HESI A2 Anatomy and Physiology Study Guide: Key Topics

The HESI A2 Anatomy and Physiology section assesses your understanding of basic anatomical structures, terminology, and body-system functions. Because schools choose which HESI A2 sections applicants must complete, confirm your program’s requirements before building your study plan.

If your program requires anatomy and physiology, focus on understanding how structures and functions connect. Memorizing isolated terms can help, but you should also be prepared to apply those terms to questions about relationships within the human body.

How to study for HESI A2 Anatomy and Physiology

Instead of trying to reread an entire anatomy textbook, divide the material into manageable topics. Study one body system at a time, practice retrieving the information without your notes, and use practice questions to identify weak areas.

Important areas to review include:

• Body planes and directional terminology
• Skeletal and muscular anatomy
• Blood flow through the heart
• Immune and lymphatic function
• Endocrine glands and hormones
• Nervous-system organization
• Special senses
• Reproductive anatomy and cell division

1. Body planes

Body planes provide reference points for describing anatomical locations and movements. The three primary planes are:

• Sagittal plane: Divides the body into right and left portions. The midsagittal plane divides the body into equal right and left halves.
• Frontal or coronal plane: Divides the body into anterior and posterior portions.
• Transverse or horizontal plane: Divides the body into superior and inferior portions.

Practice visualizing each plane and identifying how a structure or movement would appear within it.

2. Anatomical positions and directional terms

Directional terms describe where one structure is located relative to another:

• Superior: Above or toward the head
• Inferior: Below or toward the feet
• Anterior or ventral: Toward the front of the body
• Posterior or dorsal: Toward the back of the body
• Medial: Toward the body’s midline
• Lateral: Away from the body’s midline
• Proximal: Closer to the point of attachment or origin
• Distal: Farther from the point of attachment or origin
• Superficial: Closer to the body’s surface
• Deep: Farther from the body’s surface

For example, the trachea is anterior to the esophagus, the nose is medial to the eyes, and the fingers are distal to the wrist.

3. The skeletal system

The skeletal system supports the body, protects internal organs, stores minerals, produces blood cells, and works with muscles to create movement.

Important bone cells include:

• Osteogenic cells: Stem cells that can develop into osteoblasts
• Osteoblasts: Cells that build new bone matrix
• Osteocytes: Mature bone cells that maintain bone tissue
• Osteoclasts: Cells that break down bone tissue

Central, or Haversian, canals run through osteons in compact bone and contain blood vessels and nerves.

You should also recognize major bones and common joint types:

• Skull: Frontal, parietal, temporal, and occipital bones
• Shoulder and chest: Clavicle, scapula, sternum, and ribs
• Arm: Humerus, radius, and ulna
• Leg: Femur, patella, tibia, and fibula
• Hand and foot: Carpals, metacarpals, tarsals, metatarsals, and phalanges
• Ball-and-socket joints: Shoulder and hip
• Hinge joints: Elbow and knee

4. The muscular system

The body contains three types of muscle tissue:

• Skeletal muscle: Voluntary muscle attached primarily to bones
• Cardiac muscle: Involuntary muscle found in the heart
• Smooth muscle: Involuntary muscle found in structures such as blood vessels and digestive organs

Skeletal muscles have three connective-tissue layers:

• Epimysium: Surrounds the entire muscle
• Perimysium: Surrounds bundles of muscle fibers called fascicles
• Endomysium: Surrounds individual muscle fibers

Review the location and primary actions of major muscles, including the deltoid, pectoralis major, biceps, triceps, quadriceps, hamstrings, gastrocnemius, and abdominal muscles.

5. The cardiovascular system

The cardiovascular system circulates blood through the heart, lungs, and body. You should understand the chambers, valves, major vessels, and direction of blood flow.

Follow this sequence:

1. Deoxygenated blood enters the right atrium through the superior and inferior venae cavae.
2. Blood passes through the tricuspid valve into the right ventricle.
3. The right ventricle pumps blood through the pulmonary valve and pulmonary arteries to the lungs.
4. Oxygenated blood returns through the pulmonary veins to the left atrium.
5. Blood passes through the mitral, or bicuspid, valve into the left ventricle.
6. The left ventricle pumps blood through the aortic valve and into the aorta for systemic circulation.

Remember that arteries carry blood away from the heart, while veins carry blood toward the heart. Pulmonary arteries carry deoxygenated blood, and pulmonary veins carry oxygenated blood.

The heart wall has three layers:

• Epicardium: The outer layer of the heart wall
• Myocardium: The muscular middle layer responsible for contraction
• Endocardium: The inner lining of the chambers and valves

6. The immune and lymphatic systems

The lymphatic system returns excess tissue fluid to the bloodstream, absorbs certain dietary fats, and supports immune defenses. Lymph nodes filter lymph and contain immune cells that respond to pathogens.

Important cells and structures include:

• B lymphocytes: Mature in the bone marrow and can develop into antibody-producing plasma cells
• T lymphocytes: Originate in the bone marrow and mature in the thymus
• Neutrophils: Abundant white blood cells that respond rapidly to infection
• Eosinophils: White blood cells involved in allergic responses and defense against parasites
• Basophils: White blood cells that release inflammatory mediators
• Platelets or thrombocytes: Cell fragments that help form blood clots
• Thymus: An organ involved in T-cell maturation
• Spleen: An organ that filters blood and supports immune responses

7. The endocrine system

The endocrine system uses hormones to regulate processes such as metabolism, growth, reproduction, fluid balance, and the stress response.

Review the major glands, the hormones associated with them, and each hormone’s primary function:

• Pituitary gland: Releases hormones that regulate growth, reproduction, lactation, and other endocrine glands
• Thyroid gland: Produces hormones involved in metabolism and growth
• Parathyroid glands: Produce parathyroid hormone, which helps regulate blood calcium
• Adrenal glands: Produce hormones involved in stress responses, blood pressure, and electrolyte balance
• Pancreas: Produces insulin and glucagon to help regulate blood glucose
• Pineal gland: Produces melatonin, which helps regulate circadian rhythms
• Ovaries: Produce hormones such as estrogen and progesterone
• Testes: Produce testosterone

Key hormones include:

• Antidiuretic hormone: Produced in the hypothalamus and released from the posterior pituitary; increases water reabsorption by the kidneys
• Oxytocin: Produced in the hypothalamus and released from the posterior pituitary; stimulates uterine contractions and milk ejection
• Follicle-stimulating hormone: Released from the anterior pituitary and involved in gamete production
• Luteinizing hormone: Released from the anterior pituitary and involved in ovulation and reproductive hormone production
• Prolactin: Released from the anterior pituitary and stimulates milk production
• Aldosterone: Produced by the adrenal cortex and increases sodium reabsorption

8. The nervous system

The nervous system receives sensory information, processes it, and coordinates responses throughout the body.

It has two major divisions:

• Central nervous system: The brain and spinal cord
• Peripheral nervous system: Nerves outside the brain and spinal cord

The peripheral nervous system includes the somatic and autonomic systems. The autonomic nervous system is further divided into:

• Sympathetic division: Supports the “fight-or-flight” response
• Parasympathetic division: Supports the “rest-and-digest” response

Important nervous-system structures include:

• Cerebrum: Supports conscious thought, sensory processing, memory, and voluntary movement
• Cerebellum: Coordinates movement, posture, and balance
• Medulla oblongata: Helps regulate involuntary functions such as breathing, heart rate, and blood pressure
• Olfactory nerve: Carries sensory information related to smell
• Optic nerve: Carries visual information from the retina
• Vagus nerve: Provides major parasympathetic innervation to thoracic and abdominal organs

9. The special senses

Hearing and equilibrium

• The tympanic membrane vibrates in response to sound.
• The auditory ossicles transmit vibrations through the middle ear.
• The cochlea converts vibrations into nerve impulses for hearing.
• The semicircular canals detect rotational movement and support balance.

Vision

• Retina: Contains photoreceptors that respond to light
• Rods: Support vision in dim light
• Cones: Support color vision and visual detail in brighter light
• Iris: Controls pupil size
• Vitreous humor: Gel-like substance that fills the posterior portion of the eye
• Fovea centralis: Area of the retina with a high concentration of cones and the sharpest visual acuity

Smell

Olfactory receptors detect airborne chemicals in the nasal cavity. Sensory information then travels through the olfactory nerve to the brain.

10. The reproductive system and cell division

Review the primary reproductive organs, hormones, fertilization, and the basic stages of cell division.

• Ovaries: Produce oocytes and hormones such as estrogen and progesterone
• Uterine tubes: Transport the oocyte toward the uterus and are the usual site of fertilization
• Testes: Produce sperm and testosterone
• Fertilization: The union of sperm and oocyte
• Zygote: The diploid cell formed through fertilization

The stages of mitosis are:

1. Prophase: Chromosomes condense, and the mitotic spindle begins to form.
2. Metaphase: Chromosomes align near the middle of the cell.
3. Anaphase: Sister chromatids separate and move toward opposite poles.
4. Telophase: New nuclear envelopes form around the separated chromosomes.
5. Cytokinesis: The cytoplasm divides, creating two daughter cells.

Human somatic cells normally contain 46 chromosomes. Gametes—sperm and oocytes—contain 23 chromosomes.

Build a stronger HESI A2 study plan

Use active recall instead of relying only on rereading. Close your notes and try to draw the path of blood through the heart, label a body plane, match hormones to glands, or explain a body system aloud.

Practice questions can help you determine whether you recognize a term and whether you can apply it. When you answer incorrectly, review the explanation and return to that topic later. Spacing your practice across multiple study sessions will help strengthen long-term retention.

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