NEET-PG 2015 - Anatomy Practice Questions

Q: Which of the following is not a derivative of foregut?

Cecum. ***Cecum*** - The **cecum** and the entire large intestine (except the distal third of the transverse colon) are derivatives of the **midgut** [1]. - The midgut is supplied by the **superior mesenteric artery**, differentiating it developmentally from the foregut. *First part of the duodenum* - The **first part of the duodenum** (from the pylorus to the major duodenal papilla) is derived from the **foregut**. - This section receives its blood supply from branches of the **celiac trunk**, consistent with its foregut origin. *Liver* - The **liver** develops as a budding from the distal foregut and is therefore a **foregut derivative** [2]. - It plays a crucial role in metabolism and detoxification, consistent with its early development from this segment. *Pancreas* - The **pancreas** develops from dorsal and ventral buds of the distal foregut, making it a **foregut derivative**. - Both its exocrine and endocrine functions are vital for digestion and glucose homeostasis.

Q: Which Brodmann's area is primarily associated with motor speech?

Area 44. Area 44 - **Brodmann Area 44** is primarily known as **Broca's area**, which is critical for **motor speech production** and language processing [1]. - Damage to this area typically results in **Broca's aphasia**, characterized by non-fluent speech and difficulty forming complete sentences [1]. Area 1, 2, 3 - These Brodmann areas constitute the **primary somatosensory cortex**, responsible for processing **tactile and proprioceptive information** from the body. - They are involved in sensory perception, not directly with motor speech production. Area 4, 6 - **Brodmann Area 4** is the **primary motor cortex**, involved in executing voluntary movements [2]. **Brodmann Area 6** is the **premotor and supplementary motor cortex**, involved in planning and coordinating movements [2]. - While these areas are crucial for motor control, they are not specifically associated as the primary center for motor speech in the same way Broca's area is. Area 40 - **Brodmann Area 40**, also known as the **supramarginal gyrus**, is part of the **parietal lobe** and is involved in phonological processing, language perception, and spatial cognition. - While it plays a role in language, it is not the primary area for motor speech production.

Q: In the context of blood pressure regulation, where are baroreceptors primarily located?

Tunica adventitia. ***Tunica adventitia*** - **Baroreceptors** are specialized mechanoreceptive nerve endings that detect changes in blood pressure by sensing arterial wall stretch. - These sensory nerve endings are primarily located in the **tunica adventitia** (outermost layer) of the **carotid sinus** and **aortic arch** [1]. - The adventitia contains the **nerve fibers and endings** (including baroreceptors), as well as the vasa vasorum and connective tissue supporting the vessel wall [1]. - The nerve terminals extend from the adventitia toward the adventitial-medial border where they sense wall tension changes. *Tunica media* - The **tunica media** is the middle layer composed of **smooth muscle cells** and elastic fibers. - While this layer responds to stretch and changes thickness with blood pressure variations, it does **not contain nerve endings or baroreceptors** [1]. - The media is responsible for vasoconstriction and vasodilation but lacks the sensory innervation needed for baroreception. *Tunica intima* - The **tunica intima** is the innermost layer lined by **endothelial cells**. - Its primary functions include providing a smooth surface for blood flow and regulating vascular permeability. - This layer does not house baroreceptors or other mechanoreceptive nerve endings. *None of the options* - This option is incorrect because **tunica adventitia** is indeed the correct location of baroreceptors. - The adventitia contains the neural elements necessary for blood pressure sensing in these specialized arterial regions [1].

Q: Which organ receives dual blood supply with both sources contributing to its primary metabolic function?

Liver. ***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.

Q: Where are the stretch receptors located in the left atrium?

Entrance of the pulmonary veins. ***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].

Q: Which part of the stomach is primarily responsible for receiving and storing ingested food?

Body. ***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].

Q: Elastic fibers of tunica media are secreted by

Smooth muscle. 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]

Q: Where do primitive red blood cells first originate during early embryonic development?

Yolk sac. ***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.

Q: Intercalated disc is present in:

Cardiac muscle. ***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.

Q: Blood testis barrier in testis is formed by?

Sertoli cells. ***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 1

Which of the following is not a derivative of foregut?

Accepted Answer

Cecum

Answer

Liver

Answer

Pancreas

Answer

First part of the duodenum

Question 2

Which Brodmann's area is primarily associated with motor speech?

Accepted Answer

Area 44

Answer

Area 1, 2, 3

Answer

Area 4, 6

Answer

Area 40

Question 3

In the context of blood pressure regulation, where are baroreceptors primarily located?

Accepted Answer

Tunica adventitia

Answer

Tunica intima

Answer

None of the options

Answer

Tunica media

Question 4

Which organ receives dual blood supply with both sources contributing to its primary metabolic function?

Accepted Answer

Liver

Answer

Heart

Answer

Kidney

Answer

Lung

Question 5

Where are the stretch receptors located in the left atrium?

Accepted Answer

Entrance of the pulmonary veins

Answer

None of the options

Answer

Atrioventricular septum

Answer

Septum between the atria

Question 6

Which part of the stomach is primarily responsible for receiving and storing ingested food?

Accepted Answer

Body

Answer

Antrum

Answer

Pylorus

Answer

Fundus

Question 7

Elastic fibers of tunica media are secreted by

Accepted Answer

Smooth muscle

Answer

Endothelium

Answer

External lamina

Answer

Fibroblast

Question 8

Where do primitive red blood cells first originate during early embryonic development?

Accepted Answer

Yolk sac

Answer

Liver

Answer

Bone marrow

Answer

Spleen

Question 9

Intercalated disc is present in:

Accepted Answer

Cardiac muscle

Answer

Smooth muscle

Answer

Skeletal muscle

Answer

All of the options

Question 10

Blood testis barrier in testis is formed by?

Accepted Answer

Sertoli cells

Answer

Germ cells

Answer

Leydig cells

Answer

Granulosa cells

NEET-PG 2015 — Anatomy