AP2 Ch20 Heart

arteries

blood vessel: carry blood away from heart

veins

blood vessel: carry blood back to heart

capillaries

blood vessel: small thin membrane vessels that exchange gases with cells; where blood gets oxygenated in lungs; aka exchange vessels

right atrium

heart chamber: receives blood from systemic circuit and passes to right ventricle

right ventricle

heart chamber: pumps blood into pulmonary circuit

left atrium

heart chamber: receives blood from pulmonary circuit and passes to left ventricle

left ventricle

heart chamber: transports blood to systemic circuit; thicker than RV due to higher pressure required to push blood to systemic circuit

heart

located near anterior chest wall and slightly left of midline; surrounded by the pericardial cavity; consists of outer covering, muscular walls, inner covering, chambers, valves

visceral pericardium

pericardium layer: covers outer surface of heart; aka epicardium

parietal pericardium

pericardium layer: lines inner surface of pericardial sac

pericardial fluid

fluid that fills area between the two pericardium layers to reduce friction as heart beats

auricle

extension of an atrium

apex

inferior part of heart

base

superior part of heart

epicarium

heart layer: outer layer

myocardium

heart layer: muscular wall that forms atria and ventricles; middle layer

endocardium

heart layer: inner layer made the same as the epicardium

intercalated disks

double membrane that connects 2 adjacent cardiac muscle cells, which allows the contraction command to be passed from cell to cell by gap junctions

atrioventricular valves (AV)

valves that prevent backflow of blood from ventricles to atria

• tricuspid, bicuspid valves

semilunar valves

valves that prevent backflow of blood from vessels to ventricles

• pulmonary, aortic

tricuspid valve

right AV valve; transports blood from RA to RV; closes when RV contracts

bicuspid valve

left AV valve; transports blood from LA to LV; closes when LV contracts

pulmonary semilunar valve

semilunar valve: opening of pulmonary trunk (right side); transports blood from RV to pulmonary trunk

aortic semilunar valve

semilunar valve: opening of aorta; transports blood from LV to ascending aorta

2

How many great veins does the right atrium receive blood from?

superior vena cava

great vein for RA: blood coming from head, neck, upper limbs, chest

inferior vena cava

great vein for RA: blood coming from lower trunk, lower limbs

foramen ovale

connects RA and LA to allow blood flow before fetus is fully developed inside the womb; closes ~48 hours after birth

pulmonary arteries

After entering the pulmonary circuit through the pulmonary trunk, blood gets split into the left and right _____ _____, which bring the blood to the lungs to get oxygenated.

pulmonary veins

After being oxygenated in capillaries in lungs, blood passes into the left and right _____ _____ and returns to the LA.

ascending aorta > aortic arch > descending aorta

Describe the blood path in the aorta.

• answer format: [] > [] > []

ascending aorta

The right and left coronary arteries begin at the _____ _____.

marginal branch; posterior interventricular

List the 2 right coronary arteries (in alphabetical order).

• []; []

anterior interventricular; circumflex

List the 2 left coronary arteries (in alphabetical order).

• []; []

cardiac veins

return blood from heart cells to RA

• coronary sinus

• great cardiac vein

• posterior cardiac vein

• middle cardiac vein

• small cardiac vein

conducting cells; contracting cells

2 types of cardiac cells involved in heartbeat (in alphabetical order)

• answer format: []; []

contractile cell

cells that receive the stimuli for contraction; resting potential is about -90 mV

1; rapid depolarization

step _/3 of heart contraction: _____ _____

Contractile cells receive stimuli (resting potential -90 mV). Na+ channels open and Na+ ions enter.

• cause: Na+ entry

• duration: 3-5 ms

• ends with: closure of fast Na+ channels

answer format: []; []

2; plateau

step _/3 of heart contraction: _____

When transmembrane potential reaches +30 mV, Na+ channels close. As transmembrane potential reaches -60 mV, Na+ is pumped out. Then slow Ca2+ channels open and Ca2+ binds troponin; transmembrane potential remains around 0

• cause: Ca2+ entry

• duration: 175 ms

• ends with: closure of slow calcium

answer format: []; []

3; repolarization

step _/3 of heart contraction: _____

Slow Ca2+ channels close and slow K+ channels open, so K+ rushes out to reduce the positive change inside the cell.

• cause: K+ closs

• duration: 75 ms

• ends with: closure of slow K+ channels

answer format: []; []

absolute refractory period

the time when a cell will not respond to a second stimuli; lasts about 200 ms

relative refractory period

short time after absolute refractory period; cell will not respond to a second normal stimuli but will respond to a greater stimuli

conducting system

cardiac muscle contracts on its own (unlike skeletal muscle, which needs neural or hormone stimulator)

• consists of sinoatrial node, atrioventricular node, conducting cells

sinoatrial (SA) node

part of conducting system: located in posterior wall of RA near entrance of superior vena cava; smaller node

• contains pacemaker cells, which start contractions and stimulate the AV node

• innervated by the vagus nerve and sympathetic fibers

atrioventricular (AV) node

part of conducting system: larger node; located at junction between RA and RV

• takes 100 ms for impulse to pass through AV node and enter AV bundle

• the impulse travels from AV bundle through intraventricular septum to bottom of ventricles, where they stimulate Purkinje fibers

• Purkinje fibers relay the impulse throughout both ventricles

conducting cells

part of conducting system: found in atria and ventricles

• in atria: found in internodal pathway

• in ventricles: include AV bundle and Purkinje fibers

tachycardia

faster than normal heartbeat

bradycardia

slower than normal heart beat

1

step _/5 of conducting system:

SA node is activated; time = 0 ms

2

step _/5 of conducting system:

stimulus spreads from SA across both atria and reaches the AV node; time = 50 ms

3

step _/5 of conducting system:

stimulus is delayed for 100 ms, then both atria contract; time = 150 ms

4

step _/5 of conducting system:

stimulus travels along interventricular septum within the AV bundle; this branches to become the Purkinje fibers; time = 175 ms

5

step _/5 of conducting system:

Purkinje fibers distribute the stimuli to the myocardium (heart muscle), causing ventricles to contract; time = 225 ms

auscultation

listening to heart sounds; there are 4, but normally we can only hear the first 2

S1

heart sound: normally audible (“lubb”); caused by AV valves closing

S2

heart sound: normally audible (“dupp”); caused by semilunar valves closing

S3

heart sound: normally inaudible; blood flowing into ventricle

S4

heart sound: normally inaudible; atrial contraction

P wave

ECG/EKG: depolarization (contraction) of atria

QRS wave

ECG/EKG: signals ventricle depolarization (contraction); large due to ventricle muscle being more massive than atria

T wave

ECG/EKG: signals ventricular repolarization (relaxation)

systole

when a section/chamber of the heart contracts; blood leaves the chamber during contraction

diastole

when a section/chamber of the heart relaxes; blood enters the chamber at rest

1; atrial diastole (relaxation)

phase _/4 of the cardiac cycle: _____ _____ (_____)

fills with blood; AV valves open; blood (about 70%) passively enters ventricle

• answer format: []; []

2; atrial systole (contraction)

phase _/4 of the cardiac cycle: _____ _____ (_____)

atria contracts, pushing remaining blood (30%) into ventricles

• answer format: []; []

3; ventricular systole (contraction)

phase _/4 of the cardiac cycle: _____ _____ (_____)

AV valves close; semilunar valves open as blood is ejected into arteries; pressure in aorta reaches 120 mm Hg

• answer format: []; []

4; ventricular diastole (relaxation)

phase _/4 of the cardiac cycle: _____ _____ (_____)

semilunar valves close; AV valves open; blood passively enters ventricles from atria; aorta rebounds and pressure drops to 80 mm Hg; all chambers are relaxed.

• answer format: []; []

cardiodynamics

refers to the movements and forces generated during cardiac contractions

cardiac output (CO)

amount of blood pumped per minute

• CO = heart rate (HR) x stroke volume (SV)

end diastolic volume (ECV)

factor affecting stroke volume: the amount of blood left in each ventricle at the end of ventricular diastole

end systolic volume (ESV)

factor affecting stroke volume: the amount of blood (about 50 mL) left in each ventricle at the end of ventricular systole

stroke volume (SV)

amount of blood (about 70-80 mL) pumped out of each ventricle during a single beat

• SV = EDV - ESV

ejection fraction

percentage of EDV represented by SV

autonomic innervation

factors affecting heart rate:

• sympathetic and parasympathetic innervation

• medulla oblongata

• atrial reflex (when walls of RA are stretched, stretch receptors trigger a reflexive increase in HR)

hormones

factors affecting heart rate:

• epinephrine

• norepinephrine

• thyroid hormones