HESI A2 quick reference
HESI A2 Cheat Sheet
Everything worth committing to memory for the HESI A2, on one page. Use it in the final fortnight, once you already understand the material and only need the recall to be automatic.
Last updated August 2026
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The HESI A2 is a closed-book exam. No reference material may be taken into the testing room. This sheet is for study beforehand, nothing else.
Mathematics formulas
Conversions
- 1 kg = 2.2 lb
- 1 inch = 2.54 cm
- 1 L = 1000 mL; 1 g = 1000 mg
- 1 tsp = 5 mL; 1 tbsp = 15 mL; 1 oz ≈ 30 mL
- °F = (°C × 9/5) + 32; °C = (°F − 32) × 5/9
Working
- Dosage = (desired dose / stock dose) × volume
- Percentage change = (new − old) / old × 100
- Ratio and proportion: cross-multiply, then solve
- Mean = sum / count; median = middle value; mode = most frequent
- Order of operations: brackets, indices, division and multiplication, addition and subtraction
Anatomy and physiology facts
Cardiovascular
- Right atrium receives deoxygenated blood from the body
- Left ventricle has the thickest wall
- The pulmonary artery is the only artery carrying deoxygenated blood
- Sinoatrial node is the natural pacemaker; normal rate 60 to 100 bpm
- Capillaries are where gas and nutrient exchange happens
Respiratory
- Path: nose, pharynx, larynx, trachea, bronchi, bronchioles, alveoli
- Gas exchange occurs in the alveoli by diffusion
- The diaphragm contracts to draw air in
- Tidal volume is a normal breath, roughly 500 mL
- Most carbon dioxide is transported as bicarbonate
Nervous and endocrine
- Central nervous system is brain and spinal cord
- Depolarisation is sodium in; repolarisation is potassium out
- Insulin lowers glucose, glucagon raises it
- Thyroid hormones set metabolic rate, regulated by TSH
- The pituitary is the master gland
Digestive, renal and other
- Most absorption happens in the small intestine
- The liver makes bile; the gallbladder stores it
- The nephron is the functional unit of the kidney
- Skin is the largest organ
- Osteoblasts build bone, osteoclasts break it down
Biology facts
- Mitochondria produce ATP; ribosomes build proteins.
- Mitosis produces two identical cells; meiosis produces four with half the chromosomes.
- DNA pairs A with T and C with G. RNA replaces thymine with uracil.
- Dominant alleles are expressed when present; recessive only when both are.
- Macromolecules: carbohydrates for energy, lipids for storage and membranes, proteins for structure and enzymes, nucleic acids for information.
- pH below 7 is acidic, above 7 is basic, 7 is neutral.
Grammar and vocabulary rules
- Subject and verb must agree in number, however many words separate them.
- Affect is usually the verb, effect usually the noun.
- Its shows possession; it is is the only thing "it's" ever means.
- A comma goes before and, but or or when it joins two complete sentences.
- A semicolon joins two complete related sentences without a conjunction.
- Prefixes carry meaning: brady is slow, tachy is fast, hyper is above, hypo is below.
Rapid review
| Which chamber pumps blood to the body? | Left ventricle. |
|---|---|
| Where does gas exchange occur? | Alveoli of the lungs. |
| Which hormone lowers blood glucose? | Insulin. |
| Pacemaker of the heart? | Sinoatrial node. |
| Functional unit of the kidney? | Nephron. |
| How many mL in a teaspoon? | Five. |
| Convert 154 lb to kg. | 70 kg (divide by 2.2). |
| Organelle that produces ATP? | Mitochondrion. |
| Which base replaces thymine in RNA? | Uracil. |
| Affect or effect: "the drug will ___ her heart rate"? | Affect. |
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HESI Math
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