Physiology of Skeletal Muscle and Cardiac Output

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Questions and Answers

What does cardiac output measure?

The force of heart contractions

The oxygen content in the blood

The rate of heartbeats per minute

The volume of blood pumped by the heart (correct)

To which part of the skeletal muscle does the all-or-none law apply?

The muscle tendon

A single muscle fiber (correct)

The neuromuscular junction

The entire muscle group

Which of the following accurately describes cardiac output?

It indicates the heart's ability to pump blood efficiently. (correct)

It is the total volume of blood in the body.

It is measured in liters per hour.

It represents the pressure of blood in the arteries.

What is the unit of measurement for cardiac output?

Liters per minute Signup and view all the answers

Which statement regarding skeletal muscle and the all-or-none law is true?

The law only applies to individual muscle fibers. Signup and view all the answers

What is the primary function of the lumbar arteries?

To provide blood for the muscles and spinal cord Signup and view all the answers

Which artery is responsible for supplying blood to the lower extremities?

External iliac artery Signup and view all the answers

What does the internal iliac artery primarily supply?

Pelvic viscera Signup and view all the answers

What anatomical structure does NOT receive blood supply from the external iliac artery?

Pelvic organs Signup and view all the answers

Which statement accurately reflects the function of lumbar arteries and their connection to other arteries?

They provide blood for the muscles and spinal cord. Signup and view all the answers

What does mean circulatory filling pressure (MCFP) refer to?

The pressure in the circulatory system if the heart stops suddenly Signup and view all the answers

How does ventricular compliance affect end-diastolic volume (EDV)?

It is directly proportional to EDV Signup and view all the answers

What is the typical value of mean circulatory filling pressure (MCFP)?

7-8 mmHg Signup and view all the answers

What is the relationship between ventricular stiffness and EDV?

Greater stiffness leads to a lower EDV Signup and view all the answers

Which of the following statements about end-diastolic volume (EDV) is true?

EDV is directly proportional to compliance and inversely proportional to stiffness Signup and view all the answers

What happens to stroke volume (SV) when heart contractions are more forceful?

Stroke volume increases. Signup and view all the answers

What is indicated by a lower end-systolic volume (ESV)?

More blood is ejected from the ventricle. Signup and view all the answers

What does the term 'inotropic' refer to in cardiovascular physiology?

Heart contractility. Signup and view all the answers

How do forceful heart contractions affect blood volume in the ventricle?

Decrease the blood volume remaining in the ventricle. Signup and view all the answers

Which of the following relationships is correct regarding heart contractions and stroke volume?

Increased contraction strength leads to reduced end-systolic volume. Signup and view all the answers

What does the length of the arrow in a vector represent during the cardiac cycle?

The magnitude of the electrical current Signup and view all the answers

In the context of vectors, what does the orientation of the arrow signify?

The direction of the current flow Signup and view all the answers

What does the tip of the arrow in a vector represent?

The positive pole of the electrical current Signup and view all the answers

What geometric shape do the three standard limb leads form in Einthoven's Triangle?

Equilateral triangle Signup and view all the answers

Who is known as the father of the modern ECG?

Walter Einthoven Signup and view all the answers

Study Notes

Skeletal Muscle

The all-or-none law only applies to individual muscle fibers, meaning they either contract fully or not at all.

Cardiac Output

Cardiac output (CO) measures the volume of blood pumped by each ventricle per minute.

Blood Supply

Lumbar arteries supply blood to muscles and the spinal cord.
Branches of the external iliac artery supply blood to the lower extremity.
The internal iliac artery supplies blood to the pelvic viscera.

Venous Pressure Gradient

Mean circulatory filling pressure (MCFP) is the pressure measured in the circulatory system if the heart stops suddenly, and blood is redistributed evenly.
MCFP is typically 7-8 mmHg.

Cardiac Performance

End-diastolic volume (EDV) is influenced by ventricular filling, compliance, and stiffness.
EDV is directly proportional to compliance and inversely proportional to stiffness.
A more forceful contraction increases the stroke volume (SV) and decreases the end-systolic volume (ESV), meaning more blood is ejected from the heart.
Inotropy refers to the strength of heart contractions.

Electrocardiogram (ECG)

Each moment during the cardiac cycle can be represented by a vector showing the net electrical activity as seen by a lead.
The vector is visualized as an arrow with length representing the magnitude of the electrical current, orientation representing the direction of current flow, the tip representing the positive pole, and the tail representing the negative pole.

Einthoven's Triangle

The three standard limb leads (I, II, III) are arranged in an equilateral triangle called Einthoven's triangle.
Walter Einthoven is considered the father of the modern ECG.

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Description

This quiz covers key concepts of skeletal muscle function, cardiac output, and the blood supply system. You will learn about the all-or-none law, the cardiac output measurement, and factors affecting cardiac performance. Test your understanding of human physiology and its components.