Anatomy and Physiology

What to remember

• Anatomy is the study of body structure; physiology is the study of how the structures work. The body is built in levels: cell, tissue, organ, system.
• Normal adult values to know: temperature 37 °C (98.6 °F), pulse about 72 per minute, respiration 12 to 20 per minute, blood pressure about 120/80 mm Hg.
• Every system works to keep a steady internal state (homeostasis); a health worker reads these values to spot illness early.

1. Body organisation

• Cell is the basic unit of life. Parts: cell membrane, cytoplasm, nucleus (holds DNA), mitochondria (energy, "power house"), ribosomes (protein), lysosomes (digestion).
• Tissues: epithelial (covering and lining), connective (support; bone, blood, cartilage, fat), muscular (movement), nervous (conduction).
• Organs join to form systems. Body cavities: cranial and spinal (dorsal), thoracic and abdominopelvic (ventral). The diaphragm separates thoracic and abdominal cavities.
• Anatomical position: standing straight, face forward, palms facing forward.
• Terms: anterior (front), posterior (back), superior (upper), inferior (lower), medial (toward the midline), lateral (away from the midline), proximal (near the trunk), distal (away).

2. Skeletal system

The adult skeleton has 206 bones. A newborn has more (about 300) because many fuse later.

Vertebral column: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused into the sacrum) and 4 coccygeal (fused as coccyx). The first cervical vertebra is atlas and the second is axis.

• Long bones: femur (longest and strongest), humerus, radius, ulna, tibia, fibula.
• Smallest bone: stapes in the middle ear.
• Types of joints: fibrous (immovable, skull sutures), cartilaginous (slightly movable, vertebrae) and synovial (freely movable). Synovial types: ball and socket (shoulder, hip), hinge (elbow, knee), pivot (neck between atlas and axis), gliding (wrist) and saddle (thumb base).
• Functions of the skeleton: support, protection, movement, storage of calcium and making blood cells in the marrow.
• Bone needs calcium, phosphorus and vitamin D.

3. Muscular system

• Muscles are joined to bone by tendons; bones are joined to bones by ligaments.
• Muscles work in pairs (biceps flexes the arm and triceps extends it).
• Largest muscle: gluteus maximus. Smallest muscle: stapedius.

4. Circulatory system

Heart: a muscular pump in the chest, slightly to the left. Four chambers: right atrium, right ventricle, left atrium, left ventricle. Valves: tricuspid (right atrium to right ventricle), bicuspid or mitral (left atrium to left ventricle), pulmonary and aortic semilunar valves.

• Blood flow: body → right atrium → right ventricle → lungs (pulmonary artery) → left atrium (pulmonary veins) → left ventricle → aorta → body.
• Arteries carry blood away from the heart (thick wall); veins carry blood to the heart (have valves); capillaries are the exchange vessels. Pulmonary artery carries deoxygenated blood and pulmonary veins carry oxygenated blood.
• Heart sounds: "lub" (closure of AV valves) and "dub" (closure of semilunar valves).

Blood: plasma (about 55 %) and cells.

• Red blood cells carry oxygen with haemoglobin; made in bone marrow; life about 120 days.
• White blood cells fight infection (neutrophils, lymphocytes, monocytes, eosinophils, basophils).
• Platelets help clotting.
• Normal haemoglobin is about 12 to 16 g/dL in women and 13 to 17 g/dL in men. A low value means anaemia.
• ABO groups: A, B, AB, O. O is the universal donor of red cells; AB is the universal recipient. Rh factor: Rh positive or negative; Rh negative mother with an Rh positive baby needs preventive care.
• Pulse rate about 72 per minute (adult) and higher in children.
• Blood pressure = systolic over diastolic. Normal about 120/80 mm Hg.

5. Respiratory system

Path of air: nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli. Gas exchange takes place in the alveoli.

• Right lung has 3 lobes; left lung has 2 lobes (to make room for the heart).
• The diaphragm and intercostal muscles move air. Inspiration: diaphragm contracts and lungs expand. Expiration is mostly passive.
• Larynx (voice box) has vocal cords. Epiglottis covers the larynx during swallowing.
• Tidal volume (normal breath) is about 500 mL. Respiratory rate: about 12 to 20 per minute in adults and faster in infants.
• Oxygen travels in blood bound to haemoglobin. Carbon dioxide leaves mostly as bicarbonate.
• Respiratory centre in the medulla controls breathing.

6. Digestive system

Path: mouth → pharynx → oesophagus → stomach → small intestine → large intestine → rectum → anus.

• Bile helps fat digestion (emulsification). Largest gland: liver.
• Vitamin K and some B vitamins are made by gut bacteria.
• Peristalsis is the wave-like movement that moves food.

7. Urinary system

• Kidneys filter blood and form urine. The functional unit is the nephron (glomerulus plus tubule).
• Urine path: kidney → ureter → urinary bladder → urethra.
• Adult urine output is about 1 to 1.5 litres a day. The kidneys also control water balance, salts and blood pressure; they make erythropoietin.
• Skin and lungs also excrete waste.

8. Nervous system and sense organs

• Central nervous system (CNS): brain and spinal cord. Peripheral: 12 pairs of cranial nerves and 31 pairs of spinal nerves.
• Neuron is the unit of the nervous system: cell body, dendrites and axon.
• Brain parts: cerebrum (thought, memory, voluntary action), cerebellum (balance and coordination), medulla oblongata (heart rate, breathing), hypothalamus (temperature, hunger and thirst).
• Autonomic system: sympathetic ("fight or flight") raises heart rate; parasympathetic ("rest and digest") lowers it.
• Eye: cornea, lens, retina (rods for dim light; cones for colour). Lack of vitamin A affects rods and causes night blindness.
• Ear: outer, middle (three ossicles: malleus, incus, stapes) and inner (cochlea for hearing; semicircular canals for balance).
• Taste on the tongue; smell in the nose; touch, pain and temperature in the skin.

9. Endocrine system

Lack of insulin causes diabetes. Lack of iodine causes goitre.

10. Female reproductive system

• Parts: ovaries (make ova), fallopian tubes (fertilization usually in the outer third of the tube), uterus (womb), cervix and vagina.
• Menstrual cycle about 28 days; ovulation about day 14; menstrual bleeding about 3 to 5 days.
• After fertilization the egg is implanted in the uterus and the placenta forms. The placenta passes oxygen and food to the baby and removes waste. The umbilical cord links the baby to the placenta.
• Normal pregnancy lasts about 40 weeks (280 days) from the last menstrual period.
• Hormones: oestrogen (builds uterine lining), progesterone (maintains pregnancy), oxytocin (labour and milk ejection), prolactin (milk making).
• Breast milk: colostrum is the first yellowish milk and is rich in antibodies.

11. Skin, lymphatic system and immunity

• Skin has epidermis, dermis and hypodermis. Functions: protection, temperature control, sensation, vitamin D making and excretion by sweat. Melanin gives colour.
• Lymph nodes filter germs; the spleen filters blood; the thymus helps T cells mature.
• Immunity: innate (skin, mucus) and acquired (antibodies). Vaccines give active acquired immunity. Antibodies in breast milk give passive immunity.

12. Vital signs and quick calculations

• Body temperature: 37 °C = 98.6 °F. F = (C × 9/5) + 32. Fever above 38 °C.
• Cardiac output = heart rate × stroke volume. Example: 72 × 70 mL = 5,040 mL per minute (about 5 L).
• Minute ventilation = respiratory rate × tidal volume. Example: 15 × 500 mL = 7,500 mL per minute.
• Pulse pressure = systolic - diastolic. 120 - 80 = 40 mm Hg.
• Mean arterial pressure = diastolic + one third of pulse pressure. 80 + 13.3 = 93.3 mm Hg.
• BMI = weight (kg) ÷ height (m)². Weight 60 kg and height 1.5 m: 60 ÷ 2.25 = 26.7. Normal range is about 18.5 to 24.9; Indian guidance uses lower cut-offs for overweight.

Exam traps

• 1. Pulmonary artery carries deoxygenated blood; pulmonary vein carries oxygenated blood.
• 2. Tendon joins muscle to bone; ligament joins bone to bone.
• 3. Right lung has 3 lobes; left lung has 2.
• 4. Tricuspid valve is on the right side; bicuspid (mitral) is on the left.
• 5. Rods work in dim light; cones give colour vision.
• 6. Sympathetic raises heart rate; parasympathetic lowers it.
• 7. Femur is the longest bone; stapes is the smallest.
• 8. Insulin lowers blood sugar; glucagon raises it.

One-liners

• 1. Adult skeleton has 206 bones.
• 2. Skull has 22 bones.
• 3. There are 12 pairs of ribs.
• 4. Vertebral column has 7 cervical, 12 thoracic and 5 lumbar vertebrae.
• 5. The heart has four chambers.
• 6. Normal pulse is about 72 per minute.
• 7. Normal BP is about 120/80 mm Hg.
• 8. Red cells live for about 120 days.
• 9. Gas exchange takes place in the alveoli.
• 10. Bile is made in the liver and stored in the gall bladder.
• 11. The nephron is the functional unit of the kidney.
• 12. Pituitary is the master endocrine gland.

Practice questions

1. Night blindness is caused by lack of

   1. vitamin K
   2. vitamin D
   3. vitamin A
   4. vitamin C
   Answer

   C. vitamin A

   Vitamin A is needed for rods.

2. Which gland produces both digestive enzymes and insulin?

   1. Pituitary
   2. Thyroid
   3. Liver
   4. Pancreas
   Answer

   D. Pancreas

   It has exocrine and endocrine parts.

3. Which blood cells carry oxygen?

   1. Platelets
   2. Red blood cells
   3. Plasma cells
   4. White blood cells
   Answer

   B. Red blood cells

   Haemoglobin carries oxygen.

4. Which muscle type is involuntary and striated?

   1. Cardiac
   2. Smooth
   3. None
   4. Skeletal
   Answer

   A. Cardiac

   Cardiac muscle works without will.

5. The master gland of the endocrine system is the

   1. Pancreas
   2. Pituitary
   3. Adrenal
   4. Thyroid
   Answer

   B. Pituitary

   The pituitary controls other glands.

6. How many bones are there in the adult human skeleton?

   1. 206
   2. 250
   3. 300
   4. 180
   Answer

   A. 206

   Adult skeleton has 206 bones.

7. Statements: 1. Red blood cells live for about 120 days. 2. Platelets help in clotting. Which is correct?

   1. 1 only
   2. 2 only
   3. Both 1 and 2
   4. Neither 1 nor 2
   Answer

   C. Both 1 and 2

   Both statements are correct.

8. Where does gas exchange take place in the lungs?

   1. Trachea
   2. Larynx
   3. Bronchi
   4. Alveoli
   Answer

   D. Alveoli

   Alveoli are the exchange sacs.

9. Statements: 1. Ligaments join muscle to bone. 2. Tendons join muscle to bone. Which is correct?

   1. 1 only
   2. 2 only
   3. Both 1 and 2
   4. Neither 1 nor 2
   Answer

   B. 2 only

   Ligaments join bone to bone.

10. Statements: 1. The tricuspid valve is on the left side. 2. The mitral valve is on the left side. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    The tricuspid valve is on the right side.

11. A woman weighs 60 kg and is 1.5 m tall. Her BMI is about

    1. 20
    2. 40
    3. 26.7
    4. 30.7
    Answer

    C. 26.7

    60 ÷ 2.25 = 26.7.

12. Lack of iodine causes

    1. goitre
    2. anaemia
    3. diabetes
    4. night blindness
    Answer

    A. goitre

    Thyroid enlarges without iodine.

13. How many lobes does the left lung have?

    1. Three
    2. One
    3. Four
    4. Two
    Answer

    D. Two

    Left lung has 2 lobes; right lung has 3.

14. Statements: 1. Glucagon lowers blood sugar. 2. Parathormone raises blood calcium. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Glucagon raises blood sugar.

15. A 50 kg person has a BMI of 20. The height is

    1. 2.0 m
    2. 1.20 m
    3. 1.8 m
    4. 1.58 m
    Answer

    D. 1.58 m

    Height² = 50 ÷ 20 = 2.5; height ≈ 1.58 m.

16. How many chambers does the human heart have?

    1. Three
    2. Two
    3. Four
    4. Five
    Answer

    C. Four

    Two atria and two ventricles.

17. The valve between the left atrium and left ventricle is the

    1. Bicuspid (mitral) valve
    2. Pulmonary valve
    3. Aortic valve
    4. Tricuspid valve
    Answer

    A. Bicuspid (mitral) valve

    Left side has two flaps.

18. Pepsin acts on

    1. starch
    2. fat
    3. protein
    4. vitamins
    Answer

    C. protein

    Pepsin digests protein in the stomach.

19. Which blood group is the universal donor of red cells?

    1. A
    2. B
    3. AB
    4. O
    Answer

    D. O

    Group O red cells carry no A or B antigen.

20. Respiratory rate is 15 per minute and tidal volume 500 mL. Minute ventilation is

    1. 7,500 mL
    2. 3,000 mL
    3. 750 mL
    4. 15,000 mL
    Answer

    A. 7,500 mL

    15 × 500 = 7,500 mL.

21. The ossicles of the middle ear are

    1. Cochlea, malleus and incus
    2. Stapes, ulna and radius
    3. Atlas, axis, stapes
    4. Malleus, incus and stapes
    Answer

    D. Malleus, incus and stapes

    Three tiny bones transmit sound.

22. BP is 120/80 mm Hg. The pulse pressure is

    1. 20 mm Hg
    2. 80 mm Hg
    3. 40 mm Hg
    4. 200 mm Hg
    Answer

    C. 40 mm Hg

    120 - 80 = 40.

23. The vertebral column has how many lumbar vertebrae?

    1. Five
    2. Twelve
    3. Seven
    4. Four
    Answer

    A. Five

    7 cervical, 12 thoracic, 5 lumbar.

24. Which joint is a ball and socket joint?

    1. Neck pivot
    2. Hip
    3. Knee
    4. Elbow
    Answer

    B. Hip

    Hip and shoulder are ball and socket.

25. Statements: 1. Bile is stored in the gall bladder. 2. The liver makes bile. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both statements are correct.

26. Fertilization usually occurs in the

    1. uterus
    2. cervix
    3. vagina
    4. fallopian tube
    Answer

    D. fallopian tube

    Sperm meet the egg in the tube.

27. Which is the longest bone in the body?

    1. Femur
    2. Tibia
    3. Fibula
    4. Humerus
    Answer

    A. Femur

    The thigh bone is the longest.

28. The functional unit of the kidney is the

    1. Villus
    2. Nephron
    3. Alveolus
    4. Neuron
    Answer

    B. Nephron

    The nephron filters blood.

29. Which part of the brain controls balance and coordination?

    1. Hypothalamus
    2. Cerebellum
    3. Cerebrum
    4. Medulla
    Answer

    B. Cerebellum

    Cerebellum coordinates movement.

30. Which organ makes bile?

    1. Gall bladder
    2. Stomach
    3. Pancreas
    4. Liver
    Answer

    D. Liver

    The gall bladder only stores bile.

31. Statements: 1. The pulmonary artery carries deoxygenated blood. 2. The pulmonary vein carries oxygenated blood. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both statements are correct.

32. Which vessel carries oxygenated blood from the lungs to the heart?

    1. Pulmonary vein
    2. Aorta
    3. Vena cava
    4. Pulmonary artery
    Answer

    A. Pulmonary vein

    Pulmonary vein is an exception among veins.

33. Which part of the eye has rods and cones?

    1. Lens
    2. Retina
    3. Iris
    4. Cornea
    Answer

    B. Retina

    The retina holds the light cells.

34. Which hormone maintains pregnancy?

    1. Insulin
    2. Oxytocin
    3. Progesterone
    4. Thyroxine
    Answer

    C. Progesterone

    Progesterone supports the uterine lining.

35. Which is the smallest bone in the body?

    1. Radius
    2. Incus only
    3. Femur
    4. Stapes
    Answer

    D. Stapes

    Stapes is in the middle ear.

36. The first cervical vertebra is called the

    1. Atlas
    2. Sacrum
    3. Axis
    4. Coccyx
    Answer

    A. Atlas

    Atlas supports the skull.

37. Which hormone lowers blood glucose?

    1. Glucagon
    2. Insulin
    3. Thyroxine
    4. Adrenaline
    Answer

    B. Insulin

    Insulin comes from the pancreas.

38. Colostrum is

    1. a blood protein
    2. a hormone
    3. a fat in the skin
    4. the first milk rich in antibodies
    Answer

    D. the first milk rich in antibodies

    Colostrum protects the newborn.

39. A person has heart rate 72 per minute and stroke volume 70 mL. Cardiac output is

    1. 1,008 mL/min
    2. 50,400 mL/min
    3. 5,040 mL/min
    4. 502 mL/min
    Answer

    C. 5,040 mL/min

    72 × 70 = 5,040 mL.

40. A temperature of 38.6 °C equals what in °F?

    1. 101.5 °F
    2. 98.6 °F
    3. 86.6 °F
    4. 110 °F
    Answer

    A. 101.5 °F

    38.6 × 9/5 + 32 = 101.5.

41. BP is 120/80 mm Hg. The mean arterial pressure is about

    1. 93 mm Hg
    2. 100 mm Hg
    3. 120 mm Hg
    4. 40 mm Hg
    Answer

    A. 93 mm Hg

    80 + 40/3 = 93.3.

42. Statements: 1. Parasympathetic activity raises heart rate. 2. Sympathetic activity prepares the body for stress. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Parasympathetic lowers heart rate.

43. Statements: 1. The right lung has three lobes. 2. The left lung has three lobes. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    The left lung has two lobes.

44. Which structure connects muscle to bone?

    1. Ligament
    2. Tendon
    3. Cartilage
    4. Fascia only
    Answer

    B. Tendon

    Ligaments join bone to bone.

45. Normal adult body temperature is

    1. 40 °C
    2. 32 °C
    3. 35 °C
    4. 37 °C
    Answer

    D. 37 °C

    37 °C equals 98.6 °F.