Which organ receives dual blood supply with both sources contributing to its primary metabolic function?
Where are the stretch receptors located in the left atrium?
Which part of the stomach is primarily responsible for receiving and storing ingested food?
Where do primitive red blood cells first originate during early embryonic development?
Intercalated disc is present in:
Blood testis barrier in testis is formed by?
B cells are located in which region of lymph nodes?
Elastic fibers of tunica media are secreted by
Base of sphenoid fuses with occiput at the age of -
Which of the following statements is true regarding an epidural hematoma?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 121: Which organ receives dual blood supply with both sources contributing to its primary metabolic function?
- A. Heart
- B. Liver (Correct Answer)
- C. Kidney
- D. Lung
Explanation: ***Liver*** - The liver receives blood from two sources: the **hepatic artery** (supplying oxygenated blood, ~25% of blood flow) and the **hepatic portal vein** (supplying nutrient-rich, deoxygenated blood from the gastrointestinal tract, ~75% of blood flow). - Both blood supplies are essential for the liver's primary metabolic functions, detoxification, and nutrient processing [1]. - This is the classic example of dual blood supply in medical education. *Heart* - The heart receives its blood supply primarily from the **coronary arteries**, which branch off the aorta. - While it has an extensive arterial network, it has a single primary source of blood supply. *Kidney* - The kidneys receive their blood supply exclusively from the **renal arteries**, which branch directly from the aorta. - Each kidney typically has a single renal artery supplying it for high-pressure filtration. *Lung* - The lungs do receive blood from two sources: **pulmonary arteries** (deoxygenated blood for gas exchange) and **bronchial arteries** (oxygenated blood for tissue nourishment, <5% of flow). - However, the primary function (gas exchange) is served by pulmonary circulation alone, while bronchial circulation only nourishes lung tissue. - The liver is the standard answer for dual blood supply where both sources serve the organ's primary function.
Question 122: Where are the stretch receptors located in the left atrium?
- A. None of the options
- B. Atrioventricular septum
- C. Septum between the atria
- D. Entrance of the pulmonary veins (Correct Answer)
Explanation: ***Entrance of the pulmonary veins*** - **Stretch receptors** are mechanoreceptors that detect changes in pressure and volume. In the left atrium, they are primarily located at the **junction of the pulmonary veins and the left atrium** [1]. - These receptors play a crucial role in the **Bainbridge reflex** and the release of **atrial natriuretic peptide (ANP)** in response to increased blood volume [1]. *Atrioventricular septum* - The **atrioventricular septum** separates the atria from the ventricles and primarily contains components of the **cardiac conduction system**, such as the AV node and bundle of His [2]. - While it has specialized tissues, it is not the primary location for **stretch receptors** involved in volume sensing. *Septum between the atria* - The **interatrial septum** primarily separates the right and left atria. - Although it contains some myocardial cells, it is not the main site for **stretch receptors** responsible for monitoring left atrial volume. *None of the options* - This option is incorrect because the **entrance of the pulmonary veins** is indeed the primary location for stretch receptors in the left atrium [1].
Question 123: Which part of the stomach is primarily responsible for receiving and storing ingested food?
- A. Antrum
- B. Pylorus
- C. Body (Correct Answer)
- D. Fundus
Explanation: ***Body*** - The **body (corpus)** is the largest part of the stomach, situated between the fundus and the antrum [1]. - This region is **primarily responsible for receiving and storing ingested food** as the main reservoir [2]. - It also produces **gastric acid and enzymes** (like pepsinogen) for the initial digestion of food [1]. - The body serves as the **principal storage chamber** where food accumulates after passing through the cardia [2]. *Fundus* - The **fundus** is the dome-shaped upper part of the stomach, located superior to the cardia. - While it can temporarily hold food and gas, it is **not the primary storage site** [2]. - Its main role is to serve as a **pressure buffer** and accumulation site for gases during digestion [2]. *Antrum* - The **antrum** is the lower, narrower part of the stomach, located before the pylorus. - It plays a crucial role in **mixing and grinding food with gastric juices** and propelling chyme towards the pylorus [1], [2]. - This is the **grinding chamber**, not a storage area [2]. *Pylorus* - The **pylorus** is the opening that connects the stomach to the duodenum, controlled by the pyloric sphincter. - Its main function is to **regulate the emptying of chyme** into the small intestine, not to store food [3].
Question 124: Where do primitive red blood cells first originate during early embryonic development?
- A. Liver
- B. Yolk sac (Correct Answer)
- C. Bone marrow
- D. Spleen
Explanation: ***Yolk sac*** - The **yolk sac** is the primary site of **hematopoiesis** during the first few weeks of embryonic development. - Primitive erythroid cells (red blood cells) originate here to supply the developing embryo with oxygen. *Liver* - The **liver** takes over as the main hematopoietic organ from about the 6th week of gestation, after the yolk sac [1]. - While it produces various blood cells, it is not the *first* site of primitive red blood cell formation. *Bone marrow* - **Bone marrow** becomes the primary site of hematopoiesis during the **fetal period** (around the 20th to 24th week) and continues throughout postnatal life [2]. - It is not involved in the initial production of primitive red blood cell formation in early embryogenesis. *Spleen* - The **spleen** plays a minor role in fetal hematopoiesis, mainly producing lymphoid cells and some myeloid cells, and can take on myeloid functions if the bone marrow is compromised. - It is not the initial site of red blood cell production in the early embryo.
Question 125: Intercalated disc is present in:
- A. Cardiac muscle (Correct Answer)
- B. Smooth muscle
- C. Skeletal muscle
- D. All of the options
Explanation: ***Cardiac muscle*** - **Intercalated discs** are unique structures found only in cardiac muscle, forming specialized cell-cell junctions [1]. - These discs contain **gap junctions** for electrical coupling and **desmosomes** for strong adhesion, allowing the heart muscle to contract in a coordinated fashion. *Smooth muscle* - **Smooth muscle cells** are spindle-shaped and lack striations and organized sarcomeres. - They do not possess intercalated discs; instead, communication and coordination are often mediated by **gap junctions** scattered along the cell membranes [2]. *Skeletal muscle* - **Skeletal muscle cells** are long, multinucleated, and highly organized with prominent striations [3]. - They do not have intercalated discs as individual muscle fibers are innervated separately and generally do not directly communicate via specialized junctions for coordinated contraction. *All of the options* - As **intercalated discs** are characteristic features *only* of **cardiac muscle**, this option is incorrect. - Their presence in all three muscle types would contradict the specific cellular organization of smooth and skeletal muscle.
Question 126: Blood testis barrier in testis is formed by?
- A. Germ cells
- B. Sertoli cells (Correct Answer)
- C. Leydig cells
- D. Granulosa cells
Explanation: ***Sertoli cells*** - **Sertoli cells** form tight junctions with each other, creating the **blood-testis barrier** [1] - This barrier divides the seminiferous epithelium into **basal and adluminal compartments** [1] - Essential for protecting developing **germ cells** from immune attack and maintaining a specialized microenvironment for **spermatogenesis** [1] - The tight junctions between Sertoli cells are among the tightest in the human body *Granulosa cells* - **Granulosa cells** are found in the **ovary**, not the testis - They surround the oocyte in ovarian follicles and produce **estrogen** - Completely unrelated to testicular structure or function *Germ cells* - **Germ cells** (spermatogonia, spermatocytes, spermatids, spermatozoa) are the developing sperm cells [1] - They are **protected by** the blood-testis barrier, not forming it [1] - Located within the seminiferous tubules but do not create barrier structures [1] *Leydig cells* - **Leydig cells** are interstitial cells located in the connective tissue **between seminiferous tubules** - Their primary function is production of **testosterone**, not forming barriers [2] - They are outside the seminiferous tubules and not involved in barrier formation [2]
Question 127: B cells are located in which region of lymph nodes?
- A. Paracortical region
- B. Cortical follicles (Correct Answer)
- C. Subcapsular region
- D. Medullary sinuses
Explanation: ***Cortical follicles*** - **B cells** are predominantly found within the **cortical follicles** of lymph nodes, where they mature and become activated upon encountering antigens [2]. - These follicles can be primary (inactive) or secondary (active, containing **germinal centers** for B cell proliferation and differentiation). *Paracortical region* - The **paracortical region** is primarily occupied by **T cells** and is the site where T cells interact with antigen-presenting cells [1]. - While it's adjacent to B cell areas, it's not the primary location for B cells. *Medullary sinuses* - **Medullary sinuses** are channels in the medulla of the lymph node, containing macrophages and plasma cells, which are *differentiated B cells*. - They are not the primary residence for undifferentiated B cells. *Subcapsular region* - **Subcapsular region** is the space immediately beneath the capsule of the lymph node where lymph initially enters. - It contains macrophages and dendritic cells that sample antigens but is not a primary B cell zone.
Question 128: Elastic fibers of tunica media are secreted by
- A. Endothelium
- B. Smooth muscle (Correct Answer)
- C. External lamina
- D. Fibroblast
Explanation: Correct: Smooth muscle - Smooth muscle cells within the tunica media are primarily responsible for synthesizing and secreting elastic fibers along with collagen and proteoglycans [1] - This extracellular matrix provides elasticity and structural integrity to blood vessels, allowing them to stretch and recoil with blood flow [1] - In elastic arteries (like the aorta), smooth muscle cells produce fenestrated elastic membranes that are characteristic of the tunica media Incorrect: Endothelium - Endothelial cells form the innermost lining of blood vessels (tunica intima) and are involved in regulating vascular tone, blood clotting, and inflammation [1] - They do not typically secrete the bulk of elastic fibers found in the tunica media Incorrect: External lamina - The external lamina (or external basal lamina) is an extracellular matrix layer, not a cellular component that secretes elastic fibers - It is actually secreted by the smooth muscle cells themselves and serves as structural support around individual muscle cells Incorrect: Fibroblast - Fibroblasts are connective tissue cells that primarily produce collagen and other extracellular matrix components in many tissues - While they contribute to the tunica adventitia (outermost layer), the tunica media's elastic fibers are primarily produced by smooth muscle cells [1]
Question 129: Base of sphenoid fuses with occiput at the age of -
- A. 20 years (Correct Answer)
- B. 30 years
- C. 40 years
- D. 50 years
Explanation: ***20 years*** - The **spheno-occipital synchondrosis** typically fuses by the age of **20 to 25 years**, marking the cessation of growth in the cranial base. - This fusion is an important indicator of skeletal maturity and is often used in **forensic anthropology** for age estimation. *30 years* - Fusion of the **spheno-occipital synchondrosis** beyond the early twenties is considered late and is not the typical age for this event. - By 30 years, most cranial sutures and synchondroses are already fused. *40 years* - At 40 years of age, the **spheno-occipital synchondrosis** would have been completely fused for many years, making this an incorrect age for the fusion process itself. - This age is well past the usual developmental timeframe for cranial base closure. *50 years* - Fusion at 50 years would be an **anomalous finding** as this synchondrosis is known to fuse much earlier in life. - By this age, the skull is fully mature, and fusion events of this nature have long since completed.
Question 130: Which of the following statements is true regarding an epidural hematoma?
- A. Inside the brain
- B. Between skull and dura mater (Correct Answer)
- C. Between skull and outermost periosteal layer
- D. Between scalp and outer skull layer
Explanation: ***Between skull and dura mater*** - An **epidural (extradural) hematoma** occurs when bleeding accumulates in the **potential space between the skull and the dura mater** [1]. - More precisely, it forms between the **periosteal layer of dura** (adherent to skull) and the **meningeal layer of dura**, stripping the dura away from the skull. - This typically results from a tear in the **middle meningeal artery** following traumatic head injury, classically from a **temporal bone fracture**. - Classic presentation: **lucid interval** followed by deterioration with **biconvex (lentiform) appearance** on CT scan [1]. *Inside the brain* - Bleeding *inside the brain parenchyma* itself is an **intracerebral hemorrhage**, not an epidural hematoma. - Caused by hypertension, trauma, vascular malformations, or hemorrhagic stroke. - CT shows intraparenchymal blood collection, not extra-axial. *Between skull and outermost periosteal layer* - This is anatomically **not a potential space** since the periosteal layer of dura is **firmly adherent** to the inner table of the skull. - An epidural hematoma actually strips this periosteal layer *away* from the skull, creating the space. - This option is incorrectly phrased and anatomically impossible as stated. *Between scalp and outer skull layer* - Bleeding *between the scalp and outer skull surface* is a **subgaleal hematoma** (crosses suture lines) or **cephalhematoma** in neonates (limited by suture lines). - These are **extracranial** collections, superficial to the skull bones. - Completely different from an **intracranial** epidural hematoma.