BIOL 233: Cardiovascular and Blood

a good way to describe the cardiovascular system is

"pressure is distance"

the heart is ______ anchored to anything

NOT

an average HR is ~

72 bpm

an athlete's HR is typically

an example is ~40 bpm

much lower

Heart rate is NOT ______; instead, it is _____

static; dynamic

Heart sounds come from

valves closing

when the heart is challenged, it meets that by

changing (ex. shape)

the heart is _______ in the body

midline

the heart's apex points towards

the left hip

the heart is encased in the

pericardium

How much pericardial fluid is normal?

~2-3 tsp

Pericardium is:

fixed, so it can't expand

the problem with the pericardium being fixed, is that ___________; what is that condition called

when fluid surrounds the heart, the sac can't expand; pericarditis

how many layers of the heart is there

3

What is the outtermost layer of the heart wall

epicardium

what is the middle layer of the heat wall

myocardium

What is the innermost layer of the heart?

endocardium

heart muscle looks like its being

rung like a sponge from the bottom up

the right ventricle can be

pretty thin

What is the BP in the right ventricle?

25/8

Which ventricle is thicker?

left ventricle

Why is the left ventricle thicker than the right?

because it is opposed by more force

What is the BP in the left ventricle?

120/80

the left ventricle only gets bigger if you

work it

muscle is NOT

unilateral

what is the purpose of heart valves

prevent back flow of blood

Heart valves open and close in response to __________.

pressure

AV valves are _____ between beat

open

AV valves are loose leaflets of _________ (they have no __________)

connective tissue; structure

semilunar valves are ________ between beats

closed

What are the 2 AV valves?

tricuspid and bicuspid (mitral)

the left AV valve is called

bicuspid or mitral valve

the right AV valve is called

tricuspid valve

What are the 2 semilunar valves?

pulmonary and aortic

the left semilunar valve is called

aortic valve

the right semilunar valve is called

pulmonary valve

AV valves have a ring of ___________ to anchor them

connective tissue

tendinous cords

what is the purpose of tendinous cords

keeps the valves from going back

papillary muscles

papillary muscle contracts the same time as the

walls

Why don't semilunar valves have chordae tendineae?

because they're closed until pressure builds

What are the two circuits of the heart?

pulmonary circuit and systemic circuit

which circuit of the cardiovascular system needs more pressure

systemic

Where does the pulmonary circuit go?

heart--->lungs--->heart

where does the systemic circuit go?

heart--->body--->heart

coronary circulation is it's own

circuit

the coronary arteries come right off the

aorta

how many heartbeats per lifetime

2 1/2 billion

cardio muscle is NOT ________; it is more "_________" together

unidirectional; woven

What do intercalated discs do?

provides additional structure and keeps the heart from ripping itself apart

What do intercalated discs contain?

desmosomes and gap junctions

What are gap junctions?

channels that allow exchange of material

what is the reason for the heart being able to beat so much

mitochondria

why do mitochondria keep the heart beating so much?

keeps it in an aerobic state

What is aerobic?

requires oxygen

What are cardiomyocytes?

cardiac muscle cells

cardiomyocytes

what is the trigger for muscle contraction

binding of calcium to troponin

you need to have calcium on the outside of the cell in order to __________; what is this called?

release other calcium; calcium-induced calcium release (CICR)

Depolarization

contraction happens

what is the charge inside of the cell during depolarization

positive

what makes it positive during depolarization

Na+ (sodium)

what allows for repolarization

K+ (potassium)

Repolarization

relaxation

what is the charge inside the cell during repolarization

more negative

How does repolarization occur?

via the opening of V-gated K+ channels

what is the first step of an action potential in cardiomyocytes

voltage gated Na+ channels open

what is the second step of an action potential in cardiomyocytes

Na+ inflow depolarizes the membrane and triggers the opening of still more Na+ channels, creating a positive feedback cycle and a rapidly rising membrane voltage

what is the third step of an action potential in cardiomyocytes

Na+ channels close when the cell depolarizes, and the voltage peaks at nearly +30 mV

what is the fourth step of an action potential in cardiomyocytes

Ca2+ entering through slow Ca2+ channels prolongs depolarization of membrane, creating a plateau. Plateau falls slightly because of some K+ leakage, but most K+ channels remain closed until end of plateau

what is the fifth step of an action potential in cardiomyocytes

Ca2+ channels close and Ca2+ is transported out of cell. K+ channels open, and rapid K+ outflow returns membrane to its resting potential

look at the __________ to determine contraction length

plateau

why do some contractions last longer?

because Ca2+ is around longer

When the AV valves are open

the semilunar (pulmonary and aortic) valves are shut

what occurs during phase 1 of the cardiac cycle

ventricular filling/passive filling between beats and atrial contraction

during passive filling, what is the percentage of blood volume in the left ventricle

80%

during atrial contraction, what is the percentage of blood volume

20%

what is the name of the total of volume in phase 1

End diastolic volume (EDV)

What does end diastolic volume mean? What does it equal?

EDV: AMOUNT OF BLOOD IN VENTRICLES AT THE END OF FILLING; Venous Return aka PRELOAD

What is preload?

volume of blood in ventricles at end of diastole

what happens during phase 2a of the cardiac cycle

isovolumetric contraction phase

what occurs during isovolumetric contraction?

all four valves are closed

isovolumetric contraction makes up the

first heart sound (S1)

What is afterload?

resistance left ventricle must overcome to circulate blood

what must happen in isovolumetric contraction

afterload

what happens during phase 2b of the cardiac cycle

ventricular (rapid) ejection

what is open during ventricular ejection

aortic valve

what happens during phase 3 of the cardiac cycle

isovolumetric relaxation

what occurs during isovolumetric relaxation

all 4 valves are closed

isovolumetric relaxation makes up what

second heart sound (S2)

what is the name of the total volume during isovolumetric relaxation

End Systolic Volume

What is end systolic volume (ESV)?

volume of blood remaining in each ventricle after contraction

what happens after isovolumetric relaxation

the cardiac cycle goes back to the "beginning" with ventricular filling

how do you measure cardiac output (CO)?

CO= Stroke Volume (SV) x Heart Rate (HR)

What is stroke volume?

how much blood is ejected and how much is left

how do you calculate SV?

End Diastolic Volume (EDV) - End Systolic Volume (ESV)

how can you regulate stroke volume

contractility, afterload, and preload

the main thing to focus on with contractility, is the concentration of

calcium

more calcium =

can bind to more troponin