30 Questions
What is the main function of desmosomes in cardiac muscle cells?
To anchor cardiac muscle cells together mechanically
How do gap junctions in cardiac muscle cells contribute to synchronous contraction?
By providing a low-resistance pathway for ion flow
What is the structural feature unique to cardiac muscle cells' intercalated discs?
Desmosomes
What happens when an action potential moves continuously along the sarcolemma of cardiac muscle cells?
Synchronous contraction occurs
Why are cardiac muscle cells described as forming a functional syncytium?
Due to fusion of cells into a multinucleated mass
What is the role of protein pores in cardiac muscle cells?
To allow the flow of ions between adjacent cells
What is the main function of the fibrous skeleton in the heart?
Provide electrical insulation
How are cardiac muscle cells arranged in relation to the fibrous skeleton?
In spiral bundles around heart chambers
What happens when the atria contract?
The wall of the chambers is compressed inward
How is the contraction pattern of the ventricles likened to?
Wringing of a mop
Which part of the heart receives blood first when the ventricles contract?
Arterial trunks
Why is it significant that cardiac muscle cells are arranged in spiral bundles around the heart chambers?
To allow for compression of chamber walls during contraction
What is the main energy source for cardiac muscle?
Fatty acids
Which protein in cardiac muscle binds oxygen when the muscle is at rest?
Myoglobin
What does creatine kinase catalyze in cardiac muscle?
Transfer of Pi from creatine phosphate to ADP
Why does cardiac muscle have numerous mitochondria?
To meet the high demand for energy production
What percentage of cardiac muscle cell volume is comprised of mitochondria?
25%
Which molecule can cardiac muscle cells use as a fuel source?
Ketone bodies
What is the purpose of the pericardium surrounding the heart?
To provide a protective layer around the heart
What is the function of the parietal layer of the serous pericardium?
It adheres to the inner surface of the fibrous pericardium
Which layer of the pericardium is attached to the diaphragm and arterial trunks?
The fibrous pericardium
What is the relationship between the two serosal layers of the pericardium?
They are continuous with one another near the great vessels of the heart
What is the purpose of the potential space called the pericardial cavity?
To allow the heart to move freely within the thoracic cavity
Which layer of the pericardium directly adheres to the heart?
The visceral layer of the serous pericardium
What is the function of the pectinate muscles in the right atrium?
To aid in blood flow from the right atrium to the right ventricle
What is the purpose of the fossa ovalis in the adult human heart?
It is a remnant of the fetal foramen ovale, which is no longer functional
Which of the following vessels drains deoxygenated blood into the right atrium?
Coronary sinus
What is the function of the right atrioventricular opening?
To allow blood to flow from the right atrium to the right ventricle
Which of the following statements about the fetal foramen ovale is true?
It allowed oxygenated blood to bypass the lungs during fetal life
Which of the following vessels is not directly connected to the right atrium?
Pulmonary artery
Study Notes
Heart Location and Pericardium
- The heart is located within the mediastinum of the thoracic cavity between the lungs.
- The heart is enclosed in three layers, collectively called the pericardium.
- The pericardium consists of: • Fibrous pericardium (outer layer): dense irregular connective tissue that encloses the heart but does not attach to it. • Parietal layer of the serous pericardium (middle layer): simple squamous epithelium and an underlying delicate layer of areolar connective tissue; adheres to the inner surface of the fibrous pericardium. • Visceral layer of the serous pericardium (inner layer): also composed of simple squamous epithelium and an underlying delicate layer of areolar connective tissue; adheres directly to the heart, forming the visceral pericardium (or epicardium).
Cardiac Muscle and Energy Needs
- Cardiac muscle has features that support its great demand for energy, including: • Extensive blood supply • Numerous mitochondria • Myoglobin (globular protein that binds oxygen) • Creatine kinase (catalyzes the transfer of Pi from creatine phosphate to ADP, yielding ATP and creatine)
- Cardiac muscle relies almost exclusively on aerobic cellular respiration.
- Cellular structures and metabolic processes support this, including: • Large number of mitochondria (approximately 25% of cardiac muscle cell volume) • Ability to use different types of fuel molecules (fatty acids, glucose, lactate, amino acids, and ketone bodies)
Heart Chambers and Blood Circulation
- The four heart chambers are involved in the continuous process of blood circulation.
- The right atrium: • Has a smooth posterior surface and muscular ridges (pectinate muscles) on its anterior wall and within the auricle. • Has an oval depression called the fossa ovalis, which occupies the former location of the fetal foramen ovale. • Receives deoxygenated blood from the coronary sinus, superior vena cava, and inferior vena cava.
- The right atrioventricular opening contains the right AV valve, allowing deoxygenated blood to flow into the right ventricle.
Cardiac Muscle Cells and Intercalated Discs
- Cardiac muscle cells are unique in having intercalated discs, which link cells together mechanically and electrically.
- Intercalated discs contain: • Desmosomes (protein filaments that anchor into a protein plaque located on the internal surface of the sarcolemma) • Gap junctions (protein pores between the sarcolemma of adjacent cardiac muscle cells)
- Gap junctions allow for the flow of ions between cardiac cells, resulting in synchronous contraction of the chamber.
Fibrous Skeleton
- The fibrous skeleton is composed of dense irregular connective tissue that provides both mechanical support and electrical insulation within the heart.
- Cardiac muscle cells are arranged in spiral bundles around the heart chambers, attached to the fibrous skeleton.
- When the atria contract, they compress the wall of the chambers inward, moving blood inferiorly into the ventricles.
Learn about the location of the heart within the mediastinum of the thoracic cavity and its relationship to other organs, as well as the layers of the pericardium. This quiz covers anatomical details of the heart and great vessels.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
