cardiac physiology

Heart is located within…

the mediastinum just above the diaphragm

the heart is enclosed in a…

pericardium

the heart is a hollow…

muscle double pump

the heart is divided into…

4 chambers

left and right chambers of the heart have a…

collecting chamber and a pumping chamber

collecting chamber

atrium

pumping chamber

ventricle

three principal circulatory divisions in the cardiovascular system:

systemic circulation

pulmonary circulation

coronary circulation

systemic circulation carries oxygenated blood from the…

left ventricle through the body, and returns venous blood to the right atrium.

pulmonary circulation carries venous blood from the right ventricle through the lungs (blood undergoes oxygentation) and delivers oxygentaed blood through…

4 pulmonary veins into the left atrium

coronary circulation delivers oxygenated blood for the…

heart through the coronary arteries

venous blood from the heart through the cardiac veins collects into…

the coronary sinus and empties into the right atrium

both pumps contract at the same time and both sides pump…

equal volumes of blood with each cycle of contraction (systole) and relaxation (diastole)

general organization of the circulatory system

Closed System
Heart
Arterial System
Venous System
Microcirculation
Systemic Circulation
Pulmonary Circulation

blood movement through the heart:

starts with?

systemic circulation (venous blood)

blood movement through the heart:

systemic circulation (venous blood) →

superior/ inferior vena cava

blood movement through the heart:

superior/ inferior vena cava →

right atrium

blood movement through the heart:

right atrium →

right ventricle

blood movement through the heart:

right ventricle →

pulmobary arteries (l/r)

blood movement through the heart:

pulmonary arteries (L/R) →

pulmonary circulation

blood movement through the heart:

pulmonary circulation →

pulmonary veins

blood movement through the heart:

pulmonary veins →

left atrium

blood movement through the heart:

left atrium →

left ventricle

blood movement through the heart:

left ventricle →

aorta

blood movement through the heart:

aorta →

systemic circulation (arterial blood)

pericardium

composed of fibrous pericardium + visceral and parietal layers

epicardium

superficial visceral layer of the serous pericardium

myocardium

composed of the contractile cells- part which actually contracts

endocardium

composed of epithelial and connective tissue + elastic fibers

skeletal muscles are composed of

a big numbers of muscle fibers (cells).

each (skeletal) muslc fiber has the…

the same length as a muscle

skeletal muscle fibers have a significant number of…

nuclei (myonuclei), which are located just beneath the sarcolemma.

cardiac muscle cells

myocytes

myocytes are arranged in…

layers and are shorter than skeletal muscles

cardiac muscle has properties of…

skeletal muscle and of a smooth muscle

somatic nervous system affects?

skeletal muscle

autonomic nervous system affects?

cardiac and smooth muscle

cardiac muscle cell has only ___ nuclei (myonuclei)

1-2

cardiac muscle cells are connected through…

intercalated discs

cardiac muscle cells (myocytes):

gap junctions in the intercalated discs are similar to those in the…

smooth muscles

cardiac muscle is a…

syncytium

cardiac muscle cells (myocytes):

gap junctions in intercalated discs provide…

low electrical resistance

step 1? cardiac muscle is a ___

syncytium

step 2? intercalated discs separate…

cardiac cells

step 3? gap junctions in intercalated discs explain...

low electrical resistance

step 4? ___ synctiumm

atrial

step5? ____ syncytium

ventricular

myocyte is surrounded by the…

plasma membrane - sarcolemma

cytoplasm of the cardiac cell contains…

contractile proteins (myofilaments)

myofilaments - actin and myosin have a…

parallel orientation along the axis of a fiber/ myocyte

thin filament (actin) is anchored to the …

z disc (z-line)

distance between two z-lines is a…

functional unit of a cardiac cell - sarcomere

between myofibrils abundant _____ are found

mitochondria

the smooth endoplasmic reticulum (sarcoplasmic reticulum) is a strong site of…

calcium ions in the cell

_____ also contains carbohydrate glycogen

cytoplasm

resting membrane potential in cardiac cells

-85 to -95 mV

resting membrane potential in conductive ribers

-90 to - 100 mV

resting potential is ____

stable

Action potential in a cardiac muscle:

Phase 0

depolarization (Na enters in about 2 msec)

Action potential in a cardiac muscle:

Phase 1

early repolarization (sodium channels start to inactivate)

Action potential in a cardiac muscle:

Phase 2

plateau (Ca enters about 200 msec)

Action potential in a cardiac muscle:

Phase 3

Repolarization (K channels open)

Action potential in a cardiac muscle:

Phase 4

ion distribution restored (Na/K pump)

Action Potential in a Cardiac Muscle:

1. Prolonged AP and…

plateau in cardiac muscle

Action Potential in a Cardiac Muscle:

2. Opening of fast …

sodium channels (open 1/1000 s)- phase 0

Action Potential in a Cardiac Muscle:

3. Opening of slow …

calcium channels (open 1/10 s) - Phase 2

Action Potential in a Cardiac Muscle:

4. mainatined a prolonged period of _____

depolarization

Action Potential in a Cardiac Muscle:

5. very long (250ms)…

refractory period (impossible to cause summation of contractions)

Excitation-Contraction Coupling:

step 1

action potential

Excitation-Contraction Coupling:

step 2

calcium transients

Excitation-Contraction Coupling: Calcium transients

resting cytosolic calcium is ___

increased

Excitation-Contraction Coupling: Calcium Transients

10% of calcium enters via…

calcium influx through T-tubules into the sarcoplasmic reticulum

Excitation-Contraction Coupling: Calcium Transients

calcium is released from the…

sarcoplasmic reticulum

Excitation-Contraction Coupling:

step 3

calcium combines with troponin

Excitation-Contraction Coupling:

step 4

tropomyosin’s inhibition is removed

Excitation-Contraction Coupling:

step 5

cross-bridges are formed

Excitation-Contraction Coupling:

step 6

contraction

sarcoplasmic reticulum of cardiac cell is…

less developed than of skeletal muscles

t-tubules of cardiac cells have a large diameter

5 times more than of skeletal muscles

electronegative mucopolysaccharides bind…

calcium ions in T-tubules

T-tubules open directly to the…

outside of cardiac cells

extracellular calcium significantly affects…

cardiac cell contraction

cardiac cycle

1. atrial contraction

2. isovolumic (isometric) ventricular contraction

3. ventricular ejection (rapid ejection period and slower ejection period)

4. isovolumic (isometric) ventricular relaxation

5. passive ventricular filling

time it takes for systole

250-300 ms

time it takes for diastole

500-550 ms

what initiates atrial contraction ?

generation of action potential in the sinus node

atrial contraction

Mitral valve is opened
Aortic valve is closed
75% of blood flows directly from atrias into ventricles
25% of blood flows into ventricles due to atrias contraction

isovolumic (isometric) ventricular contraction

Mitral valve is closed
Aortic valve is closed
Volume of blood in ventricles remains constant
Ventricles contract. Pressure in the ventricles is building

ventricular ejection (rapid ejection period and slower ejection period)

mitral valve is closed

aortic valve is opened

ventricles continue contracting

isovolumic (isometric) ventricular relaxation

Mitral valve is closed
Aortic valve is closed
Ventricles Relaxing
Pressure rapidly drops to diastolic values

passive ventricular filling

Mitral valve is opened
Aortic valve is closed
Blood collects in atrias
Blood fills the ventricles
75% of blood flows directly from atria into ventricles

ESP

end systolic pressure

120 mmHg

EDP

end diastolic pressure

0mmHg

ESV

end systolic volume

EDV

end diastolic volume

SV

stroke volume

65 mL

when valves close…

pressure gradient develops

the surrounding tissue, fluids, and blood vessels ___

vibrate

sound travels through the…

chest

frequency of I think heart sounds

3 Hz - 40 Hz - 500 Hz