Human Physiology MCQ Quiz - Objective Question with Answer for Human Physiology - Download Free PDF

The correct answer is C nerve fibre

Concept:

• Nerve fibres are classified based on their diameter, conduction velocity, and function. The classification includes A, B, and C fibres, with A fibres further subdivided into A_α,A_β, A_γ, and A_δ
• Impulse conduction velocity depends on factors such as fibre diameter, myelination, and the type of nerve fibre.
• Myelination significantly increases conduction velocity, as the impulse "jumps" between the nodes of Ranvier in myelinated fibres (saltatory conduction).
• Unmyelinated fibres, such as C fibres, conduct impulses more slowly compared to myelinated fibres.

Explanation:

• C nerve fibres: These are unmyelinated fibres with the smallest diameter (0.4–1.2 µm) and the slowest conduction velocity (0.4–2 m/s). They are primarily involved in transmitting pain and temperature signals. The absence of myelination and small diameter contributes to their slow impulse conduction.
• Other options:
  • A_α $A\alpha$nerve fibres: These are heavily myelinated fibres with the largest diameter (13–20 µm) and the fastest conduction velocity (80–120 m/s). They are involved in motor functions and proprioception, making them unsuitable as the answer.
  • A_β nerve fibres: These fibres are myelinated with a slightly smaller diameter (6–12 µm) and conduction velocity (35–75 m/s) compared to AαAαAα $A\alpha$ . They are involved in touch and pressure sensation, so they are faster than C fibres.
  • B nerve fibres: These fibres are lightly myelinated, with a diameter of 1–3 µm and conduction velocity of 3–15 m/s. They are involved in autonomic nervous system functions and are slower than A fibres but faster than C fibres.

The correct answer is Blood

Explanation:

• Insulin and glucagon are hormones produced by the islets of Langerhans in the pancreas, which play crucial roles in maintaining blood glucose levels.
• The endocrine function of the pancreas involves the secretion of these hormones directly into the bloodstream, allowing them to reach their target cells in various parts of the body.
• Insulin and glucagon are secreted by the endocrine cells of the pancreas (beta cells for insulin and alpha cells for glucagon) into the blood.
• The blood serves as the transport medium for these hormones, carrying them to target tissues such as the liver, muscles, and fat cells.
• The bloodstream ensures rapid and efficient delivery, enabling the hormones to regulate blood sugar levels effectively.

The correct answer is Pain

Concept:

• Naked nerve endings, also known as free nerve endings, are unencapsulated nerve endings found in the skin, muscles, joints, and other tissues.
• These nerve endings are specialized to detect a variety of sensations, including pain, temperature (both hot and cold), and certain types of touch.
• Pain is the primary sensation initiated by impulses from naked nerve endings. This is a protective mechanism designed to alert the body to potential harm or injury.
• The pain signals are transmitted by specialized nerve fibers, such as A-delta fibers (for sharp, immediate pain) and C fibers (for dull, lingering pain).

Other Options:

• Smell: The sensation of smell is detected by specialized sensory neurons in the olfactory epithelium of the nasal cavity, not by naked nerve endings. These neurons respond to chemical molecules in the air, which bind to olfactory receptors and generate signals sent to the brain's olfactory bulb.
• Touch: Touch is primarily detected by encapsulated nerve endings, such as Meissner's corpuscles and Merkel discs, which are sensitive to light touch and pressure.
• Cold: Cold sensations are detected by specialized thermoreceptors, such as Krause end bulbs, and certain free nerve endings.

The correct answer is Presbyopia

Explanation:

• Presbyopia is a common visual condition that occurs as a natural part of aging, typically beginning around the age of 40 or older.
• The condition is characterized by a gradual loss of the eye's ability to focus on nearby objects, making activities such as reading or using a smartphone more challenging.
• This is due to the hardening of the lens in the eye and weakening of the ciliary muscles, which reduces the lens's flexibility to adjust its shape for near vision.
• It is a normal physiological change and not considered a disease.
• Presbyopia can be corrected using reading glasses, bifocals, progressive lenses, or contact lenses. Surgical options like LASIK or lens implants are also available in some cases.

Other Options:

• Myopia: This is also known as nearsightedness. It is a refractive error where distant objects appear blurry because light focuses in front of the retina. Myopia typically develops in childhood or adolescence and is unrelated to aging.
• Hypermetropia: Known as farsightedness, it is a refractive error where nearby objects appear blurry because light focuses behind the retina. It is not directly related to aging but is a congenital or developmental condition.
• Astigmatism: This is a refractive error caused by an irregularly shaped cornea or lens, leading to distorted or blurred vision at all distances. It is not specifically related to aging and can occur at any age.

The correct answer is Proximal tubule

Concept:

• The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. It consists of various structures, including the glomerulus, proximal tubule, loop of Henle, distal convoluted tubule, and collecting tubule.
• The process of urine formation involves three main steps: filtration, reabsorption, and secretion.
• Glomerular filtration occurs in the glomerulus, where blood is filtered, and the filtrate enters the nephron tubules for further processing.
• Reabsorption is the process by which essential substances such as water, glucose, amino acids, and ions are absorbed back into the bloodstream from the filtrate.

Explanation:

Proximal tubule:

• The majority of the glomerular filtrate is reabsorbed in the proximal tubule (approximately 65-70%).
• This portion of the nephron is highly specialized for reabsorption. Key substances reabsorbed here include:
  • Water: Reabsorbed due to osmotic gradients created by solute reabsorption.
  • Glucose and amino acids: Reabsorbed completely under normal physiological conditions via active transport.
  • Electrolytes such as sodium, chloride, potassium, bicarbonate, and calcium are reabsorbed through various transport mechanisms.
• The proximal tubule also plays a role in secretion, removing substances like hydrogen ions, ammonia, and certain drugs from the blood into the filtrate.

Other Options:

• Loop of Henle: The loop of Henle is primarily responsible for concentrating the urine by creating a countercurrent system.
• Only a small amount of reabsorption occurs here, mainly of water in the descending limb and sodium and chloride in the ascending limb.
• Distal convoluted tubule: The distal convoluted tubule is involved in the fine-tuning of reabsorption and secretion, especially for electrolytes like sodium and potassium, and in maintaining acid-base balance.
• Collecting tubule: The collecting tubule is mainly involved in the reabsorption of water under the influence of antidiuretic hormone (ADH) and in the secretion of potassium and hydrogen ions.

The correct answer is the Pivotal joint.

The joint where our neck joins the head is a pivotal joint. It allows us to bend our head forward and backwards and turn the head to our right or left. In a pivotal joint, a cylindrical bone rotates in a ring.
Additional Information

•  The ball and socket joint provides swinging and rotating movements.
  • The articulating bone is received into the cavity of another bone, allowing the distal bone to move around three main axes with a common centre.
  • The joint has to stabilize ligaments that limit the directions and extent to which the bones can be moved
• Hinge joints are those that allow movement along one plane.
  • They facilitate bending and straightening actions, such as flexing a finger.
  • In a hinge joint, protective cartilage covers the bones, and a thick gel called synovial fluid lubricates them, allowing them to move without rubbing against one another.

The correct answer is The iris contracts the pupil to allow less light to enter the eye.Key Points

• When we move from a brightly lit room to a dimly lit room, our eyes take some time to adjust to the change in lighting.
• This is because the iris, which controls the amount of light entering the eye, needs to adjust to the new lighting conditions.
• This helps to improve the clarity of the image that is formed on the retina.
• Dilation of the eye lens actually allows more light to enter the eye, and so this would not help in a dimly lit room.​

Additional Information

• Iris:
  • The iris is a circular muscle in the eye that controls the size of the pupil and the amount of light entering the eye.
  • It is responsible for adjusting the amount of light that enters the eye based on the lighting conditions.
• Pupil:
  • ​The pupil is the black circular opening in the center of the iris that allows light to enter the eye.
  • Its size is controlled by the iris, which adjusts it based on the amount of light available.
• Vitreous humour:
  • The vitreous humour is a gel-like substance that fills the eye and helps to maintain its shape.
  • It does not have any control over the amount of light entering the eye.
• Cornea:
  • The cornea is a transparent layer at the front of the eye that helps to focus light onto the retina.
  • It does not have any control over the amount of light entering the eye.

Concept:

• The brain is a complex and vital organ in an animal's body that controls several activities.
• Memory, motor skills, breathing, vision, hunger, libido, etc. are some of the various processes in an animal's body that are regulated by the brain.
• The brain along with the spinal cord forms the Central Nervous System.
• A brain is made up of fats, carbohydrates, water, protein and salts.
• It comprises blood vessels and nerves.
• The brain carries out several functions of the body by sending and receiving chemical and electrical signals throughout the body.
• The brain is divided into three parts:
  • Forebrain (Prosencephalon)
  • Midbrain (Mesencephalon)
  • Hindbrain (Rhombencephalon)

Explanation:

• Option 1: Medulla oblongata - INCORRECT​
  • The medulla oblongata is located in the hindbrain. 
  • It is located at a point where the brain and spinal cord connect.
  • Functions:
  1. Controls heartbeats
  2. Controls breathing as well as blood pressure
  3. Produces reflective actions such as sneezing, coughing, vomiting, etc.
• Option 2: Midbrain - INCORRECT
  • ​Midbrain comprises two parts - Tectum and Tegmentum.
  • Midbrain consists of neuron clusters that facilitate various functions.
  • Functions:
  1. Facilitates visual reflexes
  2. Hearing
  3. Determines movements concerning responses and changes in the environment.
• Option 3: Cerebrum - INCORRECT
  • Cerebrum is the largest part of the brain.
  • It is part of the forebrain that is further divided into Frontal lobe, Parietal lobe, Occipital lobe and Temporal lobe.
  • Functions:
  1. Regulates temperature
  2. Enables speech
  3. Involved in thinking, reasoning and problem-solving
  4. Co-ordinates movements
  5. Controls emotions and learning, etc.
• Option 4: Cerebellum - CORRECT
  • The cerebellum is also known as the little brain.
  • The cerebellum is located in the hindbrain above the brainstem.  
  • Functions:
  1. Controls voluntary muscular movement like walking, posture, etc.
  2. Responsible for the maintenance of posture, balance and equilibrium.

So the correct answer is option 4 (Cerebellum).

Key Points

• The Duramater is the tough and outermost layer of the meninges that covers the brain and spinal cord.
  • It is a thick and fibrous layer that protects the brain and spinal cord from external shocks or trauma.

Additional Information

• Piamater plays a crucial role in protecting and nourishing the brain.
  • The Piamater is the thin, delicate, and innermost layer that covers the surface of the brain and spinal cord.
• The Arachnoid is the middle layer of the meninges that covers the brain and spinal cord.
  • It is a delicate and web-like layer that is located between the Duramater and the Piamater.
  • The Arachnoid is filled with cerebrospinal fluid (CSF), which helps to cushion the brain and spinal cord.
• The Coracoid is a bone in the shoulder that connects the scapula and the clavicle. It has no relation to the brain or its coverings.

Correct answer: 1)

Concept:

• The respiratory system consists of organs and different structures that help in the exchange of gases in both plants and animals.
• The human respiratory system consists of the nose (nasal cavity), pharynx, larynx, trachea, bronchi, bronchioles, lungs, and alveoli.

Explanation:

• The respiratory system is divided into conducting zone and a respiratory zone.
• Conducting zone starts from the nose and ends in the bronchioles.
• The respiratory zone includes terminal bronchioles and alveoli.
• The conduction zone has different functions such as, it clears the inhaled air from foreign particles, humidifying the inhaled air, and also bringing the temperature of the inhaled air to body temperature.
• The respiratory zone is the site for an exchange of gases such as oxygen and carbon dioxide.

So, the correct answer is option 1

The correct answer is Acromegaly - Adrenaline. Key Points

• Acromegaly is a hormonal disorder that results in the excessive production of growth hormone, which is produced by the pituitary gland.
• Adrenaline is not associated with acromegaly.
• Instead, it is a hormone that is produced by the adrenal glands and is involved in the body's "fight or flight" response.
• Cushing's syndrome is a condition that is caused by the overproduction of cortisol, a steroid hormone that is produced by the adrenal glands.
• Diabetes is a condition that is characterized by high levels of glucose (sugar) in the blood.
  • It is caused by a lack of insulin, a hormone that is produced by the pancreas.
• Thyroxin, which is associated with goitre, is involved in regulating metabolism and growth.
  • It helps to regulate the body's energy production and influences the development of the brain, bones, and muscles.

Additional Information

• Cortisol, which is associated with Cushing's syndrome, is involved in regulating a variety of bodily functions, including metabolism, immune response, and stress response.
• Insulin, which is associated with diabetes, regulates the levels of glucose (sugar) in the blood.
  • It allows cells to use glucose for energy and helps to store excess glucose in the liver and muscles.
• Goitre is a condition that is characterized by an enlarged thyroid gland.
  • It is often caused by a deficiency of iodine, which is necessary for the production of thyroid hormones.

Concept:

• Exocrine glands: The glands which secrete substances on the epithelial surface through the ducts are called exocrine glands. Eg. sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate, and mucous glands.
• Endocrine glands: The glands which secrete hormones and other substances directly into the bloodstream are called endocrine glands. Eg. Pituitary, Pineal, Thyroid, Thymus, Gonads, etc.

​Explanation:

Endocrine Glands: 

• Endocrine glands lack ducts and are hence, called ductless glands. Their secretions are called hormones
• Hormones are non-nutrient chemicals that act as intercellular messengers and are produced in trace amounts
• The hormones are emptied directly into the bloodstream and then transported to target cells by blood
• The endocrine system regulates the metabolic activities of the body like body growth, sexual development & other biological processes
• The endocrine gland signalling is slow but its effects are prolonged 
• Some of the major endocrine glands are the Pituitary, Pineal, Thyroid, Thymus, Gonads, etc.

 Additional Information

The correct answer is O^-

Explanation:

• The O-ve negative is the universal donor blood group.
• It has a low risk of causing transfusion reactions.
• O-ve is given in the case of emergency if the blood group is not known.
• Red blood cells have antigens on the surface and antibodies in the plasma.
• It has four major types of antigens.
  • Type A: It has A antigens on the surface of the red blood cells and anti-B antibodies in the plasma.
  • Type B: It has B antigens on the surface of the red blood cells and anti-A antibodies in the plasma.
  • Type AB: It has both A and B antigens on the surface of the red blood cells and no antibodies in the plasma.
  • Type O: It has no antigens, but both anti-A and anti-B antibodies in the plasma.

Each group can be either RhD +ve or RhD -ve.

The correct answer is Deficiency of protein.

Key Points

• About Proteins:
  • Proteins are one of the building blocks of body tissue.
  • Proteins are made up of Carbon, Hydrogen, Oxygen, and Nitrogen.
  • Proteins help for the growth and repair of the body.
  • Proteins are the nutrient known as 'bodybuilders'.
  • Amino acid is the basic unit of proteins.
  • The Soyabean contains the highest percentage of protein.
  • The major source of proteins is meat, milk, egg, fish, gram, etc.
• Marasmus is also caused by severe protein deficiency.
• Kwashiorkor is caused by severe protein deficiency.​

Additional Information

• Deficiency of iron
  • Iron deficiency can lead to Anaemia.
  • Iron deficiency anemia is a common type of anemia — a condition in which blood lacks adequate healthy red blood cells.
  • Red blood cells carry oxygen to the body's tissues. 
  • This means that red blood cells aren’t going to be able to carry as much oxygen to your tissues.​
• Calcium deficiency occurs at any stage.
  • It can result in rickets, osteoporosis, and osteopenia.
  • Osteoporosis occurs at later stages of life and is a disease in which bone becomes more fragile and more likely leading to fractures.

• Deficiency of vitamin A
  • Severe vitamin A deficiency can lead to night blindness and poor vision. 
  • People with night blindness do not see well in the dark, But they can see normally if enough light is present.
  • Vitamin A is found in many foods like leafy green vegetables, orange vegetables (carrots, sweet potatoes, pumpkin), eggs, and cantaloupes.

The correct answer is Arteries.Key Points

• Arteries are thick-walled blood vessels that carry oxygenated blood away from the heart to various organs of the body.
• They have a muscular wall that contracts and relaxes to regulate blood pressure and flow.
• Arteries also branch out into smaller vessels called arterioles, which further divide into capillaries where exchange of nutrients and waste products takes place.
• Veins, on the other hand, carry deoxygenated blood back to the heart from various organs of the body.
• Tracheas are part of the respiratory system and carry air to and from the lungs.

Additional Information

• Veins:
  • These are thin-walled blood vessels that have valves to prevent backflow of blood.
  • They are located closer to the surface of the skin and are often visible as blue or greenish lines.
• Plasma:
  • This is the liquid component of blood that carries nutrients, hormones, and waste products.
  • It also helps in maintaining the pH balance and temperature of the body.
  • Plasma is not a vessel but a component of blood.