The human body is an extraordinarily complex biological system. It is made from trillions of cells organized into tissues, organs, and organ systems that constantly work together to keep a person alive.

An important point must be made before attempting to list the body’s parts. There is no scientifically accepted fixed number of “body parts” or even a universally agreed total number of organs. An anatomist can describe the body at many different levels: organs, bones, muscles, arteries, veins, nerves, lymph vessels, glands, ligaments, tendons, tissues, cells, microscopic structures, and subdivisions within each organ. Thousands of individual anatomical structures have been formally named.

For that reason, claiming that a short article contains literally every anatomical structure would be misleading. This article instead provides a comprehensive macroscopic overview of the human body, including all major organ systems and organs, major anatomical structures, important muscles and nerves, and the standard complete list of the 206 bones of the adult human skeleton.

Standard anatomy textbooks commonly organize the human body into 11 organ systems: integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic/immune, respiratory, digestive, urinary, and reproductive systems (Betts et al., 2022; Ernstmeyer & Christman, 2024).

The 11 Major Organ Systems at a Glance

Organ System	Main Parts and Organs	Main Function
Integumentary	Skin, hair, nails, sweat glands, sebaceous glands	Protects the body and helps regulate temperature
Skeletal	Bones, cartilage, joints, ligaments	Supports the body, protects organs, stores minerals, assists movement
Muscular	Skeletal muscles and tendons	Produces movement, maintains posture, generates heat
Nervous	Brain, spinal cord, nerves, sensory organs	Controls and coordinates body functions
Endocrine	Pituitary, thyroid, parathyroids, adrenal glands, pancreatic islets, ovaries, testes	Regulates body functions using hormones
Cardiovascular	Heart, blood, arteries, veins, capillaries	Transports oxygen, nutrients, hormones, heat, and wastes
Lymphatic/Immune	Lymph vessels, lymph nodes, spleen, thymus, bone marrow	Supports immunity and returns tissue fluid to the bloodstream
Respiratory	Nose, pharynx, larynx, trachea, bronchi, lungs	Exchanges oxygen and carbon dioxide
Digestive	Mouth, esophagus, stomach, intestines, liver, gallbladder, pancreas	Digests food and absorbs nutrients
Urinary	Kidneys, ureters, bladder, urethra	Removes wastes and regulates fluids and electrolytes
Reproductive	Male and female reproductive organs	Produces sex cells and hormones and supports reproduction

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How the Human Body Is Organized

Human anatomy can be understood through several levels of organization.

Level	Description
Chemical	Atoms such as carbon, oxygen, hydrogen, calcium, sodium, and nitrogen combine to form molecules
Cellular	Molecules form cells, the smallest independently functioning units of the body
Tissue	Similar cells work together to perform particular functions
Organ	Two or more tissue types combine to form recognizable structures
Organ system	Multiple organs cooperate to perform larger physiological functions
Organism	All organ systems work together to form the complete human being

The four basic tissue types are:

Tissue Type	Main Role	Examples
Epithelial tissue	Covers surfaces, lines cavities, forms glands	Skin surface, intestinal lining
Connective tissue	Supports, connects, stores, transports, protects	Bone, cartilage, fat, blood, tendons
Muscle tissue	Contracts to produce movement	Skeletal, cardiac, smooth muscle
Nervous tissue	Receives and transmits signals	Brain, spinal cord, nerves

(Betts et al., 2022)

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Major External Parts of the Human Body

Head and Face

Major structures include:

• Scalp
• Forehead
• Temples
• Skull
• Face
• Eyebrows
• Eyelids
• Eyelashes
• Eyes
• Ears
• Nose
• Nostrils
• Cheeks
• Mouth
• Lips
• Teeth
• Gums
• Tongue
• Upper jaw
• Lower jaw
• Chin

The head contains the brain and most of the body’s major special sensory organs.

Neck

The neck connects the head to the trunk and contains:

• Cervical vertebrae
• Spinal cord
• Pharynx
• Larynx
• Trachea
• Esophagus
• Thyroid gland
• Parathyroid glands
• Major arteries
• Major veins
• Nerves
• Muscles
• Lymph nodes

Trunk

The trunk includes:

• Chest or thorax
• Breasts
• Abdomen
• Navel or umbilicus
• Pelvis
• Groin
• Perineum
• Back
• Lower back
• Buttocks

The trunk contains most of the major internal organs.

Upper Limbs

Each upper limb includes:

• Shoulder
• Armpit or axilla
• Upper arm
• Elbow
• Forearm
• Wrist
• Hand
• Palm
• Back of the hand
• Thumb
• Index finger
• Middle finger
• Ring finger
• Little finger

Lower Limbs

Each lower limb includes:

• Hip
• Thigh
• Knee
• Leg
• Calf
• Shin
• Ankle
• Heel
• Foot
• Sole
• Great toe
• Second toe
• Third toe
• Fourth toe
• Fifth toe

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1. The Integumentary System

The integumentary system forms the body’s external covering.

Part	Main Function
Skin	Protects the body, limits water loss, helps regulate temperature
Hair	Contributes to protection, sensation, and temperature regulation
Nails	Protect the ends of fingers and toes and assist fine manipulation
Sweat glands	Produce sweat and help regulate body temperature
Sebaceous glands	Produce sebum that lubricates skin and hair
Skin sensory receptors	Detect touch, pressure, temperature, and pain

Skin

The skin is the body’s largest organ by surface area and mass.

Main Layers

Layer	Important Features
Epidermis	Outer epithelial layer containing keratinocytes, melanocytes, Langerhans cells, and Merkel cells
Dermis	Contains collagen, elastic fibers, blood vessels, nerves, sensory receptors, follicles, and glands
Hypodermis	Subcutaneous connective tissue containing fat; associated with the skin but not usually considered a true skin layer

The integumentary system provides a protective barrier and contains numerous sensory receptors (Betts et al., 2022).

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2. The Skeletal System

The skeletal system:

• Supports the body
• Protects internal organs
• Stores minerals
• Produces blood cells in bone marrow
• Works with muscles to produce movement

A typical adult human skeleton contains 206 bones. Children have more because several bones fuse during growth (Betts et al., 2022).

The skeleton is divided into:

Division	Number of Bones
Axial skeleton	80
Appendicular skeleton	126
Total	206

Complete Standard List of the 206 Adult Bones

Axial Skeleton

Region	Bones	Number
Cranial bones	Frontal, parietal ×2, temporal ×2, occipital, sphenoid, ethmoid	8
Facial bones	Maxillae ×2, zygomatic ×2, nasal ×2, lacrimal ×2, palatine ×2, inferior nasal conchae ×2, vomer, mandible	14
Auditory ossicles	Malleus ×2, incus ×2, stapes ×2	6
Hyoid	Hyoid bone	1
Cervical vertebrae	C1–C7	7
Thoracic vertebrae	T1–T12	12
Lumbar vertebrae	L1–L5	5
Sacrum	Fused sacral vertebrae	1
Coccyx	Fused coccygeal vertebrae	1
Ribs	12 pairs	24
Sternum	Manubrium, body, and xiphoid process forming one adult bone	1
Axial total		80

The stapes is the smallest bone in the human body.

Appendicular Skeleton

Region	Bones	Number
Shoulder girdle	Clavicles ×2, scapulae ×2	4
Upper arms	Humeri ×2	2
Forearms	Radii ×2, ulnae ×2	4
Wrists	8 carpals per hand	16
Hands	5 metacarpals per hand	10
Fingers	14 phalanges per hand	28
Pelvic girdle	2 hip bones	2
Thighs	Femora ×2	2
Knees	Patellae ×2	2
Legs	Tibiae ×2, fibulae ×2	4
Ankles/rear feet	7 tarsals per foot	14
Feet	5 metatarsals per foot	10
Toes	14 phalanges per foot	28
Appendicular total		126

The Eight Carpal Bones in Each Wrist

Carpal Bones
Scaphoid
Lunate
Triquetrum
Pisiform
Trapezium
Trapezoid
Capitate
Hamate

The Seven Tarsal Bones in Each Foot

Tarsal Bones
Talus
Calcaneus
Navicular
Cuboid
Medial cuneiform
Intermediate cuneiform
Lateral cuneiform

The femur is the longest and strongest bone in the human body.

Anatomical variation occurs. Some people have additional sesamoid or accessory bones, so 206 represents the standard adult anatomical count rather than an absolute number for every person (Betts et al., 2022; Standring, 2021).

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Joints, Cartilage, Ligaments, and Tendons

Structure	Main Function
Joint	Connection between bones that may allow movement
Cartilage	Supports structures, reduces friction, absorbs mechanical forces
Ligament	Primarily connects bone to bone and stabilizes joints
Tendon	Primarily connects muscle to bone and transmits muscle force

Main Joint Types

• Fibrous joints
• Cartilaginous joints
• Synovial joints

Important joints include the:

• Skull sutures
• Temporomandibular joint
• Atlanto-occipital joints
• Atlantoaxial joints
• Shoulder joints
• Elbow joints
• Radioulnar joints
• Wrist joints
• Finger joints
• Sacroiliac joints
• Pubic symphysis
• Hip joints
• Knee joints
• Tibiofibular joints
• Ankle joints
• Foot and toe joints

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3. The Muscular System

Human muscle tissue exists in three basic forms.

Type	Main Characteristics
Skeletal muscle	Usually voluntary; moves the skeleton
Cardiac muscle	Found in the heart; contracts automatically
Smooth muscle	Found in organs and blood vessels; generally involuntary

There are hundreds of named skeletal muscles. The precise number varies depending on anatomical classification, subdivisions, and normal variation, so claims that humans have one exact universal number of muscles should be treated cautiously.

Major Skeletal Muscles

Body Region	Important Muscles
Face and head	Occipitofrontalis, orbicularis oculi, orbicularis oris, buccinator, zygomaticus major and minor, nasalis, mentalis, risorius, masseter, temporalis, medial and lateral pterygoids
Eye movement	Superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique, inferior oblique, levator palpebrae superioris
Tongue	Genioglossus, hyoglossus, styloglossus, palatoglossus, intrinsic tongue muscles
Neck	Sternocleidomastoid, scalenes, platysma, splenius capitis, splenius cervicis, suprahyoid and infrahyoid muscles
Back	Trapezius, latissimus dorsi, rhomboids, levator scapulae, erector spinae, multifidus, semispinalis, rotatores
Chest	Pectoralis major, pectoralis minor, serratus anterior, intercostals, diaphragm
Abdomen	Rectus abdominis, external oblique, internal oblique, transversus abdominis, quadratus lumborum
Shoulder	Deltoid, supraspinatus, infraspinatus, teres minor, subscapularis, teres major
Upper arm	Biceps brachii, brachialis, coracobrachialis, triceps brachii, anconeus
Forearm	Pronators, supinator, wrist flexors/extensors, finger flexors/extensors, thumb muscles
Hand	Thenar muscles, hypothenar muscles, lumbricals, palmar interossei, dorsal interossei, adductor pollicis
Hip and buttock	Gluteus maximus, medius and minimus, tensor fasciae latae, iliacus, psoas major, piriformis, obturators, gemelli, quadratus femoris
Thigh	Quadriceps, hamstrings, sartorius, gracilis, pectineus, adductors
Lower leg	Tibialis anterior/posterior, gastrocnemius, soleus, plantaris, popliteus, fibularis muscles, toe flexors/extensors

Quadriceps Muscles

• Rectus femoris
• Vastus lateralis
• Vastus medialis
• Vastus intermedius

Hamstring Muscles

• Biceps femoris
• Semitendinosus
• Semimembranosus

Rotator Cuff Muscles

• Supraspinatus
• Infraspinatus
• Teres minor
• Subscapularis

Skeletal muscles generate movement by contracting and pulling on tendons and bones. They also contribute to posture, joint stability, breathing, facial expression, swallowing, speech, and temperature regulation (Betts et al., 2022).

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4. The Nervous System

The nervous system allows the body to:

• Sense the environment
• Process information
• Control muscles
• Regulate internal organs
• Produce thought
• Form memories
• Coordinate behavior and movement

It consists of:

Division	Main Components
Central nervous system	Brain and spinal cord
Peripheral nervous system	Nerves and ganglia outside the brain and spinal cord

Major Parts of the Brain

Structure	Major Functions
Cerebrum	Thought, movement, sensation, language, memory, decision-making
Frontal lobe	Planning, voluntary movement, aspects of personality and language
Parietal lobe	Processes bodily sensation and spatial information
Temporal lobe	Hearing, memory, language-related functions
Occipital lobe	Vision
Insula	Sensory, emotional, autonomic, and integrative functions
Basal nuclei	Movement regulation and other neural functions
Thalamus	Major relay center for sensory and motor information
Hypothalamus	Temperature, hunger, thirst, hormones, autonomic control
Midbrain	Eye movement, motor and sensory functions
Pons	Communication, breathing regulation, sleep-related functions
Medulla oblongata	Breathing, cardiovascular regulation, vital reflexes
Cerebellum	Coordination, balance, posture, motor learning

Protective Structures of the Central Nervous System

• Skull
• Vertebral column
• Dura mater
• Arachnoid mater
• Pia mater
• Cerebrospinal fluid

The 12 Cranial Nerves

No.	Cranial Nerve	Major Role
I	Olfactory	Smell
II	Optic	Vision
III	Oculomotor	Most eye movements and pupil control
IV	Trochlear	Eye movement
V	Trigeminal	Facial sensation and chewing
VI	Abducens	Eye movement
VII	Facial	Facial expression, taste, glandular functions
VIII	Vestibulocochlear	Hearing and balance
IX	Glossopharyngeal	Taste, swallowing, sensory and autonomic functions
X	Vagus	Swallowing, voice, parasympathetic control of many organs
XI	Accessory	Neck and shoulder movement
XII	Hypoglossal	Tongue movement

Spinal Nerves

There are 31 pairs of spinal nerves.

Region	Number of Pairs
Cervical	8
Thoracic	12
Lumbar	5
Sacral	5
Coccygeal	1
Total	31

Important peripheral nerves include:

• Phrenic nerve
• Axillary nerve
• Musculocutaneous nerve
• Median nerve
• Ulnar nerve
• Radial nerve
• Femoral nerve
• Obturator nerve
• Sciatic nerve
• Tibial nerve
• Common fibular nerve

Major nerve plexuses include:

• Cervical plexus
• Brachial plexus
• Lumbar plexus
• Sacral plexus

Autonomic Nervous System

The autonomic nervous system regulates many involuntary body functions.

Its major divisions are:

• Sympathetic nervous system
• Parasympathetic nervous system

The gastrointestinal tract also contains the extensive enteric nervous system.

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The Sensory Organs

Eyes

Structure	Main Role
Cornea	Helps focus incoming light
Iris	Controls pupil size
Pupil	Opening through which light enters
Lens	Fine-tunes focus
Retina	Contains photoreceptors that detect light
Macula and fovea	Important for detailed central vision
Optic nerve	Carries visual signals toward the brain
Lacrimal glands	Produce tears
Aqueous humor	Fluid in the front of the eye
Vitreous body	Gel filling much of the eye

Other important structures include:

• Eyebrows
• Eyelids
• Eyelashes
• Conjunctiva
• Sclera
• Choroid
• Ciliary body
• Optic disc

Ears

Region	Structures	Main Function
External ear	Auricle, external acoustic canal	Collects and directs sound
Middle ear	Tympanic membrane, malleus, incus, stapes, auditory tube	Transfers sound vibrations
Inner ear	Cochlea, vestibule, semicircular canals	Hearing and balance

Smell

Smell involves:

• Nasal cavity
• Olfactory epithelium
• Olfactory nerve
• Olfactory bulb
• Central olfactory pathways

Taste

Taste depends mainly on taste receptor cells located within taste buds associated with the tongue and oral cavity.

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5. The Endocrine System

The endocrine system uses hormones to regulate:

• Growth
• Metabolism
• Stress responses
• Blood glucose
• Water balance
• Reproduction
• Sexual development
• Calcium balance

Major Endocrine Structures

Structure	Important Hormones/Functions
Hypothalamus	Regulates pituitary function and links nervous and endocrine systems
Pituitary gland	Influences growth, reproduction, adrenal function, thyroid activity, lactation, and water balance
Pineal gland	Produces melatonin and helps regulate circadian rhythms
Thyroid gland	Produces thyroid hormones and calcitonin
Parathyroid glands	Produce parathyroid hormone and regulate calcium
Adrenal cortex	Produces cortisol, aldosterone, and adrenal androgens
Adrenal medulla	Produces epinephrine and norepinephrine
Pancreatic islets	Produce insulin, glucagon, somatostatin, and other hormones
Ovaries	Produce estrogen, progesterone, and other hormones
Testes	Produce testosterone and other hormones

Other organs, including the heart, kidneys, gastrointestinal tract, liver, adipose tissue, and placenta during pregnancy, also produce hormones.

This illustrates why organs cannot always be assigned exclusively to one system.

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6. The Cardiovascular System

The cardiovascular system transports:

• Oxygen
• Carbon dioxide
• Nutrients
• Hormones
• Metabolic waste
• Immune cells
• Heat

Its main components are:

• Heart
• Blood
• Blood vessels

Heart

Structure	Function
Right atrium	Receives blood returning from the body
Right ventricle	Pumps blood toward the lungs
Left atrium	Receives oxygenated blood from the lungs
Left ventricle	Pumps oxygenated blood to the body
Tricuspid valve	Controls flow between right atrium and right ventricle
Pulmonary valve	Controls flow from right ventricle into pulmonary trunk
Mitral valve	Controls flow between left atrium and left ventricle
Aortic valve	Controls flow from left ventricle into aorta

Heart Wall

• Endocardium
• Myocardium
• Epicardium

The heart is enclosed within the pericardium.

Electrical Conduction System

• Sinoatrial node
• Atrioventricular node
• Atrioventricular bundle
• Right and left bundle branches
• Purkinje fibers

These structures help coordinate the heartbeat.

Blood Vessels

Vessel Type	Main Function
Arteries	Carry blood away from the heart
Arterioles	Regulate blood flow into capillaries
Capillaries	Permit exchange between blood and tissues
Venules	Collect blood from capillaries
Veins	Return blood toward the heart

Major named vessels include:

• Aorta
• Pulmonary trunk
• Pulmonary arteries
• Pulmonary veins
• Superior vena cava
• Inferior vena cava
• Coronary arteries
• Coronary veins
• Common carotid arteries
• Internal and external carotid arteries
• Subclavian arteries
• Axillary arteries
• Brachial arteries
• Radial arteries
• Ulnar arteries
• Celiac trunk
• Superior mesenteric artery
• Renal arteries
• Inferior mesenteric artery
• Common iliac arteries
• Internal iliac arteries
• External iliac arteries
• Femoral arteries
• Popliteal arteries
• Tibial arteries

Blood

Component	Function
Plasma	Liquid carrying proteins, electrolytes, nutrients, hormones, and wastes
Red blood cells	Transport oxygen mainly through hemoglobin
White blood cells	Participate in immune defense
Platelets	Contribute to clotting and vessel repair

Major White Blood Cell Types

• Neutrophils
• Lymphocytes
• Monocytes
• Eosinophils
• Basophils

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7. The Lymphatic and Immune System

The lymphatic system helps:

• Return excess tissue fluid to the bloodstream
• Absorb certain dietary fats
• Support immune defense

Major Structures

Structure	Main Role
Lymph	Fluid transported through lymphatic vessels
Lymphatic capillaries	Collect excess tissue fluid
Lymphatic vessels	Transport lymph
Lymph nodes	Filter lymph and support immune responses
Spleen	Filters blood and supports immune functions
Thymus	Important in T-lymphocyte development
Bone marrow	Produces blood and immune cells
Thoracic duct	Major lymphatic drainage channel
Right lymphatic duct	Drains lymph from part of the upper body
Intestinal lacteals	Absorb dietary fats
Mucosa-associated lymphoid tissue	Supports immune protection at mucosal surfaces

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8. The Respiratory System

The respiratory system brings oxygen into the body and removes carbon dioxide.

Major Structures

Structure	Main Function
Nose and nasal cavity	Filter, warm, and humidify air
Paranasal sinuses	Contribute to air conditioning and voice resonance
Pharynx	Passageway for air
Larynx	Protects airway and produces voice
Epiglottis	Helps protect the airway during swallowing
Trachea	Conducts air toward the lungs
Bronchi	Carry air into the lungs
Bronchioles	Distribute air within the lungs
Alveoli	Sites of gas exchange
Lungs	Main organs of respiration
Pleura	Membranes surrounding the lungs

Lung Lobes

Lung	Lobes
Right lung	Superior, middle, inferior
Left lung	Superior, inferior

The left lung has less volume partly because of the position of the heart.

Alveoli

Alveoli are microscopic air sacs where gases move between air and blood.

• Oxygen moves from the alveoli into the blood.
• Carbon dioxide moves from the blood into the alveoli for exhalation.

Main Breathing Muscles

• Diaphragm
• External intercostals
• Internal intercostals
• Accessory respiratory muscles during increased breathing effort

The respiratory system also contributes to:

• Acid-base regulation
• Speech
• Smell
• Air filtration
• Warming and humidifying inspired air

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9. The Digestive System

The digestive system breaks food down into components that can be absorbed and used by the body.

Major Digestive Organs

Organ/Structure	Main Function
Mouth	Receives food and begins mechanical and chemical digestion
Teeth	Cut, tear, and grind food
Tongue	Manipulates food and participates in taste and swallowing
Salivary glands	Produce saliva
Pharynx	Participates in swallowing
Esophagus	Carries swallowed material to the stomach
Stomach	Stores and mixes food and begins major protein digestion
Small intestine	Major site of digestion and nutrient absorption
Large intestine	Absorbs water and electrolytes and forms feces
Liver	Processes nutrients, produces bile, stores glycogen, metabolizes substances
Gallbladder	Stores and concentrates bile
Pancreas	Produces digestive enzymes and bicarbonate; also produces hormones
Rectum	Stores feces before elimination
Anus	Controls expulsion of feces

Adult Permanent Teeth

A typical adult may have up to 32 permanent teeth.

Tooth Type	Number
Incisors	8
Canines	4
Premolars	8
Molars	12
Maximum typical total	32

Not every adult has all 32 because of developmental variation, missing teeth, or extraction.

Major Salivary Glands

• Parotid glands
• Submandibular glands
• Sublingual glands

Numerous minor salivary glands are also present.

Stomach Regions

• Cardia
• Fundus
• Body
• Pyloric region

Small Intestine

Part	Position
Duodenum	First section
Jejunum	Middle section
Ileum	Final section

Large Intestine

• Cecum
• Vermiform appendix
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon
• Rectum
• Anal canal
• Anus

Liver Functions

The liver:

• Processes nutrients
• Produces bile
• Metabolizes drugs and toxins
• Produces many plasma proteins
• Stores glycogen
• Helps regulate blood glucose
• Processes bilirubin
• Participates in lipid metabolism

Peritoneum and Related Structures

• Parietal peritoneum
• Visceral peritoneum
• Mesenteries
• Greater omentum
• Lesser omentum

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10. The Urinary System

The urinary system regulates body fluids and removes many metabolic wastes.

Main Organs

Organ	Main Function
Kidneys	Filter blood and regulate fluid, electrolytes, and acid-base balance
Ureters	Transport urine to the bladder
Urinary bladder	Stores urine
Urethra	Carries urine outside the body

Kidney Structures

• Renal capsule
• Renal cortex
• Renal medulla
• Renal pyramids
• Renal columns
• Minor calyces
• Major calyces
• Renal pelvis
• Renal artery
• Renal vein
• Ureter

Nephron

The nephron is the microscopic functional unit of the kidney.

Nephron Part	General Role
Glomerulus	Filters blood plasma
Glomerular or Bowman’s capsule	Receives filtrate
Proximal convoluted tubule	Reabsorbs large amounts of useful substances and water
Nephron loop	Important in concentrating urine
Distal convoluted tubule	Fine-tunes electrolyte and acid-base regulation
Collecting duct	Receives tubular fluid and contributes to final urine concentration

The kidneys also:

• Remove many wastes
• Regulate water
• Regulate electrolytes
• Contribute to acid-base balance
• Help regulate blood pressure
• Produce erythropoietin
• Participate in vitamin D activation

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11. The Reproductive System

The reproductive system produces sex cells and hormones and makes human reproduction possible.

Male Reproductive System

Structure	Main Function
Testes	Produce sperm and testosterone
Scrotum	Houses the testes and helps regulate their temperature
Epididymides	Support sperm maturation and storage
Vas deferens	Transports sperm
Ejaculatory ducts	Carry semen toward the urethra
Seminal vesicles	Produce fluid contributing to semen
Prostate gland	Produces secretions that contribute to semen
Bulbourethral glands	Produce lubricating secretions
Urethra	Carries urine and semen at different times
Penis	Contains erectile tissue and provides an external passage for urine and semen
Spermatic cords	Contain vessels, nerves, and the vas deferens associated with each testis

Female Reproductive System

Structure	Main Function
Ovaries	Produce oocytes and hormones
Uterine tubes	Transport the oocyte; usual site of fertilization
Uterus	Supports pregnancy and fetal development
Cervix	Lower portion of the uterus opening into the vagina
Vagina	Muscular canal between cervix and exterior
Vulva	Collective term for external female genital structures
Clitoris	Erectile sensory organ
Labia majora	Outer folds of the vulva
Labia minora	Inner folds of the vulva
Greater vestibular glands	Produce lubricating secretions
Paraurethral glands	Small glands near the urethra
Mammary glands	Produce milk after childbirth under appropriate hormonal control

Uterine Tube Regions

• Infundibulum
• Ampulla
• Isthmus
• Intramural or uterine portion

Uterus

Major regions:

• Fundus
• Body
• Cervix

Main wall layers:

• Endometrium
• Myometrium
• Perimetrium

Placenta

The placenta is a temporary organ that develops during pregnancy. It enables exchange of gases, nutrients, wastes, and signaling substances between maternal and fetal circulations while the blood itself normally remains in separate vascular systems.

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Other Important Structures That Belong to More Than One System

Structure	Importance
Fascia	Surrounds and connects muscles, vessels, nerves, and organs
Adipose tissue	Stores energy, insulates, cushions, and produces signaling molecules
Bone marrow	Produces blood cells and contributes to immune function
Mucous membranes	Line parts of the respiratory, digestive, urinary, and reproductive tracts
Serous membranes	Reduce friction around organs
Tendons	Transfer muscle force to bones
Ligaments	Stabilize joints
Cartilage	Supports structures and reduces joint friction
Bursae	Reduce friction between moving tissues
Menisci	Fibrocartilage structures that help distribute forces in certain joints
Intervertebral discs	Cushion and connect adjacent vertebral bodies

Major Serous Membranes

• Pleura around the lungs
• Pericardium around the heart
• Peritoneum associated with abdominal and pelvic organs

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How All the Body Systems Work Together

The body’s organ systems do not work independently.

For example, when you run:

System	What It Does
Nervous system	Sends signals that initiate and coordinate movement
Muscular system	Contracts to create movement
Skeletal system	Provides leverage and structural support
Respiratory system	Increases oxygen intake and carbon dioxide removal
Cardiovascular system	Delivers oxygen and nutrients to working tissues
Endocrine system	Adjusts metabolism and energy availability
Urinary system	Helps regulate fluid and electrolyte balance
Integumentary system	Produces sweat and helps release excess heat

The body’s ability to keep its internal environment within suitable limits is called homeostasis.

Important examples include regulation of:

• Body temperature
• Blood glucose
• Blood pressure
• Blood oxygen
• Carbon dioxide
• Blood pH
• Water
• Sodium
• Potassium
• Calcium

The nervous and endocrine systems are particularly important in coordinating these processes, but virtually every organ system contributes to maintaining life (Hall & Hall, 2021).

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So, How Many Organs Does the Human Body Have?

You may encounter online claims that humans have exactly 78, 79, or another specific number of organs.

Such claims can be misleading.

There is no universally authoritative fixed organ count because the answer depends on what is classified as a separate organ.

Questions that affect the count include:

• Are each of the hundreds of lymph nodes counted individually?
• Are bones counted as individual organs?
• Are individual teeth counted?
• Are paired structures counted separately?
• Are tendons considered organs?
• Is the placenta included during pregnancy?
• Should subdivisions of larger organs be counted separately?

Modern anatomy therefore focuses more on accurately defining structures than on assigning the body one definitive organ number. Organs can also contribute to more than one organ system (Betts et al., 2022).

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Can Anyone Truly List Every Single Part of the Human Body in One Article?

Not realistically.

A literally complete anatomical inventory would have to include:

• 206 standard adult bones
• Hundreds of skeletal muscles
• Every muscle attachment
• Every joint
• Every ligament
• Every tendon
• Every bursa
• Every artery
• Every arterial branch
• Every vein
• Every venous tributary
• Every cranial nerve
• Every spinal nerve
• Every peripheral nerve branch
• Every autonomic ganglion
• Every lymph node group
• Every lymphatic vessel
• Every gland
• Every layer of every organ
• Every named brain nucleus and tract
• Every microscopic kidney structure
• Every microscopic lung structure
• Every gastrointestinal gland
• Every recognized cell type
• Every tissue subdivision
• Numerous developmental and anatomical variants

That level of detail fills professional anatomical atlases and textbooks containing thousands of pages.

Gray’s Anatomy, for example, is one of the major comprehensive professional references for human anatomy and covers body regions, cells, tissues, development, nerves, vascular structures, organ anatomy, and numerous other structures (Standring, 2021).

Therefore, it would be scientifically inaccurate for a short online article to claim that it has named literally every structure in the human body.

This article instead provides a broad but detailed map of the principal structures of the human body and explains how its major organs and systems function.

Conclusion

The human body is not simply a collection of separate organs. It is an interconnected biological system.

System/Structure	Major Role
Skin	Protects the body
Skeleton	Supports the body and protects organs
Muscles	Produce movement
Brain, spinal cord, and nerves	Control and coordinate activity
Endocrine glands	Communicate through hormones
Heart and blood vessels	Circulate blood
Lymphatic and immune systems	Support defense and fluid balance
Lungs	Exchange oxygen and carbon dioxide
Digestive system	Breaks down food and absorbs nutrients
Kidneys and urinary tract	Regulate fluids and remove wastes
Reproductive system	Makes human reproduction possible

None of these systems works completely alone.

Human survival depends on continuous communication and cooperation between cells, tissues, organs, and organ systems.

Understanding this interconnectedness is one of the most important principles of human anatomy and physiology.

Medical and Educational Disclaimer

This article is intended for general educational purposes only. It is not a substitute for an anatomy textbook, medical education, diagnosis, treatment, or professional medical advice. Anatomical structures and physiology can vary among individuals because of age, sex characteristics, development, genetics, surgery, disease, and normal anatomical variation.

Readers who require detailed medical or anatomical information should consult qualified health professionals and recognized anatomy and physiology references.

References

Betts, J. G., Young, K. A., Wise, J. A., Johnson, E., Poe, B., Kruse, D. H., Korol, O., Johnson, J. E., Womble, M., & DeSaix, P. (2022). Anatomy and physiology 2e. OpenStax, Rice University. https://openstax.org/details/books/anatomy-and-physiology-2e

Dalley, A. F., II, & Agur, A. M. R. (2023). Moore’s clinically oriented anatomy (9th ed.). Wolters Kluwer.

Ernstmeyer, K., & Christman, E. (Eds.). (2024). Medical terminology (2nd ed.). Chippewa Valley Technical College. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK607445/

Hall, J. E., & Hall, M. E. (2021). Guyton and Hall textbook of medical physiology (14th ed.). Elsevier.

National Library of Medicine. (n.d.). Anatomy. MedlinePlus. https://medlineplus.gov/anatomy.html

Standring, S. (Ed.). (2021). Gray’s anatomy: The anatomical basis of clinical practice (42nd ed.). Elsevier.