Microscopic Anatomy — MCQs
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Which of the following statements about diploic veins is false?
Respiratory bronchioles proceed into
Which of the following is a feature of the Y chromosome?
Where are the mitochondria of a sperm located?
Blister formation in a burn case occurs in which layer?
Where is the organ of Corti located within the cochlea?
Microscopic Anatomy Indian Medical PG Practice Questions and MCQs
Question 241: Which of the following statements about diploic veins is false?
- A. Present in cranial bones
- B. These have no valves
- C. Have a thin wall lined by single layer of endothelium
- D. Contain valves like other peripheral veins (Correct Answer)
Explanation: ***Contain valves like other peripheral veins*** - This statement is **false**. Diploic veins are notable for their **lack of valves**, which is a crucial anatomical feature distinguishing them from typical peripheral veins that contain valves to prevent backflow. - Their valveless nature allows for pressure equalization between intracranial and extracranial venous systems. *These have no valves* - This statement is **true** about diploic veins. They are unique in that they **lack valves**, which facilitates bidirectional blood flow. - The absence of valves is a key characteristic that distinguishes diploic veins from most peripheral veins. *Present in cranial bones* - This statement is **true**. Diploic veins are specifically located within the **cancellous bone** (diploë) of the cranial vault. - They connect the meningeal veins, dural venous sinuses, and veins of the scalp. *Have a thin wall lined by single layer of endothelium* - This statement is **true**. Diploic veins, like most veins, have relatively **thin walls** compared to arteries [1]. - Their inner lining is composed of a single layer of **endothelial cells**, which is characteristic of the vascular system [1].
Question 242: Respiratory bronchioles proceed into
- A. Terminal bronchiole
- B. Bronchi
- C. Tertiary bronchiole
- D. Alveolar duct (Correct Answer)
Explanation: ***Alveolar duct*** - **Respiratory bronchioles** are the first part of the respiratory tree that contain scattered **alveoli**, allowing for some gas exchange [1]. - They branch into **alveolar ducts**, which are entirely lined with alveoli, leading directly to alveolar sacs [2]. *Terminal bronchiole* - **Terminal bronchioles** are located *before* respiratory bronchioles in the bronchial tree [1]. - They are the smallest bronchioles involved solely in **conduction**, without any gas exchange [3]. *Bronchi* - **Bronchi** are much larger airways, typically containing cartilage, and are located much earlier in the respiratory tree, before the **bronchioles** [1]. - They are responsible for **conducting air** to the smaller airways and do not lead directly from respiratory bronchioles. *Tertiary bronchiole* - The term **tertiary bronchiole** is not standard anatomical terminology in the respiratory system. - Bronchi typically branch into **lobar (secondary) bronchi** and then **segmental (tertiary) bronchi**, which are still much larger and earlier in the conducting system than bronchioles.
Question 243: Which of the following is a feature of the Y chromosome?
- A. Acrocentric (Correct Answer)
- B. Telocentric
- C. Metacentric
- D. Submetacentric
Explanation: Acrocentric - An **acrocentric chromosome** has its **centromere** located very near one end, leading to a very short arm and a long arm. - The **Y chromosome** in humans is classified as acrocentric due to the position of its centromere. *Telocentric* - A **telocentric chromosome** has its **centromere** at the very tip, meaning it only has one arm. - **Human chromosomes** do not typically include telocentric chromosomes. *Metacentric* - A **metacentric chromosome** has its **centromere** located in the middle, resulting in arms of approximately equal length. - Examples include human chromosomes 1, 3, 16, 19, and 20, but not the Y chromosome. *Submetacentric* - A **submetacentric chromosome** has its **centromere** slightly off-center, producing one arm that is noticeably shorter than the other. - Examples include human chromosomes 2, 4-12, 17, 18, and X, but not the Y chromosome.
Question 244: Where are the mitochondria of a sperm located?
- A. Head
- B. Neck
- C. Body (Correct Answer)
- D. Tail
Explanation: ***Body*** - The **midpiece** (or body) of the sperm is rich in **mitochondria**, which are essential for producing the **ATP** required for flagellar movement [1]. - This anatomical arrangement ensures a continuous energy supply for the sperm's journey towards the egg. *Head* - The sperm **head** contains the **nucleus**, which carries the paternal genetic material, and the **acrosome**, an enzyme-filled cap vital for fertilization [1]. - It lacks significant mitochondrial presence, as its primary role is genetic delivery and penetration. *Neck* - The **neck** is a short, constricted region connecting the head to the body of the sperm. - It contains the **centrioles**, which are involved in early embryonic development, but not the primary site for mitochondria. *Tail* - The sperm **tail** (flagellum) is primarily composed of the **axoneme**, a microtubule structure responsible for propulsion. - While it facilitates movement, the crucial energy production for this movement comes from the mitochondria located in the midpiece [1].
Question 245: Blister formation in a burn case occurs in which layer?
- A. Subepidermal (Correct Answer)
- B. Subdermal
- C. Subfascial
- D. Intraepidermal
Explanation: ***Subepidermal*** - Blister formation in burns commonly occurs in the **subepidermal space**, where the epidermis separates from the dermis due to fluid accumulation. - This separation is characteristic of **partial-thickness (second-degree)** burns, where the epidermis is damaged but the underlying dermis remains viable [1]. *Intraepidermal* - **Intraepidermal blisters** involve separation within the epidermal layer itself, often seen in conditions like **pemphigus vulgaris** [2] or certain drug reactions. - While fluid accumulates in the epidermis, the characteristic large blisters of burns typically form at the dermal-epidermal junction. *Subdermal* - **Subdermal** refers to the layer beneath the dermis, also known as the **subcutaneous tissue** or hypodermis. - Blister formation in this layer is not characteristic of typical burn blisters; rather, severe burns can lead to damage to subcutaneous tissue, but not typically a discrete blister cavity at this depth. *Subfascial* - **Subfascial** refers to the space beneath the fascia, which is a connective tissue layer covering muscles. - Burns that reach this depth are **full-thickness (third-degree)** [1] or even **fourth-degree burns**, where tissue destruction is extensive and blister formation is not the primary feature due to complete necrosis of the epidermal and dermal layers.
Question 246: Where is the organ of Corti located within the cochlea?
- A. Basilar membrane (Correct Answer)
- B. Utricle
- C. Saccule
- D. Reissner's membrane
Explanation: ***Basilar membrane*** - The **organ of Corti** is the sensory organ of hearing, and it sits directly on the **basilar membrane** within the cochlea [2]. - The vibratory movements of the basilar membrane, induced by sound waves, stimulate the **hair cells** of the organ of Corti [2], [4]. - This membrane separates the scala media from the scala tympani and is critical for the transduction of mechanical vibrations into neural signals. *Utricle* - The **utricle** is part of the **vestibular system** and is located in the **membranous labyrinth** of the inner ear [1], [3]. - Its primary function is to detect **linear acceleration** and **head tilts** in the horizontal plane, contributing to balance, not hearing [1], [3]. *Saccule* - The **saccule** is also a component of the **vestibular system**, similar to the utricle [1], [3]. - It specifically detects **linear acceleration** and **head tilts** in the vertical plane, contributing to balance rather than auditory perception [3]. *Reissner's membrane* - **Reissner's membrane** (vestibular membrane) separates the **scala vestibuli** from the **scala media** in the cochlea [2]. - While it is part of the cochlear structure, the organ of Corti is located on the basilar membrane, not Reissner's membrane.
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