Muscle Types and Diseases Quiz

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Questions and Answers

What is the primary distinguishing feature of cardiac muscle compared to skeletal muscle?

Cardiac muscle has longer fibers than skeletal muscle.

Cardiac muscle contraction is initiated by nerve impulses.

Cardiac muscle is composed of branched cells. (correct)

Cardiac muscle is involuntarily controlled. (correct)

Which type of muscle is not under voluntary control?

Cardiac muscle (correct)

Smooth muscle (correct)

Striated muscle

Skeletal muscle

What condition is most commonly associated with ischemia of the heart?

Hypertension

Atherosclerosis (correct)

Arrhythmia

Heart murmur

Which disorder represents a spectrum disease from left ventricular dysfunction to end-stage overt heart failure?

Congestive Heart Failure (CHF) Signup and view all the answers

What type of muscle fiber is characterized by rapid contraction and fatigue easily?

Fast-twitch fibers Signup and view all the answers

Which of the following statements accurately describes smooth muscle?

It is found in involuntary structures. Signup and view all the answers

Which therapy is commonly used in managing Congestive Heart Failure?

Angiotensin-converting enzyme (ACE) inhibitors Signup and view all the answers

What leads to myocardial infarction in ischemic heart disease?

Complete occlusion of coronary arteries Signup and view all the answers

What characteristic feature distinguishes cardiomyopathy from other muscle disorders?

Inadequate muscle contraction due to direct damage to myocardium cells Signup and view all the answers

Which of the following best describes muscular dystrophy?

It consists of a group of genetic diseases causing progressive weakness of skeletal muscle. Signup and view all the answers

What is a significant feature of Duchenne’s muscular dystrophy (DMD)?

Most individuals have a deletion in the dystrophin gene. Signup and view all the answers

Which of the following defines the ideal cardiac marker for myocardial infarction (MI)?

Should be abundant in myocytes and detectable in blood after injury Signup and view all the answers

How do cardiac biomarkers indicate myocardial injury?

Their plasma levels correlate with the degree of myocardial injury. Signup and view all the answers

What major category of muscle disorders does Duchenne's muscular dystrophy (DMD) fall under?

Muscle fiber disorders Signup and view all the answers

What is a common clinical finding in patients with Duchenne’s muscular dystrophy?

Greatly elevated serum CK enzyme levels prior to symptom onset Signup and view all the answers

What factor is NOT a characteristic of the ideal cardiac marker for diagnosing myocardial infarction?

Should be detectable only in blood post-injury Signup and view all the answers

What characterizes the ischemic injury in myocardial infarction?

It is an irreversible process causing cell death and necrosis. Signup and view all the answers

Which biomarkers are considered the cornerstone for the detection of myocardial infarction?

cTnT and cTnI Signup and view all the answers

When do CK-MB levels typically elevate after the onset of chest pain in myocardial infarction?

4 to 6 hours after onset Signup and view all the answers

What is the significance of measuring blood samples at intervals during myocardial infarction diagnosis?

To track the temporal pattern of cardiac biomarkers. Signup and view all the answers

How do troponin elevations compare to CK-MB levels in diagnosing cardiac injury?

Troponins are more sensitive and specific for cardiac injury than CK-MB. Signup and view all the answers

What does the distinct rise and fall of CK values indicate during an MI?

A possible reinfarction or new MI event. Signup and view all the answers

What is the optimal timing for taking blood samples after a myocardial infarction is suspected?

At intervals including 2 to 4 hours, 6 to 8 hours, and 12 hours after suspicion. Signup and view all the answers

What are the two types of subunits that compose the total creatine kinase enzyme?

M and B Signup and view all the answers

What is the primary reason for using cardiac troponin levels in diagnosing myocardial infarction (MI)?

Troponins are specific to cardiac muscle damage. Signup and view all the answers

How long can troponin levels remain elevated in the blood after a myocardial infarction?

4 to 10 days. Signup and view all the answers

Which of the following statements about Cardiac Troponin I (cTnI) is correct?

cTnI remains elevated for 3 to 7 days after an acute MI. Signup and view all the answers

When does Cardiac Troponin T (cTnT) typically start to rise in serum after a myocardial infarction?

After 4 hours following MI. Signup and view all the answers

What distinguishes cTnI from CK-MB in the context of skeletal muscle injury?

cTnI is not affected by any skeletal muscle injuries. Signup and view all the answers

What is a significant characteristic of myoglobin when assessing for myocardial infarction?

It can be detected as early as 1 to 2 hours after symptom onset. Signup and view all the answers

What does the sustained elevation of cardiac troponin levels indicate following a myocardial infarction?

Recent myocardial dysfunction. Signup and view all the answers

Which statement regarding the peak values of cTnT is true?

cTnT has a peak or plateau at 1 to 6 days after MI. Signup and view all the answers

Study Notes

Cardiac & Skeletal Muscle Disease, and Muscle Biomarkers

The presentation covers cardiac and skeletal muscle diseases and associated biomarkers.
The date of the presentation is 17-18/12/2024.

Muscle Anatomy and Function

There are three types of muscle: skeletal, cardiac, and smooth.
Skeletal muscle is made up of unbranched, cylindrical muscle cells arranged in parallel bundles.
Muscle fibers run the entire length of the muscle.
Skeletal muscle contractions are neurogenic, initiated by nerve impulses.
Skeletal muscle can be categorized into fast-twitch and slow-twitch types, differing in their biochemical properties.

Cardiac Muscle

Cardiac muscle is exclusively found in the heart.
Similar to skeletal muscle, it contains actin and myosin filaments.
The contraction of cardiac muscle filaments pumps blood from the atria and ventricles.
Cardiac muscle control is involuntary, termed myogenic.

Smooth Muscle

Smooth muscle is composed of elongated, non-striated cells with a single, centrally located nucleus.
Smooth muscle cells are also called involuntary muscles.
Smooth muscle is found in the walls of tubes and sacs like blood vessels, the uterus, bladder, and intestines.

Pathological Conditions

Cardiac disorders, including ischemic heart disease, acute coronary syndrome (ACS), congestive heart failure (CHF), and cardiomyopathy, are discussed.
Ischemia is a condition where an organ lacks adequate blood supply for its functions, often caused by atherosclerosis.
Atherosclerosis involves cholesterol deposits in arterial walls, potentially occluding arteries.
Ischemic heart diseases range from unstable angina to frank myocardial infarction (with large areas of necrosis).
ACS refers to a group of conditions that obstruct or severely reduce blood flow to the heart muscle, potentially harming it.
CHF is a condition related to reduced blood pumping capability.
Cardiomyopathy features insufficient muscle contraction due to myocardial cell damage, typically resulting in heart failure.

Myocardial Infarction (MI)

MI is a damaging process where ischemic injury is irreversible, leading to cell necrosis.
Diagnosis relies on patient history, ECG interpretation, and serum levels of cardiac-specific biomarkers.
cTnT and cTnI are now considered cornerstones for MI detection.
Biomarker levels in the blood, like CK-MB and troponins, become elevated after MI onset, with different time courses.

Cardiac Biomarkers in MI

CK-MB is an isoenzyme of creatine kinase (CK), a dimeric enzyme composed of subunits 'M' for muscle and 'B' for brain origin.
Myocardium is the primary tissue containing CK-MB.
Cardiac troponins are more sensitive and specific than CK-MB for cardiac injury.
Troponins remain elevated in the blood for several days after MI.

Myoglobin

Myoglobin exists in both cardiac and skeletal muscle; limiting its cardiac specificity.
Myoglobin is a useful early marker for MI because levels rise in the blood within 1 to 2 hours of symptom onset.
Myoglobin is not cardiac-specific and might also elevate in conditions unrelated to cardiac muscle damage.

CK & CK Isoenzymes in Non-MI Conditions

In diseases other than MI, CK-isoenzyme patterns are not typically rise-and-fall patterns but instead show prolonged elevations.
Conditions like Duchenne muscular dystrophy, polymyositis, and others can cause marked elevations of CK-MB.
Elevated total CK levels in non-cardiac conditions are frequently significantly higher than in MI.

Diagnostic Use of Cardiac Troponins

Troponin plays a significant role in diagnosing and assessing risk in acute coronary syndromes (ACS).
Release kinetics of cardiac troponins are comparable to CK-MB after MI; levels remain elevated for a prolonged time.
Very low troponin values in those without cardiac disease permit the use of lower discriminatory values for MI diagnosis.
Troponin's cardiac specificity helps to eliminate diagnostic uncertainty due to possible skeletal muscle injury-related CK-MB elevation.

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Description

This quiz explores the various types of muscles including cardiac, skeletal, and smooth muscles, along with their functions and associated diseases. It also delves into muscle biomarkers relevant to cardiac and skeletal muscle diseases. Test your knowledge on muscle anatomy and physiology!