Cardiac Muscle Physiology Overview

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Where is the heart located in the body?

Below the diaphragm

Above the liver

Between the kidneys

In the mediastinum between the lungs (correct)

Which structure separates the heart from other structures?

Endocardium

Myocardium

Pericardium (correct)

Epicardium

Which chamber of the heart collects blood and pushes it into lower chambers?

Auricle

Sulcus

Ventricle

Atrium (correct)

What is the main function of ventricles in the heart?

Pump blood out to the body or lungs Signup and view all the answers

Which layer of the heart produces lubricating fluid?

Epicardium Signup and view all the answers

What is the middle thickest layer of the heart made up of?

Muscle cells, nerve fibers, and blood vessels Signup and view all the answers

What happens at 0mV with Ca++ and K+ channels?

Ca++ channels close and K+ channels open Signup and view all the answers

Which ion binds to troponin to allow the myosin and actin cross bridge?

Ca++ Signup and view all the answers

If not for endocrine control, how many times would the SA node fire per minute?

80 - 100 times Signup and view all the answers

Which part of the heart's conduction system would fire 30 - 40 times per minute?

Atrioventricular bundle Signup and view all the answers

What do electrodes on the body record when performing an ECG?

Electrical signals of the heart Signup and view all the answers

During which phase of the cardiac cycle does the depolarization of the atria occur?

Atrial systole Signup and view all the answers

What is the purpose of artificial pacemakers in the heart?

To ensure effective heart contractions by delivering electrical impulses Signup and view all the answers

Which part of the heart's electrical activity masks the repolarization of the atria?

QRS complex Signup and view all the answers

What characterizes the end-systolic volume (ESV) of the ventricles?

Amount of blood left in ventricles after stroke volume is pushed out Signup and view all the answers

What is the primary purpose of AEDs in relation to cardiac issues?

To correct fibrillations Signup and view all the answers

What is the role of myoglobin in heart cells?

Storing oxygen in muscle cells Signup and view all the answers

Which layer of the heart is responsible for releasing endothelins, strong vasoconstrictors?

Endocardium Signup and view all the answers

How many septa are found in the heart?

3 Signup and view all the answers

Which valve separates the right atrium from the right ventricle?

Tricuspid valve Signup and view all the answers

What feature is unique to the left ventricle compared to the right ventricle?

Thinner muscle Signup and view all the answers

What causes the closure of tricuspid and mitral valves?

Papillary muscles Signup and view all the answers

Which coronary artery brings blood to the myocardium and other components?

Coronary artery Signup and view all the answers

What is the function of desmosomes in cardiac muscle cells?

Stop cells from ripping apart Signup and view all the answers

Where is the SA node located in the heart?

Right atrium Signup and view all the answers

What is the function of Purkinje fibers in the heart?

Spread impulses around the ventricles Signup and view all the answers

What happens at +30mV in cardiac contractile cells?

Na+ channels close, Ca++ channels open, and K+ channels open. Signup and view all the answers

What is the function of S1 heart sound?

Closing of atrioventricular valves Signup and view all the answers

What event is likely to happen before the S1 and S2 heart sounds?

S4 - blood being pushed into a stiff ventricle Signup and view all the answers

What is the formula for calculating Cardiac Output (CO)?

CO = SV * HR Signup and view all the answers

What is the normal range for Cardiac Output (CO) in liters per minute?

4 - 8 L/min Signup and view all the answers

Which factor can decrease Heart Rate?

Hypoxia (lack of O2) Signup and view all the answers

What is the effect of caffeine and nicotine on Heart Rate?

+Increase HR Signup and view all the answers

From where does the nervous control of Heart Rate come?

Medulla oblongata Signup and view all the answers

What is the primary effect of sympathetic stimulation on Heart Rate?

+Increases HR Signup and view all the answers

'Atrial reflex' results in what response to increased blood in the atria?

+Sympathetic response to increase rate of firing Signup and view all the answers

'Stroke Volume' can be compensated for by what factor if filling time decreases?

+Heart contractility Signup and view all the answers