Human Physiology & Anatomy — Part 2: 40 MCQs with Explanations

The respiratory system is responsible for gas exchange (O2 and CO2), it helps regulate blood pH via CO2 levels, and is involved in phonation, but not food digestion.

The synapse is the functional junction between two neurons, where neurotransmitters are released to carry the signal across the gap.

The correct pathway: stimulus activates a receptor, which sends an impulse via a sensory neuron to the CNS. The CNS processes and sends an impulse via a motor neuron to an effector (muscle/gland).

The nephron is the microscopic structural and functional unit of the kidney responsible for filtration, reabsorption, and secretion to form urine.

Vitamin K is synthesized by bacteria in the large intestine and is essential for blood clotting factor synthesis.

The central nervous system (CNS) consists of the brain and spinal cord only. Cranial nerves are part of the peripheral nervous system (PNS).

The thyroid gland secretes thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, growth, and development.

The urea cycle (ornithine cycle) occurs in the liver, converting toxic ammonia into less toxic urea for excretion by kidneys.

Fertilization typically occurs in the ampulla region of the fallopian tube (oviduct), after which the zygote moves to the uterus for implantation.

Oxytocin, secreted by the posterior pituitary gland, stimulates powerful contractions of the uterine muscles during labor and also triggers milk ejection.

The appendix is considered a vestigial organ—a remnant of a larger cecum that was functional in herbivorous ancestors for cellulose digestion.

The generally accepted sequence is Australopithecus (4-2 mya) → Homo habilis (2.4-1.4 mya) → Homo erectus (1.9 mya-140 kya) → Homo sapiens (300 kya-present).

Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. They are the only veins carrying oxygenated blood.

The sarcomere, defined as the segment between two Z-lines, is the basic contractile unit of striated muscle containing actin and myosin filaments.

Villi are finger-like projections in the small intestine for absorption, not part of the respiratory system. Trachea, bronchi, and alveoli are respiratory structures.

Trypsin (secreted by pancreas as trypsinogen) digests proteins into smaller peptides in the small intestine. Pepsin works in the stomach.

Gas exchange occurs in the lungs, not skin (except minimal amounts in amphibians). Human skin functions in protection, temperature regulation, vitamin D synthesis, and sensation.

The iris, containing pigmented muscles, controls pupil size to regulate light entry into the eye.

The pelvic girdle (hip bones) is part of the appendicular skeleton. The axial skeleton includes skull, vertebral column, ribs, and sternum.

Gas exchange is performed by the lungs. Kidneys filter blood, regulate blood pressure (via renin), produce erythropoietin (stimulates RBC production), and maintain electrolyte balance.

The retina is part of the eye, not the ear. Pinna, cochlea, and semicircular canals are components of the external, inner, and vestibular parts of the ear respectively.

Thrombin, formed from prothrombin, catalyzes the conversion of soluble fibrinogen to insoluble fibrin threads that form the clot mesh.

Prolactin, secreted by the anterior pituitary gland, stimulates milk production (lactogenesis) in mammary glands after childbirth.

The medulla oblongata controls vital autonomic functions including heartbeat, breathing rate, blood pressure, and reflexes like vomiting and coughing.

Parathyroid hormone (PTH) increases blood calcium levels by stimulating osteoclast activity (bone resorption), kidney reabsorption of calcium, and activation of vitamin D.

Progesterone, secreted by the corpus luteum after ovulation, thickens and maintains the endometrium for potential implantation of a fertilized egg.

The trachea is part of the respiratory system, conducting air to the lungs. The esophagus conducts food to the stomach.

Lipase (pancreatic and gastric) hydrolyzes triglycerides into fatty acids and glycerol.

The lymphatic system returns interstitial fluid to blood, absorbs dietary fats, and plays a crucial role in immune defense through lymph nodes and lymphocytes.

Cortisol (a glucocorticoid) is secreted by the adrenal cortex and regulates metabolism, immune response, and stress response. Adrenaline/noradrenaline are secreted by the adrenal medulla.

During anaerobic respiration (in muscles under oxygen debt), pyruvate is reduced to lactate by lactate dehydrogenase, regenerating NAD⁺ for glycolysis to continue.

Luteinizing hormone (LH) surge triggers ovulation—the release of a mature ovum from the ovarian follicle—around day 14 of the menstrual cycle.

Calcitonin, secreted by the thyroid gland, lowers blood calcium levels by inhibiting osteoclast activity and promoting calcium deposition in bones.

Melatonin, secreted by the pineal gland in response to darkness, regulates circadian rhythms and promotes sleep.

Oxytocin and ADH (vasopressin) are synthesized in the hypothalamus and stored/released from the posterior pituitary gland.

External respiration is the diffusion of oxygen from alveoli into pulmonary capillaries and carbon dioxide from blood into alveoli.

Estrogen, produced primarily by ovarian follicles, promotes development of female secondary sexual characteristics (breast development, wider hips, fat distribution) during puberty.

The cochlea is part of the inner ear for hearing. Cornea, iris, and retina are components of the eye.

Thromboplastin (tissue factor), released from damaged tissues, catalyzes the conversion of prothrombin to thrombin in the presence of calcium ions during blood clotting.

Thyroid Stimulating Hormone (TSH), secreted by the anterior pituitary, stimulates the thyroid gland to produce and release thyroxine (T4) and triiodothyronine (T3).

Cerebral Hemorrhage is the correct answer to “It is the discharge of blood from blood vessels”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

All of the follwing are blood clots except: Atheroma .

Blood pressure is the correct answer to “It is the measure of force with which blood pushes up against the walls of blood vessels.”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Collagen fibers of bone are hardened by deposition of Ca & PO4 .

Triceps is the correct answer to “Which of the following muscle is an antagonistic member of Biceps brachii”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Earthworm is the correct answer to “Which of the following animal uses Setae and Muscles for their Iocomotion”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Z- Line is the correct answer to “A smallest contractile unit of muscle contraction called sarcomere is the area between two:”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

In an annelids, the contraction of circular muscle results in Thinning of body .

Z- lines get closer is the correct answer to “What happens during muscle contraction to the length of each myosin and action filament”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Tropomyosin gets removed from the binding sites of actin filaments. is the correct answer to “Which of the following step occurs immediately after binding of Ca2+ with troponin molecule during muscle contraction.”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Alternating dark and light bands appear on their surface when visualized via a microscop is the correct answer to “Why skeletal muscles are called striated muscles”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

They contain O2 storing molecules called hemoglobin. is the correct answer to “Which of the following statements is incorrect about skeletal muscle fibers”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

If two ends of fractured bone are opened and kept united via screws and wires drilled in bone substance. This step in fracture repair is called Open reduction. .

A smooth muscle is the correct answer to “The contraction of which of the following muscle fibers, is controlled by hormones”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Between femur and tibia. is the correct answer to “In which of the following joint muscles are arranged in the same plane as that of joint”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Joint between two parietal bones, which is infact immovable one is an example of Fibrous joints. .

The blood enters the Posterior side of heart.

The increase in pH of blood has plus ve effect on the oxygen carrying capacity of haemogolobin.

Arterial blood contains 50 ml of CO2 per 100 ml of blood.

During rest the breathing occurs rhythmically at the frequency of 15-20 times per minute in human.

The maximum amount of oxygen which normal human blood absorbs and carries at sea level is 20 ml per 100 ml of blood.

It is one of the convulsive disorders of nerves which are characterized by abrupt transient symptoms of motor, sensory, psychic or autonomic nature Epilepsy .

Regeneration is the correct answer to “Which of the following feature is not related to neuron”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Sensory neuron is the correct answer to “Which of the following transmits nerve impulse from receptors to central nervous system”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

In which of the following neurons length of dendrite is greater than axon Sensory neuron .

Sensory neuron is the correct answer to “Which of the following neuron has a single long dendron”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Microscopic gaps between the neuron endings are called Synapses .

Which of the following ions are involved in the initiation of nerve impulse Na+ .

Maximum speed of nerve impulse transmission is 120m/sec .

Number of pairs of cranial nerves is 12 .

Which of the following statement about neuron is incorrect Like all the living cell, when they mature and divide to form similar cells .

Secretin is a hormone produced by Duodenum .

Type of neurons found exclusively in CNS are Associative neurons .

The only promoter of leaf senescence in the following plant hormones is Abscisic Acid .

Megaphylls i.e. leaves with divided veins with an expanded lamina is a dharacteristic of Both b and c .

Lies on dorsal side is the correct answer to “Main blood vessel of arthropods usually:”. Items of this type are drawn from the Human Physiology & Anatomy — Part 2 syllabus of Pakistani competitive exams, where the fact is tested verbatim.

Approximately 200 species of bacteria are known to cause diseases in humans.

Hepatic and Pancreatic secretions are also stimulated by a hormone produced by the intestinal mucosa. The hormone is Secretin .

Anus is surrounded by 2 types of muscles.

Masses of dilated tortuous veins in the anorectal mucosa are known as Hemorrhoids .