79 Questions
What factor has the most influence on blood flow in vessels?
Vessel diameter
Which type of cardiac muscle cells have a pacemaker potential and membrane potential that 'never rests'?
Myocardial Autorhythmic Cells
What slows down blood flow in vessels?
Blood viscosity
Which factor affecting blood flow remains relatively constant?
Blood viscosity
In terms of blood flow, what does resistance primarily depend on?
Vessel diameter, tube length, and blood viscosity
Which type of cardiac muscle cells have a different looking action potential due to calcium channels?
Myocardial Contractile Cells
Which of the following is NOT a factor that affects blood flow?
'Never rests' pacemaker potential
Which hormone enhances heart rate and contractility?
Epinephrine
What type of cells in the heart contribute to the generation of the heart's electrical signal?
'Never rests' pacemaker potential cells
Which factor increases heart rate and enhances the effects of norepinephrine and epinephrine?
Thyroxine
What is a common age-related change affecting the heart?
Sclerosis and thickening of valve flaps
Which congenital heart defect involves a narrowed aorta?
Coarctation of the aorta
What is a common arrhythmia disorder related to age and underlying heart disease?
Atrial fibrillation
What is the most common disorder that involves the superior part of the interventricular septum failing to form?
Ventricular septal defect
Which ion concentration must be maintained for normal heart function?
$Ca^{2+}$
'Tetralogy' in 'Tetralogy of Fallot' refers to how many defects?
$4$
What is the purpose of gap junctions in cardiac muscle cells?
To ensure the heart contracts as a unit
What happens when depolarization opens voltage-gated fast Na+ channels in cardiac myocytes?
Reversal of membrane potential from -90 mV to +30 mV
What prolongs the depolarization phase (plateau) in cardiac muscle cells?
Surge of Ca2+ ions
What is responsible for the repolarization phase in cardiac muscle cells?
Inactivation of Ca2+ channels and opening of K+ channels
What role do slow Ca2+ channels play during cardiac muscle contraction?
Maintain depolarization in plateau phase
What is the function of automaticity in cardiac cells?
Self-excitability or spontaneous depolarization
Which event causes the sarcoplasmic reticulum (SR) to release Ca2+ in cardiac muscle cells?
Depolarization wave in T tubules
What is responsible for the long absolute refractory period (250 ms) in cardiac myocytes?
Fast Na+ channel inactivation
What is a common way patients describe an arrhythmia?
As a palpitation or fluttering sensation in the chest
What is one of the symptoms patients may experience due to arrhythmias?
Dizziness
What is a frequent cause of arrhythmia according to the text?
Coronary artery disease
What happens when cardiac cells lack oxygen according to the text?
They become depolarized
What can ectopic foci lead to in the heart?
Bradycardia
What is altered impulse conduction commonly associated with within the heart?
Reentry that leads to abnormal conduction
What can ectopic foci cause in terms of heartbeats?
Premature beats
How do ectopic foci impact the normal pacemaker activity of the SA node?
Replacing it with another pacemaker
What is the function of intercalated discs in cardiac cells?
Allow branching of the myocardium
Which structure is responsible for fast cell-to-cell signals in cardiac cells?
Gap Junctions
What is the main function of the intrinsic cardiac conduction system?
Initiate and distribute impulses to coordinate heart contraction
What characterizes pacemaker-autorhythmic cells in the heart?
Unstable resting potentials with open slow Na+ channels
What event leads to the rising phase of the action potential in cardiac cells?
Explosive Ca2+ influx
What causes repolarization in cardiac cells after depolarization?
Inactivation of Ca2+ channels and opening of voltage-gated K+ channels
What is responsible for the slow depolarization known as pacemaker potential?
Opening of Na+ channels and closing of K+ channels
What leads to repolarization in cardiac cells after depolarization?
Closing of Na+ channels and opening of K+ channels
What is the final stage of maturation for red blood cells?
Nucleus incorporation
Which organelle in red blood cells is responsible for transporting iron into the mitochondria?
Endoplasmic reticulum (ER)
What is the main function of hemoglobin in red blood cells?
Carrying oxygen
Which component is NOT found in mature red blood cells?
Nucleus
What remarkable transformation do erythrocytes undergo during maturation?
Exclusion of Golgi bodies
What is the role of mitochondria in developing erythrocytes?
Transporting iron
What makes veins more compliant compared to arteries?
One-way valves
What is the primary function of erythrocytes in the bloodstream?
Carrying oxygen
How do nutrients like glucose and amino acids leave the capillaries in the body?
Diffusion
What is the main mechanism through which CO2 moves at the capillary bed?
Diffusion
Where are small proteins or amino acids dissolved when they leave the capillaries?
Interstitial space
What is the main function of elastic fibers in venous vessels compared to arteries?
To store blood
What mainly differentiates venous vessels from arterial vessels?
Muscle composition
Where does the blood go after leaving the venules?
Veins
What is the primary role of the venous circulation within the body?
To store blood
What does the ST segment represent in an ECG?
A resting membrane potential
Which part of the ECG signifies that the ventricle is depolarized?
R wave
What does the Q wave indicate on an ECG?
Movement of action potential through the bundle branch fibers
Why are 12 to 32 leads used in clinical ECGs rather than just three leads?
To provide electrical views of the heart from multiple angles
What is the primary benefit of using ECG to monitor cardiac rhythm and rhythm disturbances?
Tracking changes in ventricular depolarization
What can be inferred if an ECG shows electrical aberrations?
Ischemic tissue or necrotic zones
What does each ECG lead provide?
An electrical view from different parts of the heart
Why is the interval between the P and R waves a straight line on an ECG?
"Slowed impulse at the A-V node"
What would happen if all blood vessels were completely dilated and fixed at a certain diameter according to the text?
All tissues would be maximally perfused.
What local factors can cause vascular smooth muscle to dilate and increase blood flow?
CO2, H+, K+, and adenosine
What is an important function of the sympathetic nervous system in relation to blood vessel diameter?
Causes constriction of blood vessels
What factor causes muscle contraction to lead to increased perfusion in working muscles?
Release of adenosine
What is the main role of smooth muscle surrounding arteries and veins anatomically?
To respond to tissue need
What effect do CO2, H+, K+, and adenosine have on vascular smooth muscle?
Relax and dilate the vessels
How do blood vessels ensure efficient distribution of blood flow according to the text?
By constantly altering their diameter based on tissue need
What is the primary function of the layer of smooth muscle surrounding arteries and veins?
To respond to tissue need for altered perfusion
What effect does nitric oxide have on smooth muscle?
Inhibits SERCA pump
How does a reduction in vascular diameter affect blood flow to tissues downstream?
Decreases flow due to increased resistance
Where is the site of greatest control of resistance in the arterial tree?
Arterioles
What is the primary determinant of flow to the tissue?
Vessel radius
Which factor increases total peripheral resistance (TPR) and reduces flow?
Decreased vascular diameter
What increases vascular diameter during exercise?
Increased metabolites from skeletal muscle
Why do arterioles play a significant role in controlling resistance?
Due to their smaller relative cross-sectional area
What determines the resistance to flow primarily in blood vessels?
Blood viscosity
Test your knowledge on the process of cardiac muscle contraction and depolarization, including topics like rhythmic depolarization, automaticity, gap junctions, refractory period, and ion channel activation.
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