkinje fibres
what do the purkinje fibres do?
they are large diameter nerve cells, thus rapidly conducting ap to stimulate the rest of the ventricular myocardium
when do ventricles contract?
following ap
when do the pulmonary trunk and aorta’s valves open?
when the pressure in the ventricles exceed the pressure in the p. trunk and aorta
what is the rate of a sa node?
initiation of ap every 0.6 secs
100x/min
what does an ecg show?
the electrical signals of an ap from each part of the heart during one cardiac cycle
by comparing an ecg to a normal one, what is determined?
- abnormal conduction path
- heart enlargement
- damaged areas
- cause of chest pain
what does the p wave show in an ecg?
- atrial depolarization
- contraction of the atria at the end of the p-wave
what does the qrs cmplex on an ecg show?
- rapid ventricular depolarization
- ventricular muscle fibres contracting
what does the t-wave in an ecg show?
ventricular repolarization; ventricles relaxing
why don’t we see atria relaxation on an ecg?
ventricles have more electrical activity so it masks the electrical activity of the atria
what is one cardiac cycle?
all the events (systole, diastole of both atria and ventricles) that occur in ONE heart beat
how do you measure a cardiac cycle length?
secs/beat
what is occurring during relaxation in the heart?
it’s when the myocardium is receiving its oxygen and nutrients that is needed
pressure in the left side of the heart is greater than the right side, therefore, the volumes on either side differences. t/f
false.
volume is the same.
what are the five phases of the cardiac cycle?
- ventricular filling
- atrial contraction
- isovolumetric contraction
- ventricular ejection
- isovolumetric relaxation
during ventricular filling, what is occurring?
- the heart is at rest (both a and v are relaxed)
- av valves are open to allow for passive filling of the ventricles
- no electrical activity
what is happening during atrial contraction?
- initiated by atrial depolarization
- active filling is now occurring, atria is being squeezed
- at the end of this phase, ventricular depolarization starts
what is end diastolic volume?
the volume inside the heart that is at its greatest
***vol in the ventricle at the END of RELAXATION
what is occurring during isovolumetric contraction?
onset of ventricular systole
- increased pressure in the ventricles causes the av valves to close
- semilunar valves are still closed as well
what is occurring during ventricular ejection?
- increased contraction of the ventricles which causes the pressure in the ventricles to be higher than the p. trunk and aorta – SL valves open
- blood ejected from ventricles
- repolarization of ventricles initiated
what is occurring during the isovolumetric relaxation?
- ventricle relaxation (diastole) which causes the pressure to fall = sl valve closing
- *av valves are still closed therefore, no passive filling yet
how do you calculate cardiac output? what’s the units?
co = sv * hr
co (ml/min)
sv = stroke volume (ml/beat)
hr = heart rate (beats/min)
what is the stroke volume? how is it calculated?
it is the volume of blood ejected by the VENTRICLES during each contraction
the difference between the end diastolic volume and the end systolic volume.
ex. sv = 130 ml - 60 ml = 70 ml/beat
what is the end systolic volume?
when the ventricles are the least full
*** vol in the ventricle at the END of CONTRACTION
what is ejection fraction?
how do you calculate ejection fraction?
it is the percentage of blood ejected from the ventricle in one beat
EJ = SV/EDV *100%
during stress the ejection fraction will increase by 10x. t/f
false.
it’ll only increase by ~5%
what are the three factors that effect the stroke volume?
- preload
- contractibility
- afterload
what is preload?
the degree of stretch the heart gets before it contracts
what is contractibility?
the force of contraction of individual ventricular muscle fibers
what is after load?
the pressure that must be exceeded before blood can be ejected from the ventricles
↑ preload = ______ SV
↑ contractibility = ______ SV
↑ afterload = _____ SV
↑ preload/contractibility = ↑ SV
↑ afterload = ↓ SV
how do you increase preload?
by increasing EDV
- increasing the length of diastole
- increasing venous return
- vasoconstriction
how does moderate exercise and extreme exercise differ in terms of edv?
moderate exercise = ↑ edv
↑ hr = ↓ diastole + ↑↑ venous return = ↑ edv
extreme exercise =
↑↑ hr = ↓↓ diastole + ↑ venous return = ↓ edv
how does positive inotropic agents affect contractility?
positive ino = stimulate SNS, E/NE =
increase ca2+ flow during cardiac ap = increase contractility
how does negative inotropic agents affect contractility?
negative ino = inhibit SNS; channel-blockers, beta-blockers =
decrease ca2+ flow during cardiac ap = decrease contractility
what is the pressure in the r ventricle? left ventricle?
right = ~20 mmHg
left = ~80 mmHg
why does sv decrease if afterload increases?
it’ll take more time to exceed the higher pressure, so there is less time to squeeze out blood during systole (shortening the ventricular ejection period)
what is considered the short term control of bp and co?
hr (which is controlled by a negative feedback loop)
how does the stimulation of the sympathetic nerves affect the output to the heart? parasympathetic nerves?
sympathetic = cardiac accelerator = increases the span. depolarization in sa/av node which increases heart rate; it also increases contractility to increase stroke volume
parasympathetic = decrease rate of spontaneous depolarization of SA and AV node which decreases heart rate
what else impacts heart rate?
- hormones (E/NE, thyroid hormones that enhance E/NE)
- cations (Na+, K+, Ca2+)
- age, gender, physical fitness, body temp.
what’s the general blood flow through vessels?
arteries, arterioles, capillaries, venues veins
arteries carry blood _______ heart.
veins carry blood _______ heart.
arteries - AWAY from heart
veins - TO heart
what is the difference between arteries and veins?
- arteries have the extra internal elastic lamina and external elastic lamina that is between the smooth muscles
- the smooth muscle of the arteries are much more dense
- veins have valves and larger lumen (hold more blood)
- arteries can contract and relax
what does the internal/external elastic lamina do?
it allows for the diffusion of O2 and nutrients and to remove wastes
what are the 3 layers that make up the wall of vessels?
- tunica interna
- tunica media
- tunica externa
what are the 3 components of the tunica interna in arteries?
- the inner endothelial layer - continuous squamous epithelial
- basement membrane - allows for the anchoring of endothelial layer to connective tissue
- internal elastic lamina - allows for the diffusion due to the holes
what does the tunica media consists of?
smooth muscle cells and lots of elastic fibers
what does the tunica externa consists of?
elastic and collagen fibers as well as nerves and tiny blood vessels to supply the tissue of the vessel walls
what are the different types of capillaries?
- continuous
- fenestrated (porous)
- sinusoid (most open)
where do you find continuous capillaries?
lungs, skeletal muscles and smooth muscles
where do you find fenestrated capillaries?
kidneys, villi of intestines, choroid plexuses, endocrine glands
where do you find sinusoid capillaries?
spleen, liver, rbm endocrine glands
what forms the valves found in veins?
tunica interna
describe the venous sinuses.
- no smooth muscles, no valves and have dense ct that replaces the outer layers
what is anastomosis?
the joining of two or more vessels supplying the same body region
what is collateral circulation?
alternative route of blood flow due to anastomosis - allows for perfusion despite the primary blood supply getting blocked
what is an end artery?
an artery that doesn’t undergo anastomosis
*therefore if it is blocked, there will be no perfusion to the part or all of that organ
what is blood flow? total blood flow?
bf = the volume of blood that flows through any tissue at any given time (ml/min)
total bf = volume of blood circulating through blood vessels per minute
what are flows dependent on?
pressure differences and resistance
greater difference in pressure = _____ flow.
greater resistance = ______ flow.
higher pressure difference = increase flow
greater resistance = decrease flow
what are the other two mechanisms that assist in pumping blood back to the heart?
- skeletal muscle pump
- respiratory pump
what is the flow rule with pressure differences?
flows from an area of higher pressure to lower pressure
what does vascular resistance depend on?
vessel size and length, blood viscosity
what is blood pressure? how is it generated?
the pressure exerted by the blood on the walls of the arteries during ventricular sys and dia
generated by the ventricular contractions
where is blood pressure the highest? lowest?
highest - aorta
lowest - superior vena cava
what influences bp?
- cardiac output
- blood volume
- vascular resistance
what is normal arterial pressure during systole?
90-120 mmHg
what is normal arterial pressure during diastole?
60-80 mmHg
what is considered high bp? low bp?
high = >=140 mmHg sys, >=90 mmHg dia
low = <90 mmHg sys
what happens when the vasomotor nerves get stimulated?
it’ll cause vasoconstriction which increases blood pressure
what happens during high bp?
the stimulation of vagus nerves – decrease rate decreases
what happens during low bp?
the stimulation of cardiac accelerator nerves which increases rate and contractility
what does E/NE do and its effect on bp?
it’ll increase blood pressure by increasing heart rate and contractility which results in increased cardiac output.
E/NE = ↑ CO = ↑ BP = ↑ HR and ↑ contractility
what does aldosterone, antidiuretic hormones do and its effect on bp?
increases blood volume = ↑ BP
what does atrial natriuretic peptide do?
it decreases the blood volume = decrease bp
what hormones increase vascular resistance? what does increasing vascular resistance do to bp?
angiotensin II, antidiuretic hormones (ADH) vasopressin, NE/E
increasing vr = ↑BP
what hormones causes vasodilation (decrease vascular resistance) and what does decreasing vascular resistance do for bp?
ANP, E, nitric oxide
decreasing vr = decreasing bp
what is autoregulation?
the ability of tissue to automatically adjust blood flow within capillaries to match the required metabolic demands by vasoconstriction and vasodilation of arterioles
what are the two main stimuli that causes autoregulation?
- physical changes in tissues (i.e heat = vd; cooling = vc)
- VC and VD chemicals released by local cells
what is unique about the autoregulation in the lungs in response to low o2?
low o2 in the lungs = vasoconstriction
the mean arterial pressure is the average bp in the arteries. what affects it?
cardiac output and resistance
what do we use to measure bp?
sphygomomanometer and stethoscope
where do you usually measure bp?
brachial artery
what is auscultation?
listening to the blood hitting against the walls
what is the first sound you hear when measuring bp?
systolic pressure
the disappearance of sound is the ____ pressure.
diastolic
what are korotkoff sounds?
sounds that are produced due to the pressure cuffs changing the flow of the blood through the artery
what is shock?
- the failure of the cv system to deliver enough o2 and nutrients to meet the metabolic needs of the cells
- inadequate floor of blood to tissues
what are the four kinds of shock?
- hypovolemic
- cardiogenic
- vascular
- obstructive
when does hypovolemic shock occur?
when there is a decrease in blood volume
how do you decrease blood volume?
internal/external hemorrhaging
excessively sweating, diarrhea, vomiting
diabetes mellitus or insipidus - excess urination
when does cardiogenic shock occur? what is the usual cause?
due to poor heart function (valve issues, excessive preload and afterload, arrhythmias)
usual cause = MI
when does vascular shock occur?
because of inappropriate vasodilation
what are some examples of inappropriate vasodilations?
- anaphylaxis - histamine release
- neurogenic shock - head trauma=issues with cv centre
- septic shock - toxins from pathogens
when does obstructive shock occur?
when there is an obstruction to blood flow
what are the 4 divisions of the largest artery in the body?
ascending, arch, thoracic and abdominal
what splits into the right and left common iliac arteries? where do they supply blood to?
the abdominal aorta
the pelvis and lower limbs
what are the five changes that occur after birth?
- ductus arteriosus
- foramen ovale
- ductus venosus
- umbilical vein
- umbilical arteries
what is ductus ateriosus? what is the result called?
connecting of the pulmonary trunk to the aorta
results in ligaments arteriosum
what is foramen ovale? what is the result called?
the opening between the right and left atria
called = fossa ovalis
what is ductus venosus? what is the result called?
change that allows blood to bypass the hepatic portal vein and flow into the inferior vena cava
called = ligaments venosum
what is umbilical vein? what’s the result called?
carrying of o2 from placenta to fetal circulation
becomes = ligamentum teres
what is umbilical arteries? what are the results called?
carrying of co2 blood from fetal circulation to placent
becomes = medial umbilical ligaments
