Patho ch 25 - cardiovascular system

main function of cardiovascular system

main function of cardiovascular system

transport (oxygen, nutrients, waste products, electrolytes, hormones, immune substances)

also helps regulate temp via dilating/constricting vessels

this holds the heart in a fixed position and provides a barrier to infection and physical protection

pericardium

the outer layer of the pericardium is called the ___ and is attached to ___

fibrous pericardium

central tendon of diaphragm

inner layer of the pericardium is called ___ and has (one/multiple) layers

serous pericardium

multiple layers (visceral and parietal)

visceral pericardium

layer of the inner layer of the pericardium, aka epicardium (lines the heart)

epicardium

the visceral layer of the serous (inner) layer of the pericardium

contents of pericardial cavity

30-50 mL of serous fluid to minimize friction during contraction and relaxation of the heart

myocardium relies heavily on ___ for contraction

extracellular calcium ions

the sarcoplasmic reticulum of cardiac muscle isn’t as well defined as the SR of skeletal muscle (can’t store a lot of calcium)

this regulates the calcium-mediated contraction of cardiac muscle

tropomyosin-troponin complex

endocardium has how many layers

3 (innermost, middle, outermost)

innermost layer of the endocardium lines the (heart chambers/myocardium)

heart chambers

innermost layer of endocardium is made of (connective tissue/endothelial cells)

endothelial cells - continuous with the blood vessels that enter and leave the heart

middle layer of endocardium is made of (dense/irregular) connective tissue

dense - contains elastic fibers

outer layer of endocardium is continuous with the (heart chambers/myocardium)

myocardium

outer layer of endocardium is made of (dense/irregular) connective tissue

irregular - contains the conducting system and blood vessels

mitral valve location

between LA and LV

bicuspid

tricuspid valve location

between RA and RV

semilunar valves

aortic valve (between LV and aorta)

pulmonic valve (between RV and pulmonary artery)

___ provides structural support and isolating force for ___ impulse in the heart

fibrous skeleton; electrical

the fibrous skeleton provides support for the ___ and insertion for ___

attachment of valves

insertion of cardiac muscle

the period during which ventricles are contracting

systole

the period when ventricles are relaxed and filling with blood

diastole

end diastolic volume (definition and approximate amount)

the amount of blood present in the ventricles at the end of diastole (maximum fill)

~120 mL

isovolumetric period of ventricular systole begins with closure of (AV/SL) valves

AV valves

ejection period of ventricular systole occurs when the ___ pressure is greater than ___ pressure

ventricular > artery (causing SL valves to open)

S1 heart sound

closure of AV valves (beginning of isovolumetric ventricular systole)

normal to hear

ventricular diastole begins with closure of (AV/SL) valves

SL valves - no more blood leaving ventricles

S2 heart sound

closure of aortic and pulmonic valves (SL valves)

normal to hear

S3 heart sound

sound of ventricular filling (occurs during ventricular diastole)

normal to hear in young children, pregnant women; otherwise pathological (CHF)

describe what happens in the 3 thirds of ventricular diastole

1. rapid filling (S3 sound)

2. middle third - filling continues

3. last third - atrial contraction to complete filling (S4 sound)

S4 heart sound

sound of atrial contraction

pathological to hear - only in stiff, noncompliant ventricles (HTN, ventricular hypertrophy)

state of AV/SL valves in ventricular diastole (open/shut?)

AV valves are open

SL valves are shut

end diastolic volume

the amount of blood increase in the ventricles during diastole (~120 mL)

end systolic volume

amount of blood left in the ventricles after contraction (systole) (~50mL)

stroke volume

EDV - ESV (amount of blood ejected from the LV during each heartbeat)

ejection fraction

% of blood in the left ventricle that is ejected with each heartbeat (55-75%)

SV/EDV

test used to measure end diastolic volume

ECHO

average cardiac output in an adult

4-6 L/min

cardiac output calculation

SV x HR

cardiac reserve

the maximum % increase in CO that can be achieved above a person’s normal resting level

higher in younger adults, athletes (max 300-400%)

force of heart contraction is greatest when fibers are stretched to ___x their normal resting length

2.5

preload is largely determined by (arterial/venous) pressure

venous pressure/venous blood return

situations that increase preload (physiologic and pathologic)

• exercise, excitement

• hypervolemia (increased blood volume), regurgitation of heart valves, heart failure

exercise (increases/decreases) preload of the heart

increases - increases venous pressure to increase venous return to the heart

Frank-Starling Mechanism

the greater the volume of blood in the heart before contraction, the greater the volume of blood ejected from the heart (due to increased stroke volume)

HOWEVER - eventually the elastic limit of the heart is reached and causes thinning of heart walls (dilated cardiomyopathy) which is bad

afterload

the pressure the heart needs to generate to eject blood from the chamber

factors that increase afterload of the heart

aortic stenosis (increases resistance in the aorta)

HTN (increased total peripheral resistance of all vessels, especially the arteries)

the resistance the left ventricle must overcome to circulate blood: __

afterload

cardiac workload is increased with (increased/decreased) afterload

increased

valve regurgitation effect on preload

increases preload because blood flows back into the chamber (atria or ventricle) and increases the amount of blood that needs to be pumped out; then this happens again and again and causes a backup of blood in the chamber which increases the load on the heart

contractility refers to the changes of the force of heart contraction due to ___

calcium ions

positive inotropic effects

(affect contractility)

sympathetic stimulation (increases calcium availability)

oxygen (more ATP/energy)

negative inotropic effects

(affect contractility)

hypoxia - anaerobic respiration, lack of ATP (and buildup of lactic acid)

increased HR (increases/decreases) cardiac output

decreases - because there is less time available for ventricular (diastolic) filling
→ decreases SV and therefore CO

right heart is (pulmonary/systemic) circulation

pulmonary

left heart is (pulmonary/systemic) circulation

systemic

capacitance vessels

veins (collections and storage vessels)

central circulation includes blood in the ___ and ___

heart and pulmonary circulation

peripheral circulation is blood outside of ___ and ___

the heart and pulmonary circulation

pulmonary circulation is (high/low) pressure

low (12 mmHg)

systemic circulation is (high/low) pressure

high (90-100 mmHg)

fraction of blood volume in the arterial system

1/6

fraction of blood in the venous system

2/3

pressure is (proportionately/inversely) related to volume

inversely (higher volume = lower pressure, ex. veins)

blood flow is determined by ___ and ___ of the blood vessel

pressure difference between the 2 ends; resistance

equation of blood flow

F = (change in P) / R

blood flow in the circulatory system is represented by (heart rate/cardiac output)

cardiac output

laminar blood flow

characterized by plasma on the edges and cells in the center of the vessel; so flow is smooth (prevents clotting factors from coming into contact with the vessel wall, reduces frictional forces)

layering of components in the center of the bloodstream

turbulent blood flow

disordered; the blood moves crosswise and lengthwise

(laminar/turbulent) blood flow requires more pressure to push the blood through the vessel

turbulent

turbulent blood flow can be caused by:
- (increased/decreased) velocity
- (increased/decreased) vessel diameter
- (high/low) blood viscosity

increased velocity

decreased vessel diameter

low blood viscosity (as seen in anemia, because it allows faster BF)

(longer/shorter) vessel length increases resistance

longer

(larger/smaller) radius increases resistances

smaller

decreased temperature results in (increased/decreased) blood viscosity

increased

(increased/decreased) blood viscosity causes increased resistance

increased - friction of molecules in the fluid

wall tension is the force in the vessel wall that opposes ___

distending pressure inside the vessel

law of Laplace (describing relationship between wall tension, intraluminal pressure, and radius)

P = T/r → T = P x r (to describe the effect of radius on wall tension)

as the radius increases, wall tension becomes (greater/lesser)

greater - important concept for aneurysms

smaller radii require (more/less) pressure to dilate

more

wall tension (increases/decreases) as vessel walls become thinner

increases (and so decreases as the walls become thicker)

(veins/arteries) are more compliant

veins - 24x more than its corresponding artery

(arteries/veins) are more distensible

veins

tunica externa/adventitia is made of (smooth muscle/fibrous connective tissue/endothelial cells)

fibrous connective tissue

function of tunica externa

protect the vessel and anchor it to surrounding structures

tunica media is made of (smooth muscle/fibrous connective tissue/endothelial cells)

smooth muscle

function of tunica media

regulate the diameter of the vessel

thicker in arteries than veins

tunica intima is made of (smooth muscle/fibrous connective tissue/endothelial cells)

endothelial cells - with minimal elastic layer to join them to the tunica media

these cells are adjacent to the blood

arteries (do/do not) have properties of stretch and recoil during systole and diastole

do - due to large amount of elastic fibers

__ are resistance vessels for the circulatory system

arterioles

tissues (are/are not) able to regulate blood flow without input from the CNS

are
- do this as a result of changes in flow to the tissue or local tissue factors (oxygen, metabolite concentration)

metabolites that can affect local control of blood flow

accumulation of lactic acid, potassium, hydrogen ions

reactive hyperemia increases local blood flow due to ___

occluded blood supply (once the occlusion is removed)

(functional hyperemia is increase in BF due to increased activity)

endothelial control of blood flow: NO

causes vasodilation - normally released by endothelial cells and can be increased by Ach, histamine, bradykinin, thrombin, stress on endothelium

NO effect on platelets

inhibits aggregation to protect against thrombosis and the resulting vasoconstriction

endothelial control of blood flow: examples of vasoconstrictors

endothelin-1, angiotensin II, vasoconstrictor prostaglandins (F)

long term regulation of blood flow occurs via (autoregulation/collateral circulation)

collateral circulation - anastomotic channels and angiogenesis

cells important for angiogenesis

fibroblasts - produce VEGF, angiotensin, other important growth factors

histamine effect on blood flow

increases due to vasodilation

also increases cap permeability

serotonin effect on blood flow

causes vasoconstriction (S-2 receptors)

bradykinin effect on blood flow

causes vasodilation of arterial smooth muscles, increased permeability of capillaries, constricts venules