System Physiology Animal MCQ Quiz in తెలుగు - Objective Question with Answer for System Physiology Animal - ముఫ్త్ [PDF] డౌన్‌లోడ్ కరెన్

The correct answer is Option 4 i.e. H+ secretion

Key Points

• Selective reabsorption is the process where useful substances are reabsorbed from the glomerulus filtrate and transferred to the blood capillaries.
• Selective reabsorption occurs throughout the renal tubules through active as well as passive reabsorption.
• Important substances are reabsorbed actively while water is reabsorbed passively.

1. Reabsorption in PCT:
   • PCT is lined by columnar cells that have multiple finger-like projections called microvilli to increase the surface area of reabsorption.
   • here active reabsorption of amino acids, glucose and vitamins takes place.
   • It also reabsorbs most of Ca²⁺, it also reabsorb K⁺, Na⁺, Cl^-.
   • 75% of water reabsorb is absorbed passively and the filtrate becomes hypertonic.
2. Reabsorption in descending limb of Henle's loop: 
   • About 5% of the water is reabsorbed.
   • Na+, other salts and urea is reabsorbed actively.
3. Reabsorption in ascending limb of Henle's loop:
   • Reabsorption of K⁺ and Na⁺ takes place actively 
   • Cl^- is reabsorbed passively or by diffusion
   • This region is impermeable to water and filtrate becomes hypotonic.
4. Reabsorption of DCT and collecting duct
   • In DCT and collection duct, Na+ is absorbed actively while Cl^- is absorbed passively.
   • Na+ is reabsorbed in exchange for some K⁺ ions.
   • Reabsorption of water is dependent on the secretion and concentration of ADH. 
   • It maintains the pH and homeostasis. 
   • At the end of this hypertonic urine is secreted.

Explanation:

• Principle cells or P-cells are present in the collecting duct of the kidney. 
• They play a central role in the salt and water transport through their three main transporters - epithelial Na+ channel (ENaC), the renal outer medullary K+ channel(ROMK), and the aquaporin 2 (AQP2) water channel. 
• Reabsorption of Na⁺ by ENaC is balanced by the secretion of K⁺ by ROMK.
• Here, the secretion or absorption of H⁺ does not occur. 

Hence, the correct answer is Option 4.

The correct answer is Option 2 i.e. follicle-stimulating hormone

Key Points

• A protein called inhibin is secreted by the granulosa cells in women and the Sertoli cells in males.
• It decreases the amount of LH-releasing hormone in the hypothalamus and prevents the pituitary organ from producing and releasing follicle-stimulating hormone.
• Additionally, it prevents the ovaries from producing progesterone and the male gonads' ability to multiply spermatogonia.
• Understanding the pathophysiology of puberty, ovulation, menopause, and different kinds of infertility may be aided by inhibin measurements in biological fluids.

Explanation:

Option 1: Luteinizing hormone

• Inhibin B does not inhibit luteinizing hormone (LH).
• LH is another hormone secreted by the pituitary gland that plays an important role in regulating the reproductive system.
• In males, LH stimulates the production of testosterone by the Leydig cells in the testes, while in females, it triggers ovulation and the formation of the corpus luteum. 

• Inhibin B inhibits follicle-stimulating hormone (FSH) secretion.
• FSH is a hormone secreted by the pituitary gland that stimulates the growth and maturation of follicles in the ovaries and seminiferous tubules in the testes.
• Inhibin B is produced by the granulosa cells in the ovaries and Sertoli cells in the testes.
• It acts as a negative feedback signal to the pituitary gland, inhibiting the secretion of FSH.
• This helps to regulate the growth and maturation of follicles and spermatogenesis.

• Inhibin B does not inhibit prolactin secretion.
• Prolactin is a hormone secreted by the pituitary gland that plays a role in lactation and breast development. 

• Inhibin B does not inhibit thyroid-stimulating hormone (TSH) secretion.
• TSH is a hormone secreted by the pituitary gland that stimulates the thyroid gland to produce and release thyroid hormones. 

Therefore, the correct answer is Option 2.

The correct answer is not show peak D and may not show C, but would show A and B.

Concept:

• Electrical stimulation of a region of the nervous system generates nerve impulses in centers receiving input from the site of stimulation.
• This method, using microelectrodes, has been widely used in animal studies; however, the precise path followed by the artificially generated impulse may be difficult to establish.
• Electrical and optical measurements of the nerve impulse for different stimulation voltages.
• The optical measurements were done in the pulsed mode using 1000 averages.
• The figures show the signals in time, the square-root of the power spectral density PSD and the 400 Hz frequency component.

​Fig 1: Optical measurement of nerve impulse

Fig 2: Action potential

• In addition to changes in the frequency of activity, nerve terminal impulse shape also changed with heating and cooling.
• At the same ambient temperature, nerve terminal impulses were larger in amplitude and faster in time course during heating than those recorded during cooling.
• Since the ion channels take time to open to allow the ions to travel across the membrane, cooling a neuron causes the ion channels to open more slowly, causing a reduction in the speed of the action potential as it travels down the axon.

Explanation:

• Lower temperatures generally slow down physiological processes, including the propagation of action potentials along nerve fibers.
• The peaks A, B, C, and D in the diagram likely represent action potentials or similar electrical activities arriving at the recording site at different times, which could be due to different conduction velocities in different fibers within the nerve bundle.
• At a lower temperature, the conduction velocity would decrease, particularly affecting the fibers that transmit signals for peaks C and D, which are later peaks and might represent fibers with inherently slower conduction velocities or longer pathways.
• Peaks A and B, arriving earlier, likely represent faster-conducting fibers that would still be able to transmit their signals at a reduced temperature, although possibly with some delay or reduction in amplitude.

​Hence the correct answer is Option 3

Explanation:

• Hematopoiesis is the process of blood cell formation and development in humans, which occurs primarily in the bone marrow.
• Bone marrow stem cells differentiate into various types of blood cells, including red blood cells (RBCs), white blood cells (WBCs), and platelets, as well as other specialized cells.
• In adults, hematopoiesis is restricted to specific bones (e.g., pelvis, vertebrae, ribs, and sternum) and not all bones actively contribute to blood cell production.

Statement A: "Bone marrow stem cells are not the source of osteoclasts and mast cells."

• This statement is incorrect. Bone marrow stem cells (specifically, hematopoietic stem cells) are indeed the source of mast cells and osteoclasts.
• Osteoclasts are derived from hematopoietic stem cells through a monocyte/macrophage lineage, and mast cells are also derived from hematopoietic progenitor cells.

Statement B: "Normally, three-fourths of the cells in the marrow cavities mature to white blood cells and one-fourth to red blood cells."

• This statement is correct. The bone marrow produces a higher proportion of white blood cells compared to red blood cells, as WBCs have a shorter lifespan and need to be replaced more frequently.
• RBCs, on the other hand, have a longer lifespan (approximately 120 days) and are produced in relatively smaller proportions in steady-state hematopoiesis.

Statement C: "In adults, blood cells are not actively produced in the marrow cavities of all the bones."

• This statement is correct. In adults, active hematopoiesis is restricted to specific bones such as the pelvis, vertebrae, ribs, sternum, and proximal ends of the femur and humerus.
• In contrast, during infancy and early childhood, most bones contain active red marrow, but this activity diminishes with age as the red marrow is replaced by yellow marrow in many bones.

Statement D: "Hematopoietic stem cells are derived from committed cells."

• This statement is incorrect. Hematopoietic stem cells (HSCs) are primitive, multipotent cells and are not derived from committed cells. Instead, HSCs give rise to committed progenitor cells that further differentiate into specific blood cell lineages.
• Committed cells, such as common myeloid progenitors or common lymphoid progenitors, are downstream of HSCs in the hematopoietic hierarchy.

The correct answer is Helicobacter pylori 

Explanation:

• Caenorhabditis elegans (1): This is a model organism (a nematode) commonly used in biological research, but it does not express urease enzyme.
• Drosophila melanogaster (2): Commonly known as the fruit fly, it is also widely used in genetic research, but it does not produce urease.
• Helicobacter pylori (3): This is a type of bacteria that colonizes the stomach lining and produces urease. The enzyme helps neutralize stomach acid by converting urea into ammonia, creating a more hospitable environment for the bacteria, which can lead to gastric ulcers and other gastrointestinal issues. Urease plays a crucial role in the survival of H. pylori in the acidic environment of the stomach. By generating ammonia, it helps create a more alkaline microenvironment around the bacteria, allowing it to thrive and contribute to conditions such as peptic ulcers and gastritis
• Homo sapiens (4): Humans do not produce urease as a functional enzyme. Instead, urea is processed primarily in the liver and excreted in urine.

The correct answer is B and C

Explanation:

The axon hillock is a specialized part of the neuron, located at the junction of the axon and the cell body (soma). This region plays a critical role in the initiation of action potentials due to several reasons:

• High Density of Voltage-Gated Sodium Channels: The axon hillock has a significantly higher density of voltage-gated sodium (Na⁺) channels compared to other parts of the neuron. These channels are sensitive to changes in the membrane potential. When the membrane potential reaches a certain threshold, these channels open rapidly, allowing a large influx of Na⁺ ions into the neuron. This influx causes the membrane potential to become more positive, a process known as depolarization.
• Threshold Potential: The concentration of Na⁺ channels at the axon hillock lowers the threshold potential required to trigger an action potential. This means that it is easier for the axon hillock to reach the critical membrane potential necessary to start an action potential compared to other parts of the neuron.

Propagation of Action Potential:
Once an action potential is initiated at the axon hillock, it propagates along the axon to the axon terminals. This propagation is characterized by the following features:

• Unidirectional Propagation: Action potentials typically move from the axon hillock towards the axon terminals and not in the reverse direction. This unidirectional flow is ensured by the refractory period, which is the period immediately following the action potential during which the neuron is unable to fire another action potential.
• Refractory Period:

1. Absolute Refractory Period: During this phase, the Na⁺ channels that just opened to initiate the action potential become inactivated. Even if the membrane potential reaches the threshold again, these channels cannot reopen immediately. This prevents the backward propagation of the action potential.
2. Relative Refractory Period: This follows the absolute refractory period. During this phase, a higher-than-normal stimulus is required to initiate another action potential because some Na⁺ channels are still in the process of recovering from inactivation and the membrane is partially repolarized.

The mechanisms of action potential initiation and propagation are crucial for the rapid transmission of electrical signals over long distances in the body. This rapid signaling is essential for the coordination of complex processes such as reflexes, motor actions, sensory perceptions, and cognitive functions.

Conclusion:

Therefore, the correct answer is Option 2

The correct answer is Option 3 i.e. The plasma oxygen tension reaches equilibrium with the oxygen tension of air.

Explanation:

The process of gas exchange in the lungs is governed by the principles of diffusion, where molecules move from an area of higher concentration to an area of lower concentration until equilibrium is reached. This principle explains why the air in our lungs never becomes fully deoxygenated and why the oxygen pressure doesn't drop much below 100 mmHg, despite oxygen being continuously absorbed into the blood and carbon dioxide being released from it.

The plasma oxygen tension reaches equilibrium with the oxygen tension of air," is the correct explanation because:

• Diffusion and Partial Pressure: In the alveoli (the tiny air sacs in the lungs where gas exchange occurs), oxygen diffuses from the air into the blood because the partial pressure of oxygen in the alveolar air is higher than the partial pressure of oxygen in the deoxygenated blood coming from the body. Similarly, carbon dioxide diffuses from the blood (where its partial pressure is higher) into the alveolar air (where its partial pressure is lower).
• Equilibrium: The process of oxygen entering the blood continues until the partial pressure of oxygen in the blood is roughly equal to the partial pressure of oxygen in the alveolar air. At this point, an equilibrium is reached, and the net diffusion of oxygen into the blood slows down significantly. This equilibrium prevents the complete deoxygenation of the air in the lungs, and it is established at a partial pressure of oxygen in the alveolar air that is around 100 mmHg.
• Hemoglobin Saturation: Additionally, the binding of oxygen to hemoglobin in red blood cells is not linear but follows a sigmoidal curve known as the oxygen-hemoglobin dissociation curve. At the high partial pressures of oxygen present in the lungs (around 100 mmHg), hemoglobin is nearly saturated with oxygen (about 97-98% saturation). This saturation level means that hemoglobin's ability to bind additional oxygen molecules is quite limited, further contributing to the difficulty of extracting all the oxygen from the alveolar air.
• Constant Renewal of Alveolar Air: The process of breathing continually replenishes the oxygen in the alveoli and removes carbon dioxide, helping to maintain the partial pressures of these gases in the alveolar air and preventing the air from becoming fully deoxygenated.

Therefore, the reason the blood cannot extract all the oxygen from the lungs, leading to an oxygen pressure that doesn't drop much below 100 mmHg, is due to the equilibrium reached between the oxygen tension in the plasma and the oxygen tension of the air in the alveoli. This equilibrium is fundamental to the efficient exchange of gases and the constant supply of oxygen needed for the body's metabolic processes.

The correct answer is Option 3 i.e.A - ii; B - iii; C - i

Explanation-

• Aldosterone is a steroid hormone that plays a crucial role in the regulation of electrolyte and fluid balance in the body. It is synthesized in the adrenal glands, specifically in the outermost layer of the adrenal cortex called the zona glomerulosa.
• The synthesis of aldosterone involves several enzymatic steps within the adrenal cortex. The key steps in aldosterone synthesis include the conversion of cholesterol to aldosterone through a series of enzymatic reactions.
• Cholesterol Uptake: Cholesterol is taken up by the zona glomerulosa cells.
• Conversion to Pregnenolone: Cholesterol is converted to pregnenolone through a series of enzymatic reactions, with the rate-limiting step often involving the enzyme CYP11A1 (also known as P450scc).
• Conversion to Aldosterone: Pregnenolone is further metabolized to aldosterone through several intermediate steps, involving enzymes such as 3-beta-hydroxysteroid dehydrogenase (3β-HSD), 21-hydroxylase (CYP21A2), and aldosterone synthase (CYP11B2).
• The intracellular locations of these enzymatic reactions take place within the mitochondria and endoplasmic reticulum of the zona glomerulosa cells. These organelles provide the necessary machinery for the synthesis of steroid hormones.

Concept:

• The adrenal glands are small, triangular-shaped glands located on top of each kidney.
• Each adrenal gland is structurally and functionally divided into two main parts: the adrenal cortex (outer part) and the adrenal medulla (inner part).
• The adrenal cortex itself is organized into three distinct zones, each responsible for the production of different hormones:

• This is the outermost layer, which produces mineralocorticoids like aldosterone. It regulates electrolyte balance and blood volume.

Zona fasciculata:

• The zona fasciculata is in the middle and is the thickest of the three zones.
• This is the region of the adrenal cortex that secretes glucocorticoids, such as cortisol. Glucocorticoids are steroid hormones that regulate a wide array of functions in the body, including metabolism, inflammatory response, immune function, and the body's response to stress.
• In response to stress, the hypothalamic-pituitary-adrenal axis regulates the secretion of glucocorticoids.

• The innermost layer which secretes adrenal androgens.
• These hormones serve as precursors that are converted to other sex hormones in different tissues.

• This is the inner region of the adrenal gland, but it is not part of the adrenal cortex.
• The adrenal medulla secretes catecholamines like epinephrine (also known as adrenaline) and norepinephrine, which are stress-responsive hormones that help prepare the body for "fight or flight" reactions.

• This middle layer of the adrenal cortex is primarily responsible for producing and secreting glucocorticoids, including cortisol, which is the main glucocorticoid in humans.
• These hormones have numerous effects on the body, including the regulation of metabolism and immune response, as well as helping the body respond to stress.

Hence the correct answer is option 2

Concept:

• The leads in an ECG system are used to provide different views or perspectives of the electrical activity of the heart.
• Each lead represents a specific pathway between two or more electrodes, which are the conductive pads attached to the skin.
• They help in observing and recording the electrical signals of the heart to generate an ECG graph.
• A standard 12-lead ECG contains ten physical electrodes that create twelve distinct views or leads.
• There are basically three types of leads:

1. Limb Leads:
   • Also known as bipolar leads, limb leads consist of Leads I, II, and III.
   • They measure the electrical activity in the heart in a frontal plane, providing a vertical view.
2. Augmented Limb Leads:
   • ​Also known as unipolar leads, these include aVR, aVL, and aVF.
   • They are called 'augmented' because their electrical activity is magnified in order to create readable ECG tracings.
3. Chest (Precordial) Leads:
   • The chest leads are also unipolar and are denoted by V1 through V6.
   • They provide a horizontal view of the heart, specifically of the activity in the anterior and lateral sections of the heart.

• The role of these leads is to help diagnose various cardiac conditions by recognizing abnormal patterns of electrical conduction, which might, for instance, hint at heart disease or electrolyte imbalances.
• Different leads provide different angles of view, and examining them all collectively provides a comprehensive picture of the heart's electrical activity.

Hence the correct answer is option 2