Anatomy & physiology · Study guide
Anatomy and physiology study guide
The first-exam material of an anatomy and physiology course on one page: the 11 organ systems with their organs and jobs, the levels of organization, homeostasis, body position and direction terms, a study plan, flashcards and 25 practice questions with every answer explained. Free, and for study only.
- 11 organ systems
- 38 flashcards
- 25 practice questions
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1 · Organ systems
The 11 organ systems
Each system, the organs the textbook lists for it, and what it does. Every system gets its own chapter later in the course; this is the map.
Integumentary
Organs: Skin, hair, nails
Does: Encloses the internal body structures and holds many of the body’s sensory receptors.
Skeletal
Organs: Bones, joints, cartilage
Does: Supports the body and, together with the muscular system, makes movement possible.
Muscular
Organs: Skeletal muscles, tendons
Does: Moves the body with the skeletal system, and helps keep body temperature steady.
Nervous
Organs: Brain, spinal cord, peripheral nerves
Does: Detects and processes sensory information and triggers the body’s responses.
Endocrine
Organs: Pituitary gland, thyroid gland, pancreas, adrenal glands, testes, ovaries
Does: Secretes hormones and regulates body processes.
Cardiovascular
Organs: Heart, blood vessels
Does: Delivers oxygen and nutrients to the tissues and evens out temperature across the body.
Lymphatic
Organs: Thymus, spleen, lymph nodes, lymphatic vessels
Does: Returns fluid to the blood and defends the body against pathogens.
Respiratory
Organs: Nasal passages, trachea, lungs
Does: Removes carbon dioxide from the body and delivers oxygen to the blood.
Digestive
Organs: Stomach, liver, gallbladder, small intestine, large intestine
Does: Processes food for the body to use and removes the waste left from undigested food.
Urinary
Organs: Kidneys, urinary bladder
Does: Controls the body’s water balance and removes wastes from the blood and excretes them.
Reproductive
Organs: Testes and epididymis; ovaries, uterus, mammary glands
Does: Produces sex hormones and gametes (sperm and eggs); the female system supports a developing fetus until birth and produces milk.
Quick answers
- How many bones are in the body?
206 in an adult
80 in the axial skeleton (the skull, the vertebral column and the thoracic cage of ribs and sternum, plus the hyoid and the ear ossicles) and 126 in the appendicular skeleton (the limbs and the bones that attach them to the trunk). Younger people have more, because some bones fuse during childhood and adolescence. The skull alone has 22 bones. (ch. 7.1)
- What is the largest organ in the body?
The skin
Two layers, the epidermis and the dermis, over a fatty third layer, the hypodermis. The skin with its hair and nails makes up the integumentary system. (ch. 5.1; NCI SEER)
- Where are the lymph nodes?
Along the lymphatic vessels, in clusters near the neck, armpits, groin, chest and abdomen
Small, bean-shaped organs, about 500 to 600 of them, that filter debris and pathogens out of lymph on its way back to the blood. In regional terms the clusters sit in the cervical (neck), axillary (armpit) and inguinal (groin) regions. (ch. 21.1, 1.6)
- What is normal body temperature?
About 37 °C (98.6 °F)
The set point the body’s temperature control loop works around; it dips and rises a little through the day, and feedback loops pull it back. (ch. 1.5)
2 · Levels of organization
From atoms to a person
Six levels, each built from the one below it. Exam questions ask for the order and for the definition of each step.
Chemical
Atoms and the molecules they form.
For example: Water, glucose, a protein
Cellular
The cell: the smallest unit of a living organism that functions on its own.
For example: A muscle cell, a neuron
Tissue
A group of many similar cells working together on one function.
For example: Cardiac muscle tissue
Organ
An anatomically distinct structure built from two or more tissue types.
For example: The heart, the stomach
Organ system
A group of organs that work together on a major function of the body.
For example: The cardiovascular system
Organism
The whole living being, all of its systems working together.
For example: A person
At the tissue level there are only four types: epithelial, connective, muscle, nervous. Every tissue in the body is one of them (ch. 4.1).
3 · Homeostasis
Homeostasis and feedback loops
Homeostasis is the body keeping its internal conditions within a normal range. Each range centers on a set point, and a feedback loop pulls a value back when it drifts.
Step 1
Sensor (or receptor)
Monitors a value, such as temperature or blood glucose, and reports it to the control center.
Step 2
Control center
Compares the value with its normal range and, if it has drifted too far, switches on an effector.
Step 3
Effector
Causes a change that reverses the drift and returns the value to its normal range.
Negative feedback · reverses the change
Body temperature
- The set point is about 37 °C (98.6 °F).
- Too warm: the brain’s heat-loss center responds. Blood vessels in the skin widen, sweat glands put out more sweat and breathing deepens, so the body loses heat.
- Too cold: the brain’s heat-gain center responds. Blood flow to the skin drops, shivering can start, and thyroid hormone and epinephrine raise heat production.
Negative feedback · reverses the change
Blood glucose
- After a meal, endocrine cells in the pancreas detect the extra glucose in the blood.
- Beta cells in the pancreas release insulin, which signals muscle, fat and liver cells to take glucose in, so the blood level falls.
- As the level comes back down, insulin release stops.
Positive feedback · strengthens the change
Childbirth
- Positive feedback strengthens a change instead of reversing it, and runs until an outside event ends it.
- Stretching of the cervix triggers the release of oxytocin, which makes the uterine muscle contract harder, which stretches the cervix more, which releases more oxytocin, until the baby is born.
Positive feedback · strengthens the change
Blood clotting
- Each step of clotting triggers the release of more clotting substances, so a damaged vessel is sealed quickly.
For study only. These are the textbook loops, written to explain the idea, not advice about anyone’s health.
4 · Position, direction, planes and cavities
The language of the body
Short on purpose: the terms you need to read every other chapter. Anatomical position comes first, because every direction word is defined from it.
Anatomical position
Standing upright, feet parallel and shoulder-width apart, toes forward, arms at the sides with the palms facing forward. Every direction term below is defined from this pose, whatever position the body is actually in. Prone is lying face down; supine is lying face up.
Directional terms
| Term | Means | Example |
|---|---|---|
| Anterioror ventral | Toward the front of the bodyThe sternum is anterior to the heart. | The sternum is anterior to the heart. |
| Posterioror dorsal | Toward the back of the bodyThe vertebral column is posterior to the heart. | The vertebral column is posterior to the heart. |
| Superioror cranial | Above; toward the headThe chest is superior to the abdomen. | The chest is superior to the abdomen. |
| Inferioror caudal | Below; toward the feet (the tail end)The pelvis is inferior to the abdomen. | The pelvis is inferior to the abdomen. |
| Medial | Toward the midline of the bodyThe big toe is the medial toe. | The big toe is the medial toe. |
| Lateral | Away from the midline, toward the sideThe ears are lateral to the nose. | The ears are lateral to the nose. |
| Proximal | Closer to the trunk or to where a limb attachesThe upper arm is proximal to the forearm. | The upper arm is proximal to the forearm. |
| Distal | Farther from the trunk or from where a limb attachesThe fingers are distal to the wrist. | The fingers are distal to the wrist. |
| Superficial | Closer to the surface of the bodyThe skin is superficial to the bones. | The skin is superficial to the bones. |
| Deep | Farther from the surface of the bodyThe brain is deep to the skull. | The brain is deep to the skull. |
Planes
Sagittal
A vertical plane that divides the body into right and left parts. The midsagittal (median) plane runs down the exact middle, making equal halves; a parasagittal plane is off-center and makes unequal parts.
Frontal (or coronal)
A vertical plane that divides the body into anterior (front) and posterior (back) portions.
Transverse (or horizontal)
A horizontal plane that divides the body into upper and lower portions; a cut along it is a cross section.
Oblique
A cut at an angle to the three main planes, rather than along any of them.
Body cavities
- Dorsal (posterior) cavityThe brain and spinal cord, in two parts.
- Cranial cavityThe brain.
- Spinal (vertebral) cavityThe spinal cord.
- Ventral (anterior) cavityThe organs of the chest, abdomen and pelvis, in two parts separated by the diaphragm.
- Thoracic cavityThe lungs and heart, enclosed by the rib cage; the diaphragm is its floor.
- Pleural cavities (two)One around each lung.
- Pericardial cavityAround the heart, inside the mediastinum, the central region of the chest.
- Abdominopelvic cavityThe largest body cavity; no membrane divides its two parts.
- Abdominal cavityThe digestive organs.
- Pelvic cavityThe reproductive organs.
Serous membranes, regions and quadrants
- Pleura around each lung
- Pericardium around the heart
- Peritoneum around the abdominopelvic organs
Each serous membrane has two layers: the parietal layer lines the wall of the cavity and the visceral layer covers the organ. Both secrete a slippery serous fluid, so the organ moves against the wall without friction.
The abdominopelvic cavity is mapped two ways: nine regions (right and left hypochondriac, epigastric, right and left lumbar, umbilical, right and left iliac, hypogastric) for detail, or four quadrants (right upper, left upper, right lower, left lower), the simpler scheme used more often in clinical settings.
5 · Study plan
A study plan for the course
Courses usually spread the textbook’s six units over one or two terms. Map the units onto your syllabus, then keep the weekly habits below; they are the whole method.
Before the course starts
Learn the language first
- Memorize the direction terms, the planes and the cavities on this page: every chapter after this one is written in them.
- Learn the 11 systems with two or three organs each. You will meet each system again in its own chapter; a first pass now makes that chapter a review.
- Pick up the common word parts (cardi/o, hepat/o, -itis, -ectomy). A medical-terms decoder is linked at the end of this page.
Every week
Read ahead, write cards, retrieve
- Skim the assigned section before the lecture, so the lecture is your second pass, not your first.
- The same day, turn the lecture into flashcards in your own words: one structure or one function per card, never a paragraph.
- Study from the cards, not the notes: say the answer out loud before you flip. Twenty-five to forty minutes a day, most days, holds better than one long weekend session.
- Draw and label a structure from memory, then compare with the book. The gaps are your list for tomorrow.
- Teach one topic back to a classmate, a friend or an empty room. If you cannot explain it, you do not have it yet.
Lab days
Name it from every angle
- Use the direction terms out loud when you point at a model: “the left atrium is posterior to the right ventricle”.
- Turn each model or slide and name the structures again from the new view; exams rarely show the textbook angle.
- Keep a one-line note per structure: what it is, where it sits, and one thing it does.
Three days before each exam
Three passes, then sleep
- Day 3: go through every card for the unit and set aside the ones you miss. Re-read only the sections those cards came from.
- Day 2: practice questions, and for each one say why the other choices are wrong. Rework your missed cards once more.
- Day 1: a one-page summary from memory (the printable guide on this page is a model), a short card review, and a full night’s sleep.
The six units of the textbook
Unit 1
Chapters 1 to 4
Levels of organization
The language of the body (this page), chemistry, the cell, the four tissue types.
Unit 2
Chapters 5 to 11
Support and movement
Skin, bone tissue, the axial and appendicular skeletons, joints, muscle tissue, the muscular system.
Unit 3
Chapters 12 to 17
Regulation, integration and control
Nervous tissue, the brain and spinal cord, the somatic and autonomic systems, the neurological exam, the endocrine system.
Unit 4
Chapters 18 to 21
Fluids and transport
Blood, the heart, blood vessels and circulation, the lymphatic and immune systems.
Unit 5
Chapters 22 to 26
Energy, maintenance and environmental exchange
Respiratory, digestive, metabolism and nutrition, urinary, fluid and electrolyte balance.
Unit 6
Chapters 27 and 28
Human development and the continuity of life
The reproductive systems, development and inheritance.
6 · Flashcards
38 anatomy and physiology flashcards
The organ systems, the direction terms, planes, cavities, homeostasis and the key numbers. Tap a card (or press Enter) to flip it, use the arrows or the left and right keys to move, and shuffle when the order starts to feel familiar.
Card 1 of 38, Organ systems. Prompt: Integumentary system: organs and job.
See all 38 cards as a list
- Integumentary system: organs and jobSkin, hair, nails. Encloses the internal body structures and holds many of the body’s sensory receptors.
- Skeletal system: organs and jobBones, joints, cartilage. Supports the body and, together with the muscular system, makes movement possible.
- Muscular system: organs and jobSkeletal muscles, tendons. Moves the body with the skeletal system, and helps keep body temperature steady.
- Nervous system: organs and jobBrain, spinal cord, peripheral nerves. Detects and processes sensory information and triggers the body’s responses.
- Endocrine system: organs and jobPituitary gland, thyroid gland, pancreas, adrenal glands, testes, ovaries. Secretes hormones and regulates body processes.
- Cardiovascular system: organs and jobHeart, blood vessels. Delivers oxygen and nutrients to the tissues and evens out temperature across the body.
- Lymphatic system: organs and jobThymus, spleen, lymph nodes, lymphatic vessels. Returns fluid to the blood and defends the body against pathogens.
- Respiratory system: organs and jobNasal passages, trachea, lungs. Removes carbon dioxide from the body and delivers oxygen to the blood.
- Digestive system: organs and jobStomach, liver, gallbladder, small intestine, large intestine. Processes food for the body to use and removes the waste left from undigested food.
- Urinary system: organs and jobKidneys, urinary bladder. Controls the body’s water balance and removes wastes from the blood and excretes them.
- Reproductive system: organs and jobTestes and epididymis; ovaries, uterus, mammary glands. Produces sex hormones and gametes (sperm and eggs); the female system supports a developing fetus until birth and produces milk.
- Levels of organization, smallest to largestChemical, cellular, tissue, organ, organ system, organism
- The four tissue typesEpithelial, connective, muscle, nervous
- Sensor (receptor)Monitors a value and reports it to the control center
- Control centerCompares the value with its normal range and switches on an effector when it drifts
- EffectorCauses the change that reverses the drift and returns the value to its range
- Negative vs positive feedbackNegative reverses a change (temperature, blood glucose); positive strengthens it until an outside event ends it (childbirth, clotting)
- Anterior (ventral)Toward the front of the body. The sternum is anterior to the heart.
- Posterior (dorsal)Toward the back of the body. The vertebral column is posterior to the heart.
- Superior (cranial)Above; toward the head. The chest is superior to the abdomen.
- Inferior (caudal)Below; toward the feet (the tail end). The pelvis is inferior to the abdomen.
- MedialToward the midline of the body. The big toe is the medial toe.
- LateralAway from the midline, toward the side. The ears are lateral to the nose.
- ProximalCloser to the trunk or to where a limb attaches. The upper arm is proximal to the forearm.
- DistalFarther from the trunk or from where a limb attaches. The fingers are distal to the wrist.
- SuperficialCloser to the surface of the body. The skin is superficial to the bones.
- DeepFarther from the surface of the body. The brain is deep to the skull.
- Sagittal planeVertical; right and left parts. Midsagittal = equal halves down the middle; parasagittal = off-center
- Frontal (coronal) planeVertical; anterior (front) and posterior (back) portions
- Transverse planeHorizontal; upper and lower portions (a cross section)
- Dorsal (posterior) cavityCranial cavity (brain) and spinal cavity (spinal cord)
- Thoracic cavityLungs (in two pleural cavities) and heart (pericardial cavity, inside the mediastinum); floor = the diaphragm
- Abdominopelvic cavityAbdominal cavity (digestive organs) and pelvic cavity (reproductive organs); the largest body cavity
- Parietal vs visceral layerParietal lines the cavity wall; visceral covers the organ; serous fluid between them cuts friction
- Bones in the adult skeleton206: 80 axial (skull, vertebral column, thoracic cage) + 126 appendicular (limbs and their girdles)
- Largest organThe skin: epidermis and dermis over the fatty hypodermis
- Lymph nodesAbout 500 to 600 bean-shaped filters along the lymphatic vessels; clusters in the neck, armpits, groin, chest and abdomen
- Normal body temperatureAbout 37 °C (98.6 °F), the set point of the temperature loop
7 · Practice questions
25 practice questions
The organ systems, the levels, homeostasis, position and direction, planes, cavities and the bone count, multiple choice, one at a time. Every answer is explained, and your score is free: no sign-up needed.
Question 1 of 25
Which organ system is made up of the skin, hair and nails?
Bonus · unlocks with your email
The printable one-page study guide and 40 more questions
- A one-page study guide you can print: all 11 organ systems with their organs and jobs, the six levels, the feedback loop with its examples, the ten direction terms, the planes, the cavities and the key numbers (206 bones, the largest organ, the lymph nodes, 37 °C), on one sheet for the first exam.
- 40 more practice questions, every answer explained: position and direction, planes and cavities, the skeleton, the skin, the lymphatic system and the feedback loops.
Enter your email in the box above and the bonus opens right here, and stays open on this browser.
More free study tools
Next on the same shelf
Sources
Where the facts come from
Every fact on this page is reworded from one of these public sources; the chapter number sits next to each fact. Check anything important against your course materials.
- OpenStax, Anatomy and Physiology 2e: 1.1 Overview of Anatomy and Physiology
- OpenStax, Anatomy and Physiology 2e: 1.2 Structural Organization of the Human Body (the 11 organ systems)
- OpenStax, Anatomy and Physiology 2e: 1.5 Homeostasis
- OpenStax, Anatomy and Physiology 2e: 1.6 Anatomical Terminology
- OpenStax, Anatomy and Physiology 2e: 4.1 Types of Tissues
- OpenStax, Anatomy and Physiology 2e: 5.1 Layers of the Skin
- OpenStax, Anatomy and Physiology 2e: 7.1 Divisions of the Skeletal System
- OpenStax, Anatomy and Physiology 2e: 21.1 Anatomy of the Lymphatic and Immune Systems
- OpenStax, Anatomy and Physiology 2e: table of contents (the six units in the study plan)
- NCI SEER Training Modules: Anatomy of the Skin
Questions
Common questions
Integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary and reproductive. Part 1 of this page lists the organs and the main job of each, in the wording of a free open college textbook.
The body keeping its internal conditions, such as temperature and blood glucose, within a normal range. Each range centers on a set point. A negative feedback loop (sensor, control center, effector) reverses a drift away from it; a positive feedback loop, as in childbirth and blood clotting, strengthens a change until an outside event ends it.
An adult has 206: 80 in the axial skeleton (the skull, vertebral column and thoracic cage, with the hyoid and the ear ossicles) and 126 in the appendicular skeleton (the limbs and the bones that attach them). Children have more, because some bones fuse as they grow.
The skin. It has two layers, the epidermis and the dermis, over a fatty third layer, the hypodermis, and with the hair and nails it makes up the integumentary system.
Along the lymphatic vessels throughout the body, about 500 to 600 of them, with clusters near the neck, the armpits, the groin, the chest and the abdomen. They filter debris and pathogens out of lymph on its way back to the blood.
Anatomy is the study of the body’s structures; physiology is the study of how those structures work, their chemistry and physics. Gross anatomy covers what is visible without magnification, microscopic anatomy what needs a microscope; regional anatomy studies everything in one region, systemic anatomy follows one system through the body.
No. This is a study aid for people in anatomy and physiology prerequisite courses and healthcare programs. It describes textbook structure and function; it does not diagnose, treat or say anything about any person’s health. Your textbook and your instructor come first.
The whole guide, the flashcards and the 25 practice questions with your score are free with no sign-up. An email unlocks the bonus: the printable one-page study guide and 40 more questions.