Preparing for the NCLEX exam or any nursing physiology test? You’re in the right place! This post covers NCLEX Physiology MCQs (51–100) with correct answers and simple explanations. These practice questions are designed for nursing students, NCLEX candidates, and medical learners who want to strengthen their understanding of human physiology. Each MCQ is explained in a clear, exam-focused way, making it highly valuable for self-study and exam revision.
51. Which organ is primarily responsible for filtering blood and maintaining fluid balance?
A. Heart
B. Liver
C. Kidney ✅
D. Pancreas
👉 Explanation: The kidneys filter waste products, regulate electrolytes, and maintain fluid balance.
52. What is the normal pH range of human blood?
A. 6.8–7.0
B. 7.35–7.45 ✅
C. 7.5–7.8
D. 7.0–7.2
👉 Explanation: Blood pH is slightly alkaline, normally between 7.35–7.45.
53. Which hormone regulates blood calcium levels?
A. Insulin
B. Parathyroid hormone (PTH) ✅
C. Thyroxine
D. Cortisol
👉 Explanation: PTH increases calcium levels by stimulating bone resorption and kidney reabsorption.
54. What is the primary function of hemoglobin?
A. Clot formation
B. Oxygen transport ✅
C. Immune defense
D. Digestion
👉 Explanation: Hemoglobin in red blood cells binds oxygen in the lungs and releases it to tissues.
55. The pacemaker of the heart is known as?
A. AV node
B. SA node ✅
C. Purkinje fibers
D. Bundle of His
👉 Explanation: The sinoatrial (SA) node initiates the electrical impulses that regulate heart rhythm.
56. Which part of the brain controls voluntary movement?
A. Cerebellum
B. Cerebrum ✅
C. Medulla oblongata
D. Hypothalamus
👉 Explanation: The cerebrum controls voluntary movement, memory, emotions, and higher functions.
57. What is the main function of alveoli in the lungs?
A. Produce mucus
B. Gas exchange ✅
C. Transport oxygen
D. Filter air
👉 Explanation: Alveoli are tiny air sacs where oxygen enters the blood and carbon dioxide leaves it.
58. Which vitamin is essential for calcium absorption?
A. Vitamin A
B. Vitamin B12
C. Vitamin D ✅
D. Vitamin K
👉 Explanation: Vitamin D promotes calcium absorption in the intestines and is vital for bone health.
59. What is the normal resting heart rate for adults?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm ✅
D. 100–120 bpm
👉 Explanation: A healthy adult’s resting heart rate ranges between 60 and 100 beats per minute.
60. Which structure connects muscles to bones?
A. Ligaments
B. Tendons ✅
C. Cartilage
D. Fascia
👉 Explanation: Tendons attach muscles to bones, enabling movement when muscles contract.
61. Which part of the nephron is responsible for most water reabsorption?
A. Glomerulus
B. Loop of Henle
C. Proximal convoluted tubule ✅
D. Collecting duct
👉 Explanation: About 65–70% of water reabsorption occurs in the proximal convoluted tubule.
62. Which gland regulates metabolism through thyroid hormones?
A. Pituitary gland
B. Adrenal gland
C. Thyroid gland ✅
D. Hypothalamus
👉 Explanation: The thyroid gland produces T3 and T4, which control the body’s metabolism and energy use.
63. Which blood vessel carries oxygenated blood from the lungs to the heart?
A. Pulmonary artery
B. Aorta
C. Pulmonary vein ✅
D. Vena cava
👉 Explanation: Pulmonary veins are the only veins that carry oxygen-rich blood, delivering it to the left atrium.
64. The functional unit of the nervous system is the?
A. Nephron
B. Axon
C. Neuron ✅
D. Synapse
👉 Explanation: Neurons transmit electrical signals, making them the basic functional units of the nervous system.
65. Which type of muscle is involuntary and found in internal organs?
A. Skeletal muscle
B. Cardiac muscle
C. Smooth muscle ✅
D. Striated muscle
👉 Explanation: Smooth muscles are involuntary and control movements in organs like the stomach and intestines.
66. Which hormone helps regulate blood sugar by lowering glucose levels?
A. Glucagon
B. Insulin ✅
C. Cortisol
D. Epinephrine
👉 Explanation: Insulin, secreted by the pancreas, lowers blood glucose by facilitating its entry into cells.
67. Which structure controls balance and coordination?
A. Medulla oblongata
B. Cerebrum
C. Cerebellum ✅
D. Thalamus
👉 Explanation: The cerebellum ensures smooth, coordinated movement and helps maintain posture and balance.
68. Which type of blood cell is responsible for clotting?
A. Red blood cells
B. Platelets ✅
C. White blood cells
D. Plasma cells
👉 Explanation: Platelets (thrombocytes) form clots to prevent bleeding after injury.
69. Which organ produces bile?
A. Stomach
B. Liver ✅
C. Pancreas
D. Gallbladder
👉 Explanation: The liver produces bile, which is stored in the gallbladder and helps digest fats.
70. Which blood group is considered the universal donor?
A. A
B. B
C. AB
D. O negative ✅
👉 Explanation: O negative blood has no antigens, making it safe for transfusion to most patients.
71. Which blood group is known as the universal recipient?
A. O positive
B. B negative
C. AB positive ✅
D. A negative
👉 Explanation: AB positive individuals can receive all blood types due to the absence of antibodies against A, B, and Rh.
72. Which chamber of the heart pumps oxygenated blood to the body?
A. Right atrium
B. Right ventricle
C. Left atrium
D. Left ventricle ✅
👉 Explanation: The left ventricle has the thickest wall and pumps oxygenated blood into the aorta.
73. Which hormone is released in response to stress?
A. Insulin
B. Cortisol ✅
C. Thyroxine
D. Estrogen
👉 Explanation: Cortisol, secreted by the adrenal cortex, helps the body respond to stress by increasing blood sugar and energy supply.
74. Which structure regulates body temperature?
A. Cerebrum
B. Cerebellum
C. Hypothalamus ✅
D. Medulla
👉 Explanation: The hypothalamus acts as the body’s thermostat, maintaining normal body temperature.
75. Which organ is responsible for producing insulin?
A. Kidney
B. Pancreas ✅
C. Liver
D. Gallbladder
👉 Explanation: The pancreas contains beta cells in the islets of Langerhans, which secrete insulin.
76. Which artery supplies blood to the brain?
A. Carotid artery ✅
B. Femoral artery
C. Radial artery
D. Pulmonary artery
👉 Explanation: The carotid arteries deliver oxygenated blood from the heart to the brain.
77. Which process converts glucose into energy in cells?
A. Osmosis
B. Respiration ✅
C. Photosynthesis
D. Filtration
👉 Explanation: Cellular respiration breaks down glucose to produce ATP, the body’s energy currency.
78. What is the normal respiratory rate in adults at rest?
A. 8–10 breaths per minute
B. 12–20 breaths per minute ✅
C. 20–25 breaths per minute
D. 25–30 breaths per minute
👉 Explanation: A normal adult breathes between 12 and 20 times per minute at rest.
79. Which organ produces digestive enzymes and also regulates blood sugar?
A. Stomach
B. Pancreas ✅
C. Liver
D. Gallbladder
👉 Explanation: The pancreas produces digestive enzymes (lipase, amylase) and hormones like insulin and glucagon.
80. Which type of joint allows the widest range of movement?
A. Hinge joint
B. Pivot joint
C. Ball-and-socket joint ✅
D. Gliding joint
👉 Explanation: Ball-and-socket joints (like the hip and shoulder) allow movement in multiple directions.
81. Which part of the brain controls breathing and heart rate?
A. Cerebrum
B. Medulla oblongata ✅
C. Cerebellum
D. Thalamus
👉 Explanation: The medulla oblongata regulates vital functions such as respiration and heartbeat.
82. Which hormone regulates calcium levels in blood?
A. Insulin
B. Parathyroid hormone ✅
C. Cortisol
D. Aldosterone
👉 Explanation: Parathyroid hormone increases blood calcium levels by stimulating bone resorption.
83. Which structure transports urine from the kidney to the bladder?
A. Urethra
B. Nephron
C. Ureter ✅
D. Collecting duct
👉 Explanation: Ureters are tubes that carry urine from kidneys to the urinary bladder.
84. Which blood vessel carries blood away from the heart?
A. Vein
B. Artery ✅
C. Capillary
D. Venule
👉 Explanation: Arteries always carry blood away from the heart, usually oxygenated blood.
85. Which electrolyte is most important for muscle contraction?
A. Sodium
B. Calcium ✅
C. Potassium
D. Chloride
👉 Explanation: Calcium triggers muscle contraction by binding to troponin.
86. Which part of the digestive system absorbs most nutrients?
A. Stomach
B. Small intestine ✅
C. Large intestine
D. Pancreas
👉 Explanation: The small intestine (jejunum and ileum) is the primary site for nutrient absorption.
87. What is the main function of hemoglobin?
A. Blood clotting
B. Carrying oxygen ✅
C. Producing energy
D. Fighting infections
👉 Explanation: Hemoglobin in red blood cells binds oxygen in the lungs and delivers it to tissues.
88. Which organ stores and releases glucose as glycogen?
A. Kidney
B. Pancreas
C. Liver ✅
D. Spleen
👉 Explanation: The liver maintains blood glucose levels by storing and breaking down glycogen.
89. Which part of the eye regulates the amount of light entering?
A. Retina
B. Cornea
C. Iris ✅
D. Lens
👉 Explanation: The iris adjusts the size of the pupil to control light entry.
90. Which hormone helps with milk production after childbirth?
A. Estrogen
B. Progesterone
C. Prolactin ✅
D. Oxytocin
👉 Explanation: Prolactin stimulates the mammary glands to produce milk.
91. Which hormone triggers uterine contractions during childbirth?
A. Oxytocin ✅
B. Prolactin
C. Estrogen
D. Cortisol
👉 Explanation: Oxytocin causes powerful uterine contractions and also aids in milk ejection.
92. Which organ produces red blood cells in adults?
A. Liver
B. Spleen
C. Bone marrow ✅
D. Kidney
👉 Explanation: Bone marrow produces red blood cells through hematopoiesis.
93. Which blood component fights infections?
A. Platelets
B. Red blood cells
C. White blood cells ✅
D. Plasma
👉 Explanation: White blood cells (leukocytes) defend the body against bacteria, viruses, and pathogens.
94. Which ion is essential for nerve impulse transmission?
A. Calcium
B. Sodium ✅
C. Chloride
D. Magnesium
👉 Explanation: Sodium influx initiates action potentials in nerve cells.
95. Which organ is called the “master gland” of the endocrine system?
A. Thyroid
B. Pituitary gland ✅
C. Pancreas
D. Adrenal gland
👉 Explanation: The pituitary gland regulates other endocrine glands via hormones.
96. Which part of the ear maintains balance?
A. Cochlea
B. Tympanic membrane
C. Semicircular canals ✅
D. Eustachian tube
👉 Explanation: Semicircular canals detect changes in head position and movement.
97. What is the normal pH of human blood?
A. 6.8–7.0
B. 7.35–7.45 ✅
C. 7.5–8.0
D. 6.5–7.2
👉 Explanation: The normal blood pH is slightly alkaline, maintained between 7.35 and 7.45.
98. Which vitamin is essential for blood clotting?
A. Vitamin A
B. Vitamin D
C. Vitamin K ✅
D. Vitamin C
👉 Explanation: Vitamin K is crucial for synthesizing clotting factors in the liver.
99. Which organ filters and removes old red blood cells?
A. Liver
B. Spleen ✅
C. Pancreas
D. Kidney
👉 Explanation: The spleen removes aged or damaged red blood cells and also stores white blood cells.
100. Which valve prevents backflow of blood into the left atrium?
A. Tricuspid valve
B. Pulmonary valve
C. Mitral valve ✅
D. Aortic valve
👉 Explanation: The mitral (bicuspid) valve allows blood flow from the left atrium to the left ventricle but prevents backflow.
You’ve completed the NCLEX Physiology MCQs (51–100) with answers and explanations. ✅ Keep practicing more MCQs to boost your confidence and improve your exam score. For complete preparation, check out our other NCLEX Nursing MCQs on Pharmacology, Anatomy, and Physiology. Stay consistent, and success in NCLEX is yours! 🚀