npb101 cardiovascular system

name the 3 principal components of the cardiovascular system

heart, blood vessels, blood

what 3 body systems impact the cardiovascular system?

endocrine, nervous, renal

name the functions of the cardiovascular system

- supply oxygen, nutrients to all cells in the body
- remove metabolic wastes
- temperature regulation
- distribute hormones
- clotting of open wounds
- immuno-vigilance

name the components of blood

plasma, leukocytes, platelets, erythrocytes, immune system component

t/f: blood plasma is at least 90% water

t

do mature RBCs divide like "normal" cells?

no

t/f: RBCs have large surface areas that favor diffusion

t

protein that binds oxygen and carbon dioxide

hemoglobin

what is the average life span of an RBC?

120 days

hormone from kidneys that triggers differentiation of stem cells into RBCs

erythropoietin

process that synthesizes RBCs in red bone marrow

erythropoiesis

what are the 2 loops in the circulatory system?

pulmonary, systemic

this loop carries deoxygenated blood to lungs and back to heart

pulmonary

this loop carries oxygenated blood from the heart to the rest of the body

systemic

t/f: the circulatory system is a closed system (i.e. leaks are bad)

t

generally, veins carry blood (to/away from) the heart

to

generally, arteries carry blood (to/away from) the heart

away from

name the 4 chambers of the heart

right atria, right ventricle, left atria, left ventricle

of the 4 chambers, which is the most powerful/highest pressure and why?

left ventricle because it's sending blood to the rest of the body

what is the path of blood?

right atria -> right ventricle -> lungs -> left atria -> left ventricle -> systemic loop

name the 4 valves and the direction they facilitate blood through

- right AV valve/tricuspid: RA -> RV
- pulmonary/semilunar valve: RV -> pulmonary artery
- left AV valve/bicuspid/mitral: LA -> LV
- aortic/semilunar valve: LV -> aorta

t/f: valves ensure a one-way bloodflow

t

when pressure is greater behind the valve, the valve will (open/close)

open

when pressure is greater in front of the valve, the valve will (open/close)

close

order the 3 walls of the heart from innermost to outermost

endocardium, myocardium, epicardium

cells in the myocardium are connected by _____

intercalated disks

what are the 2 types of contacts in the myocardium's cardiac muscle? describe their functions.

desmosomes: mechanically hold cells together
gap junctions: provide low-resistance paths to electrical current flow between cells

gap junctions in the myocardium enable cardiac muscle to form a functional ___

syncytium

the epicardium is filled with a small volume of ____ fluid

pericardial

what are the 2 types of cardiac cells and their prevalence (%)?

- force producing cells (a.k.a. myocytes, contractile cells): 99% of cardiac cells
- pacemaker cells: 1% of cardiac cells

force producing cells vs. pacemaker cells

- myocytes: contraction activity
- pacemaker cells: no contractile components, sets rhythm of heart

what does it mean that the heart is autorhythmic?

the heart is capable of generating its own electrical activity

pacemaker cells are grouped together into ___

nodes

what are the 4 types of vg channels involved in electrical pacemaker activity, in order?

1. f-type (funny) sodium channel
2. t-type (transient) calcium channel
3. l-type (long-lasting) calcium channel/DHP channel
4. potassium channels, several types

the slope of pacemaker potential affects ___ ____

heart rate

name the steps of electrical pacemaker activity in order.

.

what are the 2 nodes in the heart?

sinoatrial (SA) and atrioventricular (AV)

autorhythmicity of SA node

70 AP/min

audtorhythmicity of AV node

50 AP/min

what is the internodal pathway?

conveys electrical info from SA node -> AV node

- tract of specialized cardiac pacemaker cells
- originates at AV node
- projects into left/right ventricles

bundle of his

- small terminal fibers of specialized cardiac pacemaker cells
- extend from bundle of his -> spread throughout ventricular myocardium

Purkinje fibers

purkinje fibers have a very (fast/slow) conduction velocity

fast

autorhythmmicity of purkinje fibers

30 AP/min

what are the 2 pacemaker pathways?

interatrial and internodal

- conducts pacemaker activity from RA -> LA
- both atria contract at the same time due to fast conduction velocity

interatrial pathway

AV nodal delay function

ensures ventricles contract after atrial conraction

cardiac APs in pacemaker vs. contractile cells

contractile cells: more negative resting potential, Na+ influx facilitated by VG Na+ channel (not F), has plateau and falling phase

what causes the plateau phase in an AP in a contractile cell?

increase in Ca2+ permeability via L channels, decrease in K+ permeability

what causes the falling phase in an AP in a contractile cell?

decrease in Ca2+ permeability, increase in K+ permeability via VG K channels

cardiac muscle contraction vs. voluntary (skeletal) muscle contraction

cardiac: longer APs, has plateau period, doesn't require nerve stimulation (autorhythmic), contraction occurs DURING the AP

what is the purpose of the heart's long twitch and prolonged refractory period?

allows time for ventricles to fill with blood before pumping

name the steps of excitation-contraction coupling in order

.

what is the "trigger" Ca2+ involved in excitation-contraction coupling in cardiac muscle?

it's a small amount that binds to and opens the ryanodine receptor Ca2+ channels in the SR

what do ECGs measure?

voltage differences between 2 points on the body's surface, a composite of electrical activity (i.e. NOT a single AP)

what does the P-wave represent on an ECG?

depolarization of atria via SA node

what does the QRS complex represent on an ECG?

depolarization of ventricles, with simultaneous repolarization of the atria

what does the T-wave represent on an ECG?

repolarization of ventricles

fast heartbeat

tachycardia

extrasystole

premature beat

ventricles weakly contract over and over again instead of pumping blood, no QRS complexes (i.e. ventricles don't depolarize)

ventricular fibrillation

what does an ECG scan of a complete heart block look like?

QRS and P waves happen at random times, responding independently

what is the cause of a complete heart block?

SA node may be signaling normally to the AV node, but the AV node doesn't pass on those signals

all the events involved with blood flow through the heart during 1 heart beat is called the

cardiac cycle

ventricular contraction phase

systole

ventricular relaxation phase

diastole

list the steps of the cardiac cycle

.

amount of blood in ventricles at end of diastole (nearly full)

end-diastolic volume

amount of blood left in ventricles at end of systole (nearly empty)

end-systolic volume

amount of blood ejected during systole

stroke volume

how is stroke volume calculated?

SV = EDV - ESV

what is the % ejection fraction during rest?

50-75%

the first heart sound represents closing of the ___ valves

AV

the second heart sound represents closing of the ___ valves

semilunar

what does the first heart sound sound like?

low-pitched, soft, long, "lub"

what does the second heart sound sound like?

high-pitched, sharp, short, "dup"

abnormal heart sounds often associated with cardiac disease

heart murmurs

what is the cause of heart murmurs?

turbulent flow of blood through malfunctioning valves

stiff, narrow valve that doesn't open completely

stenotic valve

what is the cause of turbulence in a stenotic valve?

blood must be forced through the valve at high velocity

what does a stenotic valve sound like?

whistling sound

valve that doesn't close properly

insufficient valve

what is the cause of turbulence for an insufficient valve?

blood flows backward through the valve, colliding with blood moving in opposite directions

what does an insufficient valve sound like?

swishing sound

laminar flow

non-turbulent blood flow

list 3 potential causes of heart murmurs

rheumatic fever, mitral stenosis, septal effects (holes in heart)

what is the type of valve defect, timing of murmur, and valve disorder of the following heart sound:
lub-whistle-dup

stenotic, systolic, stenotic semilunar valve

what is the type of valve defect, timing of murmur, and valve disorder of the following heart sound:
lub-dup-whistle

stenotic, diastolic, stenotic AV valve

what is the type of valve defect, timing of murmur, and valve disorder of the following heart sound:
lub-swish-dup

insufficient, systolic, insufficient AV valve

what is the type of valve defect, timing of murmur, and valve disorder of the following heart sound:
lub-dup-swish

insufficient, diastolic, insufficient semilunar valve

volume of blood pumped by each ventricle per minute

cardiac output

what 2 factors determine cardiac output?

heart rate and stroke volume

how is CO calculated?

CO = HR x SV

what is the average HR in bmp?

70

what is the average SV in mL?

70

what is the average cardiac output in L/min?

5

HR is regulated by what 2 systems

parasympathetic and sympathetic NS

SV is regulated extrinsically by the

sympathetic NS

SV is regulated intrinsically by

the volume of venous blood returning to the ventricles

Ach results in a (shallower/steeper) slope at the beginning of pacemaker potential

shallower