Human Anatomy: The Heart Overview

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Questions and Answers

What proportion of the heart lies to the left of the median plane?

1/2
1/3
3/4
2/3 (correct)

What is the approximate weight of an adult male's heart?

300 grams (correct)
400 grams
250 grams
350 grams

Which of the following best describes the shape of the heart?

Inverted cone (correct)
Cube-shaped
Spherical
Flat oval

The apex of the heart is located at which intercostal space?

5th intercostal space (B) Signup and view all the answers

What percentage of the body weight is the heart in an adult male?

0.5% (A) Signup and view all the answers

What is the primary function of the atria in the heart?

Routing blood to the ventricles (B) Signup and view all the answers

Which layer of the heart is referred to as the myocardium?

Middle layer (C) Signup and view all the answers

Which of the following statements is true regarding the heart's chambers?

There are two superior chambers known as the atria. (A) Signup and view all the answers

What are the names of the two atria in the heart?

Right atrium and left atrium (D) Signup and view all the answers

Which layer lies beneath the myocardium?

Endocardium (B) Signup and view all the answers

What primary role do veins serve in the circulatory system?

Act as capacitance vessels or reservoirs (D) Signup and view all the answers

Which characteristic defines continuous capillaries?

Lack of perforations and passage of small molecules only (B) Signup and view all the answers

In comparing vessel walls, what is a likely difference between veins and arteries?

Veins have less elastic tissue than arteries (A) Signup and view all the answers

What type of vessel is designed primarily for gas exchange in tissues?

Capillaries (B) Signup and view all the answers

Which of the following statements about the circulatory system is correct?

Veins contain valves that prevent backflow of blood (A), Continuous capillaries are restrictive in what they allow to pass (C) Signup and view all the answers

What structure separates the atrial and ventricular contractile cells?

Fibrous skeleton (C) Signup and view all the answers

Which characteristic describes the gap junctions between atrial and ventricular contractile cells?

They do not exist between these cells. (B) Signup and view all the answers

What primarily supports and surrounds the heart valves?

Fibrous skeleton (A) Signup and view all the answers

Why is the fibrous skeleton significant in cardiac physiology?

It separates the atria from the ventricles. (D) Signup and view all the answers

Which of the following is NOT true about the electric properties of the heart's structure?

Atria and ventricles can contract simultaneously. (D) Signup and view all the answers

What is the primary function of the pulmonary circulation?

To carry blood between the heart and lungs (C) Signup and view all the answers

Which statement best describes systemic circulation?

It carries blood between the heart and all body systems (C) Signup and view all the answers

What distinguishes pulmonary circulation from systemic circulation?

Pulmonary circulation connects the heart to the lungs, systemic connects the heart to body systems (B) Signup and view all the answers

Which area is not supplied by systemic circulation?

The air sacs of the lungs (B) Signup and view all the answers

What can be inferred about the relationship between pulmonary and systemic circulation?

They function as interconnected loops for transporting blood (D) Signup and view all the answers

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Study Notes

The Heart

Located in the chest cavity, between the lungs; approximately 2/3 on the left side and 1/3 on the right side of the median plane.
Size is roughly equal to a closed man’s fist.
Shape resembles an inverted cone, with the base at the top and the apex situated at the 5th intercostal space along the mid-clavicular line (MCL).
Average weight in an adult male is about 300 grams, accounting for 0.5% of total body weight.

Heart Layers

Comprises three layers:
- Epicardium (outer layer)
- Myocardium (middle layer)
- Endocardium (inner layer)

Chambers of the Heart

Contains two superior chambers known as the atria:
- Right atrium (RA) and left atrium (LA) serve as blood reservoirs.
Atrial and ventricular contractile cells lack gap junctions, preventing electrical impulses from passing directly between them.
The atria and ventricles are physically separated by a fibrous skeleton, which is nonconductive and provides structural support for the valves.

Vessels and Circulation

Veins function as capacitance vessels, acting as reservoirs for blood.
Capillaries are classified as continuous, allowing only small molecules to pass through due to the absence of perforations.
The pulmonary circulation forms a closed loop, transporting blood between the heart and lungs.
The systemic circulation encompasses a network of vessels linking the heart to all body systems, excluding the air sacs of the lungs which are served by pulmonary circulation.